Oct 22, 2014

Humpback Dino Was Literally Unsinkable

New fossils for an incredibly long-armed dinosaur nicknamed "Horrible Hands" reveal that it had a prominent hunchback, ate both plants and animals, and had features that prevented it from sinking into wet ground.

The discoveries, presented in the latest issue of the journal Nature, unravel a nearly 50-year-old mystery concerning the dinosaur, Deinocheirus mirificus. Fossils for the dinosaur's 8-foot-long arms were found in 1965, but little else, leaving paleontologists with a lot of unanswered questions concerning "Horrible Hands."

With two almost complete skeletons now pieced together, most of the mysteries have been resolved, yet the dinosaur has lost none of its shock value.

Lead author Yuong-Nam Lee told Discovery News that the dinosaur had "a peculiar humpbacked form with a duckbill-like skull. It measured 36 feet long, weighed 14,000 pounds and lived 70 million years ago."

Lee is director of the Geological Museum at the Korea Institute of Geoscience and Mineral Resources. He and his colleagues came to the conclusions after studying the newly found fossils.

The fossils were originally located at the Nemegt Formation in Mongolia. Poachers not associated with the research team found some of the parts that wound up in private hands before being repatriated to Mongolia, making the recent study possible.

"Horrible Hands" turns out not to have been so horrible. Because its arms are the longest on record for any two-legged animal, paleontologists suspected that the dinosaur could have been a ferocious predator on par with meat-loving hunters like T. rex and Allosaurus.

The dinosaur, however, lacked an important feature that would have completed such an imagined picture: teeth.

Toothless Deinocheirus instead sported a beak. Stomach remains suggest that the dinosaur died with a belly full of fish and probably plants too. Gastroliths (small swallowed stones) helped to pulverize all of the edibles grabbed by the dinosaur's beak and claws.

"Long forearms with giant claws may have been used for digging and gathering herbaceous plants in riverside and lakeside environments," Lee said, adding that he and his colleagues doubt that the dinosaur swam.

Instead, they believe it frequently stood on very wet substrates, which can be like quicksand for animals. To support such a lifestyle, the dinosaur evolved sink-repellent squared-off toes that functioned similar to snowshoes.

"The tips of the pedal unguals (toe bones) are wide and flattened," he explained. "Much less downward force per unit area causes the blunt unguals not to sink in deeper on substrates. Some fossils show that theropod (two-legged carnivorous) dinosaurs died after becoming mired in mud."

As for the dinosaur's prominent hump, he and his team believe it was primarily for display. The intricate system of ligaments within it also likely helped to support the dinosaur's abdomen from the hips and hind limbs "in a manner similar to an asymmetrical cable-stayed bridge."

"The new finds help close a chapter on a mystery," said vertebrate paleontologist Thomas Holtz, Jr., of both the University of Maryland and the National Museum of Natural History. "We've known about Deinocheirus as long as I've been alive. Basically every book on dinosaurs featured these enormous theropod arms with the statement, 'Some day we may know what the whole dinosaur looks like.' Well, now we do."

Read more at Discovery News

Ancient Human Skulls Shed Light on Dairy Use

The DNA from ancient human bones is shedding new light on the prehistory of Europe, such as when changes in skin color and lactose tolerance occurred, researchers say.

This research unexpectedly revealed that ancient Europeans started dairying thousands of years before they evolved genes to make the most of milk in adulthood, investigators added.

Scientists examined ancient DNA extracted from 13 individuals in archaeological burial sites unearthed during highway construction in the Great Hungarian Plain in Central Europe. This crossroads for Eastern and Western cultures experienced significant transformations in culture and technology known to have shaped European prehistory. The bones at the site span about 5,000 years, from 5,700 B.C. to 800 B.C., ranging across the Stone, Copper, Bronze and Iron Ages.

After several years of experimentation with a variety of kinds of bones, the researchers discovered the best place to recover ancient DNA for analysis in humans is the petrous bone, a pyramidal bone at the base of the skull. The name petrous comes from the Latin word "petrosus," meaning "stonelike." The petrous bone is the hardest bone in the human body and very dense, forming a protective case for the inner ear.

"The high-percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold,"the study's joint senior author Ron Pinhasi, an archaeologist at University College Dublin in Ireland, said in a statement. "This gave us anywhere between 12 percent and almost 90 percent human DNA in our samples, compared to somewhere between 0 percent and 20 percent obtained from teeth, fingers and rib bones."

The DNA the scientists recovered helped them systematically examine the skeletons. "Our findings show progression towards lighter skin pigmentation as hunter-and-gatherers and nonlocal farmers intermarried," Pinhasi said in the statement.

The scientists also found that great changes in prehistoric technology, such as the adoption of farming, and the first use of hard metals such as bronze and then iron, were each associated with the substantial influx of new people.

In the Neolithic or New Stone Age, ancient central Europeans did not look anything like modern central Europeans, "but were closer to Sardinians," or people from the Italian island of Sardinia, Pinhasi told Live Science. "With the Bronze Age, you get a total shift into populations that look more like Western Europeans, and in the Iron Age you get another shift, with people genetically coming from the East, such as the Caucasus or Asia. These shifts were probably associated with major migrations and population turnovers in Central Europe."

Surprisingly, Pinhasi and his colleagues found that ancient Central Europeans apparently remained intolerant to lactose, the natural sugar in the milk of mammals, until the Bronze Age, about 4,000 years after these people began dairying. Artifacts that archaeologists previously unearthed suggest ancient Europeans started dairying 7,500 years ago in the Neolithic period. Most of the world is lactose intolerant, unable to digest lactose as adults, and the evolution of the ability to break down this sugar in adulthood helped Europeans take advantage of animal milk, a highly nutritious food.

"These ancient Europeans would have raised domesticated animals such as cows, sheep and goats without having yet developed the genetic tolerance for drinking milk from mammals without problems," Pinhasi said.

Pinhasi suggested ancient Europeans may have practiced dairying "not to drink milk, but to consume milk products such as cheese and yogurt," he said. "The processes that make cheese and yogurt break down lactose. Nowadays, in the Caucasus region, most people eat cheese and yogurt, but milk drinking is not a big thing."

Read more at Discovery News

45,000-Year-Old Man Was Human-Neanderthal Mix

A bone found by chance on the banks of a Siberian river has yielded the oldest modern human genome yet recovered, according to a new study that sheds light on when people left Africa and first interbred with Neanderthals living in Europe and Asia.

The man, who lived 45,000 years ago, was definitely related to both humans and Neanderthals, the study published in the journal Nature reports. His DNA showed that the two human groups first mated around 60,000 years ago.

Project leader Chris Stringer of the Natural History Museum in London explained to Discovery News that the Siberian man belonged to a population that was closely related to the ancestors of today’s Europeans and Asians. He carried only slightly more Neanderthal DNA than they do.

“But his genomic segments of Neanderthal ancestry are on average about three times the length of those found in genomes today,” Stringer said.

This is highly informative, he continued, “as the chunks of Neanderthal DNA have been gradually broken up each generation since the time of interbreeding.”

He and his team charted the rate of that change to the present, when all living non-Africans possess 2 percent Neanderthal in their DNA. Going backwards in time, the researchers could then see that the mating with Neanderthals took place 7,000–10,000 years before the Siberian man lived. This means the human/Neanderthal interbreeding happened no more than 60,000 years ago.

A simple explanation would then be that Homo sapiens first left Africa at around 60,000 years ago, but other finds dispute that. Anthropologists have found 100,000-year-old skeletons for our species in the Israeli caves of Skhul and Qafzeh.

Putting the pieces together results in two possible scenarios:

1- People left Africa sometime around 100,000 years ago but failed to have successful, lasting settlements. A later group left Africa approximately 60,000 years ago, resulting in a successful dispersal. This group gave rise to all of today’s non-Africans.

2. People left Africa 100,000 years ago and were successful. Members of their group took a while to disperse, with one wave reaching southern Asia before 75,000 years ago, eventually reaching Australia and New Guinea. Then, Stringer said, describing this scenario, “a second wave at around 60,000 years ago carried the ancestors of present day Eurasians and Native Americans out of Africa.”

So which scenario is the one that really happened? The Siberian man provides a constraint on the theories, indicating that interbreeding with Neanderthals is unlikely to have happened before 60,000 years ago.

Read more at Discovery News

'Hobbit Humans' Actually Might Not Have Been Human

Ten years after being discovered, the “Hobbit Human” remains a controversial figure, with some researchers now thinking that this diminutive human-like being might not have been human after all.

A commentary in the latest issue of Nature theorizes that the Hobbit Human could have descended from a more ancient pre-human group called Australopithecus, of which the 3.2-million-year-old skeleton “Lucy” is the most famous representative. Lucy might have to share the spotlight with the Hobbit, though, if the theory is proven to be correct.

A quick refresher: The Hobbit Human, aka Homo floresiensis, was a 3 1/2 foot tall species with huge feet that lived on the remote Indonesian island as early as 13,000 years ago.

The prevailing theory has been that the Hobbit was a member of our family tree, belonging to the genus Homo and having descended from a population of Homo erectus that made its way to the island and shrunk in stature over evolutionary time due to the “island effect.” (Because islands are relatively closed communities, evolution tends to lead to smaller forms.) Remains for a handful of Hobbits were found with stone tools and bones of a pygmy form of the now-extinct, elephant-like Stegodon.

Renowned paleoanthropologist Chris Stringer from the Natural History Museum in London questioned some parts of this theory.

In his Nature commentary, Stringer wrote that the tiny brain of one of the excavated Hobbits as well as its body shape and individual bones “look more primitive than those of any human dating to within the past million years.”

The Hobbit jaw and chin are “most like those in pre-human fossils more than 2 million years old,” Stringer wrote.

The Hobbit therefore shares traits with Australopithecus. This presents a real mind blower.

We’ve tended to assume that only Homo sapiens left Africa, interbred with locals in Europe and Asia (like Neanderthals and Denisovans), resulting in today’s non-Africans.

But what if other species, like Australopithecus, also left Africa, made it to places like Indonesia, and successfully settled there until more recent times? The plot thickens.

Read more at Discovery News

Fantastically Wrong: The Scientist Who Thought That Birds Migrate to the Moon

A couple hundred feet down, a couple hundred thousand miles to go.
In the classic millennial film The Mighty Ducks, which was so awesome it convinced me and my frail pre-teen body to become a roller hockey goalie (to predictable ends), the team makes use of the iconic “Flying V” formation when in a pinch. The power of such a formation is of course proven in migrating birds, which can better cruise when in the upwash of the individuals ahead of them as they make their way to more hospitable climes in the winter.

Sure, now we know where they go, but our forebears really struggled with the problem of birds disappearing every winter. There were all kinds of theories, but none was more bizarre than that of English minister and scientist Charles Morton, who in the 17th century wrote a surprisingly well-reasoned, though obviously totally inaccurate, treatise claiming birds migrate to the moon and back every year.

That’s right. To the moon and back. And Morton was even aware of how epic this journey would be. He estimated the one-way trip to be 179,712 miles (he wasn’t so far off—the moon varies between 226,000 miles and 252,000 miles away, on account of its elliptical orbit), and reckoned it would take the birds 60 days to reach our satellite flying a dizzying 125 mph. Still, Morton reasoned, they pulled it off. And, really, because some species seem to disappear entirely, the only logical conclusion is that they set off into space. “Now, whither should these creatures go, unless it were to the moon?” he asked.

Whither should they go indeed.

Flock and Awe

Before we get to the particulars of Morton’s strange theory of migration, it’s worth noting the many other theories of antiquity, beginning with Aristotle, who reckoned that some birds hibernate while others simply transform into different species when winter comes around. Redstarts, for instance, morph into robins in winter—a fantastical claim that’s easier to understand when you consider that redstarts indeed migrate to Africa as robins make their way to Greece.

A pygmy battles his ruthless enemy, the crane, with nothing but a stick and a sombrero.
Later, the great Roman naturalist Pliny the Elder wrote of the pygmies, a race of tiny humans in Africa that do eternal battle with cranes (the birds, not the construction equipment). He notes “that in springtime their entire band, mounted on the backs of rams and she-goats and armed with arrows, goes in a body down to the sea and eats the cranes’ eggs and chickens, and that this outing occupies three months.” It’s an echo of Homer’s mention of cranes in the Iliad, birds that do indeed migrate from Europe to Africa: “shriek of cranes down from heaven / who flee the winter and the terrible rains / and fly off to the world’s end / bringing death and doom to the Pygmy-men / as they open fierce battle at dawn.”

Barnacle geese hatch from a tree.
Medieval bestiaries, sorts of zoological encyclopedias that every once in a while contained actual facts, often featured the barnacle goose, which supposedly grows on trees over water. It was a convenient explanation for geese simply turning up, seemingly out of nowhere, after their migration. Also convenient: Catholics aren’t supposed to eat meat other than fish on Fridays, but because the barnacle goose isn’t born from an egg, wrote Gerald of Wales in 1187, “in some parts of Ireland, bishops and men of religion make no scruple of eating these birds on fasting days, as not being flesh, because they are not born of flesh.” (The same logic has variously been applied to beavers, whose tails apparently taste like fish, as well as the giant rodent capybara of South America, which spends so much time in marshes that some argued to the church that it should be classified as a fish.)

In the 16th century, the great cartographer and writer Olaus Magnus championed the theory that swallows disappear in the winter not because they travel to tropical climes to pick up coconuts, but because they bury themselves in the clay at the bottom of rivers. They come together in the fall in huge swarms, then sink down into the mud en masse, only to reemerge in the spring. But in his famous map the Carta Marina, Magnus also echoed the tale of the barnacle goose with an illustration of ducks being born from a tree.

Fly Me to the Moon

But back to Morton. According to Thomas P. Harrison in his essay “Birds in the Moon,” Morton quite rightly noted that migrating avians recognize “changes of the air where they are,” or notice the “alteration of abatement of their daily food,” and are therefore stirred to “obtain what is more suitable to them or to avoid what is offensive” and begin their migration. He refutes, however, the position of Olaus Magnus that birds make their way into the clay at the bottoms of rivers. There’s the rather glaring problem of the lack of air, he notes, not to mention frigid temperatures.

A woodcock passionately denying rumors that it migrates to the moon. Yes, this is what it looks like when birds passionately deny rumors.
Instead, because no one has seen where these birds go, they must be leaving Earth. Why else, then, would sailors report a woodcock flying in to land on their ship not from the horizon, but “right down from above”? It had to have been returning to our planet from space.

But how could they get back and forth between the celestial bodies? Luckily, in space the birds “encounter no air resistance and are unaffected by gravitation,” writes Harrison. “They are sustained by excess fat,” which turns out to be true in migrating birds, “and they sleep most of the journey of two months.” (Definitely not true, though migrating birds do indeed nod off for a few seconds at a time.)

Now, it’s important to note that it was a widely held belief in Morton’s time that all of the planets in our solar system must necessarily be inhabited, since a higher power wouldn’t take the trouble of creating planets and moons and have them just sit there all lonely-like. Even the discoverer of Uranus, William Herschel, went so far as to argue in 1795 that the sun held life as well. And even as late as the early 1900s, American astronomer Percival Lowell claimed he had discovered alien-built canals on Mars, which turned out to just be an optical illusion.

So Morton’s birds would find the moon quite well-appointed with vegetation and water. Indeed, according to Harrison, Morton’s inspiration for all of this likely came from John Wilkins, a founder of the famed Royal Society, who in 1638 published “The Discovery of a New World in the Moon.” In it, Wilkins argued “that the moon, with its borrowed light, is like our earth with its seas, streams, mountains, and so on,” writes Harrison. Wilkins goes on to suggest humans might get to the moon by attaching wings to our arms, or train birds to take us there.

The adventurous Domingo Gonsales and his flying machine made of swans.
Then along comes the author Francis Godwin, who just five months after Wilkins’ work publishes the tale of the adventurer Domingo Gonsales. Our hero trains 25 probably-somewhat-hesitant swans to ferry him around, but to his “unspeakable fear and amazement, [the birds] struck bolt upright” higher and higher and higher, until “the lines slacked; neither I nor the engine moved at all, but continued still, as having no manner of weight.”

They were on their way to the moon. And when they arrived Gonsales found trees three times as high and five times as thick as our own. But more importantly, there was wildlife, none of which compared to ours, “except swallows, nightingales, cuckows, woodcocks, batts, and some kind of wild fowl,” birds that “spend their time, in their absence from us, in that world.”

Such fiction became science in the 1600s, according to Harrison, and greatly influenced Morton’s theory of the moon migration. But in 1676, a man named Francis Willughby set us down the path to avian truth when he published Ornithologia, a masterwork of bird science we can file with such classics as John James Audubon’s Birds of America. While Willughby, like Morton, refuted Aristotle’s notion that swallows hibernate, he wasn’t under the impression that they instead went to the moon. More modestly, it was to the warmth of northern Africa.

Read more at Wired Science

Oct 21, 2014

6,000-Year-Old Temple with Possible Sacrificial Altars Found

A 6,000-year-old temple holding human-like figurines and sacrificed animal remains has been discovered within a massive prehistoric settlement in Ukraine.

Built before writing was invented, the temple is about 60 by 20 meters (197 by 66 feet) in size. It was a "two-story building made of wood and clay surrounded by a galleried courtyard," the upper floor divided into five rooms, write archaeologists Nataliya Burdo and Mykhailo Videiko in a copy of a presentation they gave recently at the European Association of Archaeologists' annual meeting in Istanbul, Turkey.

Inside the temple, archaeologists found the remains of eight clay platforms, which may have been used as altars, the finds suggested. A platform on the upper floor contains "numerous burnt bones of lamb, associated with sacrifice," write Burdo and Videiko, of the Institute of Archaeology of the National Academy of Sciences of Ukraine. The floors and walls of all five rooms on the upper floor were "decorated by red paint, which created ceremonial atmosphere."

The ground floor contains seven additional platforms and a courtyard riddled with animal bones and pottery fragments, the researchers found.

Massive settlement

The temple, which was first detected in 2009, is located in a prehistoric settlement near modern-day Nebelivka. Recent research using geophysical survey indicates the prehistoric settlement is 238 hectares (588 acres), almost twice the size of the modern-day National Mall in Washington, D.C. It contained more than 1,200 buildings and nearly 50 streets.

A number of other prehistoric sites, of similar size, have been found in Ukraine and other parts of Eastern Europe. These sites are sometimes referred to as belonging to the "Trypillian" culture, a modern-day name. The name is derived from the village of Trypillia in Ukraine, where artifacts of this ancient culture were first discovered.

Archaeologists found that when this prehistoric settlement was abandoned, its structures, including the newly discovered temple, were burnt down, something that commonly occurred at other Trypillian culture sites.

Ornaments and figurines

Fragments of figurines, some of which look similar to humans, were also found at the temple. Like findings at other Trypillian sites, some of the figurines have noses that look like beaks and eyes that are dissimilar, one being slightly larger than the other.

Ornaments made of bone and gold were also discovered at the temple. The gold ornaments are less than an inch in size and may have been worn on the hair, researchers say.

Read more at Discovery News

King Tut Re-Creation Presents a Shocking Image

Tutankhamun’s beautiful golden mask, the embodiment of a man secure in his power, has been flattering the pharaoh for many centuries, according to the most detailed image yet of the teenage king’s face and body.

In the flesh, King Tut had a club foot, a pronounced overbite and girlish hips, says a “virtual autopsy” built using more than 2,000 computerized tomography (CT) scans of the pharaoh’s body.

Built for the BBC documentary, “Tutankhamun: the Truth Uncovered,” the shocking 3-D computer model could shed new light on the death of the boy pharaoh at the age of 19.

Previous theories suggested King Tut may have died as a result of a chariot accident, but the virtual reconstruction showed a different scenario.

“It was important to look at his ability to ride on a chariot and we concluded it would not be possible for him, especially with his partially clubbed foot, as he was unable to stand unaided,” Albert Zink, head of the Institute for Mummies and Icemen in Italy, told the U.K. daily The Independent.

According to Ashraf Selim, an Egyptian radiologist, King Tut “also developed Kohler’s disease or death of the bones, during adolescence, which would have been incredibly painful.”

Indeed, about 130 walking sticks found in King Tut’s treasure-packed tomb would support the theory that the boy pharaoh had to rely on canes to get around.

Zink believes the pharaoh’s early death was most likely caused from his weakened state — a result of genetic impairments inherited from his parents, who were siblings.

Indeed, in 2010 an international genetic study produced a five-generation pedigree of Tutankhamun’s immediate lineage. In the study, the mummy known as KV55 — most likely the “heretic” Akhenaten — and KV35YL, also known as the Younger Lady, were identified as siblings, as well as King Tut’s parents.

The study confirmed the frail king was afflicted by malaria and suffered a badly broken leg, above his knee, just before he died.

“It is difficult to say whether malaria may have been a serious factor in the cause of death,” Zink said.

The boy pharaoh has been puzzling scientists ever since his mummy and treasure-packed tomb were discovered on Nov. 22, 1922, in the Valley of the Kings by British archaeologist Howard Carter.

Read more at Discovery News

500-Year-Old Traces of Monster Hawaii Tsunami Discovered

A powerful earthquake in Alaska sent towering waves up to 30 feet (9 meters) tall crashing down on Hawaii about 500 years ago, leaving behind fragments of coral, mollusk shells and coarse beach sand in a sinkhole located on the island of Kauai, new research finds.

The quake, likely a magnitude 9.0, sent the mighty waves toward Hawaii sometime between 1425 and 1665, the study found. It's possible that another large Alaskan earthquake could trigger a comparable tsunami on Hawaii's shores in the future, experts said.

The tsunami was at least three times the size of the damaging 1946 tsunami, which was driven by an 8.6-magnitude earthquake off the Aleutian Islands. Mammoth tsunamis, like the one described in the study, are rare, and likely happen once every thousand years. There's a 0.1 percent chance it could happen in any given year, the same probability that northeastern Japan had for the 9.0-magnitude 2011 Tohoku earthquake and related tsunami, said Gerald Fryer, a geophysicist at the pacific Tsunami Warning Center in Ewa Beach, Hawaii, who was not involved in the study.

Results of the study have already prompted Honolulu officials to revise their tsunami evacuation maps, Fryer said. The new maps, which will affect nearly 1 million people who live in Honolulu County, would include more than twice the area of evacuation in some areas, Fryer said in a statement. County officials hope to distribute the new maps by the end of 2014, Fryer said.

"You're going to have great earthquakes on planet Earth, and you're going to have great tsunamis," said the study's lead researcher, Rhett Butler, a geophysicist at the University of Hawaii at Manoa. "People have to at least appreciate that the possibility is there."

Evidence of the colossal tsunami surfaced in the late 1990s during the excavation of the Makauwahi sinkhole, a collapsed limestone cave on the south coast of Kauai. About 6.5 feet (2 meters) below the surface, study researcher David Burney found a bounty of old debris that must have come from the ocean.

Curiously, the sinkhole's mouth is 328 feet (100 m) away from the present-day shore, and 23 feet (7 m) above sea level, suggesting the enormous quantities of corals and shells were probably carried there by a gigantic wave, Burney, a paleoecologist at the National Tropical Botanical Garden in Kalaheo, said. But he needed more evidence to back up his claim.

Tsunami surge

The debris remained a mystery until the 2011 Tohoku earthquake hit Japan. The earthquake triggered a rapid surge of water that stood 128 feet (39 m) above sea level and pummeled the Japanese coast. Soon after, researchers revisited Hawaii's tsunami evacuation maps. The maps are largely based on the 1946 tsunami, which caused water to rise 8 feet (2.5 m) up the side of the Makauwahi sinkhole.

"[The Japan earthquake] was bigger than almost any seismologist thought possible," Butler said. "Seeing [on live TV] the devastation it caused, I began to wonder, did we get it right in Hawaii? Are our evacuation zones the correct size?"

Butler and his colleagues assembled a wave model to predict how a tsunami might flood Kauai's coastline. They simulated earthquakes ranging between magnitudes 9.0 and 9.6 along the Aleutian-Alaska subduction zone, a 2,113-mile-long (3,400 kilometers) ocean trench where the Pacific tectonic plate slips under the North American plate.

In the aftermath of a large earthquake, the eastern Aleutians' distinctive geography could send a large tsunami toward Hawaii, the researchers found. In fact, a magnitude- 9.0 earthquake in just the right spot could easily direct water levels of 26 to 30 feet (8 to 9 m) high toward Kauai, carrying debris into the Makauwahi sinkhole, they found.

The researchers also looked for tsunami evidence in other places. Radiocarbon dating showed that the marine deposits in the sinkhole, on Sedanka Island off the coast of Alaska and along the west coasts of Canada and the United States all date back to the same time period, and may have come from the same tsunami.

"[The researchers] stitched together geological evidence, anthropological information as well as geophysical modeling to put together this story that is tantalizing for a geologist, but it's frightening for people in Hawaii," Robert Witter, a geologist at the U.S. Geological Survey in Anchorage, Alaska, who was not involved in the study, said in the statement.

More evidence is needed to determine whether the deposits came from the same tsunami, Witter said. For instance, radiocarbon dating, which the study researchers relied on, only gives a rough time estimate. It's possible that multiple tsunamis between 350 and 575 years ago deposited the debris at the three locations, he said.

Read more at Discovery News

When Massive Black Holes Snuff Out Star Birth

As galaxies mature, they stop forming stars — but why? Now astronomers are hot on the trail of finding the culprit.

By now we know that the vast majority of galaxies have supermassive black holes in their cores. These galactic behemoths generate some energetic phenomena, especially when matter falls onto their accretion disks and event horizons. Often, the energy generated by active galactic nuclei (where these rambunctious black holes reside), will regulate the star formation processes in their host galaxy.

Now, in a new study published in the journal Monthly Notices of the Royal Astronomical Society, researchers believe that they’ve found the reason why maturing galaxies seem to “switch off” star formation all together.

“When you look into the past history of the universe, you see these galaxies building stars,” said Tobias Marriage, of Johns Hopkins University and co-lead author of the study. “At some point, they stop forming stars and the question is: Why? Basically, these active black holes give a reason for why stars stop forming in the universe.”

Marriage and his colleagues used an established method for studying large clusters of galaxies and applying it to single galaxies. By doing this, they discovered that supermassive black holes are driving “radio-frequency feedback,” which is heating up the galaxies, preventing interstellar gases from cooling, clumping and forming new stars.

In short, massive black holes, at a certain age, act like a switch and are snuffing out star formation before it can even take hold.

Normally, the Sunyaev–Zel’dovich (SZ) effect signature is used to study how the primordial cosmic microwave background radiation (the ‘echo’ of the Big Bang) interacts with the electrons inside interstellar gases locked in clusters of hundreds of galaxies. But for the first time, this method has been down-scaled to gauge the interstellar environment of single galaxies.

“The SZ is usually used to study clusters of hundreds of galaxies but the galaxies we’re looking for are much smaller and have just a companion or two,” said Megan Gralla, also of Johns Hopkins.

“What we’re doing is asking a different question than what has been previously asked,” Gralla said. “We’re using a technique that’s been around for some time and that researchers have been very successful with, and we’re using it to answer a totally different question in a totally different subfield of astronomy.”

So, while studying the SZ effect signature in galaxies, the researchers found that all the galaxies displaying radio-frequency feedback coincided with galaxies that also lacked signs of star formation. It just so happened that these particular galaxies were large and mature elliptical galaxies, where their heated interstellar gas was prevented from cooling down.

“If gas is kept hot, it can’t collapse,” said Marriage. If the gas cannot collapse, no new stars can form.

Read more at Discovery News

Oct 20, 2014

Puppy-Sized Spider Romps in Rainforest

Piotr Naskrecki was taking a nighttime walk in a rainforest in Guyana, when he heard rustling as if something were creeping underfoot. When he turned on his flashlight, he expected to see a small mammal, such as a possum or a rat.

"When I turned on the light, I couldn't quite understand what I was seeing," said Naskrecki, an entomologist and photographer at Harvard University's Museum of Comparative Zoology.

A moment later, he realized he was looking not at a brown, furry mammal, but an enormous, puppy-size spider.

Known as the South American Goliath birdeater (Theraphosa blondi), the colossal arachnid is the world's largest spider, according to Guinness World Records. Its leg span can reach up to a foot (30 centimeters), or about the size of "a child's forearm," with a body the size of "a large fist," Naskrecki told Live Science. And the spider can weigh more than 6 oz. (170 grams) — about as much as a young puppy, the scientist wrote on his blog.

Some sources say the giant huntsman spider, which has a larger leg span, is bigger than the birdeater. But the huntsman is much more delicate than the hefty birdeater — comparing the two would be "like comparing a giraffe to an elephant," Naskrecki said.

The birdeater's enormous size is evident from the sounds it makes. "Its feet have hardened tips and claws that produce a very distinct, clicking sound, not unlike that of a horse's hooves hitting the ground," he wrote, but "not as loud."

When Naskrecki approached the imposing creature in the rainforest, it would rub its hind legs against its abdomen. At first, the scientist thought the behavior was "cute," he said, but then he realized the spider was sending out a cloud of hairs with microscopic barbs on them. When these hairs get in the eyes or other mucous membranes, they are "extremely painful and itchy," and can stay there for days, he said.

But its prickly hairs aren't the birdeater's only line of defense; it also sports a pair of 2-inch-long (5 centimeters) fangs. Although the spider's bite is venomous, it's not deadly to humans. But it would still be extremely painful, "like driving a nail through your hand," Naskrecki said.

And the eight-legged beast has a third defense mechanism up its hairy sleeve. The hairs on the front of the spider's body have tiny hooks and barbs that make a hissing sound when they rub against each other, "sort of like pulling Velcro apart," Naskrecki said.

Yet despite all that, the spider doesn't pose a threat to humans. Even if it bites you, "a chicken can probably do more damage," Naskrecki said.

Despite its name, the birdeater doesn't usually eat birds, although it is certainly capable of killing small mammals. "They will essentially attack anything that they encounter," Naskrecki said.

The spider hunts in leaf litter on the ground at night, so the chances of it encountering a bird are very small, he said. However, if it found a nest, it could easily kill the parents and the chicks, he said, adding that the spider species has also been known to puncture and drink bird eggs.

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