Mar 15, 2014

Little Foot is oldest complete Australopithecus, new stratigraphic research shows

After 13 years of meticulous excavation of the nearly complete skeleton of the Australopithecus fossil named Little Foot, South African and French scientists have now convincingly shown that it is probably around 3 million years old.

In a paper published March 14, 2014 in the Journal of Human Evolution, the latest findings by Professor Ron Clarke from the University of the Witwatersrand and his colleagues refute previous dating claims that suggested Little Foot is younger.

The paper is titled: "Stratigraphic analysis of the Sterkfontein StW 573 Australopithecus skeleton and implications for its age," and is the result of a detailed study of the stratigraphy, micro-stratigraphy, and geochemistry around the skeleton.

Little Foot's Story

The Sterkfontein caves of Gauteng, South Africa have been world famous since 1936 for producing large numbers of fossils of the ape-man Australopithecus. However, for sixty years, these fossils consisted only of partial skulls and jaws, isolated teeth and fragments of limb bones. These were obtained by blasting or drilling and breaking of the calcified ancient cave infill or by pick and shovel excavation of the softer decalcified infills.

Questions arose about the age of these fossils, of how they came to be in the caves, and also of how a complete skeleton would appear. Then in 1997 Ron Clarke, Stephen Motsumi and Nkwane Molefe of the University of the Witwatersrand discovered an almost complete Australopithecus skeleton with skull embedded in hard, calcified sediment in an underground chamber of the caves. They began to carefully excavate this skeleton in order to expose it in place in the cave and to understand the ancient processes that contributed to its burial and preservation.

This was the first time that such an excavation of an Australopithecus has taken place in an ancient calcified deposit. During the course of this excavation, it became clear that the skeleton had been subjected to ancient disturbance and breakage through partial collapse into a lower cavity and that calcareous flowstone had subsequently filled voids formed around the displaced bones.

Despite this fact being published, some other researchers dated the flowstones and claimed that such dates represent the age of the skeleton. This has created a false impression that the skeleton is much younger than it actually is.

A French team of specialists in the study of limestone caves, Laurent Bruxelles, Richard Maire and Richard Ortega, together with Clarke and Dominic Stratford of Wits University, have now, with this research published in the Journal of Human Evolution today, shown that the dated flowstones filled voids formed by ancient erosion and collapse and that the skeleton is therefore older, probably considerably older, than the dated flowstones.

Little Foot is probably around 3 million years old, and not the 2.2 million years that has been wrongly claimed by other researchers. The skeleton has been entirely excavated from the cave and the skull, arms, legs, pelvis and other bones have been largely cleaned of encasing rock.

Read more at Science Daily

New fossil species reveals parental care of young from 450 million years ago

A portrait of prehistoric parenthood captured deep in the fossil record has been uncovered by an international team of scientists led by University of Leicester geologist Professor David Siveter.

The 'nursery in the sea' has revealed a species new to science -- with specimens preserved incubating their eggs together with probable hatched individuals. As a result, the team has named the new species Luprisca incuba after Lucina, goddess of childbirth, and alluding to the fact that the fossils are ancient and in each case the mother was literally sitting on her eggs.

The find, published in the journal Current Biology, provides conclusive evidence of a reproductive and brood-care strategy conserved for at least 450 million years. It also represents the oldest confirmed occurrence of ostracods in the fossil record.

Professor Siveter, Emeritus Professor of Palaeontology at the University of Leicester, said: "This a very rare and exciting find from the fossil record. Only a handful of examples are known where eggs are fossilized and associated with the parent. This discovery tells us that these ancient tiny marine crustaceans took particular care of their brood in exactly the same way as their living relatives."

The team from the UK, USA and Japan has discovered a new and scientifically important species of a fossil ostracod- an animal group related to shrimps, lobsters and crabs -- in mudstone rocks from New York State, USA, dating back to the Ordovician period of geological time. Ostracods are tiny crustaceans known from thousands of living species in oceans to rivers, lakes and ponds today and from countless fossil shells.

The newly discovered fossils are two to three millimetres long and are especially informative because they are exceptionally well preserved, complete with not only the shell but also the soft parts of the animal that in all but very rare cases are lost to the fossil record. Limbs and in some specimens a clutch of eggs are present within the bivalved shell, enabling the scientists to identify and gender such specimens. These anatomical features were preserved in the mineral pyrite, which facilitated the use of x-ray techniques to reveal morphological details hidden within the shells and the rock.

Professor Siveter, of the University of Leicester's Department of Geology, together with researchers from the universities of Yale and Kansas, USA, Oxford, UK, and the Japan Agency of Marine Science and Technology, discovered the tiny arthropods.

Read more at Science Daily

Mar 14, 2014

Secrets of Chinese Terra-Cotta Warrior Weapons Revealed

One of the most astounding archaeological discoveries of the 20th century is arguably the life-size terra-cotta army buried alongside China's first emperor. Now, scientists have figured out how the bronze triggers for the crossbows of the 8,000 terra-cotta warriors were manufactured.

Teams of craftspeople worked in small groups to produce the bronze pieces in batches for the tomb of ancient Emperor Qin Shi Huang, according to a new study detailed in the March issue of the journal Antiquity.

Prepared for the afterlife

Historical documents suggest that soon after Emperor Qin Shi Huang ascended to the throne in 246 B.C., he began work on his tomb near Xi'an, China. When the tomb was first unearthed in the 1970s,it revealed thousands of lifelike terra-cotta statues of artisans, musicians, officials, horses and soldiers. The epic effort conscripted 700,000 laborers, many of whom were convicts or people who were in debt to the empire, said study co-author Xiuzhen Janice Li, an archaeologist who was at the University College London at the time of the new work and is now at the Emperor Qin Shi Huang’s Mausoleum Site Museum in China.

The massive undertaking had an important goal: ensuring the emperor's military power and resources in the afterlife.

As part of the huge project, craftspeople sculpted about 8,000 colorful warriors — likely using real human beings as inspiration — and those warriors wore stone armor and "wielded" lances, swords and crossbows.

But it wasn't clear exactly how these ancient weapons were made. The crossbows were made of wood or bamboo that rotted long ago, and only the tips and triggers for the bows remained, Li told Live Science.

Small workshops

To learn more about how the massive trove was built, Li and her colleagues visually inspected and measured about 216 of the five-part crossbow triggers from the mausoleum.

The lack of wear on the metal pieces suggests the weapons were never used in actual battle, but were instead built solely for the tomb, the researchers said.

In addition, the team analyzed the spots where triggers were found in the tomb, as well as the variation in the size and shape of the pieces.

The pieces were mostly uniform, suggesting the interlocking trigger parts were made in the same or nearly-identical molds and produced in small batches. Each batch of the trigger pieces was likely then assembled in small cells, or workshops, perhaps headed by an overseer. That model contrasts with the "assembly line" hypothesis that some archaeologists thought might have been used.

Mirror of society

The organization into small workshops was similar to the structure the emperor imposed on the rest of society in ancient China, said study co-author Marcos Martinón-Torres, an archaeologist at the University College London.

"He abolished any privileges inherited by blood, and the population was divided in small groups that were collectively responsible for their adherence to imperial laws," Martinón-Torres wrote in an email to Live Science. "For example, if someone in one of these groups committed a crime, all of them were held responsible, unless they reported the culprit and allowed them to be punished."

Ancient 'Ritual Wand' Etched with Human Faces Found in Syria

Archaeologists have unearthed an ancient staff carved with two realistic human faces in southern Syria.

The roughly 9,000-year-old artifact was discovered near a graveyard where about 30 people were buried without their heads — which were found in a nearby living space.

"The find is very unusual. It's unique," said study co-author Frank Braemer, an archaeologist at the Centre National de la Recherche Scientifique in France.

The wand, which was likely used in a long-lost funeral ritual, is one of the only naturalistic depictions of human faces from this time and place, Braemer said.

Ancient site

Researchers first uncovered the wand during excavations in 2007 and 2009 at a site in southern Syria called Tell Qarassa, where an artificial mound made from the debris of everyday human life gradually built up in layers over millennia. (Though many stunning archaeological sites have been looted or bombed since the onset of the Syrian Civil War, this site is in a fairly peaceful area and has so far escaped damage.)

Other archaeological evidence from the site suggests the ancient inhabitants were amongst the world's first farmers, consuming emmer (a type of wheat), barley, chickpeas and lentils, and herding or hunting goats, gazelles, pigs and deer, the authors write in the March issue of the journal Antiquity.

Mysterious wand

After the skeletons and wand were buried, someone seems to have dug up and removed the skulls, placing them in the inhabited portion of the settlement.

The bone wand was likely carved from the rib of an auroch, the wild ancestor of cows, and was about 4.7 inches (12 centimeters) long. Two natural-looking faces, with eyes closed, were carved into the bone, though the wand was intentionally broken at both ends, with more faces likely originally adorning the staff.

The relic's purpose and symbolism remain a mystery.

"It's clearly linked to funerary rituals, but what kind of rituals, it's impossible to tell," Braemer told Live Science.

The find marks a transition in culture toward more interest in the human form. Older artifacts typically showed stylized or schematic representations of humans, but realistic depictions of animals. Art unearthed in what is now Jordan and Anatolia from the same time period also employs delicate, natural representations of the human form, suggesting this trend emerged simultaneously in regions throughout the Middle East, Braemer said.

The artistic innovation may have been tied to the emerging desire to create material representations of identity and personhood, the authors write in the paper.

Read more at Discovery News

Human Ancestor's Skeleton Dated to 3 Million Years

For more than a decade, anthropologists have debated the age of the Australopithecus fossil called “Little Foot,” as they excavated the nearly complete skeleton of the extinct potential ancestor of humans. Now scientists say they have conclusively shown the specimen is about 3 million years old.

A recent analysis of stone surrounding the fossils found evidence of the bones’ age and suggested Little Foot may be the oldest nearly complete Australopithecus skeleton ever found.

Soon after the initial find, a magnetic study suggested the bones were 3.3 million years old. However, a 2006 study published in Science started an anthropological controversy when it suggested Little Foot’s bones were 2.2 million years old, based on the age of calcium-rich rocks surrounding the fossils. Two other later studies dated the skeleton to 2.35 and 2.58 million years ago, using a technique known as uranium-lead decay dating.

Recently, Little foot’s discoverer, anthropologist Ronald Clarke of the University of Witwatersrand in South Africa, and colleagues weighed in. They suggested geology may have confounded the estimates of Little Foot’s age, in a paper published in the Journal of Human Evolution.

Clarke and his team observed the layering of the rock around Little Foot and the chemical composition of those rocks. They presented evidence that a partial collapse of the fossil-bearing stones into a lower cavity of the cave led to a confusing geological juxtaposition.

After the collapse, a calcium carbonate rock, known as flowstone, formed in the spaces around the fossils. This led to a mix-up millions of years later when scientists dated the younger rock and believed it had formed at nearly the same time as the fossils.

In 1994, Clarke identified the the small foot bones of a hominid, or human-like ape species, in a museum collection. He then hen went looking for the rest of the skeleton in the Sterkfontein Grotto cave in South Africa. In 1997, Clarke and his team found the upper leg bone of Little Foot.

Read more at Discovery News

The Murderous 10-Foot-Tall Bird With a Beak Like a Pickax

Like human babies riding in cars, millions of years ago certain species of mammals found themselves simply unable to stay awake while in the jaws of the terror birds. So sleepy!
You’d be forgiven for looking at a pigeon and straining to believe that its ancestors were dinosaurs. This is a creature, after all, that descended from some of the finest killing machines evolution has ever produced to now drink gutter water and assault old people for bread crumbs. But millions of years before birds were bumming for handouts in parks, they had risen right to the top of the food chain. In fact, they filled the vacated niches of their menacing theropod forebears like Velociraptor.

These are the terror birds: scrappy, powerful critters that drove their enormous hooked beaks through small mammals as easily as that guy who put a pickax through my crazy uncle’s skull in a bar fight that one time (he survived, and no, I’m not even kidding). The 18 known species, the tallest growing to a staggering 10 feet tall, didn’t bother with flying, instead opting to chase down all those creatures that had only just thrown their good-riddance-to-the-massive-carnivorous-dinosaurs party. The poor things woke up with a hangover, and the hangover was the terror bird.

It was 60 million years ago in South America, which had not yet joined with its northern counterpart, where the terror birds rose to power in isolation as apex predators. Even given their success, their fossils are fragmentary and extremely rare, according to paleontologist Luis Chiappe, who in 2007 described the titanic, strangely boxy noggin of the biggest terror bird ever: Kelenken, named after the fearsome bird spirit of Patagonia’s native Tehuelche people.

To the best of paleontologists’ knowledge, terror birds weren’t see-through. But then again, no one has definitively disproved that they were see-through.
“It’s the largest known skull for terror birds,” he said. “As a matter of fact, it’s the largest known bird skull, period. It’s about two-and-a-half feet long, an enormous, colossal beast with a very big hook at the end of the beak like an eagle.”

From fossils like these, paleontologists reckon that terror birds were no crumb-loving pigeons, and not just because there was no bread back then. While a skull can’t tell us exactly how it killed, for Chiappe, this is clearly the beak of a carnivore.

“I mean, we know that a little parrot, a cockatoo, can take your finger out,” he said. “Imagine what a bird like this could have done, the damage it could have done with just a strike of this massive skull and beak. So that’s obviously one very easy way of imagining this is how these animals killed their prey.”

The terror birds called forests their home, likely lying in wait to ambush the many small mammals that proliferated in South America after the fall of the dinosaurs. But their skulls and beaks probably weren’t strong enough to tackle large prey, biomechanical studies have shown. With their massively developed legs, they would have been more than capable of chasing down scampering critters: These were extremely nimble, swift predators, hitting speeds of perhaps 30 mph. (This shouldn’t come as a surprise to anyone who has witnessed the surprisingly frantic, not to mention hilarious, way that ostriches run, like giant 40-mph feather dusters having panic attacks.)

The 2.5-foot-long skull of Kelenken, the largest known species of terror bird. That massive hook led Kelenken’s prey to disparagingly refer to the predator as “Captain Hook.” The terror bird, they knew, was real sore about being rejected from the armed forces, what with its lack of arms.
At the end of terror bird legs were talons, so it could have been that the beasts fired an initial jab with their beaks, then stood on their prey and rapidly shivved it to death. Or perhaps chomped down on their quarry and shook it until its spine snapped.

And we might also look for clues in the terror birds’ living cousins, the seriemas, for further speculation. These South American birds are only a couple of feet tall, but are nonetheless adept hunters, snagging lizards and rodents and such with their talons and bashing them on rocks to shatter their bones.

I included this fairly ugly photograph because it’s so crummy that it almost makes the terror bird look real, like bigfoot in that grainy video. Also, I like how disgusted this guy is by his creation. Such is the tortured existence of the artist, I suppose.
It’s even been suggested that the terror birds weren’t terrors at all. Instead, they were full-blown vegetarians, terroir birds, if you will. Last year, German scientists announced the results of a geochemical analysis of terror bird bones, finding that their calcium isotope compositions aligned them more with herbivores than carnivores.

But Chiappe dismisses the notion that such a powerfully built creature was anything but a predator. The terror birds, he argues, sported truly massive heads relative to body size, much like modern eagles and very much unlike modern omnivorous terrestrial birds like emus and ostriches and cassowaries.

“I think that personally you can come up with all these very rather innovative views, but I think that it makes a lot of sense that these animals were predators,” he said. “It’s just the same when someone came up with the idea that T. rex was a scavenger. I’m sure they ate dead meals, but I’m sure it killed.”

“Maybe [the terror birds’] bite force was not strong enough,” he added, “maybe they were limited to preying on certain animals, but that doesn’t make them in my opinion a non-predatory bird.”

A terror bird freaks right out about how poorly its shadow was drawn.
Whatever their diet, and whatever their methods of feeding, the empire of the terror birds entered a slow decline starting around 4.5 million years ago, when the Central American isthmus formed, joining two heretofore self-contained continents. All those creatures that had evolved in isolation for millions of years now found themselves mingling and schmoozing and shaking hands — with their teeth.

Terror birds made their way up into what is now the southern United States, while North America’s top predators — bears and big cats — colonized South America. “So they had to face new competition for the same resources,” said Chiappe, “and that combined with perhaps changes in climate they may not have been able to cope with and that may have impacted their hunting strategies, probably drove them to extinction.”

Read more at Wired Science

Mar 13, 2014

Extinct Mammal Had an Extreme Underbite

The remains of a long-lost porpoise reveal that the marine mammal sported a distinct and unusual underbite, which is described in the latest issue of Current Biology.

The porpoise, Semirostrum ceruttii, lived between 1.6 and 5 million years ago in waters off of what is now the coast of California. Researchers think it used the long, lower part of its snout to hunt for food.

“The extinct porpoise is a bizarre new animal, with the mandible extending well beyond the beak-like snout, which it may have used for probing and ‘skimming’ in the substrate,” co-author Rachel Racicot of Yale University said in a press release. “Although this morphology has been recorded in birds and fish, this is the first described mammal with this anatomy.”

The birds and fish that she refers to are black skimmers (birds) and small fish called half beaks. Both have long, lower jaws that help them to feel around for food at night, or under low-light conditions.

Remains of the porpoise were first found in early rock formations along the California coast in 1990. More recent medical CT scans of the specimen revealed the porpoise’s unusual anatomy.

In addition to the underbite, it possessed eyes that were tinier than those of today’s porpoises. The extinct mammal therefore probably had poor eyesight, making its jaw probing all the more important to its survival.

The researchers think the animal was, at least in some ways, similar to today’s freshwater river dolphins.

“Today we don’t find anything resembling river dolphins in the same kinds of habitats that Semirostrum likely occupied,” Racicot said, adding that the porpoise lineage may have become more specialized over time.

Read more at Discovery News

T. rex Had a Small, Cute Cousin

Toothy Tyrannosaurus rex had a tiny cousin, suggests new research.

The dwarf dino, named Nanuqsaurus hoglundi, lived 70 million years ago in Alaska, according to a new study, published in the journal PLOS ONE.

The skull for the newly identified dinosaur measured 25 inches long, compared to 60 inches for T. rex. The new dino was a tyrannosaur though, conclude researchers Anthony Fiorillo and Ronald S. Tykoski from the Perot Museum of Nature and Science and their colleagues.

Tyrannosaurs marched around on two legs, loved meat and had a large skull relative to the size of their body, which was balanced by a hefty, long tail.

T. rex lived throughout what is now western North America. This latest discovery, however, is at the extreme north of the known range. The fossils were recovered from Prince Creek Formation in Northern Alaska.

“The ‘pygmy tyrannosaur’ alone is really cool because it tells us something about what the environment was like in the ancient Arctic,” Fiorillo said in a press release. “But what makes this discovery even more exciting is that Nanuqsaurus hoglundi also tells us about the biological richness of the ancient polar world during a time when the Earth was very warm compared to today.”

The smaller body size of N. hoglundi compared to most tyrannosaurs from lower latitudes may reflect an adaptation to variability in resources in the arctic seasons. In other words, things were probably feast or famine for the dinosaur, which still somehow managed to eke out an existence.

Read more at Discovery News

Ancient Greek Tombstones Served as Therapy

Greek tombstones were not just commemorative markers, but served as therapy for the bereaved, says a study on images and epitaphs found on 2,300-year-old gravestones.

The research examined 245 grave reliefs from the Greek city-states of Smyrna and Kyzikos in present-day Turkey.

Dating to the Hellenistic period (323-31 B.C.), when production of funerary reliefs was at its height in western Asia Minor, the rather expensive tombstones probably belonged to the equivalent of middle class individuals.

According to Sandra Karlsson, a doctoral student at the University of Gothenburg, Sweden, the rarely investigated sepulchral imagery can offer precious insights about funerary rituals, demographics, and family structures. Most of all, the reliefs reflect people’s way of relating to death.

"In classical antiquity there were strict conventions for grieving for the dead, based on the belief that death is not an evil and hence not a reason for sorrow," Karlsson wrote in her doctoral thesis in classical archaeology and ancient history.

However, in the Hellenistic age artists had a more naturalistic approach and tended to represent emotional expressions in sculpture and funerary art.

"The emotional semiotics that confronts us ranges in content from solemn expressions of introspective mourning in the case of Smyrna to more explicit outpourings of grief in the case of Kyzikos," Karlsson said.

In this view, the tombstones became a place of interaction between the living and the dead and served as "visual therapy" for the bereaved.

"Viewed through the experience of the mourner, the images fulfilled a soothing and consoling function, preserving and enhancing the memory of the deceased," Karlsson said.

For example, the dead were often portrayed as standing next to their grave markers, indicating they were happily existing in the underworld.

Servants and family members were also represented with the dead. But while relatives were lined up next to each other like statues, servants performed various gestures signifying mourning and grief. For example, they sat on the ground or touched their chin with one hand.

"Social conventions encouraged individuals of lower standing to mourn," Karlsson said.

On the contrary, people with higher status were less likely to express grief.

By analyzing the tombstones, Karlsson noted that untimely death was a recurrent theme in both reliefs and epitaphs.

"I found the strongest expressions of grief for deceased children and adolescents," she said. She noted that children were often depicted holding grapes, a symbol of eternal life.

"The grapes' presence might be imbued with hopes for a continued existence after death; surely a comforting reminder for a grieving family member," Karlsson said.

Read more at Discovery News

Nine Unopened Dead Sea Scrolls Found

Nine newly found penny-sized pieces of parchment belonging to the Dead Sea Scrolls laid unopened for nearly six decades before they were rediscovered in Israel.

The scrolls went unnoticed for years until one scholar came across them while searching through the Israel Antiquities Authority's (IAA) storerooms, the Times of Israel reported.

"Either they didn't realize that these were also scrolls, or they didn't know how to open them," the IAA's head of artifact treatment and conservation Pnina Shor explained.

The tiny scrolls were found inside three phylacteries, small leather boxes with Biblical versus written on them (called tefillin) that are worn by Jews during their morning prayers. Their discoverer, Yonatan Adler, had the boxes scanned by CT at a hospital in Israel in hopes there would be parchment inside.

He was right.

Once unopened, the scrolls are expected to shed new light on the religious practices of the Jewish people during the Second Temple Period between the years of 530 BC and 70, an era named for a holy place of worship for the Jewish people that was constructed by the builder of ancient Jerusalem King Herod. The Dome of the Rock stands today where the Second Temple purportedly once stood.

At least two dozen phylactery scrolls were discovered in the 1940s and 50 along with the rest of the Dead Sea Scrolls in a limestone cave in the West Bank's Qumran in Israel.

" found a number of fragments of tefillin cases from Qumran Cave 4, together with seven rolled-up slips," Adler told the Times of Israel.

Until now, the scrolls remained bound inside the phylacteries for approximately 2,000 years.

The IAA has been tasked with the difficult job of unrolling the scrolls without damaging them.

Read more at Discovery News

Mar 12, 2014

Secret to Ancient Sloths' Aquatic Lives Found

Millions of years ago, aquatic sloths roamed shallow waters off the coast of modern-day Chile and Peru. These now-extinct swimmers had highly dense bones that facilitated their transition from land to sea by helping them sink to seafloors to graze on vegetation, according to a new report.

Only two groups of sloths exist today, both of which live in trees and grow to be the size of small monkeys. But during the Miocene and Pliocene — about 25 million to 4 million years ago — a great diversity of sloths crawled the Earth, including giant sloths that grew to be the size of elephants, and slightly smaller ones that spent time underwater.

Fossil remains suggest these aquatic sloths originated on land and gradually transitioned to life underwater. A series of fossil beds along the coast of Peru contain remnants of five different species of extinct sloths that researchers have interpreted to be aquatic based on the structure of their bones. For example, the density of their bones is much higher than the density of terrestrial mammal bones, but similar to bones of aquatic mammals that graze on seafloor vegetation, such as manatees.

Researchers based at Sorbonne University in Paris were interested in confirming this transition from land to sea and analyzing the timing of the transition by studying the changes in bone density within progressively younger species preserved in the Peruvian fossil beds.

"It was really important for us to show that of course the compactness that was found is really over the top and clearly shows the aquatic adaption, because such high levels of compaction are only found in aquatic animals," study co-author Eli Amson told Live Science.

The team found that the density of the sloths' tibias (shin bones) and ribs all increased by roughly 20 percent over the course of roughly 3 million years beginning about 8 milliono years ago. This is relatively fast in the scope of geologic time, the team says.

These fossils provide the best evidence yet of the timing of any four-legged mammal's transition from a terrestrial to aquatic lifestyle, the team says.

Cause for transition, extinction

The sloths' transition from land to sea probably resulted from a lack of food along the coast of Peru.

"At that time, the coast of Peru was a desert, like it is today," Amson said. "There was nothing to eat, so they had to enter the water to consume food."

Land-dwelling ancestors of the aquatic sloths also had relatively dense bones compared with other mammals, so the researchers believe perhaps the high bone density served some unrelated function on land, and then later helped facilitate their transition to water. The researchers are unsure how the sloths may have benefited from dense bones on land, but note that some other land animals do have unusually compact bones today as well. For example, rhinoceroses have relatively dense bones thought to help them charge at other animals, Amson said.

Aquatic sloths went extinct about 4 million years ago, around the time the Isthmus of Panama closed and the Pacific Ocean became cut off from what is now the Caribbean Sea. This transition caused the waters off South America to become much colder than they had been, killing off the sea grasses the sloths fed on. Researchers think the sloths went extinct either due to the loss of their main food source, or simply because they were unable to tolerate the cold water, Amson said.

Read more at Discovery News

Mild Weather, Rain May Have Propelled Rise of Genghis Khan

A pleasantly warm and wet spell in central Mongolia eight centuries ago may have propelled the rise of Genghis Khan, according to new research.

The study was based on an analysis of tree rings spanning 11 centuries, showing that the conqueror seized power during dry times and was able to expand his empire across Asia during an unusual stretch of good weather.

The years before Genghis Khan's rule were marked by severe drought from 1180 to 1190, said the study in the Proceedings of the National Academy of Sciences.

But from 1211 to 1225, as the empire spread, Mongolia saw an unusual period of sustained rainfall and mild temperatures.

"The transition from extreme drought to extreme moisture right then strongly suggests that climate played a role in human events," said study co-author Amy Hessl, a tree-ring scientist at West Virginia University.

"It wasn't the only thing, but it must have created the ideal conditions for a charismatic leader to emerge out of the chaos, develop an army and concentrate power."

For the oldest samples, Hessl and lead author Neil Pederson, a tree-ring scientist at Columbia University's Lamont-Doherty Earth Observatory, focused on an unusual clutch of trees found while researching wildfires in Mongolia.

The strand of gnarled, stunted Siberian pines were emerging from cracks in an old solid-rock lava flow in the Khangai Mountains, according to a statement from Columbia.

Trees living in such conditions grow slowly and are particularly sensitive to changes in weather, so they provided an abundance of data to study.

Some of the trees had lived for more than 1,100 years. One piece of wood they found had rings going back to about 650 B.C.

Researchers compared those samples to younger fallen trees and some pieces bored from living trees.

Read more at Discovery News

Vast Oceans Beneath Earth Revealed by Gem

A water-rich mineral embedded in a Brazilian diamond provides further evidence that a vast water layer lies deep beneath the surface of the Earth. Canadian geologists discovered the mineral, which may have formed in a massive watery region within the Earth's layer known as the transition zone, which lies between 410 to 660 kilometers below the Earth's surface.

Water makes up approximately 1.5 percent of the weight of the mineral — known as ringwoodite — which a University of Alberta graduate student found embedded in a  commercially useless brown diamond mined from the Mata Grosso region of Brazil. The journal Nature published the results of ringwoodite analysis.

“This sample really provides extremely strong confirmation that there are local wet spots deep in the Earth in this area,” said Graham Pearson of the University of Alberta in a press release. “That particular zone in the Earth, the transition zone, might have as much water as all the world’s oceans put together. One of the reasons the Earth is such a dynamic planet is the presence of some water in its interior. Water changes everything about the way a planet works.”

Geologists have debated the existence of water in the transition zone, but evidence seems to be mounting that the Earth has a vast amount of water in the mantle, the region between the core and the crust.

Read more at Discovery News

Monster Rare Yellow Hypergiant Star Discovered

A gargantuan star, measuring 1,300 times the size of our sun, has been uncovered 12,000 light-years from Earth — it is one of the ten biggest stars known to exist in our galaxy. The yellow hypergiant even dwarfs the famous stellar heavyweight Betelgeuse by 50 percent. While its hulking mass may be impressive, astronomers have also realized that HR 5171 is a double star with a smaller stellar sibling physically touching the surface of the larger star as they orbit one another.

“The new observations also showed that this star has a very close binary partner, which was a real surprise,” said Olivier Chesneau, of the Observatoire de la Côte d’Azur in Nice, France. “The two stars are so close that they touch and the whole system resembles a gigantic peanut.”

This recent observation was made by Chesneau’s team using data from the ESO’s Very Large Telescope Interferometer (VLTI) in Chile. They have built on sixty years of observational data to realize that the primary star in the binary system, HR 5171A, is going through very rapid changes, indicating that it has entered a very short phase in its life cycle.

Yellow hypergiants are rare stellar objects, only a dozen have been identified in the Milky Way, so all are considered cosmic jewels. The yellow hypergiant is actually a short phase that some of the most massive stars (depending on their mass) go through before burning all their fuel reserves. During this phase, violent internal convulsions blast huge quantities of stellar gases into space, creating a vast nebula around the star.

Although it’s located moderately far from Earth, HR 5171 can just about be seen on a clear night in the constellation of Centaurus with the naked eye and has been measured to have a magnitude of between 6.10 and 7.30.

Read more at Discovery News

Lost Einstein Paper Posed Alternate Cosmic Theory

Albert Einstein wasn’t always convinced that the universe began with a big bang.

In a newly discovered manuscript, the famed physicist pondered over a so-called “steady state” theory and described a cosmos that can continuously and spontaneously replenish itself with new matter to form stars and galaxies. That would mean the overall density of space would remain stable, even as the universe expands.

Researchers believe Einstein’s manuscript, found “hiding in plain sight” in the Hebrew University’s online Albert Einstein Archives, was written in 1931 — nearly 20 years before British astrophysicist Fred Hoyle championed a similar and controversial theory.

Physicist Cormac O’Raifeartaigh, with the Waterford Institute of Technology in Ireland, tells Nature magazine he “almost fell out of his chair” when he realized what he had found. The document, written in German — Einstein’s native tongue — was mistakenly identified as a first draft of another paper.

“If only Hoyle had known, he would certainly have used it to punch his opponents,” O’Raifeartaigh told Nature.

Ultimately, Hoyle’s theory didn’t hold up to observational evidence. And Einstein apparently abandoned the idea when his calculations didn’t jibe with equations for his general theory of relativity.

Read more at Discovery News

Mar 11, 2014

'Death stars' in Orion blast planets before they even form

The Orion Nebula is home to hundreds of young stars and even younger protostars known as proplyds. Many of these nascent systems will go on to develop planets, while others will have their planet-forming dust and gas blasted away by the fierce ultraviolet radiation emitted by massive O-type stars that lurk nearby.

A team of astronomers from Canada and the United States has used the Atacama Large Millimeter/submillimeter Array (ALMA) to study the often deadly relationship between highly luminous O-type stars and nearby protostars in the Orion Nebula. Their data reveal that protostars within 0.1 light-years (about 600 billion miles) of an O-type star are doomed to have their cocoons of dust and gas stripped away in just a few millions years, much faster than planets are able to form.

"O-type stars, which are really monsters compared to our Sun, emit tremendous amounts of ultraviolet radiation and this can play havoc during the development of young planetary systems," remarked Rita Mann, an astronomer with the National Research Council of Canada in Victoria, and lead author on a paper in the Astrophysical Journal. "Using ALMA, we looked at dozens of embryonic stars with planet-forming potential and, for the first time, found clear indications where protoplanetary disks simply vanished under the intense glow of a neighboring massive star."

Many, if not all, Sun-like stars are born in crowded stellar nurseries similar to the Orion Nebula. Over the course of just a few million years, grains of dust and reservoirs of gas combine into larger, denser bodies. Left relatively undisturbed, these systems will eventually evolve into fully fledged star systems, with planets -- large and small -- and ultimately drift away to become part of the galactic stellar population.

Astronomers believe that massive yet short-lived stars in and around large interstellar clouds are essential for this ongoing process of star formation. At the end of their lives, massive stars explode as supernovas, seeding the surrounding area with dust and heavy elements that will get taken up in the next generation of stars. These explosions also provide the kick necessary to initiate a new round of star and planet formation. But while they still shine bright, these larger stars can be downright deadly to planets if an embryonic solar systems strays too close.

"Massive stars are hot and hundreds of times more luminous than our Sun," said James Di Francesco, also with the National Research Council of Canada. "Their energetic photons can quickly deplete a nearby protoplanetary disk by heating up its gas, breaking it up, and sweeping it away."

Earlier observations with the Hubble Space Telescope revealed striking images of proplyds in Orion. Many had taken on tear-drop shapes, with their dust and gas trailing away from a nearby massive star. These optical images, however, couldn't reveal anything about the amount of dust that was present or how the dust and gas concentrations changed in relation to massive stars.

The new ALMA observations detected these and other never-before-imaged proplyds, essentially doubling the number of protoplanetary disks discovered in that region. ALMA also could see past their surface appearance, peering deep inside to actually measure how much mass was in the proplyds.

Combining these studies with previous observations from the Submillimeter Array (SMA) in Hawai'i, the researchers found that any protostar within the extreme-UV envelope of a massive star would have much of its disk of material destroyed in very short order. Proplyds in these close-in regions retained only a fraction (one half or less) of the mass necessary to create one Jupiter-size planet. Beyond the 0.1 light-year radius, in the far-UV dominated region, the researchers observed a wide range of disk masses containing anywhere for one to 80 times the mass of Jupiter. This is similar to the amount of dust found in low-mass star forming regions.

Read more at Science Daily

Chimps Trust Some People More Than Other Chimps

Chimpanzees that have had positive experiences with humans appear to trust people more than they do baboons and unfamiliar chimps, a new study suggests.

The findings, published in the latest Proceedings of the Royal Society B, indicate that chimpanzees can learn to bond and exhibit empathy for members of another species, such that trust develops even at the subconscious level.

As for what chimps think of kind and caring humans, lead author Matthew Campbell told Discovery News, "I have no doubt that we are different in their minds, but an okay kind of different."

Campbell, a researcher at the Yerkes National Primate Research Center, said that an older female chimp named Tai is so pleased to see co-author Frans de Waal, whom she's known for 20 years, that she excitedly pants, bobs her head and stretches out her hand. All of these are behaviors chimps use when greeting each other.

For the study, Campbell and de Waal used contagious yawning to measure "involuntary empathy" among 19 adult chimps at Yerkes that were all raised by other chimps in captivity.

"We think that the mechanism for copying the yawns of others is the same for copying other facial expressions, like happiness, sadness or fear," he explained. "For our purposes, yawning is simply a contagious expression we can easily see and count. Contagious smiles, frowns and fearful expressions may be tiny twitches of muscles that cannot be seen, but yawns can't be missed."

He added, "We catch all of these expressions more the closer we feel to someone, and that's why we think that empathy is involved."

The behavior is further thought to occur at the subconscious level, suggesting that the trust between the individuals happens this deeply as well.

The chimpanzees yawned in sync with humans, as well as trusted family members and chimp friends. They did not exhibit such involuntary empathy for unfamiliar chimpanzees and Gelada baboons, however.

The researchers conclude that their responses were based on life experiences.

"I think that they may have been conditioned to think that humans are generally okay," Campbell explained. "Therefore, meting a new human may be an opportunity for a new positive interaction, since that has been their experience."

Chimpanzees are territorial in the wild and exclude strangers, so unfamiliar chimps could have evoked an innate hostile response. Baboons, on the other hand, are "basically meaningless" to these captive chimps, so the chimps were indifferent to them.

Chimpanzees, therefore, are not completely hard-wired to feel a certain way about any given primate, including humans. They instead show flexibility in forming trusted, empathic connections with different species, including unknown members of that species.

Read more at Discovery News

Elephants Can Tell Gender, Ethnicity in Human Voices

African elephants can differentiate between human languages and move away from those considered a threat, a skill they have honed to survive in the wild, researchers said.

The study suggests elephants, already known to be intelligent creatures, are even more sophisticated than previously believed when it comes to understanding human dangers.

African elephants (Loxodonta africana) are the largest land animals on Earth and are considered a vulnerable species due to habitat loss and illegal hunting for their ivory tusks.

Researchers played recordings of human voices for elephants at Amboseli National Park in Kenya to see how they would respond, according to a report in the Proceedings of the National Academy of Sciences.

Some of the voices were from local Maasai men, a group that herds cattle and sometimes comes into conflict with elephants over access to water and grazing space. Occasionally, elephants are killed in clashes with Maasai men, and vice-versa.

Other recorded voices were from Kamba men, who tend to be farmers or employees of the national park, and who rarely represent a danger to elephants.

Still other voices tested on the elephants included female Maasai speakers and young boys.

All were saying the same phrase: "Look, look over there, a group of elephants is coming."

The recorded voices were played for hundreds of elephants across 47 family groups during daylight hours.

When elephants heard the adult male Maasai voices, they tended to gather together, start investigative smelling with their trunks, and move cautiously away.

But when elephants heard females, boys, or adult male Kamba speakers, they did not show concern.

Discriminating between languages

"The ability to distinguish between Maasai and Kamba men delivering the same phrase in their own language suggests that elephants can discriminate between different languages," said co-author Graeme Shannon, a visiting fellow in psychology at the University of Sussex.

That is not the same as understanding what the words mean, but still shows that elephants can decipher the more sing-songy Maasai language from the Kamba tongue, perhaps based on inflections, use of vowels, and other cues.

"It is very sophisticated what the elephants are doing," said Keith Lindsay, a conservation biologist and member of the scientific advisory committee of the Amboseli Elephant Research Project.

"A lot of animals will take flight at just the general threat posed by people, but a smart animal doesn't do that," he told AFP.

"Their response to hearing Maasai men talking was to be alert, to move away, but not to run away in total fear," added Lindsay, who was not involved in the study.

"It is suggesting that elephants are capable of thinking, (of) recognizing that if Maasai men are talking, they are not likely to be hunting because if they were hunting, they would be quiet."

Wiser with age

Elephant groups with older matriarchs in their midst did best at assessing the threat from different speakers, further bolstering the presumed role of learning in the animals' behavior.

The elephants also did not act the same way as they did when recordings of lions were played, as was shown in a previous study.

In those scenarios, they bunched together so that juveniles -- those most at risk from a lion attack -- were in the center, and moved toward the sounds as if to scare the lion away.

When it comes to recognizing people, elephants may not be alone in this ability. Other research has suggested that wild bottlenose dolphins in Brazil have become so familiar with humans that they engage in cooperative hunting with artisanal fisherman.

Great apes, crows and even prairie dogs have also been shown to differentiate between humans on some level.

Read more at Discovery News

Venus Express Orbiter Basks in Venusian Glory

The European Space Agency’s Venus Express orbiter has spotted a very terrestrial phenomenon in the high-altitude cloud cover of Earth’s hellish ‘sister’ world.

While orbiting Venus, with the sun at its back, Venus Express used its cameras to observe a “glory” — the rainbow-like halo that is usually seen from an aircraft flying over clouds. This is the first time a glory has been observed on another planet.

Glories appear as tight circular rainbow structures surrounding the shadow of an aircraft and are only formed when the cloud consists of tiny water droplets of approximately same size. On Earth, glories are a rare treat as the atmospheric conditions and location of the observer to the sun need to be just right. But if the conditions are met, sunlight can bounce off the water droplets, refracting back to the observer.

Venus, however, doesn’t have temperate, life-giving water droplets in its high-altitude clouds. But in an effort to determine the characteristics of the droplets contained within the Venusian sulfuric acid clouds, mission scientists waited until the sun was directly behind Venus Express and took this shot of the corrosive clouds far below.

On July 24, 2011, the satellite spotted its first extraterrestrial glory in Venus’ cloud tops 70 kilometers (44 miles) above the planet’s surface. According to an ESA news release, the glory was 1,200 kilometers (746 miles) wide as seen from the spacecraft that was orbiting 6,000 kilometers (3,728 miles) above.

From this observation, scientists have been able to determine the dimensions of Venus’ sulfuric acid cloud drops. They found the droplets to measure 1.2 micrometres across — approximately a fiftieth of the width of a human hair. The fact that the glory was 1,200 kilometers wide suggests that all the droplets within that area were around the same size.

But there were some surprises that may help us understand the complex chemistry at play in Venus’s atmosphere.

“The variations of brightness of the rings of the observed glory is different than that expected from clouds of only sulfuric acid mixed with water, suggesting that other chemistry may be at play,” writes ESA.

Read more at Discovery News

Mar 10, 2014

Oldest Masks Go on Display

The first known masks are Halloween-like stone portraits of the dead, according to an upcoming exhibition at the Israel Museum in Jerusalem.

The exhibit, called Face to Face: The Oldest Masks in the World, reveals for the first time 12 Neolithic masks featuring wide toothy smiles and large eyes.

According to the curators, who set up the display after 10 years of investigative work, the eerie stone portraits were carved out of limestone some 9,000 years ago by Stone Age people who were among the first to abandon nomadic life.

Analysis into the type of stone revealed the masks came from the Judean Hills and nearby Judean desert in Israel. Although there is no record of their use — they predate writing by 3,500 years — experts believe the artifacts might represent various ancestors of an early Stone Age religion.

“It is important to say that these are not living people, these are spirits,” Debby Hershman, curator of prehistoric cultures at the Israel Museum who organized the exhibit, told the Times of Israel.

The masks were probably used in rites of healing and magic and in ceremonies celebrating the deceased. They weigh about 2 to 4 pounds and likely would have been painted, as the color traces on one of them suggest.

Each of the 12 masks is unique, and shows old and young faces of various size. One even resembles a human skull.

“They are the first glimmerings of existential reflection,” James Snyder, the museum’s director, told the Times of Israel.

Several masks feature a set of holes along the outer edge, as if they were hung or worn.

Read more at Discovery News

Fickle Sun Changed Europe's Climate for 1,000 Years

Variations in the sun’s output may explain some of the natural changes in Europe’s climate during the past 1,000 years, including the deadly cold winters of the 16th and 18th centuries. Earth scientists recently discovered that as solar output dipped so did temperatures in the North Atlantic, which then may have cooled the climate in Europe.

When the sun produces less energy, known as a solar minima, a high pressure system may form in the atmosphere over the North Atlantic, according to the study published in Nature Geoscience. That high-pressure system blocks warm winds flowing from west to east, known as the westerlies, and allows cold northern air to flow over Europe.

“Indeed we propose that this combined ocean-atmospheric response to solar output minima may help explain the notoriously severe winters experienced across Europe between the 16th and 18th centuries, so vividly depicted in many paintings, including those of the famous London Frost Fairs on the River Thames, but also leading to extensive crop failures and famine as corroborated in the record of wheat prices during these periods,” said lead author Paola Moffa-Sanchez of Cardiff University, in a press release.

This analysis of the interplay between sun, sea and climate used a combinations of fossils, sun-spot records and computer simulations. The chemicals held within fossils of marine microorganism provided information about the temperature and salinity of the ocean over the past millennia.

Sun-spot records gave clues to solar activity, since low numbers of spots means low solar output. The data from fossils and sun spots was then input into a computer to create a model of how solar changes influence Europe’s climate.

Read more at Discovery News

Asteroid Strike Drenched World in Acid Rain

Global ocean acidification caused by acid rain occurred just days after a massive asteroid slammed into the Earth 66 million years ago, new research suggests.

The rapid acidification could explain why surface-dwelling organisms such as ammonites and carbon-secreting plankton were wiped out, while some deep ocean dwellers as well as freshwater species such as crocodiles survived one of the largest mass extinction events in history.

Most scientists believe the Cretaceous-Palaeogene mass extinction event, which wiped out 75 per cent of all life on Earth including the non-avian dinosaurs, was triggered by the impact of a 10-kilometre wide asteroid off Mexico's Yucatan Peninsula.

However, questions about why most species were wiped out while some others survived have remained an area of intense debate among scientists.

The impact, which created the 180-kilometre wide Chicxulub crater, covers an area of seabed that contains anhydrite, a sulphur-rich rock.

While it had been hypothesized that acid rain could have caused the extinction patterns, previous work suggested that sulphur dioxide would have stayed in the atmosphere for months — much too long to cause rapid acidification.

But now Japanese researchers led by Sohsuke Ohno of the Chiba Institute in Japan have examined the composition of the vapor cloud generated by the impact.

Their research, published in the journal Nature Geoscience suggests far more sulphur trioxide than sulphur dioxide was released into the atmosphere.

"Our experiments suggest that the Chicxulub impact released a huge quantity of sulphur trioxide into the atmosphere, where it would have rapidly combined with water vapor to form sulphuric acid aerosol particles," the authors write.

Ohno and colleagues used lasers to fire impactors into anhydrite test samples at velocities of 13 to 25 kilometers per second, which are similar to the speeds expected in an asteroid impact.

The resulting vapour cloud was examined using quadrupole mass spectrometer (QMS) analysis, finding impacts resulted in the release of far more sulphur trioxide molecules than sulphur dioxide.

Sulphur trioxide reacts quickly with atmospheric water vapour to form sulphuric acid aerosols.

These aerosols would stick to heavier silicate debris particles ejected high into the atmosphere by the impact, and would have fallen back to the surface within two days, much faster than previously thought.

Eureka moment

Professor Mike Archer of the University of New South Wales says the extremely intense acid rainfall and dramatic acidification of global marine surface waters explains the disappearance of many species during this period including ammonites and carbonate secreting plankton.

"It's solved a number of mysteries that have always bothered me," says Archer, who was not involved in the research.

"Their work shows the asteroid could have done all the damage that we suspected it did."

Archer says the relatively moderate rates of extinction in freshwater species could be due to the acid-neutralizing effects of the mineral larnite.

"So the crocodiles and many of the terrestrial aquatic organisms would have been able to survive because the acid impact wouldn't have been as bad as it was in the ocean," says Archer.

Read more at Discovery News

'Cosmos: A Spacetime Odyssey': A Triumph for Science

When I first heard that Carl Sagan’s classic “Cosmos” television series from 1980 was going to be remade for a modern audience, I was skeptical. How could Neil deGrasse Tyson hope to carry on where Sagan left off? Would an over-reliance on CGI dumb-down the science to such an extent that it would just be a shiny yet soulless reboot? I’ve always been a huge fan of Tyson’s work, but could a Cosmos 2.0 be too much for the famous science communicator to handle?

But all my reservations about the Cosmos reboot, that premiered Sunday on FOX, were completely unfounded. It was a triumph for science and once again proved that Neil deGrasse Tyson is one of the heavyweight science educators of our time. For this brilliant effort, Tyson teamed up with executive producer and “Family Guy” creator Seth MacFarlane, and Ann Druyan, who co-writer of the original “Cosmos” with her late husband, Sagan.

In the one-hour first episode, “Cosmos: A Spacetime Odyssey” takes us on a dizzying journey from the Big Bang to the very edge of our observable Universe; from the tiniest particles to the galactic superclusters. Tyson gives us a history lesson of the genesis of our modern understanding of the Universe, starting with the oppressed 16th-Century astronomer Giordano Bruno who thought beyond the Copernican Principal, describing an “infinite” Universe containing other stars, planets and even life on those other worlds.

Tragically, Bruno ran afoul with the Roman Catholic Church, which imprisoned and killed him. Bruno’s story was told by Tyson through wonderful animated shorts that enhanced his awesome storytelling abilities.

From Bruno’s realization about the true scale of the Universe, the episode spiraled out to the Cosmic Calendar — first popularized by Sagan in the original “Cosmos” — where the entirety of the history of the Universe is mapped onto our 365 day year. If the Big Bang occurred on Jan. 1, the whole of human history occurred in the final few seconds of Dec. 31.

“Feeling a little small?” asks Tyson. That was the crux of this entire episode: the scale of the Universe is unfathomable and our place in it is baffling, but Cosmos is here to help the audience join the dots and hopefully grasp the immensity of the questions science is asking.

Throughout the show we are treated to some of the best CGI television has to offer and for the most part, the computer generated renderings are scientifically sound (give or take a bit of latitude for dramatic license). Personally, I loved the beach scene where Tyson is describing how life from the oceans evolved to venture onto the land — seamlessly a CGI Tiktaalik, one of the first animals to venture out of the oceans, lumbered onto the beach and it took a moment for me to realize it wasn’t real.

But deep within the spacetime fabric of this Cosmos was a beautiful emotion that had most impact.

In the last 5 minutes, Tyson describes his personal relationship with Sagan. At 17, Tyson was invited to visit Sagan at his home in Ithaca, NY — a period of his life that he remembers with great clarity. Sagan’s hospitality and kindness toward him had a strong resonance at the time. Although Tyson knew he wanted to be an astronomer, he added that he also learned from Carl the kind of person he wanted to become.

Read more at Discovery News

Mar 9, 2014

Sponges Likely Paved the Way For All Life on Earth

The seemingly lowly sponge, just by its very existence, might have paved the way for the evolution of complex life forms, including our own species, according to a new paper.

Sponges appear to have added oxygen to the deep ocean, creating an environment where more mobile, major oxygen-using animals could have evolved, holds the paper, published in the latest Nature Geoscience.

The research builds on work, presented earlier this year, which found that the most primitive sponges probably could survive in water containing very low levels of oxygen.

“There had been enough oxygen in ocean surface waters for over 1.5 billion years before the first animals evolved, but the dark depths of the ocean remained devoid of oxygen,” lead author Tim Lenton of the University of Exeter was quoted as saying in a press release. “We argue that the evolution of the first animals could have played a key role in the widespread oxygenation of the deep oceans. This in turn may have facilitated the evolution of more complex, mobile animals.”

Several lines of evidence support the theory. DNA analysis finds that the earliest sponges likely first emerged at least 700 million years ago, when the oceans contained little oxygen. Between 700 and 600 million years ago, the oceans gradually became more oxygenated, meaning more enriched with oxygen. Fossils of animals dating to 650 million years ago have been found.

Then there is the way that sponges feed. These multicellular organisms consist of pores and channels that allow nutrient-containing water to circulate through them.

As sponges feed, they filter out tiny particles of organic matter from the water. The particles millions of years ago would have included dead microbial matter, which rots and consumes oxygen as it does so. Sponges therefore helped to clean water of this material. Without all of the rotting going on, the water would have experienced increased oxygen levels, the researchers suggest.

More oxygen in the water then set the stage for even more complex life forms to emerge, such as the first predatory animals with guts that started to eat one another, marking the beginning of a modern marine ecosystem, with the type of food webs we are familiar with today.

It is widely accepted that the first terrestrial animals evolved from marine species. Mammals, including humans, are a class of animals that evolved from terrestrial species.

The jump from sponges to humans is, of course, a long one, but many researchers believe that sponges are the most likely candidate for an “Animal Eve,” referring to a single group of organisms that, through many stages of evolution, gave rise to all animals alive today.

Read more at Discovery News

In grasslands remade by humans, animals may protect biodiversity: Grazers let in the light, rescue imperiled plants

A comparative study of grasslands on six continents suggests there may be a way to counteract the human-made overdose of fertilizer that threatens to permanently alter the biodiversity of the world's native prairies.

The solution is one that nature devised: let grazing animals crop the excess growth of fast growing grasses that can out-compete native plants in an over-fertilized world. And grazing works in a way that is also natural and simple. The herbivores, or grazing and browsing animals, feed on tall grasses that block sunlight from reaching the ground, making the light available to other plants.

That's the key finding of a five-year study carried out at 40 different sites around the world and scheduled for online publication March 9, 2014 in the journal Nature. More than 50 scientists belonging to the Nutrient Network, a team of scientists studying grasslands worldwide, co-authored the study.

"This study has tremendous significance because human activities are changing grasslands everywhere," said study co-author Daniel S. Gruner, associate professor of entomology at the University of Maryland. "We're over-fertilizing them, and we're adding and subtracting herbivores. We have a worldwide experiment going on, but it's completely uncontrolled."

Gruner, a member of the Nutrient Network (which participants have nicknamed NutNet) since its founding in 2006, helped plan the worldwide study and analyze its results. Elizabeth Borer of the University of Minnesota was the study's lead author.

The U.N. Food and Agricultural Organization estimates that grasslands cover between one-fifth and two-fifths of the planet's land area and are home to more than one-tenth of humankind. But like all plant communities, grasslands are suffering from too much fertilizer.

As humans burn fossil fuels, dose crops with chemical fertilizers, and dispose of manure from livestock, they introduce extra nitrogen and other nutrients into the soil, air and water. The excess is a special problem for grasslands, where many plants, like annual wildflowers and others, have adapted to low nutrient levels. They often struggle to compete against grasses that use the extra nutrients to grow faster and bigger.

At the same time, grasslands worldwide are being converted to pastures for domestic animals, with native grazers like elk and antelope giving way to cattle and sheep.

Ecological theory asserts that grazers can counteract the effects of over-fertilizing in most cases, but the theory has never been broadly tested, Gruner said. To do that, the NutNet scientists ran essentially the same experiment worldwide, marking off test plots in groups of four at each of 40 sites. In each group, one plot was fenced to keep grazing animals out. One was treated with a set dose of fertilizers, to mimic the effect of excess nutrients from human sources, but was not fenced so the animals could graze. One was both fenced and fertilized. And one was left alone.

The researchers did not try to alter the test sites' animal populations. In some places native animals were abundant. At others they'd been mostly replaced by domestic animals like cattle, goats and sheep. And still others were former pastures where livestock had browsed in the past, but were no longer there.

In general, where fertilizer was added and grazing animals were kept out, the variety of plants in the experimental plots decreased. Where animals were allowed to graze in the fertilized plots, plant diversity generally increased. The researchers' data analysis concluded that the grazers improved biodiversity by increasing the amount of light reaching ground level.

Grassland plants have evolved a variety of strategies to take advantage of a setting where nutrients are in short supply and inconsistently available. They may be ground-hugging, or ephemeral, or shoot up when they capture a nutrient pulse, Gruner explained. These differing strategies create a diverse grassland ecosystem.

In the human-altered world where nutrients are always plentiful, plants that put their effort into growing tall to capture sunlight have an advantage. They block the sunlight from reaching most other plant species, which cannot grow or reproduce. But grazing animals cut down the light-blocking plants and give the others a chance to bloom.

Read more at Science Daily