Jun 11, 2011

New super-dense forms of carbon outshine diamond

We can all only dream of owning rocks made of these. Simulations have revealed three stable forms of pure carbon that would sparkle more than diamond if synthesised.

Carbon atoms can be combined in different configurations with widely varying properties. Graphite and diamond are the most familiar, while more exotic allotropes include graphene, with versatile electrical properties, and M-carbon and Bct-carbon, which rival diamond's legendary hardness.

To explore whether forms of carbon denser than diamond might be possible, Artem Oganov of Stony Brook University in New York and colleagues systematically simulated different configurations of carbon atoms at different temperatures and pressures. Three – named hP3, tI12 and tP12 – seemed stable enough to be made in principle.

The simulations show none would be as hard as diamond, but all three would be between 1.1 and 3.2 per cent denser. "These new allotropes are significantly denser than any of the known allotropes of carbon," says Oganov.

This gives them a higher refractive index – a measure of the extent to which they bend light – leading to greater lustre and sparkle.
Superconducting carbon?

The simulations also suggest that the three materials have band gaps – the amount of energy needed for electrons to jump from one energy level to another – that are very different to one another. One of them, tP12, has the largest band gap of any carbon allotrope. This variability may make the allotropes good candidates for superconductors – exotic substances that conduct electricity without resistance, says Oganov.

According to Boris Yakobson at Rice University in Houston, Texas, a large variation in band gap implies strong interactions between electrons and packets of energy in the lattice called phonons. This in turn could lead to the formation of electron couplings called Cooper pairs, which are necessary for superconductivity.

The presence of widely varying band gaps might also give the materials other unique properties. "The large spread of band gaps gives an excellent playground for engineering new electronic materials," adds Oganov.
Hard to make

Creating the three new materials could be difficult, though. "It is not clear how we can fabricate them," says Vadim Brazhkin of the Institute for High Pressure Physics in Troitsk, Russia, who was not involved in the research.

"Using standard pristine materials, such as graphite or amorphous carbon [an allotrope in which the atoms have no crystal structure], we can possibly obtain a tiny amount of new materials using extreme pressure treatment," he says.

Read more at New Scientist

Cloned Cows to Produce Human-Like Milk

An Argentine laboratory announced that it had created the world's first transgenic cow, using human genes that will allow the animal to produce the equivalent of mothers' milk.

"The cloned cow, named Rosita ISA, is the first bovine born in the world that incorporates human genes that contain the proteins present in human milk," Argentina's National Institute of Agrobusiness Technology said in a statement on Thursday.

Rosita ISA was born on April 6 by Ceasarian because she weighed more than 45 kilos (99 pounds), about twice the normal weight of Jersey cows, according to the statement.

As an adult, "the cow will produce milk that is similar to humans," the statement said.

"Our goal was to raise the nutritional value of cows' milk by adding two human genes, the protein lactoferrin, which provides infants with anti-bacterial and anti-viral protection, and lysozyme, which is also an anti-bacterial agent," said researcher Adrian Mutto at a press conference.

Read more at Discovery News

Jun 10, 2011

Extra Gene Copies May Trigger Some Cases of Autism

Viewed from some perspectives, autism is a genetic disease. Studies of identical twins show that, when one sibling is affected, the other is also, with a frequency approaching 90 percent. Several genes associated with autism have been identified due to their prevalence in individual families with high rates of autism. All of that, however, doesn’t help explain why there are so many of what appear to be sporadic cases of autism, where a single individual in a family has the disorder; these account for the majority of all cases of autism.

Over the past several years, a case has been building that many of the sporadic cases are also genetic, the result of brand-new mutations that appear only in the affected individual. A set of studies that appear in the journal Neuron make a compelling case that these new mutations can also account for a significant fraction of the total incidence of autism, but still aren’t common enough to fully account for the incidence of the disease.

The new studies rely heavily on a project developed by a private foundation, the Simons Simplex Collection. The Simons Foundation has worked with academic researchers to obtain DNA and cell samples from thousands of unaffected parents and their autistic children; unaffected siblings are also included. This has allowed researchers to screen for changes in the DNA that are unique to the affected individual. In this case, the papers looked for what are called copy number variations, or CNVs, which occur when a chromosome has either ended up with an extra copy of part of the genome, or seen a part of the genome deleted. CNVs will often contain genes, so they create differences in the dose of these genes.

The studies found slightly different numbers, but the same general trend: New CNVs (deletions or duplications that are not present in either parent) are much more common in autistic children than they are in their unaffected siblings. One study found that they showed up 3.4 times more often; the other showed 3.9 times. In either case, there were many more changes in the dose of genes among autistic individuals. Moreover, most of these changes are rare, showing up in only one or a few individuals. This low frequency implies that, with a larger population, even rarer CNVs would be uncovered. The statistics are such that the authors estimate that there may be several hundred potential sites in the genome that could be linked to autism.

A number of areas that were previously associated with autism came out of the screens, but many of the sites were brand-new. In one case, the authors found duplications of a region produced autism; previously, others had found that deletion of this region produced a disorder where affected individuals are unusually gregarious.

An accompanying paper looks at what the genes present in these CNVs do. In general, they seem to be involved in what you’d expect: synapse formation, the internal structure of nerve cells, and the generation of the axons and dendrites that help nerve cells form connections with one another. Thus, the findings help support the general picture that autism is associated with problems with wiring the brain up, rather than the production or function of nerve cells.

Where do these new results leave us in terms of the root causes of autism? They certainly support the general idea that even sporadic cases of autism are caused by new mutations. But on their own, CNVs don’t seem to be occurring at a rate that is sufficient to account for all the sporadic cases of autism. There is the chance that many of the same genes we see within the CNVs, however, are damaged by smaller mutations, including single base changes, that can’t be detected by the techniques used in these studies. Identifying these sorts of mutations, however, will probably require whole-genome sequencing of thousands of individuals, so we’re unlikely to see it in the near future.

Read more at Wired Science

Council quizzed over zombie invasion plans by resident

A "concerned citizen", Robert Ainsley, lodged his query on Tuesday, asking: "Can you please let us know what provisions you have in place in the event of a zombie invasion?"

He added: "Having watched several films it is clear that preparation for such an event is poor and one that councils throughout the kingdom must prepare for."

The authority has yet to formally respond but has indicated that there are no specific references to zombies in its emergency plans.

Leicester City Council has 20 working days to answer but its head of information governance, Lynn Wyeth, took to local radio yesterday to address the issue.

She said: "We've had a few wacky ones but this one did make us laugh.

"It's one of those questions that you could do a one-liner saying there is nothing specifically in the emergency plan to state a response to a zombie invasion.

"But you could look at it in more depth and say, 'Which parts of the emergency plan could you apply to a zombie invasion?' - as it would have the same impact as perhaps some other disaster or attack."

She told the BBC: "If it's specifically about zombies then I would say, from my recollection of the plan... then unfortunately there's nothing in there... saying how we would respond to zombies."

Ms Wyeth said that the council was required by law to responond to all requests made under the Freedom of Information Act.

Read more at The Telegraph

Dogs can instinctively sense a friendly face

Dog owners often claim their pets have an uncanny ability to understand them, sensing tiredness, depression and illness even if they hide the signs.

Now scientists claimed to have proved the phenomenon and that the ability is natural and not just learnt.

Dr Monique Udell and her team from Florida University carried out two experiments involving both domesticated dogs and their relative the wolf.

The two sets of animals were given the opportunity to beg for food, either from an attentive person or from a person who ignored the potential beggar.

The researchers showed for the first time that wolves, like domestic dogs, are capable of begging successfully for food by approaching the attentive human.

This demonstrates that both species – domesticated and non-domesticated – have the capacity to behave in accordance with a human's attentional state.

They are therefore likely born with the ability, since wolves would not have had much practice, which the typical pet dog gains by begging for treats during dinner and at other times.

Dogs did, however, get better at the ability the more time they spent with humans.

Dogs in shelters were not nearly as good as well loved pets, demonstrating that exposure to humans allows dogs to hone their natural people-reading skills more.

Read more at The Telegraph

Jun 9, 2011

Jack Horner the man who’s making a “Chickenosaurus”

Renowned paleontologist Jack Horner has spent his career trying to reconstruct a dinosaur. He’s found fossils with extraordinarily well-preserved blood vessels and soft tissues, but never intact DNA. So, in a new approach, he’s taking living descendants of the dinosaur (chickens) and genetically engineering them to reactivate ancestral traits — including teeth, tails, and even hands — to make a “Chickenosaurus”.

Police hunt ‘psychic’ after false tip-off about mass grave of children

Police in Texas are investigating a woman who claimed to be a psychic after she sparked an ultimately fruitless hunt for a mass grave of dismembered bodies.

Local officers and FBI agents raided a rural farmhouse in Hardin, north-east of Houston, after receiving the report that it held up to 30 bodies, including children.

After finding nothing, police gave up the search – but not before ”a source” had told CBS news that “a lot” of dismembered children’s bodies had indeed been found at the scene, sparking a global news story.

Liberty county judge Craig McNair, the county’s top elected official, said the sheriff’s office had received two calls from the person. The first came on Monday, directing officers to an address in Hardin, but after officers found nothing the same caller told police on Tuesday that they had the wrong house.

Officers approached the scene of the second tip-off on Tuesday morning and said there was blood on a back door and a foul odour coming from the house, leading to the search warrant.

“We have to take tips like this very seriously,” McNair said.

However the Houston Chronicle has since reported that the calls had come from a woman who claimed to have psychic powers, prompting questions over why police responded so vigorously.

The FBI were summoned and officers scrambled to the home on Tuesday, but not before a source apparently told CBS the bodies had already been found. Local television station KPRC was given the same information and the story was promptly followed up by news agenciesAFP and Reuters.

Before long the news that 30 bodies had been uncovered in a mass grave was leading BBC and Sky News channels in the UK and across the world. The Guardian contributed its own version.

Liberty county sheriff’s captain Rex Evans said authorities took the tip seriously in part because the caller had details about the inside of the house that only someone who had seen it could have known.

He said authorities were working to track her down. They had a name and number.

Asked if he thought the tip was a hoax, Evans said only that police found no bodies or anything to indicate a murder. “We are going to continue our investigation and find out how this individual had this information in the first place,” Evans said, adding that the caller may face criminal proceedings.

Full story at The Guardian

Jun 8, 2011

Risk, Probability and How Brains Are Easily Misled

The World Science Festival’s panel on Probability and Risk started out in an unusual manner: MIT’s Josh Tennenbaum strode onto a stage and flipped a coin five times, claiming he was psychically broadcasting each result to the audience. The audience dutifully wrote down the results they thought he had seen on note cards, and handed them in when the experiment was over. Towards the end of the program, he announced there were low odds that even one person in the audience had guessed the right order of results. When he announced them, however, about a dozen people raised their hands, saying that was what they had written down.

Is Tennenbaum psychic? The audience sprinkled with liars?

Neither, according to Tennenbaum. Instead, we’re the victims of our own tendency to expect that a series of coin tosses will produce results that look satisfyingly random to us. As a result, we’re unlikely to suggest a series of four heads followed by a tails. In the same way, we’re likely to end up choosing something like TTHTH. So likely, in fact, that if the coin flips do happen to produce one of these random looking patterns, it’ll be overrepresented in whatever crowd we’re testing. Instant psychic ability, with built in statistical significance.

The funny thing is that this isn’t the product of some mental weakness—Tennenbaum suggested that it’s the product of an excellent built-in sense of what makes for a random pattern. If you graph the frequency of various possible results, it’s possible to see a pattern of peaks at random-looking series and valleys at the ones that chance would seem to disfavor. Comparing the graph generated from our audience to one produced in the 1930s, and it was obvious that the pattern was nearly identical—what we think of as random appears to be quite stable.

The one exception, he noted, was when he performed the experiment with a math-savvy audience. There, a part of the audience recognizes that any series is equally probable, so they are more likely to put down all heads or all tails.

Subverting wisdom

Although Tennenbaum clearly felt that our intuitive feel for randomness was a positive feature, other speakers on the panel noted that human decision-making could obviously get stuck or be manipulated. Mathematician Amir Aczel mentioned that many trained mathematicians can’t wrap their heads around the Monty Hall problem, in which changing probabilities dictate how you should act on a popular game show. It’s relatively easy to run through the probabilities that show which action you should take, but the answer remains counterintuitive—even for those with an exceptional grasp of math.

And that’s assuming, as co-panelist Gerd Gigerenzer noted, that Monty isn’t being malicious. A crowd experiment run by physicist Leonard Mlodinow showed how easy it is to manipulate a people’s answers to simple questions without doing anything overt. Mlodinow divided the audience in half, and asked both halves separately to estimate the number of countries in Africa. This is a standard “wisdom of the crowds” sort of question, where the mean should be somewhere close to the actual number. Instead, the two groups had wildly divergent means, with one half of the audience answering well above the actual answer, the second significantly below.

How’d he manage this? Prior to asking the actual number, Mlodinow had asked a question that subtly primed each group. For one half of the audience, he asked if they thought there were more than 180 countries in Africa; this group ended up with a much higher mean. The second half was asked if there were more than five. Their answers were, on average, too low. Although this was a case of conscious manipulation, it’s easy to see how a similar effect could be generated accidentally, simply based on (for example) the order of questions in a survey.

How do we fix this?

Does all this mean that humans will perpetually remain stuck when it comes to risk and probability? Possibly not, but we have to be careful. That was the message of Gerd Gigerenzer, who helps train decision makers in how to evaluate probabilities. Gigerenzer consistently noted that language was important when it comes to dealing with probabilities.

The most compelling example he gave was one he used when working in medical education. He described the probabilities associated with a breast cancer test: one percent of women tested have the disease, and the test is 90 percent accurate, with a nine percent false positive rate. With all that information, what do you tell a woman who tests positive about the likelihood they have the disease? For a lot of people in medicine, the question leaves them stumped; a typical survey of doctors (and the World Science Festival audience) reveals that there’s no single consensus about the probability that the test indicates a real case of cancer.

Read more at Wired Science

Top bizarre health remedies

Below is a list of the top bizarre health remedies that have been suggested over the years.

 - A peacock feather tied to the leg cures lethal snake venom.

- Cow urine can cure liver complaints, cancers, heart ailments, AIDS and constipation. It is currently being developed into a healthy soft drink

- Cow dung keep homes antiseptic and cool when used as flooring cement.

- Crushed human skull powder can treat epilepsy

- Indian otter testicles is a cure for ‘sexual weakness'

- Green apples cure claustrophobia

- Beer bath to help slow down aging

- Bats blood for help eye infections

- Spider's webs as a cure for malaria

Taken from The Telegraph

Remembering Alan Turing

Alan Mathison Turing, OBE, FRS (23 June 1912 – 7 June 1954), was an English mathematician, logician, cryptanalyst and computer scientist. He was highly influential in the development of computer science, providing a formalization of the concepts of “algorithm” and “computation” with the Turing machine, which played a significant role in the creation of the modern computer. Turing is widely considered to be the father of computer science and artificial intelligence.

During the Second World War, Turing worked for the Government Code and Cypher School at Bletchley Park, Britain’s codebreaking centre. He devised a number of techniques for breaking Germanciphers, including the method of the bombe, an electromechanical machine that could find settings for the Enigma machine.

Turing’s homosexuality resulted in a criminal prosecution in 1952, when homosexual acts were still illegal in the United Kingdom. He accepted treatment with female hormones (chemical castration) as an alternative to prison. He died in 1954, several weeks before his 42nd birthday, fromcyanide poisoning.

An inquest determined it was suicide; his mother and some others believed his death was accidental. On 10 September 2009, following an Internet campaign, British Prime Minister Gordon Brown made an official public apology on behalf of the British government for the way in which Turing was treated after the war.

Jun 7, 2011

New Fossils Push Homo Erectus Origins Back to Asia

The story of the evolution of modern humans can be a bit confusing, species-wise, with many early hominins co-existing without an obvious linear succession. But, geographically, all the action has appeared to take place in Africa, at least until the appearance of Homo erectus, which left Africa and spread globally, only to be replaced by later species of African origin: us. Over the past year or so, however, our history has become a bit more complicated, with evidence that our ancestors interbred with earlier human relatives that had already dispersed throughout Asia. Now, earlier events are also looking a bit more confused, as archeological finds in the nation of Georgia are being promoted as evidence that Homo erectus didn’t even get its start in Africa.

The site of the new finds, Dmanisi, is only about 50km away from Georgia’s capital Tblisi, and has been making waves in the field of human origins for a while. Skeletons uncovered there date from about 1.75 million years ago, and are a confused mix of features that place them right near the base of the Homo genus. These include very ancestral skulls and upper bodies, but lower bodies and legs that appear far more modern. A number of features in these skeletons are shared with various other early Homo skeletons, including ergaster, habilis, and erectus. Confusing matters further, the skeletons were extremely small relative to the Homo erectus individuals that later spread throughout the globe—these make their first unambiguous appearance in Africa right about this time.

There have been a number of responses to these findings. The least disruptive is that these just represent a very early form of Homo erectus, and provide an indication that the species was very mobile right from its start. In this view, the Dmanisi individuals represent a side-branch that was later swamped when their larger cousins appeared on the scene. Others have placed these individuals in their own species, Homo georgicus, without necessarily clarifying its relationship to other contemporary hominins.

But the most radical interpretation has been that, if the Dmanisi skeletons look like the earliest form of Homo erectus, that’s simply because they are. In this scenario, the species originated in Asia, and evolved its larger form there before going mobile, eventually returning to the Africa that its more distant ancestors left. In this view, the Dmanisi skeletons go from being a side show in the drama of human evolution to a starring role in the main show.

The latest finds, detailed in a paper released by PNAS, don’t involve any new skeletons that will shed light on the relationship among the earliest members of our genus. But the stone tools that have shown up indicate that Dmanisi was occupied for tens of thousands of years, which suggests a significant and stable local population. And, in the authors’ view, that strengthens the case that the population could have served as the launching point for the global spread of Homo erectus.

The site itself contains a series of flaked tools that extend the site’s history nearly to the base of the sediments in the area. There’s a solid layer of basalt underneath it all, and that’s covered by some looser layers of volcanic ash immediately above that. But, just about as soon as there are indications of more abundant plant life in the area, stone tools also become apparent. And the evidence of these tools is much deeper (and therefore much older) than identifiable skeletal remains, indicating that the site was occupied for at least 80,000 years, and back as far as about 1.85 million years ago.

So, there was probably a significant population at the site. Was it old enough to be ancestral to the rest of Homo erectus? The authors clearly think yes, writing “The initial occupations of Dmanisi are possibly older than the first appearance of Homo erectus in East Africa.” It’s possible to make these comparisons fairly well, since the Dmanisi site is well dated, and the dates of occupation flank a reversal in the Earth’s magnetic field.

Read more at Wired Science

Why Some People Eat Dirt

Amid the countless edible plants and animals on Earth, there's little consideration for the ground beneath our feet. Intentionally eating dirt, also called geophagy, is a natural instinct and may serve a greater health purpose.

Some humans' urge to consume clay may stem from the activity's protective properties for the digestive system, according to new research to be published in The Quarterly Review of Biology.

After examining 482 cases of human geophagy and 330 records of the practice among animals in a meta-analysis, researchers led by Sera Young of Cornell University discovered that eating dirt had little to do with being hungry or seeking minerals the body might be lacking. Rather, the team found that geophagy may help stave off pathogens in the gut, especially for pregnant women and pre-adolescent children.

Previous theories held that geophagy resulted from hunger or even a lack of nutrients such as iron in a person's diet, but neither seems to be the case.

The research revealed the types of clay consumed have little iron, calcium and zinc, rendering them low in nutritional value. In addition, older individuals with calcium deficiencies do not generally practice geophagy, which weakens the theory that people turn to the practice when their bodies need specific minerals.

Pregnant women and children living in tropical regions of the world, the individuals who consume dirt often, are also the most vulnerable to parasites and pathogens. Practicing geophagy makes sense to these groups, especially if they're experiencing acute digestive illness.

In another study by Young, she found little evidence to support the claim that geophagy actually introduced harmful pathogens into the digestive system, despite other research linking the practice to increased illness in some school children.

Read more at Discovery News

Jun 6, 2011

Scientists 'trap' and study elusive anti-matter

Particles and anti-particles annihilate each other in a small flash of energy when they collide.

At the moment of the big bang, nearly 14 billion years ago, matter and anti-matter are thought to have existed in equal quantities. If that balance had persisted, the observable Universe we inhabit would never have come into being.

For unknown reasons -- and fortunately for us -- Nature seemed to have a slight preference for matter, and today anti-matter is rare.

This asymmetry remains one of the greatest riddles in particle physics.

But ongoing low-energy experiments with hydrogen atoms could be a key step toward solving it.

"We can keep the antihydrogen atoms trapped for 1,000 seconds. This is long enough to begin to study them -- even with the small number that we can catch so far," said Jeffrey Hangst, spokesman for the ALPHA team conducting the tests at the European Organisation for Nuclear Research (CERN) in Geneva.

In the study, published in the journal Nature Physics, researchers report trapping some 300 antiatoms.

Scientists used CERN's high-energy accelerator to create the antihydrogen atoms, and then chilled them to near-zero temperatures.

The aim is to use laser and microwave spectroscopy to compare the immobilised particles to their hydrogen counterparts.

The same team succeeded last year in trapping dozens of anti-matter atoms and holding them in place for a fraction of a second, a world first at the time.

But that was not long enough for the excitable particles to settle into the stable "ground" state needed for precise measurements.

The new benchmark extended this storage time 5,000 fold, making it possible to carry out crucial experiments.

Scientists will now look for "violations" or discrepancies in something called the charge-parity-time reversal (CPT) symmetry.

Read more at The Telegraph

Stone Age 'building boom' discovered

Previously it was thought that Neolithic causewayed enclosures, rings of raised ground up to 300 yards in diameter, emerged over as long a timespan as 700 years between 3,700BC and 3,000BC.

Now, however, academics have suggested the technique spread from the Thames estuary westwards, over less than 100 years from 3,700BC, and were largely completed in southern England by 3,500BC.

Dr Alex Bayliss, a scientific dating expert at English Heritage, said: "By dating these enclosures more accurately, we now know that something happened quite specifically some 5,700 years ago; the speed with which it took place has completely overturned our perception of prehistory."

She and Prof Alasdair Whittle from Cardiff University used radiocarbon dates in conjunction with the sequence that archaeological deposits were laid down, to more precisely date about 40 enclosures.

Recent statistical techniques have enabled they to narrow down their ages to as little as 60 years, in the case of Windmill Hill near Avebury in Wiltshire. They now think it was built between 3,700BC and 3,640BC. Before, the estimate was 3,700BC to 3,100BC.

The enclosures were used as occasional meeting places as more complex and competitive societies emerged, and were perhaps social symbols to "impress and astonish people", said Prof Whittle.

Some were used for long periods but others effectively abandoned after short spans, the new dating indicates.

The Neolithic age began in Britain in about 4,000BC, with the arrival of people from Europe bringing new settled farming techniques with them.

Prof Whittle believes the enclosures were essentially a continental import - although others dispute that idea - and it took 300 years for such foreign ideas to be absorbed by the local population.

He added: "This research fundamentally challenges the notion that little happened among our Stone Age farmers.

Read more at The Telegraph

Jun 5, 2011

Hypnotist David Days knocked out during Dorset show

BBC: Three people were left hypnotised on stage when a hypnotist knocked himself out during a show in Dorset. David Days (show in the above picture on the right) was performing at Portland’s Royal Manor Theatre on Friday when he tripped over a participant’s leg.

His team could not rouse him and the audience was asked to leave while the people were still “asleep” on stage. They were “woken up” soon after when Mr Days recovered. His manager said the performer has a voice recording which can be used to bring people round.

However, Alan Coman, treasurer of the Royal Manor Theatre, has disputed Mr Days’ claims that he passed out and said the episode was “only a joke”. ”It was part of a project for students who were filming the whole thing… but they (the people on stage being hypnotised) weren’t pretending because they didn’t get up to help.

Audience member Fiona Faye said: “He was pulled from stage and there was loads of commotion from a number of people backstage including one man who ran to the other side of the stage to get a first aid kit.

“At first the audience, including us, found it very funny and thought it was part of the act, but as time went on we began to realise that it was not part of the show and he had actually hurt himself. ”At this point we become very worried not only for David Days but also the guests that were onstage oblivious to anything as they were still hypnotised.

“They simply just sat there ‘asleep’.”

Full story at BBC News

A Plethora of Fossil Possums

In many technical papers describing fossil creatures, artists give readers a glimpse of prehistory through reconstructions of what those animals might have looked like in life. Not so with Pucadelphys andinus. In a paper published this week in Nature, artist S. Fernandez depicted a pair of the possum-like creatures at a critical point in their individual histories – just after death but before their soft tissues were stripped away to leave behind only fossilized bones.

The reason why Fernandez restored the small, fuzzy mammals right up to the point of death has everything to do with the way the creatures died. For the most part, the fossil record of small mammals consists of teeth and bits of jaw. Complete skeletons are exceptionally rare, and the few scraps of tiny mammal bones are often found in isolation. But Pucadelphys andinus, a marsupial that inhabited prehistoric Bolivia not long after the end-Cretaceous mass extinction 65 million years ago, was different. Thirty five individuals of this extinct mammal of different age groups were all found in close proximity, paleontologist Sandrine Ladevèze and colleagues report, and this collection of tiny bones may provide the oldest direct evidence of mammal social behavior yet known.

Tiupampa, Bolivia was very different during the time of Pucadelphys. Though the location was at roughly the same latitude then as it is now, Ladevèze and co-authors note, the sites at Tiupampa were actually lower in altitude and represent a lush tropical rainforest akin to the modern day Amazon. Dead animals are often rapidly recycled in these environments – bodies are often destroyed by insects, fungi, and bacteria before there is a chance of them being buried. How, then, did so many well-preserved Pucadelphys fossils wind up in so small an area?

Instead of being busted apart into a mass of disarticulated bones and skeletal fragments, the Pucadelphys individuals held together and were mixed among each other in two small sites about ten feet apart from each other. The mammals appear to have been rapidly killed and buried in a single event – perhaps when a local pond or lake flooded. (The discovery of an intact crocodile nest and the semi-complete, articulated skeletons of other small animals nearby reinforces the idea that the small-scale catastrophe rapidly buried animals in place.) Exactly what this aggregation means for the biology of these animals is another matter.

The hypothesis of Ladevèze and colleagues is that the two Pucadelphys sites represent a social group consisting of adult males, adult females, and sub-adults. They arrived at this conclusion by reviewing possible explanations for why these animals might be found together, especially since similar, modern-day marsupials such as possums and dasyurids are often solitary and territorial. While it is conceivable that the Pucadelphys came together to breed, the presence of immature animals conflicts with this hypothesis and no living possum species is known to come together in such numbers to mate. Nor does it seems likely that these animals were nesting together to share body heat and stay warm – the tropical habitat would have been plenty hot. The rapid burial of a large number of animals of different ages would seem to indicate that these animals were living in some sort social group when they died.

Frustratingly, this hypothesis is difficult to confirm. In their contribution to the book on assemblages of fossil animals – simply called Bonebeds – paleontologists Donald Brinkman, David Eberth, and Philip Currie wrote “[E]very bonebed provides an opportunity to glimpse some aspect of paleobiology.” Exactly what glimpses those aggregations offer depends on how the bonebed came together. A bonebed might represent a single catastrophic event or might have accumulated over time, and just because a group of animals is found in close association does not necessarily mean that they were a cohesive social group when they died. “[R]esearchers should also be critical of using the presence of the death assemblage itself as the primary evidence for normal or day-to-day aggregation paleobehavior,” Brinkman and colleagues cautioned, adding “Paleoenvironmental stresses such as floods, fire, drought, volcanic eruptions, and even disease often result in temporary and atypical aggregations and mass-death events among modern animals, and the same is likely to have occurred in the past.”

Read more at Wired

Under the Ice, Antarctic Land Comes Into Focus

Employing new ice-penetrating radar over a key area of Earth's largest body of ice, scientists are able to see a vast expanse of mountainous terrain and fjords that were carved by flowing glaciers when sea levels were some 200 feet higher than today.

The shape of this landscape beneath a broad region of the East Antarctic Ice Sheet known as the Aurora Subglacial Basin is critically valuable to researchers trying to figure out how quickly -- and when -- the ice burying this land will respond to rising air and sea temperatures in a warming world.

The first map of this previously uncharted region has been developed by an international research team led by geophysicist Duncan A. Young of the University of Texas at Austin and published this week in the journal Nature. Collaborators included British and Australian scientists.

"We knew almost nothing about what was going on, or could go on, under this part of the ice sheet and now we've opened it up and made is real," Young said in a statement released by the University. Co-author Donald Blankenship said the subglacial basin was studied "because it may represent the weak underbelly" of the largest potential source of sea-level rise.

The dominant feature of the region is a very large low-lying trough -- more than a kilometer below sea level -- that runs at a right angle to the modern shoreline. Branching off of this trough are large fjords that were sculpted by outlet glaciers when temperatures were warmer than today and the shoreline of the region was much farther inland, the researchers report.

In a separate evaluation of the study, Sandra Passchier, a polar ice specialist at Montclair State University, New Jersey, calls attention to this submarine, "landward-dipping" topography.

"In this configuration, ice sheets are susceptible to unstable retreat," she wrote, "and the resulting ice-loss could contribute to accelerated sea-level rise."

Read more at Discovery News