The first year of excavations in 85-foot-deep Natural Trap Cave, Wyoming, is now a wrap, but challenges remain, such as going through customs with masses of dirty bones from dead creatures.
Alan Cooper, co-leader of the excavation, caught up with Discovery News this week after emerging from the cave, where many hundreds of mammals fell to their deaths over the past 100,000 years. Thanks to sturdy caving ropes, he wasn’t one of them.
Cooper, who is director of the Australian Center for Ancient DNA, is now visiting various museums, so he left the bone samples extracted from the cave with colleague and fellow researcher Laura Weyrich. She just met one of the biggest challenges: getting the samples through Australian Quarantine and Inspection Service.
“Australian Quarantine folks are very energetic people,” Cooper said, explaining that they are usually not very familiar with the permit process that allows scientists like him to bring such materials into the country.
Weyrich had to take the bone samples — packed surrounded by ice to keep them refrigerator cold — directly into the Ancient DNA Lab. She could not go anywhere else with them. That’s because the lab, Cooper explained, is specially rated to be able to handle such materials.
As for all countries, Australia is concerned about bringing in items like seeds, bacteria and viruses. (Seeds could contain bacteria and might belong to invasive plants, for example.)
With the samples back at the lab, the next steps are to analyze them for DNA and stable isotopes. They are also being dated using radiocarbon methods. The goal is to construct a picture of how animal populations adapted and responded to past climate change and major extinction events.
The researchers have quite a cast of characters to work with, considering all of the animals that fell into the cave.
"The range of species we recovered, especially carnivores such as the American lion and cheetah-like cat, are remarkable,” Julie Meachen of Des Moines University, who is the other co-leader of the excavation, said in a press release. "The condition of the bones varies a lot, as you'd expect -- but some of it is definitely DNA-containing, which is great after 30–50,000 years."
Both she and Cooper said that, in addition to the lion and cheetah-like cat, the other bone samples come from Pleistocene-age mammal species that are now extinct in North America. These include the giant camel, several horse species, wolf, bison, mountain sheep, as well as many small mammals and birds.
Read more at Discovery News
Aug 14, 2014
Ancient Butterfly-Headed Flying Reptile Discovered
An ancient flying reptile with a bizarre, butterflylike head has been unearthed in Brazil.
The newfound reptile species, Caiuajara dobruskii, lived about 80 million years ago in an ancient desert oasis. The beast sported a strange bony crest on its head that looked like the wings of a butterfly, and had the wingspan needed to take flight at a very young age.
Hundreds of fossils from the reptile were unearthed in a single bone bed, providing the strongest evidence yet that the flying reptiles were social animals, said study co-author Alexander Kellner, a paleontologist at the Museu Nacional/Universidade Federal do Rio de Janeiro in Brazil.
Though pterosaur fossils have been unearthed in northern Brazil, no one knew of pterosaurs fossils in the southern part of the country. In the 1970s, a farmer named Dobruski and his son discovered a massive Cretaceous Period bone bed in Cruzeiro do Oeste in southern Brazil, a region not known for any fossils, Kellner said. The find was forgotten for decades, and then rediscovered just two years ago. The team dubbed the reptile Caiuajara dobruskii, after the geologic formation, called the Caiuá Group, where it was found, as well as the farmer who discovered the species, Kellner said.
C. dobruskii belonged to a group of winged reptiles known as pterosaurs, which are more commonly known as pterodactyls.
Hundreds of bone fragments from the species were crammed in an area of just 215 square feet (20 square meters). At least 47 individuals — and possibly hundreds more — were buried at the site. All but a few were juveniles, though the researchers found everything from youngsters with wingspans of just 2.1 feet (0.65 m) long to adults with wingspans reaching 7.71 feet (2.35 m). The fossils weren't crushed, so the 3D structure of the animals was preserved, the authors wrote in a research article published today (Aug. 13) in the journal PLOS ONE.
The ancient reptiles' bony crests changed in size and orientation as the pterosaurs grew.
Because the adult skeletal size (other than the head) wasn't much different from the juveniles', the researchers hypothesized that C. dobruskii was fairly precocious and could fly at a young age, Kellner said.
Based on the sediments in which the bones were found, the area was once a vast desert with a central oasis nestled between the sand dunes, the authors wrote in the paper.
Ancient C. dobruskii colonies may have lived around the lake for long periods of time and died during periods of drought or during storms. As the creatures died, the occasional desert storm would wash their remains into the lake, where the watery burial preserved them indefinitely, the researchers said. Another possibility is that the pterosaurs stopped at this spot during ancient migrations, though the authors suspect that is less likely.
Read more at Discovery News
The newfound reptile species, Caiuajara dobruskii, lived about 80 million years ago in an ancient desert oasis. The beast sported a strange bony crest on its head that looked like the wings of a butterfly, and had the wingspan needed to take flight at a very young age.
Hundreds of fossils from the reptile were unearthed in a single bone bed, providing the strongest evidence yet that the flying reptiles were social animals, said study co-author Alexander Kellner, a paleontologist at the Museu Nacional/Universidade Federal do Rio de Janeiro in Brazil.
Though pterosaur fossils have been unearthed in northern Brazil, no one knew of pterosaurs fossils in the southern part of the country. In the 1970s, a farmer named Dobruski and his son discovered a massive Cretaceous Period bone bed in Cruzeiro do Oeste in southern Brazil, a region not known for any fossils, Kellner said. The find was forgotten for decades, and then rediscovered just two years ago. The team dubbed the reptile Caiuajara dobruskii, after the geologic formation, called the Caiuá Group, where it was found, as well as the farmer who discovered the species, Kellner said.
C. dobruskii belonged to a group of winged reptiles known as pterosaurs, which are more commonly known as pterodactyls.
Hundreds of bone fragments from the species were crammed in an area of just 215 square feet (20 square meters). At least 47 individuals — and possibly hundreds more — were buried at the site. All but a few were juveniles, though the researchers found everything from youngsters with wingspans of just 2.1 feet (0.65 m) long to adults with wingspans reaching 7.71 feet (2.35 m). The fossils weren't crushed, so the 3D structure of the animals was preserved, the authors wrote in a research article published today (Aug. 13) in the journal PLOS ONE.
The ancient reptiles' bony crests changed in size and orientation as the pterosaurs grew.
Because the adult skeletal size (other than the head) wasn't much different from the juveniles', the researchers hypothesized that C. dobruskii was fairly precocious and could fly at a young age, Kellner said.
Based on the sediments in which the bones were found, the area was once a vast desert with a central oasis nestled between the sand dunes, the authors wrote in the paper.
Ancient C. dobruskii colonies may have lived around the lake for long periods of time and died during periods of drought or during storms. As the creatures died, the occasional desert storm would wash their remains into the lake, where the watery burial preserved them indefinitely, the researchers said. Another possibility is that the pterosaurs stopped at this spot during ancient migrations, though the authors suspect that is less likely.
Read more at Discovery News
New Plant Language Discovered
People tend to be fixated upon the question of whether talking to your plants stimulates them to grow, but scientists have known for several decades that various plant species talk among themselves — not with words, but by releasing chemical signals into the air that warn other trees about impending insect attacks. Most of the nearly 50 studies on the subject have found evidence of plant communication.
Add to that proof a study in the Aug. 15 issue of the journal Science by a Virginia Tech researcher, who has discovered that different plant species can share genetic information at the molecular level.
Jim Westwood, a professor of plant pathology, physiology, and weed science at the university, found evidence of this new communication mode by investigating the relationship between dodder, a parasitic plant that oddly looks like strands of spaghetti, and the flowering plant Arabidopsis and tomato plants to which it attaches and sucks out nutrients with an appendage called a haustorium.
Several past studies have indicated that dodder use chemical cues to find their host plants. But Westwood has uncovered a genetic means of communication as well — an exchange of RNA, a substance that translates information in the DNA forming an organism’s genetic blueprint. He reports that many thousands of mRNA molecules were being exchanged between the parasite and host, creating this open dialogue between the species that allows them to freely communicate.
“The discovery of this novel form of inter-organism communication shows that this is happening a lot more than any one has previously realized,” the scientist said in a Virginia Tech press release. “Now that we have found that they are sharing all this information, the next question is, ‘What exactly are they telling each other?’”
Read more at Discovery News
Add to that proof a study in the Aug. 15 issue of the journal Science by a Virginia Tech researcher, who has discovered that different plant species can share genetic information at the molecular level.
Jim Westwood, a professor of plant pathology, physiology, and weed science at the university, found evidence of this new communication mode by investigating the relationship between dodder, a parasitic plant that oddly looks like strands of spaghetti, and the flowering plant Arabidopsis and tomato plants to which it attaches and sucks out nutrients with an appendage called a haustorium.
Several past studies have indicated that dodder use chemical cues to find their host plants. But Westwood has uncovered a genetic means of communication as well — an exchange of RNA, a substance that translates information in the DNA forming an organism’s genetic blueprint. He reports that many thousands of mRNA molecules were being exchanged between the parasite and host, creating this open dialogue between the species that allows them to freely communicate.
“The discovery of this novel form of inter-organism communication shows that this is happening a lot more than any one has previously realized,” the scientist said in a Virginia Tech press release. “Now that we have found that they are sharing all this information, the next question is, ‘What exactly are they telling each other?’”
Read more at Discovery News
Interstellar Dust Discovered Inside NASA Spacecraft
Thanks to a massive effort by 30,716 volunteers, scientists have pinpointed what appear to be seven precious specks of dust from outside the solar system, each bearing unique stories of exploded stars, cold interstellar clouds and other past cosmic lives.
The Herculean effort began eight years ago after NASA’s Stardust robotic probe flew by Earth to deposit a capsule containing samples from a comet and dust grains from what scientists hoped would be interstellar space. The spacecraft was outfitted with panels containing a smoke-like substance called aerogel that could trap and preserve fast-moving particles.
Stardust twice put itself into position to fish for interstellar grains, which are so small that a trillion of them would fit in a teaspoon. The only way scientists back on Earth would be able to find them was by the microscopic trails the grains made as they plowed into the aerogel.
“When we did the math we realized it would take us decades to do the search ourselves,” physicist Andrew Westphal, with the University of California, Berkeley, told Discovery News.
The team used an automated microscope to scan the collector and put out a call for volunteers.
"This whole approach was treated with pretty justifiable criticism by people in my community. They said, ‘How can you trust total strangers to take on this project?’" Westphal said.
"We really didn’t know how else to do it. We still don’t," he added.
Recruits were trained and had to pass a test before they were given digital scans to peruse. Scientists sometimes inserted images with known trails just to see if the volunteers, known as “dusters,” would spot them.
"We were very pleased to see that people are really good at finding these tracks, even really, really difficult things to find," Westphal said.
More than 50 candidate dust motes turned out to be bits of the spacecraft itself, but scientists found seven specks that bear chemical signs of interstellar origin and travel.
The grains are surprisingly diverse in shape, size and chemical composition. The larger ones, for example, have a fluffy, snowflake-like structure.
Read more at Discovery News
The Herculean effort began eight years ago after NASA’s Stardust robotic probe flew by Earth to deposit a capsule containing samples from a comet and dust grains from what scientists hoped would be interstellar space. The spacecraft was outfitted with panels containing a smoke-like substance called aerogel that could trap and preserve fast-moving particles.
Stardust twice put itself into position to fish for interstellar grains, which are so small that a trillion of them would fit in a teaspoon. The only way scientists back on Earth would be able to find them was by the microscopic trails the grains made as they plowed into the aerogel.
“When we did the math we realized it would take us decades to do the search ourselves,” physicist Andrew Westphal, with the University of California, Berkeley, told Discovery News.
The team used an automated microscope to scan the collector and put out a call for volunteers.
"This whole approach was treated with pretty justifiable criticism by people in my community. They said, ‘How can you trust total strangers to take on this project?’" Westphal said.
"We really didn’t know how else to do it. We still don’t," he added.
Recruits were trained and had to pass a test before they were given digital scans to peruse. Scientists sometimes inserted images with known trails just to see if the volunteers, known as “dusters,” would spot them.
"We were very pleased to see that people are really good at finding these tracks, even really, really difficult things to find," Westphal said.
More than 50 candidate dust motes turned out to be bits of the spacecraft itself, but scientists found seven specks that bear chemical signs of interstellar origin and travel.
The grains are surprisingly diverse in shape, size and chemical composition. The larger ones, for example, have a fluffy, snowflake-like structure.
Read more at Discovery News
Aug 13, 2014
Mummy-Making Began Long Before Pharaohs
The ancient Egyptians began mummifying bodies as far back as 6,000 years ago, analysis of Late Neolithic and Chalcolithic funerary wrappings has revealed.
The finding predates the origins of mummification in ancient Egypt by 1,500 years, indicating that resin-soaked textiles used in the prehistoric period (c. 4500 – 3350 B.C.) are the true antecedents of Egyptian mummification.
Experts have long assumed that in the 5th and 4th millennia B.C. preservation of soft tissues was due to natural processes, since buried bodies were naturally desiccated in the hot, dry desert sand.
The start of true Egyptian mummification is generally dated to the Old Kingdom (2500 B.C.), although the use of preservative resinous recipes became evident centuries later during the Middle Kingdom (c. 2000 – 1600 B.C.).
Detailing their finding in the current issue of PLOS ONE journal, researchers from the Universities of York, Macquarie and Oxford report that complex embalming agents were soaked in linen wrappings covering bodies from Late Neolithic and Chalcolithic period tombs at Badari and Mostagedda in Upper Egypt.
"In 2002, I examined samples of funerary textiles from these sites that had been sent to various museums in the United Kingdom through the 1930s from Egypt," Jana Jones of Macquarie University, Sydney, said.
Preliminary microscopic analysis by Jones revealed resins were likely to have been used. After a number of aborted attempts by other experts, Stephen Buckley, a Research Fellow at the University of York, was able to carry successful biochemical analysis.
Using a combination of gas chromatography-mass spectrometry and sequential thermal desorption-pyrolysis, Buckley examined 23 samples of wrappings from Mostagedda. Radiocarbon dating at the Oxford Radiocarbon Accelerator Unit confirmed the Late Neolithic and predynastic dating of the textiles, with the oldest wrappings dating between 4316-3986 B.C.
Buckley identified a pine resin, an aromatic plant extract, a plant gum/sugar, a natural petroleum source, and a plant oil/animal fat in the wrappings.
"These are embalming agents," Buckley told Discovery News.
Plant oil or animal fat made up the the bulk of the balms, with far lesser amounts of a conifer resin and an aromatic plant extract, or "balsam," and minor amounts of a wax and a plant gum/sugar.
"Ingredients were brought from the North East Mediterranean. For example, the pine resin must have come from what is now south eastern Turkey," Buckley said.
According to Buckley, the mixtures, which had antibacterial properties, show the same ingredients used in approximately the same proportions in mummies from the pharaonic period some 3000 years later, when mummification was at its zenith.
At that time, evisceration and the use of a desiccant had become an integral part of the embalming process.
Buckley says there is no doubt prehistoric Egyptians experimented with artificial mummification. Experts have previously described resin-impregnated linen being used to mold the shape of the bodies around 2800 B.C. as a forerunner to a more complex process, yet this research suggests the use of embalming agents in this way started over a millennia earlier.
"Because these are complex processed mixtures, the idea that by coincidence the pharaonic embalming agents and these prehistoric recipes happen to be the same, yet have no connection, is nonsense," he said.
Early reports of burials at the site of Badari mention seven cases in which the head was wrapped in textile and one example of a pad of textile at the hands. We know that bodies were placed in pit graves and had associated artifacts such as shells, pottery and jewellery buried with them, but unfortunately the remains are now lost.
"The antibacterials would have provided some soft tissue preservation, but it is a shame that we can't do a direct comparison," Buckley said.
He believes the resinous recipes probably started as something symbolic. Then, through observation and subsequent experimentation, the preservative qualities of the recipes would have appeared as vital for the body and the spirit in the afterlife.
Read more at Discovery News
The finding predates the origins of mummification in ancient Egypt by 1,500 years, indicating that resin-soaked textiles used in the prehistoric period (c. 4500 – 3350 B.C.) are the true antecedents of Egyptian mummification.
Experts have long assumed that in the 5th and 4th millennia B.C. preservation of soft tissues was due to natural processes, since buried bodies were naturally desiccated in the hot, dry desert sand.
The start of true Egyptian mummification is generally dated to the Old Kingdom (2500 B.C.), although the use of preservative resinous recipes became evident centuries later during the Middle Kingdom (c. 2000 – 1600 B.C.).
Detailing their finding in the current issue of PLOS ONE journal, researchers from the Universities of York, Macquarie and Oxford report that complex embalming agents were soaked in linen wrappings covering bodies from Late Neolithic and Chalcolithic period tombs at Badari and Mostagedda in Upper Egypt.
"In 2002, I examined samples of funerary textiles from these sites that had been sent to various museums in the United Kingdom through the 1930s from Egypt," Jana Jones of Macquarie University, Sydney, said.
Preliminary microscopic analysis by Jones revealed resins were likely to have been used. After a number of aborted attempts by other experts, Stephen Buckley, a Research Fellow at the University of York, was able to carry successful biochemical analysis.
Using a combination of gas chromatography-mass spectrometry and sequential thermal desorption-pyrolysis, Buckley examined 23 samples of wrappings from Mostagedda. Radiocarbon dating at the Oxford Radiocarbon Accelerator Unit confirmed the Late Neolithic and predynastic dating of the textiles, with the oldest wrappings dating between 4316-3986 B.C.
Buckley identified a pine resin, an aromatic plant extract, a plant gum/sugar, a natural petroleum source, and a plant oil/animal fat in the wrappings.
"These are embalming agents," Buckley told Discovery News.
Plant oil or animal fat made up the the bulk of the balms, with far lesser amounts of a conifer resin and an aromatic plant extract, or "balsam," and minor amounts of a wax and a plant gum/sugar.
"Ingredients were brought from the North East Mediterranean. For example, the pine resin must have come from what is now south eastern Turkey," Buckley said.
According to Buckley, the mixtures, which had antibacterial properties, show the same ingredients used in approximately the same proportions in mummies from the pharaonic period some 3000 years later, when mummification was at its zenith.
At that time, evisceration and the use of a desiccant had become an integral part of the embalming process.
Buckley says there is no doubt prehistoric Egyptians experimented with artificial mummification. Experts have previously described resin-impregnated linen being used to mold the shape of the bodies around 2800 B.C. as a forerunner to a more complex process, yet this research suggests the use of embalming agents in this way started over a millennia earlier.
"Because these are complex processed mixtures, the idea that by coincidence the pharaonic embalming agents and these prehistoric recipes happen to be the same, yet have no connection, is nonsense," he said.
Early reports of burials at the site of Badari mention seven cases in which the head was wrapped in textile and one example of a pad of textile at the hands. We know that bodies were placed in pit graves and had associated artifacts such as shells, pottery and jewellery buried with them, but unfortunately the remains are now lost.
"The antibacterials would have provided some soft tissue preservation, but it is a shame that we can't do a direct comparison," Buckley said.
He believes the resinous recipes probably started as something symbolic. Then, through observation and subsequent experimentation, the preservative qualities of the recipes would have appeared as vital for the body and the spirit in the afterlife.
Read more at Discovery News
Fisherman Pulls Up Beastly Evidence of Early Americans
A 22,000-year-old mastodon skull and tool dredged from the seafloor in the Chesapeake Bay hints of early settlers in North America.
The two relics, which were pulled up together, may come from a place that hasn't been dry land since 14,000 years ago. If so, the combination of the finds may suggest that people lived in North America, and possibly butchered the mastodon, thousands of years before people from the Clovis culture, who are widely thought to be the first settlers of North America and the ancestors of all living Native Americans.
But that hypothesis is controversial, with one expert saying the finds are too far removed from their original setting to draw any conclusions from them. That's because the bones were found in a setting that makes it tricky for scientists to say with certainty where they originated and how they are related to one another.
"The bottom line is, there simply is no context for these discoveries," said Vance Holliday, an archaeologist at the University of Arizona in Tucson, who was not involved in the study.
Deep-sea fishing
Most researchers believe the first Americans crossed the Bering Strait from Siberia about 15,000 years ago and quickly colonized North America. Artifacts from these ancient settlers, dubbed the Clovis culture after one of their iconic archaeological sites in Clovis, New Mexico, have been found from Canada to the edges of North America.
But in 1974, a small wooden scallop trawler was dredging the seafloor, about 230 feet (70 meters) below the sea surface and nearly 60 miles (100 kilometers) off the coastline in the Chesapeake Bay.
"They hit a snag, or a hang, as they like to say, which meant that something pretty heavy was in their net," said Dennis Stanford, an archaeologist with the Smithsonian Institution in Washington, D.C., who has analyzed the find.
When they pulled up their net, they found the partial skull of a mastodon, a distant cousin of the woolly mammoth that began its slide into extinction about 12,000 years ago, Stanford said. The fishermen also noticed a flaked blade made of a volcanic rock called rhyolite.
Rediscovered treasure
The fisherman couldn't lug the skull back to shore in their tiny wooden boat, so they sawed off the tusks and teeth, tossed the rest overboard and eventually handed portions to the crew as souvenirs. Capt. Thurston Shawn gave the remaining tusk portions, teeth and knife to a relative, who donated the remains to Gwynn's Island Museum in Virginia. There they sat, unnoticed, for decades.
But while doing his doctoral dissertation, Darrin Lowery, a geologist at the University of Delaware, noticed the teeth and the tusk at the museum, and said, "Ooh, it's something Dennis would be real interested in," Stanford told Live Science.
By measuring the fraction of radioactive carbon isotopes (elements of carbon with different numbers of neutrons), the team found that the mastodon tusk was more than 22,000 years old.
There was no way to date the blade precisely, but the deft flint-knapping technique used to make it was similar to that found in Solutrean tools, which were made in Europe between 22,000 and 17,000 years ago.
Melting glaciers raised sea levels and submerged that area of the continental shelf about 14,000 years ago, so the knife must have been at least that old, Stanford added.
In addition, both pieces showed characteristic weathering that indicated they were exposed to the air for a while and then submerged in a saltwater marsh, before finally being buried in seawater.
That finding suggested that the two artifacts were possibly from the same environment — such as the marshes found between sand dunes that are often set back from the seashore. That would have been a perfect place for mastodons to find food, Stanford said.
"They like to chew on bushes and more rough shrubbery," Stanford said.
To Stanford, Lowery and their colleagues, the discoveries suggest that people lived along the East Coast more than 14,000 years ago — potentially thousands of years before the Clovis culture emerged there. These first American colonizers may have even crossed the Atlantic Ocean from Europe, Stanford said.
Pre-Clovis Americans?
"I think it's very convincing," said Michael B. Collins, an anthropologist at Texas State University in San Marcos, Texas, who was not involved in the current work.
The weathering on both items — first with open air, then saltwater, then seawater exposure — would be almost impossible to get without them having been on land prior to rising sea levels toward the close of the Pleistocene Epoch, which lasted from 1.7 million to 11,700 years ago, Collins said.
But the person who wielded the rhyolite knife may not have hunted the mastodon, Collins said.
"Those things could have come to rest there together at different times," with the tool possibly being 18,000 or 19,000 years old, Collins told Live Science.
The idea that the first Americans were European "has been around for a long time, and it's a tough case to make," Holliday said.
A 2007 study in the journal PLOS Genetics tied all living Native American populations to ancestors that crossed the Bering Strait from Siberia. If Europeans did reach the Americas 18,000 years ago, they left little genetic trace in living populations.
"There's absolutely no DNA evidence," Holliday said.
Archaeological evidence is also scarce. A few East Coast sites, such as Cactus Hill in Virginia and Meadowcroft Rockshelter in Pennsylvania, may have been inhabited up to 16,000 to 18,000 years ago, but the dating and provenance of artifacts from the sites are debatable, Holliday said.
Either way, it's impossible to know how the mastodon tusk and knife are connected, Holliday said.
Read more at Discovery News
The two relics, which were pulled up together, may come from a place that hasn't been dry land since 14,000 years ago. If so, the combination of the finds may suggest that people lived in North America, and possibly butchered the mastodon, thousands of years before people from the Clovis culture, who are widely thought to be the first settlers of North America and the ancestors of all living Native Americans.
But that hypothesis is controversial, with one expert saying the finds are too far removed from their original setting to draw any conclusions from them. That's because the bones were found in a setting that makes it tricky for scientists to say with certainty where they originated and how they are related to one another.
"The bottom line is, there simply is no context for these discoveries," said Vance Holliday, an archaeologist at the University of Arizona in Tucson, who was not involved in the study.
Deep-sea fishing
Most researchers believe the first Americans crossed the Bering Strait from Siberia about 15,000 years ago and quickly colonized North America. Artifacts from these ancient settlers, dubbed the Clovis culture after one of their iconic archaeological sites in Clovis, New Mexico, have been found from Canada to the edges of North America.
But in 1974, a small wooden scallop trawler was dredging the seafloor, about 230 feet (70 meters) below the sea surface and nearly 60 miles (100 kilometers) off the coastline in the Chesapeake Bay.
"They hit a snag, or a hang, as they like to say, which meant that something pretty heavy was in their net," said Dennis Stanford, an archaeologist with the Smithsonian Institution in Washington, D.C., who has analyzed the find.
When they pulled up their net, they found the partial skull of a mastodon, a distant cousin of the woolly mammoth that began its slide into extinction about 12,000 years ago, Stanford said. The fishermen also noticed a flaked blade made of a volcanic rock called rhyolite.
Rediscovered treasure
The fisherman couldn't lug the skull back to shore in their tiny wooden boat, so they sawed off the tusks and teeth, tossed the rest overboard and eventually handed portions to the crew as souvenirs. Capt. Thurston Shawn gave the remaining tusk portions, teeth and knife to a relative, who donated the remains to Gwynn's Island Museum in Virginia. There they sat, unnoticed, for decades.
But while doing his doctoral dissertation, Darrin Lowery, a geologist at the University of Delaware, noticed the teeth and the tusk at the museum, and said, "Ooh, it's something Dennis would be real interested in," Stanford told Live Science.
By measuring the fraction of radioactive carbon isotopes (elements of carbon with different numbers of neutrons), the team found that the mastodon tusk was more than 22,000 years old.
There was no way to date the blade precisely, but the deft flint-knapping technique used to make it was similar to that found in Solutrean tools, which were made in Europe between 22,000 and 17,000 years ago.
Melting glaciers raised sea levels and submerged that area of the continental shelf about 14,000 years ago, so the knife must have been at least that old, Stanford added.
In addition, both pieces showed characteristic weathering that indicated they were exposed to the air for a while and then submerged in a saltwater marsh, before finally being buried in seawater.
That finding suggested that the two artifacts were possibly from the same environment — such as the marshes found between sand dunes that are often set back from the seashore. That would have been a perfect place for mastodons to find food, Stanford said.
"They like to chew on bushes and more rough shrubbery," Stanford said.
To Stanford, Lowery and their colleagues, the discoveries suggest that people lived along the East Coast more than 14,000 years ago — potentially thousands of years before the Clovis culture emerged there. These first American colonizers may have even crossed the Atlantic Ocean from Europe, Stanford said.
Pre-Clovis Americans?
"I think it's very convincing," said Michael B. Collins, an anthropologist at Texas State University in San Marcos, Texas, who was not involved in the current work.
The weathering on both items — first with open air, then saltwater, then seawater exposure — would be almost impossible to get without them having been on land prior to rising sea levels toward the close of the Pleistocene Epoch, which lasted from 1.7 million to 11,700 years ago, Collins said.
But the person who wielded the rhyolite knife may not have hunted the mastodon, Collins said.
"Those things could have come to rest there together at different times," with the tool possibly being 18,000 or 19,000 years old, Collins told Live Science.
The idea that the first Americans were European "has been around for a long time, and it's a tough case to make," Holliday said.
A 2007 study in the journal PLOS Genetics tied all living Native American populations to ancestors that crossed the Bering Strait from Siberia. If Europeans did reach the Americas 18,000 years ago, they left little genetic trace in living populations.
"There's absolutely no DNA evidence," Holliday said.
Archaeological evidence is also scarce. A few East Coast sites, such as Cactus Hill in Virginia and Meadowcroft Rockshelter in Pennsylvania, may have been inhabited up to 16,000 to 18,000 years ago, but the dating and provenance of artifacts from the sites are debatable, Holliday said.
Either way, it's impossible to know how the mastodon tusk and knife are connected, Holliday said.
Read more at Discovery News
Petrified Wood Contains Oldest Fossilized Fire Scar
SACRAMENTO, Calif. — After serving nearly 30 years as a doorstop for a nuclear physicist, a hunk of petrified wood from Arizona has finally been recognized as a one-of-a-kind find. The 210-million-year-old piece of wood contains the first fossilized fire scar ever discovered, researchers reported here this week at the Ecological Society of America's annual meeting.
Evidence for ancient forest fires predates the dinosaurs, but the clues come from charcoal, not from marks on fossilized trees. Charcoal remains of Earth's oldest fires date back more than 400 million years. No one has ever spotted a fire scar on petrified wood before, said lead study author Bruce Byers, a natural resources consultant from Falls Church, Virginia. That's because the scientists who study petrified wood rarely cross paths with forest fire researchers, Byers suspects. But Byers thinks more fossil fire scars will be found.
"Seeing patterns in nature probably requires a mental search image for those patterns," Byers said. "Disciplinary divisions may be a barrier for sharing those patterns, but I think if people start looking, they will see those patterns."
Byers spent two decades staring at his father's 16-pound (7 kilograms) doorstop before realizing it might be from a fire-scarred tree. His father, Cleo Byers, was a nuclear physicist for Los Alamos National Laboratory in New Mexico, and took his children on hikes throughout the Southwest, Bruce Byers said. The rosy-pink stone came home with father and son 28 years ago, after a hiking trip near Utah's Bears Ears Buttes. The colorful chunk was collected on national forest land, where it's legal to take petrified wood, according to Byers, who has detailed the story on his blog. The petrified chunk likely came from the Chinle Formation, the same wood-rich rock layer that litters Arizona's Petrified Forest National Park with huge, crystallized trees.
Decades later, Bruce Byers took on a contract to help fire ecology researchers in Colorado's Front Range.
"I learned to recognize the distinctive patterns of modern fire scars, and I learned how important fire scars are in reconstructing the fire history of modern forests," Byers recalls.
Afterward, on Byers' next visit to his parents' New Mexico home, the telltale signs of a fire scar jumped out from the familiar piece of petrified wood.
A fire-wounded tree valiantly tries to heal itself. The surviving wood hugs the fire scar, growing back over the raw, burned inner wood. The healing curls of wood leave a unique pattern of growth rays as they stretch around the trunk.
Byers' petrified wood had the healing curls. When the piece was cut and polished, he could also see a light-colored band dividing the pre- and post-fire growth, a mark that is also found in modern trees, as well as the unique growth-ray pattern.
With networking and cold calls, Byers put together a dream team that could help him polish his findings and publish the results in a scientific journal. The study will appear Oct. 1 in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. His collaborators include the University of New Mexico's Sidney Ash, who may have looked at more petrified wood from the Southwest than anyone else on Earth; Dan Chaney, an expert on ancient plants at the Smithsonian National Museum of Natural History; and Lucía DeSoto, a professor at Portugal's University of Coimbra and a leader in analyzing tree growth, cell by cell.
One of the team's key findings was that the petrified tree seemed to react to fire stress in the same way as modern trees. Stress from forest fires can leave behind bands of narrow tree rings in some modern trees, a result of the struggle to recover and grow. The ancient tree was a species called Agathoxylon arizonicum, a species that never forms growth rings. However, its microscopic tree cells, called tracheids — internal highways that transfer water and nutrients — show signs of fire stress in a manner similar to tree rings. Six to eight rows of tiny tracheids suggest suppressed growth immediately after the fire, the researchers report. The next rows are bigger than prefire tracheids, likely because the forest fire's survivors had less competition for water and nutrients, Byers said. This post-fire growth spurt is also seen in modern trees.
Read more at Discovery News
Evidence for ancient forest fires predates the dinosaurs, but the clues come from charcoal, not from marks on fossilized trees. Charcoal remains of Earth's oldest fires date back more than 400 million years. No one has ever spotted a fire scar on petrified wood before, said lead study author Bruce Byers, a natural resources consultant from Falls Church, Virginia. That's because the scientists who study petrified wood rarely cross paths with forest fire researchers, Byers suspects. But Byers thinks more fossil fire scars will be found.
"Seeing patterns in nature probably requires a mental search image for those patterns," Byers said. "Disciplinary divisions may be a barrier for sharing those patterns, but I think if people start looking, they will see those patterns."
Byers spent two decades staring at his father's 16-pound (7 kilograms) doorstop before realizing it might be from a fire-scarred tree. His father, Cleo Byers, was a nuclear physicist for Los Alamos National Laboratory in New Mexico, and took his children on hikes throughout the Southwest, Bruce Byers said. The rosy-pink stone came home with father and son 28 years ago, after a hiking trip near Utah's Bears Ears Buttes. The colorful chunk was collected on national forest land, where it's legal to take petrified wood, according to Byers, who has detailed the story on his blog. The petrified chunk likely came from the Chinle Formation, the same wood-rich rock layer that litters Arizona's Petrified Forest National Park with huge, crystallized trees.
Decades later, Bruce Byers took on a contract to help fire ecology researchers in Colorado's Front Range.
"I learned to recognize the distinctive patterns of modern fire scars, and I learned how important fire scars are in reconstructing the fire history of modern forests," Byers recalls.
Afterward, on Byers' next visit to his parents' New Mexico home, the telltale signs of a fire scar jumped out from the familiar piece of petrified wood.
A fire-wounded tree valiantly tries to heal itself. The surviving wood hugs the fire scar, growing back over the raw, burned inner wood. The healing curls of wood leave a unique pattern of growth rays as they stretch around the trunk.
Byers' petrified wood had the healing curls. When the piece was cut and polished, he could also see a light-colored band dividing the pre- and post-fire growth, a mark that is also found in modern trees, as well as the unique growth-ray pattern.
With networking and cold calls, Byers put together a dream team that could help him polish his findings and publish the results in a scientific journal. The study will appear Oct. 1 in the journal Palaeogeography, Palaeoclimatology, Palaeoecology. His collaborators include the University of New Mexico's Sidney Ash, who may have looked at more petrified wood from the Southwest than anyone else on Earth; Dan Chaney, an expert on ancient plants at the Smithsonian National Museum of Natural History; and Lucía DeSoto, a professor at Portugal's University of Coimbra and a leader in analyzing tree growth, cell by cell.
One of the team's key findings was that the petrified tree seemed to react to fire stress in the same way as modern trees. Stress from forest fires can leave behind bands of narrow tree rings in some modern trees, a result of the struggle to recover and grow. The ancient tree was a species called Agathoxylon arizonicum, a species that never forms growth rings. However, its microscopic tree cells, called tracheids — internal highways that transfer water and nutrients — show signs of fire stress in a manner similar to tree rings. Six to eight rows of tiny tracheids suggest suppressed growth immediately after the fire, the researchers report. The next rows are bigger than prefire tracheids, likely because the forest fire's survivors had less competition for water and nutrients, Byers said. This post-fire growth spurt is also seen in modern trees.
Read more at Discovery News
The Universe Seems to be Missing Some Light
An extraordinary amount of ultraviolet light appears to be missing from the universe, scientists have found.
One potential source of this missing light might be the mysterious dark matter that makes up most of the mass in the cosmos. But a simpler explanation could be that ultra violet light escapes from galaxies more easily than is currently thought, according to the new research.
This puzzle begins with hydrogen, the most common element in the universe, which makes up about 75 percent of known matter. High-energy ultraviolet light can convert electrically neutral hydrogen atoms into electrically charged ions. The two known sources for such ionizing rays are hot young stars and quasars, which are supermassive black holes more than a million times the mass of the sun that release extraordinarily large amounts of light as they rip apart stars and gobble matter.
Astronomers previously found that ionizing rays from hot young stars are nearly always absorbed by gas in their home galaxies. As such, they virtually never escape to affect intergalactic hydrogen.
However, when scientists performed supercomputer simulations of the amount of intergalactic hydrogen that should exist and compared their results with observations from the Hubble Space Telescope's Cosmic Origins Spectrograph, they found the amount of light from known quasars is five times lower than what is needed to explain the amount of electrically neutral intergalactic hydrogen observed.
"It's as if you're in a big, brightly-lit room, but you look around and see only a few 40-watt lightbulbs," lead study author Juna Kollmeier, a theoretical astrophysicist at the Observatories of the Carnegie Institution of Washington in Pasadena, Calif., said in a statement. "Where is all that light coming from? It's missing."
The researchers are calling this giant deficit of ultraviolet light "the photon underproduction crisis."
"In modern astrophysics, you very rarely find large mismatches like the one we are talking about here," Kollmeier told Space.com. "When you see one, you know that there is an opportunity to learn something new about the universe, and that's amazing."
"The great thing about a 400 percent discrepancy is that you know something is really wrong," study co-author David Weinberg at Ohio State University said in a statement. "We still don't know for sure what it is, but at least one thing we thought we knew about the present day universe isn't true."
Strangely, this missing light only appears in the nearby, relatively well-studied cosmos. When telescopes focus on light from galaxies billions of light years away — and therefore from billions of years in the past — no problem is seen. In other words, the amount of ultraviolet light in the early universe makes sense, but the amount of ultraviolet light in the nearby universe does not.
"The authors have performed a careful and thorough analysis of the problem," said theoretical astrophysicist Abraham Loeb, chairman of the astronomy department at Harvard University, who did not take part in this research.
The most exciting possibility these findings raise is that the missing photons are coming from some exotic new source, not galaxies or quasars at all, Kollmeier said. For example, dark matter, the invisible and intangible substance thought to make up five-sixths of all matter in the universe, might be capable of decay and generating this extra light.
"You know it's a crisis when you start seriously talking about decaying dark matter," study co-author Neal Katz at the University of Massachusetts at Amherst said in a statement.
There still may be a simpler explanation for this missing light, however. Astronomers could be underestimating the fraction of ultraviolet light that escapes from galaxies in the nearby universe. "All that one needs is an average escape probability on the order of 15 percent to relieve the discrepancy," Loeb told Space.com.
Nearby, recent "low-redshift" galaxies have less gas to absorb ultraviolet rays that more distant, early "high-redshift" galaxies, Loeb noted.
"The more I think about it, the more plausible it appears that the escape fraction of ultraviolet photons is higher in local galaxies than in high-redshift galaxies," Loeb said.
On the other hand, "the biggest problem with this possible solution is that there are measurements of local galaxies that indicate the average escape fraction is significantly lower than 15 percent — more like 5 percent," Kollmeier said."In principle, it is possible that these galaxies are not representative and therefore we need to do more such measurements, but we cannot just dismiss the data."
Read more at Discovery News
One potential source of this missing light might be the mysterious dark matter that makes up most of the mass in the cosmos. But a simpler explanation could be that ultra violet light escapes from galaxies more easily than is currently thought, according to the new research.
This puzzle begins with hydrogen, the most common element in the universe, which makes up about 75 percent of known matter. High-energy ultraviolet light can convert electrically neutral hydrogen atoms into electrically charged ions. The two known sources for such ionizing rays are hot young stars and quasars, which are supermassive black holes more than a million times the mass of the sun that release extraordinarily large amounts of light as they rip apart stars and gobble matter.
Astronomers previously found that ionizing rays from hot young stars are nearly always absorbed by gas in their home galaxies. As such, they virtually never escape to affect intergalactic hydrogen.
However, when scientists performed supercomputer simulations of the amount of intergalactic hydrogen that should exist and compared their results with observations from the Hubble Space Telescope's Cosmic Origins Spectrograph, they found the amount of light from known quasars is five times lower than what is needed to explain the amount of electrically neutral intergalactic hydrogen observed.
"It's as if you're in a big, brightly-lit room, but you look around and see only a few 40-watt lightbulbs," lead study author Juna Kollmeier, a theoretical astrophysicist at the Observatories of the Carnegie Institution of Washington in Pasadena, Calif., said in a statement. "Where is all that light coming from? It's missing."
The researchers are calling this giant deficit of ultraviolet light "the photon underproduction crisis."
"In modern astrophysics, you very rarely find large mismatches like the one we are talking about here," Kollmeier told Space.com. "When you see one, you know that there is an opportunity to learn something new about the universe, and that's amazing."
"The great thing about a 400 percent discrepancy is that you know something is really wrong," study co-author David Weinberg at Ohio State University said in a statement. "We still don't know for sure what it is, but at least one thing we thought we knew about the present day universe isn't true."
Strangely, this missing light only appears in the nearby, relatively well-studied cosmos. When telescopes focus on light from galaxies billions of light years away — and therefore from billions of years in the past — no problem is seen. In other words, the amount of ultraviolet light in the early universe makes sense, but the amount of ultraviolet light in the nearby universe does not.
"The authors have performed a careful and thorough analysis of the problem," said theoretical astrophysicist Abraham Loeb, chairman of the astronomy department at Harvard University, who did not take part in this research.
The most exciting possibility these findings raise is that the missing photons are coming from some exotic new source, not galaxies or quasars at all, Kollmeier said. For example, dark matter, the invisible and intangible substance thought to make up five-sixths of all matter in the universe, might be capable of decay and generating this extra light.
"You know it's a crisis when you start seriously talking about decaying dark matter," study co-author Neal Katz at the University of Massachusetts at Amherst said in a statement.
There still may be a simpler explanation for this missing light, however. Astronomers could be underestimating the fraction of ultraviolet light that escapes from galaxies in the nearby universe. "All that one needs is an average escape probability on the order of 15 percent to relieve the discrepancy," Loeb told Space.com.
Nearby, recent "low-redshift" galaxies have less gas to absorb ultraviolet rays that more distant, early "high-redshift" galaxies, Loeb noted.
"The more I think about it, the more plausible it appears that the escape fraction of ultraviolet photons is higher in local galaxies than in high-redshift galaxies," Loeb said.
On the other hand, "the biggest problem with this possible solution is that there are measurements of local galaxies that indicate the average escape fraction is significantly lower than 15 percent — more like 5 percent," Kollmeier said."In principle, it is possible that these galaxies are not representative and therefore we need to do more such measurements, but we cannot just dismiss the data."
Read more at Discovery News
Fantastically Wrong: Ridiculous Mythical Critters Dreamed Up by 19th Century Lumberjacks
These are America’s little-known “fearsome critters,” which came principally from lumberjack lore. Consider the Funeral Mountain terrashot, a walking casket that blows up when it stumbles into a searing desert. Or the tripodero, which has telescoping legs for seeing over bushes and a mouth that fires dried clay at its victims. Or the hidebehind, a lumberjack-hunter that you can’t see because—conveniently enough for the myth—when you look its way it ducks behind a tree. Also, it hates alcohol, so the only way to make sure it doesn’t eat you is to be drunk all the time. Ah, America.
Perhaps the most fascinating monsters of American lore, though, are the ones that serve to explain the phenomena we encountered as we headed west. That’s no different than any other folklore, really. In the absence of solid science, we humans will come up with any spectacular theory that will do—usually to serve as some sort of moral lesson or strategy for avoiding bodily harm.
But what’s remarkable about these fearsome critters is how they go about making sense of our world in the most nonsensical ways imaginable. They’re silly. They’re irreverent. And they’re probably standing right behind you.
Here are three of my favorites.
The hugag is like a moose, minus the knees and the dignity. |
Scientific name: Rythmopes inarticulatus
Responsible for: fallen trees
Canada has the moose, but America has a 13-foot-tall moose-like… thing that has corrugated ears and an upper lip that’s so long the beast must take care to avoid tripping over it. According to William T. Cox, in his seminal encyclopedia Fearsome Creatures of the Lumberwoods (the source of the brilliant scientific names here, by the way), the hugag has “a perfect mania for traveling.” It’s harmless to humans, but is saddled with a fairly serious handicap: It has no knees, so it has to goose-step around like every day is a military parade.
Accordingly, the hugag can’t lie down, on account of not being able to get back up. So to sleep, it must lean against trees. And that, good Americans, is why you hear trees fall in the night. It’s not the beavers compromising the structural integrity of such vegetation, or that dead trees falling over on their own is a regular occurrence in the forest. It’s the floppy-lipped hugag. (By the way, if you’d like to catch one, a proven technique is sawing two-thirds of the way through a tree and waiting for a hugag to lean against it. As the tree falls, so too will the beast tumble to the ground, where it is easily slaughtered.)
This creature, though, is far from an American creation. It was Pliny the Elder, the Roman naturalist, who wrote in book eight of his Natural History of the “achlis.” It’s an animal “not unlike the elk but has no joint at the hock and consequently is unable to lie down but sleeps leaning against a tree, and is captured by the tree being cut through to serve as a trap.” He also notes its exceptionally big upper lip. “On account of this it walks backward when grazing, so as to avoid getting tripped up by it in moving forward.”
It’s likely inspired by the moose, which while iconically Canadian, also can be found in northern Europe and Russia. It also roams the northern United States, hence its adoption into American lore. I suspect the idea of the achlis or hugag leaning against trees comes from bull moose using trees to both deposit their scent during the mating season, and to scrape off the velvet tissue that covers their antlers as they grow. And while they aren’t typically known to be bested by vegetation, they sure as hell have been known to get drunk on fermented apples and get stuck in trees.
The splinter cat is like a regular cat, minus any semblance of logic. |
Scientific name: Nasusossificatus arbordemolieus
Responsible for: shattered trees
This husky feline is an indiscriminate destroyer of hollow trees, which it mines for bees and raccoons. Climbing a tree, it propels itself off with powerful legs right into another, blasting the trunk with its wedge-shaped snout and reinforced noggin. The experienced frontiersman knows well “the moronic activities of the Splinter Cat,” writes Henry H. Tryon, who published his own Fearsome Critters in 1939, three decades after Cox’s encyclopedia. “If the Cat finds food in the ruptured trunk, he is temporarily appeased. If not, he goes immediately for another tree. And right there is the big trouble. The Cat doesn’t use any judgment in selecting trees, he just smashes one after another until he gets a meal.”
“Like many of the cat tribes,” Tryon adds, “he is strictly a night traveler and hence is rarely observed. But he’s often heard, and the abundance of his work is ample evidence of his existence, numbers and activity.”
In reality, the splinter cat’s destruction is the work of lightning. When a tree is struck, sap boils and steam forms as cells in the wood explode. If the path of the lightning runs more along the edges, the tree can survive, less a good amount of its bark. But if the strike travels down its core, the whole thing can pop like it was packed with dynamite, sending wood shards flying and branches crashing to the ground, no fiendish felines required.
The gumberoo is like a bear, minus the hair and reasonable body type. |
Scientific name: Megalogaster repercussus
Responsible for: forest fires
The gumberoo is much like a bear, though it is hairless save for “prominent eyebrows and some long, bristly hairs on its chin, but the body is smooth, tough, and shiny and bears not even a wrinkle,” according to Cox. Its hide is so tough, in fact, that it can repel hornet stings, charging elk, and even bullets. Tryon notes that a certain S. W. Allen “photographed one, but the negative exploded.”
Perhaps that is why this extremely combustible beast is said to burn like celluloid film. Heat makes the thing swell and explode, and that’s how we get forest fires. Writes Cox: “Frequently during and after a forest fire in the heavy cedar near Coos Bay woodmen have insisted that they heard loud reports quite unlike the sound of falling trees, and detected the smell of burning rubber in the air.”
Read more at Wired Science
Aug 12, 2014
Our ancestor's 'leaky' membrane answers big questions in biology
All life on Earth came from one common ancestor -- a single-celled organism -- but what it looked like, how it lived and how it evolved into today's modern cells is a four billion year old mystery being solved by researchers at UCL using mathematical modelling.
Findings published in PLOS Biology suggest for the first time that life's Last Universal Common Ancestor (LUCA) had a 'leaky' membrane, which helps scientists answer two of biology's biggest questions:
1. Why all cells use the same bizarre, complex mechanism to harvest energy
2. Why two types of single-celled organism that form the deepest branch on the tree of life -- bacteria and archaea -- have completely different cell membranes
The leakiness of the membrane allowed LUCA to be powered by energy in its surroundings, most likely vents deep on the ocean floor, whilst holding in all the other components necessary for life.
The team modelled how the membrane changed, enabling LUCA's descendants to move to new, more challenging environments and evolve into two distinct types of single-celled organism, bacteria and archaea, creating the deepest branch of the tree of life.
Bacteria and archaea share many common features such as genes, proteins and mechanisms of reading DNA, initially leading scientists to believe they were just different types of bacteria. Their classification changed in the 1970's after extreme differences were found in the way they replicate DNA and in the structure of their cell membrane. As they both stemmed from LUCA, scientists set out to find answers in the structure and function of LUCA's membrane.
Dr Nick Lane (UCL Biosciences) who led the study said, "I find this work just beautiful -- it constrains a sequence of steps going from the strange cell that seems to have been the ancestor of all life today, right through to the deep division between modern cells. From a single basic idea, the model can explain the fundamental differences between bacteria and archaea. Is it right? I'd like to think so, but more importantly, it makes some clear predictions that we plan to test in the future."
Data from the study strongly suggest that LUCA lived in the area where ancient seawater, dense with positively charged particles called protons, mixed with warm alkaline vent fluid, which contained few protons. The difference in the concentration of protons across these two environments enabled protons to flow into the cell, driving the production of a molecule called adenosine triphosphate (ATP) which powered the growth of cells, just as it does today.
owever, unlike modern cells the scientists believe this could only happen if the membrane was 'leaky', enabling protons to leave the cell spontaneously so more protons could enter to power growth.
Dr Lane said: "In these deep sea vents, there is a continuous flow of alkaline fluids, which mix with the ocean waters. When they mix, the fluids neutralise each other, and that stops any build-up of charge which would otherwise prevent protons flowing into the cell. If the first cells had leaky membranes, then protons could enter and then be neutralised, or leave again, almost as if there was no barrier at all. What we've shown is that the rate at which protons enter and leave is high enough to power the growth of cells via proteins embedded in the membrane. So LUCA could have been powered by natural proton gradients in vents, but only if it had a really leaky membrane, completely unlike today's cells."
To escape from these seabed vents, LUCA had to adapt its membrane to pump protons out of the cell, in order for them to flow back in again to help drive ATP production. The study suggests that the bacteria and archaea developed completely different cell membrane structures and proton pumps, whilst keeping the same machinery for powering growth. It also explains why they differ in fundamental traits that depend on the membrane such as DNA replication.
Read more at Science Daily
Findings published in PLOS Biology suggest for the first time that life's Last Universal Common Ancestor (LUCA) had a 'leaky' membrane, which helps scientists answer two of biology's biggest questions:
1. Why all cells use the same bizarre, complex mechanism to harvest energy
2. Why two types of single-celled organism that form the deepest branch on the tree of life -- bacteria and archaea -- have completely different cell membranes
The leakiness of the membrane allowed LUCA to be powered by energy in its surroundings, most likely vents deep on the ocean floor, whilst holding in all the other components necessary for life.
The team modelled how the membrane changed, enabling LUCA's descendants to move to new, more challenging environments and evolve into two distinct types of single-celled organism, bacteria and archaea, creating the deepest branch of the tree of life.
Bacteria and archaea share many common features such as genes, proteins and mechanisms of reading DNA, initially leading scientists to believe they were just different types of bacteria. Their classification changed in the 1970's after extreme differences were found in the way they replicate DNA and in the structure of their cell membrane. As they both stemmed from LUCA, scientists set out to find answers in the structure and function of LUCA's membrane.
Dr Nick Lane (UCL Biosciences) who led the study said, "I find this work just beautiful -- it constrains a sequence of steps going from the strange cell that seems to have been the ancestor of all life today, right through to the deep division between modern cells. From a single basic idea, the model can explain the fundamental differences between bacteria and archaea. Is it right? I'd like to think so, but more importantly, it makes some clear predictions that we plan to test in the future."
Data from the study strongly suggest that LUCA lived in the area where ancient seawater, dense with positively charged particles called protons, mixed with warm alkaline vent fluid, which contained few protons. The difference in the concentration of protons across these two environments enabled protons to flow into the cell, driving the production of a molecule called adenosine triphosphate (ATP) which powered the growth of cells, just as it does today.
owever, unlike modern cells the scientists believe this could only happen if the membrane was 'leaky', enabling protons to leave the cell spontaneously so more protons could enter to power growth.
Dr Lane said: "In these deep sea vents, there is a continuous flow of alkaline fluids, which mix with the ocean waters. When they mix, the fluids neutralise each other, and that stops any build-up of charge which would otherwise prevent protons flowing into the cell. If the first cells had leaky membranes, then protons could enter and then be neutralised, or leave again, almost as if there was no barrier at all. What we've shown is that the rate at which protons enter and leave is high enough to power the growth of cells via proteins embedded in the membrane. So LUCA could have been powered by natural proton gradients in vents, but only if it had a really leaky membrane, completely unlike today's cells."
To escape from these seabed vents, LUCA had to adapt its membrane to pump protons out of the cell, in order for them to flow back in again to help drive ATP production. The study suggests that the bacteria and archaea developed completely different cell membrane structures and proton pumps, whilst keeping the same machinery for powering growth. It also explains why they differ in fundamental traits that depend on the membrane such as DNA replication.
Read more at Science Daily
Rare blurring of black hole light spotted
Scientists have used the NASA Nuclear Spectroscopic Telescope Array (NuSTAR), an orbiting X-ray telescope, to capture an extreme and rare event in the regions immediately surrounding a supermassive black hole. A compact source of X-rays that sits near the black hole, called the corona, has moved closer to the black hole over a period of just days. The researchers publish their results in a paper in Monthly Notices of the Royal Astronomical Society.
"The corona recently collapsed in toward the black hole, with the result that the black hole's intense gravity pulled all the light down onto its surrounding disk, where material is spiralling inward," said Michael Parker of the Institute of Astronomy in Cambridge, United Kingdom, lead author of the new paper.
As the corona shifted closer to the black hole, the gravity of the black hole exerted a stronger tug on the x-rays emitted by it. The result was an extreme blurring and stretching of the X-ray light. Such events had been observed previously, but never to this degree and in such detail.
Supermassive black holes are thought to reside in the centres of all galaxies. Some are more massive and rotate faster than others. The black hole in this new study, referred to as Markarian 335, or Mrk 335, is about 324 million light-years from Earth in the direction of the Pegasus constellation. It is one of the most extreme of the systems for which the mass and spin rate have ever been measured. The black hole squeezes about 10 million times the mass of our Sun into a region only 30 times the solar diameter and it spins so rapidly that space and time are dragged around with it.
Even though some light falls into a supermassive black hole never to be seen again, other high-energy light emanates from both the corona and the surrounding accretion disk of superheated material. Though astronomers are uncertain of the shape and temperature of coronas, they know that they contain particles that move close to the speed of light.
NASA's Swift satellite has monitored Mrk 335 for years, and recently noted a dramatic change in its X-ray brightness. In what is called a target-of-opportunity observation, NuSTAR was redirected to take a look at high-energy X-rays from this source in the range of 3 to 79 kiloelectron volts. This particular energy range offers astronomers a detailed look at what is happening near the event horizon, the region around a black hole from which light can no longer escape gravity's grasp.
Follow-up observations indicate that the corona still is in this close configuration, months after it moved. Researchers don't know whether and when the corona will shift back. What is more, the NuSTAR observations reveal that the grip of the black hole's gravity pulled the corona's light onto the inner portion of its superheated disk, better illuminating it. Almost as if somebody had shone a flashlight for the astronomers, the shifting corona lit up the precise region they wanted to study. The new data could ultimately help determine more about the mysterious nature of black hole coronas. In addition, the observations have provided better measurements of Mrk 335's furious relativistic spin rate. Relativistic speeds are those approaching the speed of light, as described by Albert Einstein's theory of relativity.
Read more at Science Daily
"The corona recently collapsed in toward the black hole, with the result that the black hole's intense gravity pulled all the light down onto its surrounding disk, where material is spiralling inward," said Michael Parker of the Institute of Astronomy in Cambridge, United Kingdom, lead author of the new paper.
As the corona shifted closer to the black hole, the gravity of the black hole exerted a stronger tug on the x-rays emitted by it. The result was an extreme blurring and stretching of the X-ray light. Such events had been observed previously, but never to this degree and in such detail.
Supermassive black holes are thought to reside in the centres of all galaxies. Some are more massive and rotate faster than others. The black hole in this new study, referred to as Markarian 335, or Mrk 335, is about 324 million light-years from Earth in the direction of the Pegasus constellation. It is one of the most extreme of the systems for which the mass and spin rate have ever been measured. The black hole squeezes about 10 million times the mass of our Sun into a region only 30 times the solar diameter and it spins so rapidly that space and time are dragged around with it.
Even though some light falls into a supermassive black hole never to be seen again, other high-energy light emanates from both the corona and the surrounding accretion disk of superheated material. Though astronomers are uncertain of the shape and temperature of coronas, they know that they contain particles that move close to the speed of light.
NASA's Swift satellite has monitored Mrk 335 for years, and recently noted a dramatic change in its X-ray brightness. In what is called a target-of-opportunity observation, NuSTAR was redirected to take a look at high-energy X-rays from this source in the range of 3 to 79 kiloelectron volts. This particular energy range offers astronomers a detailed look at what is happening near the event horizon, the region around a black hole from which light can no longer escape gravity's grasp.
Follow-up observations indicate that the corona still is in this close configuration, months after it moved. Researchers don't know whether and when the corona will shift back. What is more, the NuSTAR observations reveal that the grip of the black hole's gravity pulled the corona's light onto the inner portion of its superheated disk, better illuminating it. Almost as if somebody had shone a flashlight for the astronomers, the shifting corona lit up the precise region they wanted to study. The new data could ultimately help determine more about the mysterious nature of black hole coronas. In addition, the observations have provided better measurements of Mrk 335's furious relativistic spin rate. Relativistic speeds are those approaching the speed of light, as described by Albert Einstein's theory of relativity.
Read more at Science Daily
Reconstructions show how some of the earliest animals lived -- and died
New three-dimensional reconstructions show how some of the earliest animals on Earth developed, and provide some answers as to why they went extinct.
A bizarre group of uniquely-shaped organisms known as rangeomorphs may have been some of the earliest animals to appear on Earth, uniquely suited to ocean conditions 575 million years ago.
A new model devised by researchers at the University of Cambridge has resolved many of the mysteries around the structure, evolution and extinction of these 'proto animals'. The findings are reported today (11 August) in the journal Proceedings of the National Academy of Sciences.
Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Most rangeomorphs were about 10 centimetres high, although some were up to two metres in height.
These creatures were ocean dwellers which lived during the Ediacaran period, between 635 and 541 million years ago. Their bodies were made up of soft branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen in many familiar branching shapes such as fern leaves and even river networks.
Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. However, despite the fact that they looked like plants, evidence points to the fact that rangeomorphs were actually some of the earliest animals.
"We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do," said Dr Jennifer Hoyal Cuthill of Cambridge's Department of Earth Sciences, who led the research. "It's more likely that they absorbed nutrients directly from the sea water through the surface of their body. It would be difficult in the modern world for such large animals to survive only on dissolved nutrients."
"The oceans during the Ediacaran period were more like a weak soup -- full of nutrients such as organic carbon, whereas today suspended food particles are swiftly harvested by a myriad of animals," said co-author Professor Simon Conway Morris.
Starting 541 million years ago, the conditions in the oceans changed quickly with the start of the Cambrian Explosion -- a period of rapid evolution when most major animal groups first emerge in the fossil record and competition for nutrients increased dramatically.
Rangeomorphs have often been considered a 'failed experiment' of evolution as they died out so quickly once the Cambrian Explosion began in earnest, but this new analysis shows just how successful they once were.
Rangeomorphs almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.
"These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition," said Dr Hoyal Cuthill. "Mathematically speaking, they filled their space in a nearly perfect way."
Dr Hoyal Cuthill examined rangeomorph fossils from a number of locations worldwide, and used them to make the first computer reconstructions of the development and three-dimensional structure of these organisms, showing just how well-suited they were to their Ediacaran environment.
Read more at Science Daily
A bizarre group of uniquely-shaped organisms known as rangeomorphs may have been some of the earliest animals to appear on Earth, uniquely suited to ocean conditions 575 million years ago.
A new model devised by researchers at the University of Cambridge has resolved many of the mysteries around the structure, evolution and extinction of these 'proto animals'. The findings are reported today (11 August) in the journal Proceedings of the National Academy of Sciences.
Rangeomorphs were some of the earliest large organisms on Earth, existing during a time when most other forms of life were microscopic in size. Most rangeomorphs were about 10 centimetres high, although some were up to two metres in height.
These creatures were ocean dwellers which lived during the Ediacaran period, between 635 and 541 million years ago. Their bodies were made up of soft branches, each with many smaller side branches, forming a geometric shape known as a fractal, which can be seen in many familiar branching shapes such as fern leaves and even river networks.
Rangeomorphs were unlike any modern organism, which has made it difficult to determine how they fed, grew or reproduced, and therefore difficult to link them to any particular modern group. However, despite the fact that they looked like plants, evidence points to the fact that rangeomorphs were actually some of the earliest animals.
"We know that rangeomorphs lived too deep in the ocean for them to get their energy through photosynthesis as plants do," said Dr Jennifer Hoyal Cuthill of Cambridge's Department of Earth Sciences, who led the research. "It's more likely that they absorbed nutrients directly from the sea water through the surface of their body. It would be difficult in the modern world for such large animals to survive only on dissolved nutrients."
"The oceans during the Ediacaran period were more like a weak soup -- full of nutrients such as organic carbon, whereas today suspended food particles are swiftly harvested by a myriad of animals," said co-author Professor Simon Conway Morris.
Starting 541 million years ago, the conditions in the oceans changed quickly with the start of the Cambrian Explosion -- a period of rapid evolution when most major animal groups first emerge in the fossil record and competition for nutrients increased dramatically.
Rangeomorphs have often been considered a 'failed experiment' of evolution as they died out so quickly once the Cambrian Explosion began in earnest, but this new analysis shows just how successful they once were.
Rangeomorphs almost completely filled the space surrounding them, with a massive total surface area. This made them very efficient feeders that were able to extract the maximum amount of nutrients from the ocean water.
"These creatures were remarkably well-adapted to their environment, as the oceans at the time were high in nutrients and low in competition," said Dr Hoyal Cuthill. "Mathematically speaking, they filled their space in a nearly perfect way."
Dr Hoyal Cuthill examined rangeomorph fossils from a number of locations worldwide, and used them to make the first computer reconstructions of the development and three-dimensional structure of these organisms, showing just how well-suited they were to their Ediacaran environment.
Read more at Science Daily
First Captive Panda Triplets Born in Chinese Zoo
A Chinese zoo has unveiled newborn panda triplets billed as the world's first known surviving trio, in what it hailed as a "miracle" given the animal's famously low reproductive rate.
The mother panda, named Juxiao, meaning "chrysanthemum smile," delivered the triplets at Guangzhou's Chimelong Safari Park in the early hours of July 29, but was too exhausted to take care of them afterwards.
Her cubs were then put into incubators while Juxiao regained her strength, and have now been brought back to their mother for nursing and are being attended to by a round-the-clock team of feeders, the zoo said.
"They were said to be the only panda triplets that have ever survived," the safari park said in a statement released Tuesday.
An official from Sichuan Wolong National Natural Reserve, considered the foremost authority on pandas, said the trio were too young to be officially recognized as "surviving" but that they were the only known panda triplets alive.
"We can only say they are surviving once they reach six months. For now they are indeed the only surviving triplets," said an official from the center who only gave her name as Ms. Zhao.
"The triplets can be described as a new wonder of the world," Chimelong Safari Park said, describing mortality rates among newborn pandas as "extremely high."
Pictures taken earlier this month of the triplets showed the pink-colored cubs inside an incubator with their eyes closed and bodies sparsely covered with white fur.
"The mother and babies were in good condition, but the adorable newborns were particularly inspiring," the zoo said.
The gender of the cubs was not disclosed and they would be given their names at a later date.
Read more at Discovery News
The mother panda, named Juxiao, meaning "chrysanthemum smile," delivered the triplets at Guangzhou's Chimelong Safari Park in the early hours of July 29, but was too exhausted to take care of them afterwards.
Her cubs were then put into incubators while Juxiao regained her strength, and have now been brought back to their mother for nursing and are being attended to by a round-the-clock team of feeders, the zoo said.
"They were said to be the only panda triplets that have ever survived," the safari park said in a statement released Tuesday.
An official from Sichuan Wolong National Natural Reserve, considered the foremost authority on pandas, said the trio were too young to be officially recognized as "surviving" but that they were the only known panda triplets alive.
"We can only say they are surviving once they reach six months. For now they are indeed the only surviving triplets," said an official from the center who only gave her name as Ms. Zhao.
"The triplets can be described as a new wonder of the world," Chimelong Safari Park said, describing mortality rates among newborn pandas as "extremely high."
"The mother and babies were in good condition, but the adorable newborns were particularly inspiring," the zoo said.
The gender of the cubs was not disclosed and they would be given their names at a later date.
Read more at Discovery News
Aug 11, 2014
Still hot inside the Moon: Tidal heating in the deepest part of the lunar mantle
An international research team, led by Dr. Yuji Harada from Planetary Science institute, China University of Geosciences, has found that there is an extremely soft layer deep inside the Moon and that heat is effectively generated in the layer by the gravity of Earth.
The results were derived by comparing the deformation of the Moon as precisely measured by Kaguya (SELENE, Selenological and Engineering Explorer) and other probes with theoretically calculated estimates. These findings suggest that the interior of the Moon has not yet cooled and hardened, and also that it is still being warmed by the effect of Earth on the Moon. This research provides a chance to reconsider how both Earth and the Moon have been evolving since their births through mutual influence until now.
When it comes to clarifying how a celestial body like a planet or a natural satellite is born and grows, it is necessary to know as precisely as possible its internal structure and thermal state. How can we know the internal structure of a celestial body far away from us? We can get clues about its internal structure and state by thoroughly investigating how its shape changes due to external forces. The shape of a celestial body being changes by the gravitational force of another body is called tide. For example, the ocean tide on Earth is one tidal phenomenon caused by the gravitational force between the Moon and the Sun, and Earth. Sea water is so deformable that its desplacement can be easily observed. How much a celestial body can be deformed by tidal force, in this way, depends on its internal structure, and especially on the hardness of its interior. Conversely, it means that observing the degree of deformation enables us to learn about the interior, which is normally not directly visible to the naked eye.
The Moon is no exception; we can learn about the interior of our natural satellite from its deformation caused by the tidal force of Earth. The deformation has already been well known through several geodetic observations (*1). However, models of the internal structure of the Moon as derived from past research could not account for the deformation precisely observed by the above lunar exploration programs.
Therefore, the research team performed theoretical calculations to understand what type of internal structure of the Moon leads to the observed change of the lunar shape.
What the research team focused on is the structure deep inside the Moon. During the Apollo program, seismic observations (*2) were carried out on the Moon. One of the analysis results concerning the internal structure of the Moon based upon the seismic data indicates that the satellite is considered to consist mainly of two parts: the "core," the inner portion made up of metal, and the "mantle," the outer portion made up of rock. The research team has found that the observed tidal deformation of the Moon can be well explained if it is assumed that there is an extremely soft layer in the deepest part of the lunar mantle. The previous studies indicated that there is the possibility that a part of the rock at the deepest part inside the lunar mantle may be molten. This research result supports the above possibility since partially molten rock becomes softer. This research has proven for the first time that the deepest part of the lunar mantle is soft, based upon the agreement between observation results and the theoretical calculations.
Furthermore, the research team also clarified that heat is efficiently generated by the tides in the soft part, deepest in the mantle. In general, a part of the energy stored inside a celestial body by tidal deformation is changed to heat. The heat generation depends on the softness of the interior. Interestingly, the heat generated in the layer is expected to be nearly at the maximum when the softness of the layer is comparable to that which the team estimated from the above comparison of the calculations and the observations. This may not be a coincidence. Rather, the layer itself is considered to be maintained as the amount of the heat generated inside the soft layer is exquisitely well balanced with that of the heat escaping from the layer. Whereas previous research also suggests that some part of the energy inside the Moon due to the tidal deformation is changed to heat, the present research indicates that this type of energy conversion does not uniformly occur in the entire Moon, but only intensively in the soft layer. The research team believes that the soft layer is now warming the core of the Moon as the core seems to be wrapped by the layer, which is located in the deepest part of the mantle, and which efficiently generates heat. They also expect that a soft layer like this may efficiently have warmed the core in the past as well.
Concerning the future outlook for this research, Dr. Yuji Harada, the principle investigator of the research team, said, "I believe that our research results have brought about new questions. For example, how can the bottom of the lunar mantle maintain its softer state for a long time? To answer this question, we would like to further investigate the internal structure and heat-generating mechanism inside the Moon in detail. In addition, another question has come up: how has the conversion from the tidal energy to the heat energy in the soft layer affected the motion of the Moon relative to the Earth, and also the cooling of the Moon? We would like to resolve those problems as well so that we can thoroughly understand how the Moon was born and has evolved."
Another investigator, Prof. Junichi Haruyama of Institute of Space and Aeronautical Science, Japan Aerospace Exploration Agency, mentioned the significance of this research, saying, "A smaller celestial body like the Moon cools faster than a larger one like the Earth does. In fact, we had thought that volcanic activities on the Moon had already come to a halt. Therefore, the Moon had been believed to be cool and hard, even in its deeper parts. However, this research tells us that the Moon has not yet cooled and hardened, but is still warm. It even implies that we have to reconsider the question as follows: How have the Earth and the Moon influenced each other since their births? That means this research not only shows us the actual state of the deep interior of the Moon, but also gives us a clue for learning about the history of the system including both the Earth and the Moon."
The scientific paper on which this article is based appears in the Nature Geoscience.
Strong tidal heating in an ultralow-viscosity zone at the core-mantle boundary of the Moon.
Note:
*1: Geodetic observation. (This is also called "selenodetic" observation as it is for the Moon.)
Observational results on gravity and rotation of the Moon are used in this research. Precise measurements of the lunar gravity and rotation enable us to know how our natural satellite is deformed by tidal forces.
The gravity of the Moon can be measured by tracking the motion of a satellite orbiting the Moon. This is because the motion of the satellite is influenced by lunar gravity. The motion of the satellite orbiting the Moon can be determined by using radio waves between the Earth and the satellite, and between multiple satellites around the Moon. The gravity of the Moon changes when it deforms due to tidal forces. The change in gravity caused by the lunar deformation due to the tidal force is extremely small, but when the change in location of the orbiter can be determined precisely enough, it is possible to accurately detect the change in lunar gravity caused by the deformation due to the tidal force. During the last several years, the degree of the lunar deformation caused by the tidal forces has been determined by several orbiters, for example, Kaguya from Japan, Chang'e-1 from China, and Lunar Reconnaissance Orbiter (LRO) and Gravity Recovery and Interior Laboratory (GRAIL) from the USA.
The rotation of the Moon can be observed by monitoring the change in position of a kind of mirror placed in several locations on the lunar surface. The same side of the Moon is almost always facing the Earth, but strictly speaking, it changes by a slight amount according to the lunar orbit around the Earth. This means that the locations of the mirrors with respect to the Earth also changes over time. If this change in position is precisely measured, it can also be determined how the direction of the lunar axis changes. This slight change of direction also depends on the deformation caused by the tidal force. It can be seen, therefore, how the Moon deforms due to the tidal force once the change in the axis is measured precisely. Some of the above-mentioned mirrors have been left on the surface of the Moon in the framework of the lunar exploration programs led by the USA or the former USSR several decades ago, such as the Apollo program. The degree of change in the location of each mirror on the Moon can be determined by using laser beams emitted from the Earth. This experiment still continues to be carried out even today.
Read more at Science Daily
The results were derived by comparing the deformation of the Moon as precisely measured by Kaguya (SELENE, Selenological and Engineering Explorer) and other probes with theoretically calculated estimates. These findings suggest that the interior of the Moon has not yet cooled and hardened, and also that it is still being warmed by the effect of Earth on the Moon. This research provides a chance to reconsider how both Earth and the Moon have been evolving since their births through mutual influence until now.
When it comes to clarifying how a celestial body like a planet or a natural satellite is born and grows, it is necessary to know as precisely as possible its internal structure and thermal state. How can we know the internal structure of a celestial body far away from us? We can get clues about its internal structure and state by thoroughly investigating how its shape changes due to external forces. The shape of a celestial body being changes by the gravitational force of another body is called tide. For example, the ocean tide on Earth is one tidal phenomenon caused by the gravitational force between the Moon and the Sun, and Earth. Sea water is so deformable that its desplacement can be easily observed. How much a celestial body can be deformed by tidal force, in this way, depends on its internal structure, and especially on the hardness of its interior. Conversely, it means that observing the degree of deformation enables us to learn about the interior, which is normally not directly visible to the naked eye.
The Moon is no exception; we can learn about the interior of our natural satellite from its deformation caused by the tidal force of Earth. The deformation has already been well known through several geodetic observations (*1). However, models of the internal structure of the Moon as derived from past research could not account for the deformation precisely observed by the above lunar exploration programs.
Therefore, the research team performed theoretical calculations to understand what type of internal structure of the Moon leads to the observed change of the lunar shape.
What the research team focused on is the structure deep inside the Moon. During the Apollo program, seismic observations (*2) were carried out on the Moon. One of the analysis results concerning the internal structure of the Moon based upon the seismic data indicates that the satellite is considered to consist mainly of two parts: the "core," the inner portion made up of metal, and the "mantle," the outer portion made up of rock. The research team has found that the observed tidal deformation of the Moon can be well explained if it is assumed that there is an extremely soft layer in the deepest part of the lunar mantle. The previous studies indicated that there is the possibility that a part of the rock at the deepest part inside the lunar mantle may be molten. This research result supports the above possibility since partially molten rock becomes softer. This research has proven for the first time that the deepest part of the lunar mantle is soft, based upon the agreement between observation results and the theoretical calculations.
Furthermore, the research team also clarified that heat is efficiently generated by the tides in the soft part, deepest in the mantle. In general, a part of the energy stored inside a celestial body by tidal deformation is changed to heat. The heat generation depends on the softness of the interior. Interestingly, the heat generated in the layer is expected to be nearly at the maximum when the softness of the layer is comparable to that which the team estimated from the above comparison of the calculations and the observations. This may not be a coincidence. Rather, the layer itself is considered to be maintained as the amount of the heat generated inside the soft layer is exquisitely well balanced with that of the heat escaping from the layer. Whereas previous research also suggests that some part of the energy inside the Moon due to the tidal deformation is changed to heat, the present research indicates that this type of energy conversion does not uniformly occur in the entire Moon, but only intensively in the soft layer. The research team believes that the soft layer is now warming the core of the Moon as the core seems to be wrapped by the layer, which is located in the deepest part of the mantle, and which efficiently generates heat. They also expect that a soft layer like this may efficiently have warmed the core in the past as well.
Concerning the future outlook for this research, Dr. Yuji Harada, the principle investigator of the research team, said, "I believe that our research results have brought about new questions. For example, how can the bottom of the lunar mantle maintain its softer state for a long time? To answer this question, we would like to further investigate the internal structure and heat-generating mechanism inside the Moon in detail. In addition, another question has come up: how has the conversion from the tidal energy to the heat energy in the soft layer affected the motion of the Moon relative to the Earth, and also the cooling of the Moon? We would like to resolve those problems as well so that we can thoroughly understand how the Moon was born and has evolved."
Another investigator, Prof. Junichi Haruyama of Institute of Space and Aeronautical Science, Japan Aerospace Exploration Agency, mentioned the significance of this research, saying, "A smaller celestial body like the Moon cools faster than a larger one like the Earth does. In fact, we had thought that volcanic activities on the Moon had already come to a halt. Therefore, the Moon had been believed to be cool and hard, even in its deeper parts. However, this research tells us that the Moon has not yet cooled and hardened, but is still warm. It even implies that we have to reconsider the question as follows: How have the Earth and the Moon influenced each other since their births? That means this research not only shows us the actual state of the deep interior of the Moon, but also gives us a clue for learning about the history of the system including both the Earth and the Moon."
The scientific paper on which this article is based appears in the Nature Geoscience.
Strong tidal heating in an ultralow-viscosity zone at the core-mantle boundary of the Moon.
Note:
*1: Geodetic observation. (This is also called "selenodetic" observation as it is for the Moon.)
Observational results on gravity and rotation of the Moon are used in this research. Precise measurements of the lunar gravity and rotation enable us to know how our natural satellite is deformed by tidal forces.
The gravity of the Moon can be measured by tracking the motion of a satellite orbiting the Moon. This is because the motion of the satellite is influenced by lunar gravity. The motion of the satellite orbiting the Moon can be determined by using radio waves between the Earth and the satellite, and between multiple satellites around the Moon. The gravity of the Moon changes when it deforms due to tidal forces. The change in gravity caused by the lunar deformation due to the tidal force is extremely small, but when the change in location of the orbiter can be determined precisely enough, it is possible to accurately detect the change in lunar gravity caused by the deformation due to the tidal force. During the last several years, the degree of the lunar deformation caused by the tidal forces has been determined by several orbiters, for example, Kaguya from Japan, Chang'e-1 from China, and Lunar Reconnaissance Orbiter (LRO) and Gravity Recovery and Interior Laboratory (GRAIL) from the USA.
The rotation of the Moon can be observed by monitoring the change in position of a kind of mirror placed in several locations on the lunar surface. The same side of the Moon is almost always facing the Earth, but strictly speaking, it changes by a slight amount according to the lunar orbit around the Earth. This means that the locations of the mirrors with respect to the Earth also changes over time. If this change in position is precisely measured, it can also be determined how the direction of the lunar axis changes. This slight change of direction also depends on the deformation caused by the tidal force. It can be seen, therefore, how the Moon deforms due to the tidal force once the change in the axis is measured precisely. Some of the above-mentioned mirrors have been left on the surface of the Moon in the framework of the lunar exploration programs led by the USA or the former USSR several decades ago, such as the Apollo program. The degree of change in the location of each mirror on the Moon can be determined by using laser beams emitted from the Earth. This experiment still continues to be carried out even today.
Read more at Science Daily
World's Oldest European Eel Dies at 155
There was mournful news out of Sweden with the announcement that the world's oldest known European eel had passed away recently at the age of 155, after living through two world wars, the Cold War, disco, punk, grunge, and the advent of the Internet.
'Ale' the Eel was thrown into the well of a cottage in the town of Brantevik in 1859, by a young boy who was merely following the common practice at the time of putting eels in wells so they would eat any insects that might contaminate the water source.
Ale had outsized eyes, the better to live in constant darkness, and it was a longtime celebrity of sorts in Sweden.
"It was uncanny when we took off the lid and saw it in pieces. It had apparently been there for a while and had basically boiled," Thomas Kjellman, current owner of the cottage, told Sweden's The Local.
European eels, currently considered critically endangered by the International Union for Conservation of Nature, typically max out at just a few feet long, and they usually live for around 10 to 20 years. The Local reports that Ale's remains will undergo expert analysis, in hopes more can be learned about its spectacular longevity.
Meanwhile, on a happier note, Ale had a fellow eel in the well, and that swimmer is still hanging in there, at 110 years young.
From Discovery News
'Ale' the Eel was thrown into the well of a cottage in the town of Brantevik in 1859, by a young boy who was merely following the common practice at the time of putting eels in wells so they would eat any insects that might contaminate the water source.
Ale had outsized eyes, the better to live in constant darkness, and it was a longtime celebrity of sorts in Sweden.
"It was uncanny when we took off the lid and saw it in pieces. It had apparently been there for a while and had basically boiled," Thomas Kjellman, current owner of the cottage, told Sweden's The Local.
European eels, currently considered critically endangered by the International Union for Conservation of Nature, typically max out at just a few feet long, and they usually live for around 10 to 20 years. The Local reports that Ale's remains will undergo expert analysis, in hopes more can be learned about its spectacular longevity.
Meanwhile, on a happier note, Ale had a fellow eel in the well, and that swimmer is still hanging in there, at 110 years young.
From Discovery News
Chianti Wine Ancestor Found
Found in Cetamura, an ancient hilltop near Gaiole in Chianti in the province of Siena, the 105-foot-deep well yielded a bonanza of artifacts such as bronze vessels, cups, statuettes, coins and game pieces. The objects span a period of more than 15 centuries and embrace Etruscan, Roman and medieval civilization in Tuscany.
The most precious material, though, might be some 500 waterlogged grape seeds.
Found in at least three different levels of the well, which include the Etruscan and Roman levels, the perfectly preserved pips can provide key insights into the history of viticulture in a region now famous for its bold reds.
"The seeds were found at levels ranging from the third century B.C. to the first century A.D. Since they are not burned, they might carry preserved DNA," Nancy de Grummond, a professor of classics at Florida State, told Discovery News.
De Grummond, who has performed work at Cetamura since 1983, has been excavating the well for the past four years under the supervision of the Archaeological Superintendency of Tuscany and with the help of the Italian archaeological firm of Ichnos, directed by Francesco Cini.
The seeds were subjected to analysis at the lab of vegetation history and wood anatomy of the University of Naples Federico II. There, researchers led by Gaetano di Pasquale processed the obtained data with statistical software in order to highlight differences of size and shape for each pip.
It is known that seeds of wild grape (Vitis vinifera subsp. Sylvestris), the ancestor common to all cultivated species, is smaller and rounder, while cultivated grapes have bigger and elongated pips.
"The first results seem to indicate the Etruscans had a more advanced viticulture compared to the Romans. Roman seeds appear to be wild, suggesting less cultivated species were grown at that time," Di Pasquale told Discovery News.
"In any case, it is very likely that different grapes grew in Cetamura in Etruscan and Roman times," he added.
The recipe for Chianti Classico was standardized by Baron Bettino Ricasoli in the mid-19th century and called for 70 percent Sangiovese to be blended with 15 percent red Canaiolo and 15 percent white Malvasia.
Whether the Etruscans or the Romans used a composition similar to modern Chianti is not known.
The challenge for Di Pasquale's team is to identify and name the waterlogged seeds.
"An answer could come from ancient DNA analysis, but we are still at an experimental stage," Di Pasquale said.
Meanwhile, archaeologists were able to put into context the grape pips as they unearthed many objects associated with wine serving and drinking and numerous ceramic vessels related to wine storage.
"A curious detail is that the grape seeds were often found inside the bronze buckets, perhaps indicating a ritual element," de Grummond said.
She noted the seeds were also found at the very bottom of the well, along with olive pits and hazel nuts, very likely offerings made at the time when the well was completed.
A large amount of well-preserved wood, probably also part of the offerings, was also recovered from the bottom.
"Many of the pieces of wood were worked, and already several objects have been identified: parts of wooden buckets, a spatula or spoon, a spool, a rounded object like a knob or child's top," de Grummond said.
These and other finds -- from animal bones to numerous worked and unworked deer antlers -- suggest that cult activity took place at the well.
"Like other water sources in antiquity, the well was regarded as sacred," de Grummond said.
"Two Etruscan gods, named Lur and Leinth, were worshiped in a nearby sanctuary of Cetamura as gods of good fortune. They were probably the deities of the place," she added.
Offerings found in the well included hundreds of miniature votive cups, some 70 bronze and silver coins, and numerous pieces used in games of fortune, such as astragali, which are akin to jacks.
Read more at Discovery News
Old Ships' Logs Help Forecast the Future
Clement Wragge understood the importance of keeping weather records.The colorful 19th century Queensland meteorologist saw the possibility of forecasting and tracking the path of tropical cyclones using weather observations from ships' logs.
The convention of naming tropical cyclones was begun by him — although he got in trouble once he started naming them for politicians he didn't like!
He collected log books from ships that traversed the immediate Australasian region as well as the Atlantic, Indian and Pacific oceans from 1882-1903.
Now you can help scientists decipher the data in the log books kept by Wragge — you'll notice his letterhead at the top of many of the log book pages — as part of Weather Detective, ABC Science's new citizen science project.
How could weather records written down by a 19th century sea captain possibly be useful in the 21st century?
Anyone who's prepared for a cyclone or made farming decisions based on long-term weather forecasts will understand the value of accurate predictions on what the weather will do in the future.
And while these long-term weather predictions may appear definitive and insightful, they're only as good as the past data that they're based on. That's how forecasting works, it's predicting — or modelling — the future using what's happened in the past.
So gaining as much information about past weather is really useful.
We have a good idea of the Earth's climatic history over thousands of years — mostly from geological sources — but this doesn't provide the level of detail required for forecasting weather.
"The quality and quantity of the data that you're putting in is essential to the sort of product you're putting out, because if you don't have enough you're not going to be able to produce anything meaningful," says Rob Allan, meteorologist with the UK Met Office, and and co-creator with Philip Brohan of Old Weather, the UK version of Weather Detective.
Sea surface temperatures are important
Sea surface temperature is actually a measurement of the temperature of the ocean, not the temperature on board the boat. It's measured by sticking a thermometer into a bucketful of ocean water.
Because the ocean is more homogenous than land, a single sea temperature reading can give an excellent indication of the sea temperature for a large area. Since the oceans cover 70 per cent of our planet, observations at sea are very important for understanding and predicting weather.
Land-based temperature records are also important. However, microclimates on land can lead to large variations in temperatures within a small area — for example, a shaded valley may be cooler than an open plain — which means that historical records can be unrepresentative.
That doesn't mean the scientists won't use the land surface temperatures — they will! Just that sea surface temperature is particularly valuable.
"There had been quite an ongoing effort for a long time in developing sea surface temperature sets," says Allan, "and we have a long set of sea surface temperatures so this project is to see if we could recover more sea surface temperature data."
The amount of work involved in delving into the logbooks to uncover the weather observations is huge! The work involved is way too much for a small team, but with the power of citizen science, the information can be unlocked by sharing the load.
Unfortunately, it's not the sort of thing that a computer can be trained to do. Reading handwritten text is a skill that people and not computers excel in. Humans are also better at identifying important information.
The weather observations found by our citizen science weather detectives will add to our understanding of our planet's weather history.
They'll go into a database called Atmospheric Circulation Reconstructions over the Earth (ACRE) which will be available to anyone.
"The idea was to get a bigger better database of the weather, where we pick up more events like El Niño, La Niña or storms," says Allan.
"So instead of 40 or 50 years of recent data you could get 150 maybe longer years of data. And then you suddenly get this much more valuable tool to feed into whatever you want to use it for."
Ambitiously, ACRE aims to put together a full history of our planet's weather back to 1850 — providing weather details all over the globe for 200 kilometre by 200 kilometre resolutions for every three to six hours. The weather details will then be used to reconstruct a 3D picture of what was happening with air masses and air pressure systems at the time. It's really like something out of a science fiction film!
Read more at Discovery News
The convention of naming tropical cyclones was begun by him — although he got in trouble once he started naming them for politicians he didn't like!
He collected log books from ships that traversed the immediate Australasian region as well as the Atlantic, Indian and Pacific oceans from 1882-1903.
Now you can help scientists decipher the data in the log books kept by Wragge — you'll notice his letterhead at the top of many of the log book pages — as part of Weather Detective, ABC Science's new citizen science project.
How could weather records written down by a 19th century sea captain possibly be useful in the 21st century?
Anyone who's prepared for a cyclone or made farming decisions based on long-term weather forecasts will understand the value of accurate predictions on what the weather will do in the future.
And while these long-term weather predictions may appear definitive and insightful, they're only as good as the past data that they're based on. That's how forecasting works, it's predicting — or modelling — the future using what's happened in the past.
So gaining as much information about past weather is really useful.
We have a good idea of the Earth's climatic history over thousands of years — mostly from geological sources — but this doesn't provide the level of detail required for forecasting weather.
"The quality and quantity of the data that you're putting in is essential to the sort of product you're putting out, because if you don't have enough you're not going to be able to produce anything meaningful," says Rob Allan, meteorologist with the UK Met Office, and and co-creator with Philip Brohan of Old Weather, the UK version of Weather Detective.
Sea surface temperatures are important
Sea surface temperature is actually a measurement of the temperature of the ocean, not the temperature on board the boat. It's measured by sticking a thermometer into a bucketful of ocean water.
Because the ocean is more homogenous than land, a single sea temperature reading can give an excellent indication of the sea temperature for a large area. Since the oceans cover 70 per cent of our planet, observations at sea are very important for understanding and predicting weather.
Land-based temperature records are also important. However, microclimates on land can lead to large variations in temperatures within a small area — for example, a shaded valley may be cooler than an open plain — which means that historical records can be unrepresentative.
That doesn't mean the scientists won't use the land surface temperatures — they will! Just that sea surface temperature is particularly valuable.
"There had been quite an ongoing effort for a long time in developing sea surface temperature sets," says Allan, "and we have a long set of sea surface temperatures so this project is to see if we could recover more sea surface temperature data."
The amount of work involved in delving into the logbooks to uncover the weather observations is huge! The work involved is way too much for a small team, but with the power of citizen science, the information can be unlocked by sharing the load.
Unfortunately, it's not the sort of thing that a computer can be trained to do. Reading handwritten text is a skill that people and not computers excel in. Humans are also better at identifying important information.
The weather observations found by our citizen science weather detectives will add to our understanding of our planet's weather history.
They'll go into a database called Atmospheric Circulation Reconstructions over the Earth (ACRE) which will be available to anyone.
"The idea was to get a bigger better database of the weather, where we pick up more events like El Niño, La Niña or storms," says Allan.
"So instead of 40 or 50 years of recent data you could get 150 maybe longer years of data. And then you suddenly get this much more valuable tool to feed into whatever you want to use it for."
Ambitiously, ACRE aims to put together a full history of our planet's weather back to 1850 — providing weather details all over the globe for 200 kilometre by 200 kilometre resolutions for every three to six hours. The weather details will then be used to reconstruct a 3D picture of what was happening with air masses and air pressure systems at the time. It's really like something out of a science fiction film!
Read more at Discovery News
Aug 10, 2014
Water's reaction with metal oxides opens doors for researchers
A multi-institutional team has resolved a long-unanswered question about how two of the world’s most common substances interact.
In a paper published recently in the journal Nature Communications, Manos Mavrikakis, professor of chemical and biological engineering at the University of Wisconsin-Madison, and his collaborators report fundamental discoveries about how water reacts with metal oxides. The paper opens doors for greater understanding and control of chemical reactions in fields ranging from catalysis to geochemistry and atmospheric chemistry.
“These metal oxide materials are everywhere, and water is everywhere,” Mavrikakis says. “It would be nice to see how something so abundant as water interacts with materials that are accelerating chemical reactions.”
These reactions play a huge role in the catalysis-driven creation of common chemical platforms such as methanol, which is produced on the order of 10 million tons per year as raw material for chemicals production and for uses like fuel. “Ninety percent of all catalytic processes use metal oxides as a support,” Mavrikakis says. “Therefore, all of the reactions including water as an impurity or reactant or product would be affected by the insights developed.”
Chemists understand how water interacts with many non-oxide metals, which are very homogeneous. Metal oxides are trickier: an occasional oxygen atom is missing, causing what Mavrikakis calls “oxygen defects.” When water meets with one of those defects, it forms two adjacent hydroxyls — a stable compound comprised of one oxygen atom and one hydrogen atom.
Mavrikakis, assistant scientist Guowen Peng and Ph.D. student Carrie Farberow, along with researchers at Aarhus University in Denmark and Lund University in Sweden, investigated how hydroxyls affect water molecules around them, and how that differs from water molecules contacting a pristine metal oxide surface.
The Aarhus researchers generated data on the reactions using scanning tunneling microscopy (STM). The Wisconsin researchers then subjected the STM images to quantum mechanical analysis that decoded the resulting chemical structures, defining which atom is which. “If you don’t have the component of the work that we provided, there is no way that you can tell from STM alone what the atomic-scale structure of the water is when absorbed on various surfaces” Mavrikakis says.
The project yielded two dramatically different pictures of water-metal oxide reactions.
“On a smooth surface, you form amorphous networks of water molecules, whereas on a hydroxylated surface, there are much more structured, well-ordered domains of water molecules,” Mavrikakis says.
In the latter case, the researchers realized that hydroxyl behaves as a sort of anchor, setting the template for a tidy hexameric ring of water molecules attracted to the metal’s surface.
Mavrikakis’ next step is to examine how these differing structures react with other molecules, and to use the research to improve catalysis. He sees many possibilities outside his own field.
“Maybe others might be inspired and look at the geochemistry or atmospheric chemistry implications, such as how these water cluster structures on atmospheric dust nanoparticles could affect cloud formation, rain and acid rain,” Mavrikakis says.
Other researchers might also look at whether other molecules exhibit similar behavior when they come into contact with metal oxides, he adds.
“It opens the doors to using hydrogen bonds to make surfaces hydrophilic, or attracted to water, and to (template) these surfaces for the selective absorption of other molecules possessing fundamental similarities to water,” Mavrikakis says. “Because catalysis is at the heart of engineering chemical reactions, this is also very fundamental for atomic-scale chemical reaction engineering.”
Read more at Science Daily
In a paper published recently in the journal Nature Communications, Manos Mavrikakis, professor of chemical and biological engineering at the University of Wisconsin-Madison, and his collaborators report fundamental discoveries about how water reacts with metal oxides. The paper opens doors for greater understanding and control of chemical reactions in fields ranging from catalysis to geochemistry and atmospheric chemistry.
“These metal oxide materials are everywhere, and water is everywhere,” Mavrikakis says. “It would be nice to see how something so abundant as water interacts with materials that are accelerating chemical reactions.”
These reactions play a huge role in the catalysis-driven creation of common chemical platforms such as methanol, which is produced on the order of 10 million tons per year as raw material for chemicals production and for uses like fuel. “Ninety percent of all catalytic processes use metal oxides as a support,” Mavrikakis says. “Therefore, all of the reactions including water as an impurity or reactant or product would be affected by the insights developed.”
Chemists understand how water interacts with many non-oxide metals, which are very homogeneous. Metal oxides are trickier: an occasional oxygen atom is missing, causing what Mavrikakis calls “oxygen defects.” When water meets with one of those defects, it forms two adjacent hydroxyls — a stable compound comprised of one oxygen atom and one hydrogen atom.
Mavrikakis, assistant scientist Guowen Peng and Ph.D. student Carrie Farberow, along with researchers at Aarhus University in Denmark and Lund University in Sweden, investigated how hydroxyls affect water molecules around them, and how that differs from water molecules contacting a pristine metal oxide surface.
The Aarhus researchers generated data on the reactions using scanning tunneling microscopy (STM). The Wisconsin researchers then subjected the STM images to quantum mechanical analysis that decoded the resulting chemical structures, defining which atom is which. “If you don’t have the component of the work that we provided, there is no way that you can tell from STM alone what the atomic-scale structure of the water is when absorbed on various surfaces” Mavrikakis says.
The project yielded two dramatically different pictures of water-metal oxide reactions.
“On a smooth surface, you form amorphous networks of water molecules, whereas on a hydroxylated surface, there are much more structured, well-ordered domains of water molecules,” Mavrikakis says.
In the latter case, the researchers realized that hydroxyl behaves as a sort of anchor, setting the template for a tidy hexameric ring of water molecules attracted to the metal’s surface.
Mavrikakis’ next step is to examine how these differing structures react with other molecules, and to use the research to improve catalysis. He sees many possibilities outside his own field.
“Maybe others might be inspired and look at the geochemistry or atmospheric chemistry implications, such as how these water cluster structures on atmospheric dust nanoparticles could affect cloud formation, rain and acid rain,” Mavrikakis says.
Other researchers might also look at whether other molecules exhibit similar behavior when they come into contact with metal oxides, he adds.
“It opens the doors to using hydrogen bonds to make surfaces hydrophilic, or attracted to water, and to (template) these surfaces for the selective absorption of other molecules possessing fundamental similarities to water,” Mavrikakis says. “Because catalysis is at the heart of engineering chemical reactions, this is also very fundamental for atomic-scale chemical reaction engineering.”
Read more at Science Daily
Ancient shellfish remains rewrite 10,000-year history of El Nino cycles
The planet's largest and most powerful driver of climate changes from one year to the next, the El Niño Southern Oscillation in the tropical Pacific Ocean, was widely thought to have been weaker in ancient times because of a different configuration of the Earth's orbit. But scientists analyzing 25-foot piles of ancient shells have found that the El Niños 10,000 years ago were as strong and frequent as the ones we experience today.
The results, from the University of Washington and University of Montpellier, question how well computer models can reproduce historical El Niño cycles, or predict how they could change under future climates. The paper is now online and will appear in an upcoming issue of Science.
"We thought we understood what influences the El Niño mode of climate variation, and we've been able to show that we actually don't understand it very well," said Julian Sachs, a UW professor of oceanography.
The ancient shellfish feasts also upend a widely held interpretation of past climate.
"Our data contradicts the hypothesis that El Niño activity was very reduced 10,000 years ago, and then slowly increased since then," said first author Matthieu Carré, who did the research as a UW postdoctoral researcher and now holds a faculty position at the University of Montpellier in France.
In 2007, while at the UW-based Joint Institute for the Study of the Atmosphere and Ocean, Carré accompanied archaeologists to seven sites in coastal Peru. Together they sampled 25-foot-tall piles of shells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.
While in graduate school, Carré had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.
The shells provide 1- to 3-year-long records of monthly temperature of the Pacific Ocean along the coast of Peru. Combining layers of shells from each site gives water temperatures for intervals spanning 100 to 1,000 years during the past 10,000 years.
The new record shows that 10,000 years ago the El Niño cycles were strong, contradicting the current leading interpretations. Roughly 7,000 years ago the shells show a shift to the central Pacific of the most severe El Niño impacts, followed by a lull in the strength and occurrence of El Niño from about 6,000 to 4,000 years ago.
One possible explanation for the surprising finding of a strong El Niño 10,000 years ago was that some other factor was compensating for the dampening effect expected from cyclical changes in Earth's orbit around the sun during that period.
"The best candidate is the polar ice sheet, which was melting very fast in this period and may have increased El Niño activity by changing ocean currents," Carré said.
Around 6,000 years ago most of the ice age floes would have finished melting, so the effect of Earth's orbital geometry might have taken over then to cause the period of weak El Niños.
In previous studies, warm-water shells and evidence of flooding in Andean lakes had been interpreted as signs of a much weaker El Niño around 10,000 years ago.
Read more at Science Daily
The results, from the University of Washington and University of Montpellier, question how well computer models can reproduce historical El Niño cycles, or predict how they could change under future climates. The paper is now online and will appear in an upcoming issue of Science.
"We thought we understood what influences the El Niño mode of climate variation, and we've been able to show that we actually don't understand it very well," said Julian Sachs, a UW professor of oceanography.
The ancient shellfish feasts also upend a widely held interpretation of past climate.
"Our data contradicts the hypothesis that El Niño activity was very reduced 10,000 years ago, and then slowly increased since then," said first author Matthieu Carré, who did the research as a UW postdoctoral researcher and now holds a faculty position at the University of Montpellier in France.
In 2007, while at the UW-based Joint Institute for the Study of the Atmosphere and Ocean, Carré accompanied archaeologists to seven sites in coastal Peru. Together they sampled 25-foot-tall piles of shells from Mesodesma donacium clams eaten and then discarded over centuries into piles that archaeologists call middens.
While in graduate school, Carré had developed a technique to analyze shell layers to get ocean temperatures, using carbon dating of charcoal from fires to get the year, and the ratio of oxygen isotopes in the growth layers to get the water temperatures as the shell was forming.
The shells provide 1- to 3-year-long records of monthly temperature of the Pacific Ocean along the coast of Peru. Combining layers of shells from each site gives water temperatures for intervals spanning 100 to 1,000 years during the past 10,000 years.
The new record shows that 10,000 years ago the El Niño cycles were strong, contradicting the current leading interpretations. Roughly 7,000 years ago the shells show a shift to the central Pacific of the most severe El Niño impacts, followed by a lull in the strength and occurrence of El Niño from about 6,000 to 4,000 years ago.
One possible explanation for the surprising finding of a strong El Niño 10,000 years ago was that some other factor was compensating for the dampening effect expected from cyclical changes in Earth's orbit around the sun during that period.
"The best candidate is the polar ice sheet, which was melting very fast in this period and may have increased El Niño activity by changing ocean currents," Carré said.
Around 6,000 years ago most of the ice age floes would have finished melting, so the effect of Earth's orbital geometry might have taken over then to cause the period of weak El Niños.
In previous studies, warm-water shells and evidence of flooding in Andean lakes had been interpreted as signs of a much weaker El Niño around 10,000 years ago.
Read more at Science Daily
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