Dec 17, 2011

Potential Explanation for Mechanisms of Associative Memory

Researchers from the University of Bristol have discovered that a chemical compound in the brain can weaken the synaptic connections between neurons in a region of the brain important for the formation of long-term memories. The findings, published December 13 in the Journal of Neuroscience, may also provide a potential explanation for the loss of memory associated with Alzheimer's.

Acetylcholine, a neurotransmitter, is released in the brain and is known to play an important role in normal brain functions such as sleep, attention, and learning and memory. Until now the mechanisms by which this transmitter controls such processes were not well understood.

The findings, led by researchers from the University's MRC Centre for Synaptic Plasticity in the School of Physiology and Pharmacology, highlight the mechanisms by which acetylcholine controls communication between neurons located in the prefrontal cortex and may help in understanding how higher cognitive processing is controlled in this important brain area.

Professor of Cellular Neuroscience, Zafar Bashir and his team have demonstrated how electrical stimulation of the prefrontal cortex leads to the release of acetylcholine from synaptic terminals and the subsequent weakening of synaptic connections between neurons.

When acetylcholine is released it binds to specific receptors and starts a molecular cascade which triggers physiological alterations in how prefrontal cortical neurons are 'wired' together. The findings suggest that the persistent weakening of synaptic connections between neurons induced by the endogenous release of acetylcholine in the prefrontal cortex may underlie the formation of new associative memories.

The authors speculate that the memory impairments associated with Alzheimer's dementia may result, in part, from a loss of synaptic plasticity in the prefrontal cortex related to the depletion of brain acetylcholine that occurs in the disease.

Dr Douglas Caruana, who carried out the experiments, said: "Disruptions in cholinergic signaling in the prefrontal cortex are known to affect how the brain encodes lasting associations between objects and places, and a depletion of brain acetylcholine levels in the cortex is a classic hallmark of Alzheimer's dementia'."

Professor Bashir added: "Acetylcholinesterase inhibitors are the most widely used medication to treat individuals with Alzheimer's dementia and the enhancement of synaptic plasticity by acetylcholinesterase inhibition that we now demonstrate may be a way in which these drugs provide clinical efficacy."

Read more at Science Daily

Stink? Neanderthal Noses Didn't Notice

Neanderthals had bigger noses than we do, but tracking a scent was never one of their specialties (maybe for the best).

New three-dimensional medical imaging scans of fossil human skulls reveal that the so-called olfactory bulbs, the part of the brain that processes odors, are 12% larger in Homo sapiens than they were in Neanderthals.

Markus Bastir and Antonio Rosas of the Spanish Natural Science Museum and their colleagues carefully assessed the shape of the base of cranium to quantify the volume of gray matter that would have filled in above.

Their research, reported this week in Nature Communications, divulged another size difference: the temporal lobes, the part of the brain involved in language, memory and social functions, are also larger in Homo sapiens.

That latter finding may not come as a surprise, considering how modern humans have evolved linguistically and socially. But the researchers say that the fact that both the temporal lobes and olfactory bulbs are larger in modern humans suggests that our species evolved a combined use of brain functions related to cognition and olfaction that may not have been true for Neanderthals.

Evidence has been accumulating that Neanderthals and modern humans developed their large brains independently, and so the expectation, then, is that their brains might have worked differently.

For us modern humans, the tight relationship between sniffing ability and higher brain functions makes even more sense when you consider that olfaction is the only sense that establishes a direct connection between the brain and its environment. While information from our eyes and ears must pass through different filters in the brain, smell signals go straight into the highest centers of the brain—those directly responsible for processing emotion, motivation, fear, memory, pleasure, and attraction.

Read more at Discovery News

Dec 16, 2011

Remote Wilderness Polluted by Humans

Nitrogen from human activity has been polluting lakes in the northern hemisphere since the late 19th century. The clear signs of industrialisation can be found even in very remote lakes, thousands of kilometres from the nearest city. This is shown in new research findings published December 16 in the journal Science.

The research is based on studies of sediment from 36 lakes in the USA, Canada, Greenland and Svalbard, Norway. The researchers have analysed how the chemical composition of the sediment has changed over the centuries. Twenty-five of the lakes all show the same sign -- that biologically active nitrogen from human sources can be traced back to the end of the 19th century.

The nitrogen analyses of the lake sediments show that the changes began around 1895. The results also show that the rate of change has accelerated over the past 60 years, which is in agreement with the commercialisation of artificial fertiliser production in the 1950s. Sofia Holmgren, a researcher in Quaternary Geology at Lund University, Sweden, is the only Swede to take part in the comprehensive study.

"I have studied lakes on Svalbard, where the effects of the increased nitrogen deposition are clearly visible in the algal flora," says Sofia Holmgren.

She explains that both the species composition and production of diatoms -- microscopic siliceous algae -- have changed dramatically in the lakes on Svalbard since the start of the 20th century, with the most significant changes over the past decades.

Combustion of fossil fuels and use of fertiliser are the main sources of the increasing amount of nitrogen in the atmosphere. The nitrogen is transported with air currents and reaches the ground in rain or snow. It can travel thousands of kilometres and the nitrogen thus reaches even the most remote lakes and ecosystems.

Read more at Science Daily

The Physics Behind Great White Shark Attacks On Seals

A new study examining the complex and dynamic interactions between white sharks and Cape fur seals in False Bay, South Africa, offers new insights on the physical conditions and biological factors underlying predator-prey interactions in the marine environment.

University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science assistant professor Dr. Neil Hammerschlag, and a colleague from the University of British Columbia, describe how sharks are camouflaged as they stalk their prey from below. Low-light conditions, from the optical scattering of light through water, along with a shark's dark grey back and the dimly light rocky reef habitat allow sharks to remain undetected by seals swimming at the water's surface.

"Animal hunting in the ocean is rarely observed by humans," said Hammerschalg, director of the RJ Dunlap Marine Conservation Program at UM. "The high frequency of attacks by white sharks on seals at our study site in South Africa provides a very unique opportunity to uncover new insights about predator-prey relationships."

Sharks typically search, stalk and strike their prey from below. The vast majority of predatory strikes by sharks and Cape fur seals occur against small groups of young-of-the-year seals. Predatory activity by sharks is most intense within two hours of sunrise and quickly decreases as light penetration in the water column increases.

"Stealth and ambush are key elements in the white shark's predatory strategy," said Hammerschlag.

Cape fur seals also have unique techniques to detect, avoid, outmaneuver and in some cases injure the white shark in order to avoid predation by sharks.

According to the authors, if a seal is not disabled during the shark's initial shark, the small seal can use its highly maneuverable body to leap away from the shark's jaws to evade a second strike.

Read more at Science Daily

Florida Reef Restoration Successful

Nine years after a boat mangled a coral reef near Key West, Florida, the reef is back and thriving thanks to efforts from the National Oceanic and Atmospheric Administration's (NOAA).

The 35-foot long boat Lagniappe II plowed into a reef in the Florida Keys National Marine Sanctuary in August 2002. The boat's owner paid $56,671.27 in a negotiated settlement to partially cover the costs he had incurred for the American public. The money partly covered the restoration of the 376 square-feet of living coral he damaged.

NOAA went to work reattaching 473 corals, then monitored the reef's progress as it regained its health. NOAA researchers used photos and a specialized computer program to study the numbers and types of coral in the damaged area.

By 2009, the reattached coral looked just like a nearby area used as a reference. Another year later, and the damaged reef had more coral that the reference area.

“The monitoring allowed us to document changes to the restored coral and measure the success of this restoration,” said Hatsue Bailey, Florida Keys National Marine Sanctuary restoration biologist in a press release.

“With continued use of these methods, as well as additional monitoring, we learn more about habitat changes at this location and improve upon existing restoration strategies,” said Bailey.

Read more at Discovery News

Christopher Hitchens

Christopher Hitchens, who has died aged 62, described himself as an “essayist and a contrarian” and, as a journalist, critic, war correspondent and bon vivant, enjoyed a 40-year career as one of the world’s most ubiquitous, prolific and provocative public intellectuals.

He began as a leading iconoclast of the Left and, during the 1970s, was a voluble member of a talented and raffish gang, with Julian Barnes, Martin Amis, Ian McEwan and James Fenton, which gave the New Statesman magazine its glittery literary edge. But he got tired of British politics and, in 1981, moved to America where, despite occasional disagreements with his erstwhile comrades (as when he took Britain’s side against the Argentine junta in the Falklands conflict), his repeated assaults on such hate figures as Ronald Reagan and Henry Kissinger continued to guarantee him a welcome in radical circles.

All this changed after the 9/11 terrorist attacks on New York and Washington, an event he interpreted as a turning point in “a war to the finish between everything I love and everything I hate”. He became an outspoken opponent of “Islamofascism”, forging a breach with the Left which became a permanent rift after the invasion of Iraq in 2003. While his erstwhile colleagues were out on the streets proclaiming “Not in Our Name” (a slogan he found nauseating in its “unstinting self-regard”), Hitchens emerged as one of the fiercest cheerleaders for George W Bush’s strategy of “regime change”. To the inevitable accusations of betrayal (George Galloway described him as the “first ever metamorphosis of a butterfly back into a slug”), Hitchens responded with characteristic gusto: such attacks, he said, washed off him “like jizz off a porn star’s face”.

But, as Hitchens confessed in his memoir Hitch-22 (2010), there had always been a “Janus-faced” side to his personality. When he was a child, his mother told his father, during an argument over whether they could afford to send him to private school: “If there is going to be an upper class in this country, Christopher is going to be in it.”

At the time this was more her aspiration than his, yet Hitchens acknowledged that alongside the donkey-jacketed revolutionary “Chris”, veteran of the Aldermaston marches, there was the suave, good-looking and socially ambitious “Christopher” – “Hypocritchens”, as he was known at Balliol – who enjoyed the company of “confident young men who owned fast cars” and frequented the Union and the Gridiron Club.

The young man spraying pro-Vietcong slogans on car plant walls or marching the streets toting some insurgent flag, might, the same evening, be found at a Right-wing dining club happily gobbling up a pudding called “bombe Hanoi”. Friends later joked that the sentence least likely to emerge from Hitchens’s mouth was: “I don’t care how rich you are, I’m not coming to your party.”

Though he claimed to keep “two sets of books” when it came to political purpose and social ambition, his “Mr Both Ways” approach was as much intellectual as social. He claimed to be faithful to the values of “Left opposition” heroes, such as Rosa Luxembourg, Leon Trotsky and George Orwell, but was always too sceptical and independent-minded to fall for the tedious dogmas of mainstream Marxism – or any other “ism”.

He took pride in “asking annoying questions at every opportunity” and, as a journalist, made a point of going out to see things for himself, whether it was a war zone or a convention of Civil War re-enactors. Even at the height of student radicalism in 1968, he spotted, on a trip to Cuba, the oppressive side of the Castro revolution, acknowledging, when he found himself bombarded by showers of pebbles and the taunt “Sovietico” from the street urchins of Havana, that he had been granted a glimpse of “unscripted public opinion”.

The author or co-author of 17 books, as well as pamphlets and essays, Hitchens was a prolific columnist and, particularly in America, a formidable participant in public debates. He found it difficult to see a sacred cow without lobbing a hand grenade, and his more eminent targets included Mother Teresa (whom he portrayed as a fundamentalist Catholic bigot who gladhanded totalitarian regimes and was “a friend of poverty” rather than of the poor); Bill Clinton (the subject in 1999 of No-One Left to Lie to: The Triangulations of William Jefferson Clinton); and God (the target in 2007 of God Is Not Great: How Religion Poisons Everything).

Hitchens’s natural pugnacity seems to have earned him grudging admiration in some unlikely quarters. In his memoir he recalled an encounter with Mrs Thatcher (whom he found “surprisingly sexy”) not long after her election to the Tory leadership; their inevitable argument ended with the future Iron Lady ordering him to bend over so that she could spank him on the bottom with a rolled-up parliamentary order paper, afterwards mouthing the words: “Naughty boy!”

It was only later, he confessed, that he appreciated the glimpse of the “smack of firm government” which he had been afforded.

The elder of two sons (his younger brother is the journalist and author Peter Hitchens), Christopher Eric Hitchens was born on April 13 1949 in Portsmouth, where his father, a naval officer, was stationed, and was brought up as “a Navy brat” in Malta and Scotland.

His father was a kindly, decent but emotionally inhibited man whose world view epitomised an old-fashioned English conservatism and whose way of showing affection to his son, while he was at prep school, was to send him complicated naval knots tied out of pipe-cleaners, which, of course, Christopher never mastered. (Later, Hitchens was much affected by the discovery that his father was secretly giving his friends Christmas gift subscriptions to his “pinko” magazine, the New Statesman).

His mother, Yvonne, a glamorous but tragic figure whose carefully concealed Jewish ancestry Christopher would discover only when he was in his 40s, eventually left her husband for an unfrocked vicar, with whom she became a devotee of the Maharishi Mahesh Yogi (“the sinister windbag who had brought enlightenment to the Beatles in the summer of love”), and with whom she died in a suicide pact in an Athens hotel when Christopher was 24.

Hitchens’s account of this “lacerating howling moment” in his life and his journey to a junta-governed Greece to identify Yvonne’s body is one of the most powerfully moving passages in his memoir, the tragedy compounded by the revelation that, in the hours before she died, she had tried to phone him repeatedly but had failed to get through. Characteristically, though, he still found the time to file a piece for the New Statesman on the political situation in Greece.

At the Leys School in Cambridge, Christopher discovered a passion for literature, dabbled in homosexuality and was introduced to the pleasures of Marxism by the headmaster who, in a vain attempt to inoculate him against such a heresy, presented him with a copy of the Communist Manifesto.

He developed all three interests at Balliol College, Oxford, where he went up ostensibly to read PPE, but devoted more energy to sit-in and picket line duties (as well as joining the Labour Party, he became a member of the Trotskyist International Socialists) and to cultivating friendships among a camp and reactionary circle of students and academics.

These included John Sparrow, Warden of All Souls and a hate-figure for the Left, who once mischievously ambushed Hitchens in full rant at some student demo to remind him they had a date for dinner. Hitchens’s claim, in his memoirs, that, while at Oxford, he had bedded two future government ministers under Margaret Thatcher would set off an – ultimately futile – orgy of press speculation which did little to damage sales of the book.

After graduating with an inevitable Third, Hitchens launched his career in journalism as “social science correspondent” at the Times, a “Gogol-like ghost job which I held for six months before its editor said something to me that made it impossible for me to go on working for him”. (In a footnote, Hitchens noted that the exact words were: “You’re fired.”)

In the 1970s, as well as working as a freelance, he took various “mainstream” jobs, from being a researcher for the Insight team at the Sunday Times to working as a foreign correspondent for the Daily Express, before joining the New Statesman as a staff writer and editor under Anthony Howard. At the same time he became a regular at the famous Bloomsbury “Friday lunches” at which such luminaries as Clive James, Peter Porter, the Amises (père et fils), Craig Raine and others would swap jokes and gossip.

As the decade wore on and Old Labour tottered towards the political graveyard (“Weimar without the sex”, as Hitchens described the Callaghan government), Hitchens became increasingly disillusioned with the British Left and confessed to harbouring an “odi et amo” complex about Mrs Thatcher, whom he felt was “right on essential matters”. By the 1979 election (in which, for the first time, he did not vote Labour) he was starting to feel “the strong gravitational pull of the great American planet”.

Hitchens’s decision to settle in the United States was a turning point in his life, both personally and politically. As a columnist for The Nation, he continued to fulminate against familiar targets – American imperialism, military fascism, religious fundamentalism – but his rightward political odyssey rolled inexorably on, driven by a disgust with the empty pieties of the Left and an appreciation of the dynamism of the American political tradition.

Gradually he expanded his columns to the pages of mainstream publications such as The Washington Post, The Boston Globe, Harper’s Magazine, Newsday and, appropriately, Dissent. He also lectured and accepted visiting professorships at the Universities of Pittsburgh and California and the New York School for Social Research.

Hitchens’s ideological shift was driven also by a concern at the growing threat of Islamic extremism to Western freedoms. He was appalled by the “tepid reaction” of the European Left following Ayatollah Khomeini’s issue of a fatwa against his friend Salman Rushdie, and also by the events of September 11 2001 which, in his view, opened up a “whole new terrain of struggle”. In 2007 he took the oath of American citizenship at a ceremony at the Jefferson Memorial presided over by George W Bush’s Secretary of Homeland Security, Michael Chertoff.

Hitchens opened his memoir Hitch-22 with a story about a false rumour of his own mortality. A catalogue for an exhibition of photographs at the National Portrait Gallery had mistakenly described him as “the late” Christopher Hitchens, a mistake he used as a peg to muse on the subject of mortality (it was not so much the mourners at the funeral that came to mind, he wrote, but the “steady thunk of emails into my in-box on the day of my demise”). But as he toured to promote the book, he was diagnosed with oesophagal cancer and forced to cancel the remainder of his engagements.

Read more at The Telegraph

Dec 15, 2011

Dinosaurs With Killer Claws Yield New Theory About Evolution of Flight

New research from Montana State University's Museum of the Rockies has revealed how dinosaurs like Velociraptor and Deinonychus used their famous killer claws, leading to a new hypothesis on the evolution of flight in birds.

In a paper published Dec. 14 in PLoS ONE, MSU researchers Denver W. Fowler, Elizabeth A. Freedman, John B. Scannella and Robert E. Kambic (now at Brown University in Rhode Island), describe how comparing modern birds of prey helped develop a new behavior model for sickle-clawed carnivorous dinosaurs like Velociraptor.

"This study is a real game-changer," said lead author Fowler. "It completely overhauls our perception of these little predatory dinosaurs, changing the way we think about their ecology and evolution."

The study focuses on dromaeosaurids; a group of small predatory dinosaurs that include the famous Velociraptor and its larger relative, Deinonychus. Dromaeosaurids are closely related to birds, and are most famous for possessing an enlarged sickle-claw on digit two (inside toe) of the foot. Previous researchers suggested that this claw was used to slash at prey, or help climb up their hides, but the new study proposes a different behavior.

"Modern hawks and eagles possess a similar enlarged claw on their digit 2's, something that hadn't been noted before we published on it back in 2009," Fowler said. "We showed that the enlarged D-2 claws are used as anchors, latching into the prey, preventing their escape. We interpret the sickle claw of dromaeosaurids as having evolved to do the same thing: latching in, and holding on."

As in modern birds of prey, precise use of the claw is related to relative prey size.

"This strategy is only really needed for prey that are about the same size as the predator; large enough that they might struggle and escape from the feet," Fowler said. "Smaller prey are just squeezed to death, but with large prey all the predator can do is hold on and stop it from escaping, then basically just eat it alive. Dromaeosaurs lack any obvious adaptations for dispatching their victims, so just like hawks and eagles, they probably ate their prey alive too."

Other features of bird of prey feet gave clues as to the functional anatomy of their ancient relatives; toe proportions of dromaeosaurids seemed more suited for grasping than running, and the metatarsus (bones between the ankles and the toes) is more adapted for strength than speed.

"Unlike humans, most dinosaurs and birds only walk on their toes, so the metatarsus forms part of the leg itself," Fowler said. "A long metatarsus lets you take bigger strides to run faster; but in dromaeosaurids, the metatarsus is very short, which is odd."

Fowler thinks that this indicates that Velociraptor and its kin were adapted for a strategy other than simply running after prey.

"When we look at modern birds of prey, a relatively short metatarsus is one feature that gives the bird additional strength in its feet," Fowler continued. "Velociraptor and Deinonychus also have a very short, stout metatarsus, suggesting that they had great strength but wouldn't have been very fast runners."

The ecological implications become especially interesting when dromaeosaurids are contrasted with their closest relatives: a very similar group of small carnivorous dinosaurs called troodontids, Fowler said.

"Troodontids and dromaeosaurids started out looking very similar, but over about 60 million years they evolved in opposite directions, adapting to different niches," Fowler said. "Dromaeosaurids evolved towards stronger, slower feet; suggesting a stealthy ambush predatory strategy, adapted for relatively large prey. By contrast, troodontids evolved a longer metatarsus for speed and a more precise, but weaker grip, suggesting they were swift but probably took relatively smaller prey."

The study also has implications for the next closest relatives of troodontids and dromaeosaurids: birds. An important step in the origin of modern birds was the evolution of the perching foot.

"A grasping foot is present in the closest relatives of birds, but also in the earliest birds like Archaeopteryx," Fowler said. "We suggest that this originally evolved for predation, but would also have been available for use in perching. This is what we call 'exaptation:' a structure evolved originally for one purpose that can later be appropriated for a different use."

The new study proposes that a similar mechanism may be responsible for the evolution of flight.

"When a modern hawk has latched its enlarged claws into its prey, it can no longer use the feet for stabilization and positioning," Fowler said. "Instead the predator flaps its wings so that the prey stays underneath its feet, where it can be pinned down by the predator's bodyweight."

The researchers suggest that this 'stability flapping' uses less energy than flight, making it an intermediate flapping behavior that may be key to understanding how flight evolved.

"The predator's flapping just maintains its position, and does not need to be as powerful or vigorous as full flight would require. Get on top, stay on top; it's not trying to fly away," Fowler said. "We see fully formed wings in exquisitely preserved dromaeosaurid fossils, and from biomechanical studies we can show that they were also able to perform a rudimentary flapping stroke. Most researchers think that they weren't powerful enough to fly; we propose that the less demanding stability flapping would be a viable use for such a wing, and this behavior would be consistent with the unusual adaptations of the feet."

Another group of researchers has proposed that understanding flapping behaviors is key to understanding the evolution of flight, a view with which Fowler agrees.

"If we look at modern birds, we see flapping being used for all sorts of behaviors outside of flight. In our paper, we are formally proposing the 'flapping first' model: where flapping evolved for other behaviors first, and was only later exapted for flight by birds."

Read more at Science Daily

Scientists Discover Second-Oldest Gene Mutation

A new study has identified a gene mutation that researchers estimate dates back to 11,600 B.C., making it the second oldest human disease mutation yet discovered.

Researchers with the Ohio State University Comprehensive Cancer Center -- Arthur G. James Cancer Hospital and Richard J. Solove Research Institute led the study and estimate that the mutation arose in the Middle East some 13,600 years ago. Only a mutation seen in cystic fibrosis that arose between 11,000 and 52,000 years ago is believed to be older.

The investigators described the mutation in people of Arabic, Turkish and Jewish ancestry. It causes a rare, inherited vitamin B12 deficiency called Imerslund-Gräsbeck Syndrome (IGS).

The researchers say that although the mutation is found in vastly different ethnic populations, it originated in a single, prehistoric individual and was passed down to that individual's descendents. This is unusual because such "founder mutations" usually are restricted to specific ethnic groups or relatively isolated populations.

The findings were published recently in the Orphanet Journal of Rare Diseases.

"Diagnosing IGS is oftentime-consuming and inconclusive mainly because vitamin B12 deficiencies have many causes, so identifying this condition usually involves excluding other possibilities," says principal investigator Stephan M. Tanner, research assistant professor of molecular virology, immunology and medical genetics.

"Our findings permit reliable genetic diagnostics in suspected cases of IGS in that this mutation should be considered first when genetically screening patients from these populations."

Even in rare disorders, founder mutations can cause a significant fraction of all cases, he says.This mutation accounts for more than half of the cases in these populations and for about 15 percent of cases worldwide. "It is also often seen in expatriates living abroad," Tanner says.

IGS was identified just over 50 years ago. It occurs in children born with two mutated copies of either the amnionless (AMN) or the cubilin (CUBN) gene. When a genetic mistake is present in both copies of either of these two genes, a person cannot absorb vitamin B12 in the small intestine, resulting in the deficiency.

Children with IGS experience a high risk of infections, fatigue, attention deficit, paralysis and, ultimately, a form of anemia that can be fatal if left untreated. An estimated 400 to 500 cases of IGS have been described worldwide thus far. The incidence rate remains unknown. The syndrome is treatable with life-long injections of vitamin B12.

For this study, the researchers examined a total of 20 patients, 24 parents, 8 unaffected siblings, and 4 grandparents from 16 IGS families. Because the researchers found the mutation in such diverse populations, they were unsure whether it was a true founder mutation that first arose in one individual and was passed down through many generations, or whether it was simply a mutation that recurred frequently over time in different populations.

Read more at Science Daily

Spiders’ Hundreds of Fine Hairs Are Hundreds of Ears

Hunting spiders can not only watch your every move, but they can feel those moves, and that of their prey, through the air.

How their tiny specialized hairs do it has puzzled researchers for decades, but one team of scientists may have found a break. Their physics-focused work suggests each hair acts like a single, independent ear — not a network of ear parts that, together, turn a spider’s exoskeleton into one giant ear, as was previously assumed.

“Nobody had looked at these hairs in just the right way. When you look at what they are mechanically optimized to do, you could design better ones,” said physicist Brice Bathellier of the Institute Of Molecular Pathology in Vienna, who co-authored a study of trichobothria hairs Dec. 14 in the Journal of the Royal Society Interface.

“But nature optimizes. Animals evolve under stringent conditions,” Bathellier said. “So it became a question of what [the hairs] actually do, what type of signals tell animals ‘I should leave’ or ‘that’s just wind blowing on me.’”

Trichobothria are fine hairs found on spiders, insects and other animals with exoskeletons. The hairs are so sensitive that some can pick up air movement down to one ten-billionth of a meter, roughly the width of an atom, allowing animals to feel the presence of nearby predators and prey. (Crickets and flies, for example, have tufts of them on their rumps to sense prowling enemies.)

Researchers in the past thought each hair acted like those found in the cochlea of the human inner ear. In that organ, a forest of different lengths and thicknesses of hair breaks up incoming sound waves into discrete chunks, rather than picking up a wide range.

Previous experiments agreed with the assumption: Spider and insect trichobothria resonated at very specific frequencies, showing “peaks” at one particular sound frequency.

But Bathellier said almost all of the research focused on the distance the sound waves wiggled the hairs back and forth — not on how fast they wiggled them.

To measure the hairs’ wiggling velocities, Bathellier and his colleagues placed hunting spiders and crickets in a sealed glass box with a speaker mounted to it. Then they painted a laser sheet down the box and across a specimen’s trichobothria, then puffed microscopic drops of oil that lit up in the plane of the laser.

As they tweaked the speaker’s sounds, a video camera recorded the oil particles moving around the hairs. Later, a computer program deduced the speed of the moving oil droplets around the hairs.

Instead of one peak response to a single frequency, “these hairs operate at the physical limits of sensitivity across a much broader range of frequencies,” Bathellier said.

The hairs responded best to sounds between about 40 Hz, a low rumble of bass, and 600 Hz, a car horn (humans ears can detect between 20 Hz and 20,000 Hz). That they picked up such a wide range of frequencies at all could overturn previous assumptions about how trichobothria work.

“They operate like band-pass filters or microphones, not like the hairs in a human ear,” Bathellier said.

Read more at Wired Science

Found Coins May Unveil a Lost Viking

A hoard of silver found by a metal detector has provided intriguing new clues to a previously unknown Viking king, the British Museum announced on Wednesday.

Found some 16 inches beneath the surface of a field in Silverdale, a village in north Lancashire, UK, the hoard materialized as Darren Webster, a 39-year-old stonemason, lifted a lead box signalled by his detector.

A shower of 201 pieces of silver revealed an abundance of arm-rings, brooch fragments, ingots and coins.

"I had a very good idea what it was. The coins, the bracelets, I knew it was possibly Viking, more than likely Viking," Webster told the Lancashire Evening Post.

Indeed, the treasure, possibly buried by a Viking warrior before he went into battle, includes coins which evoke Viking kings such as Alfred the Great, who reigned from 871 to 899. At that time, the Vikings were fighting the Anglo-Saxons to keep control of the North of England.

"Among the many stand-out objects is a coin type none of us had seen before," said Ian Richardson, treasure registrar at the British Museum's Portable Antiquities and Treasure department.

On one side, the coin bears an inscription in the shape of a cross which reads DNS (Dominus) REX (many Vikings had converted to Christianity within a generation of settling in Britain).

More intriguingly, the inscription on the other side reads AIRDECONUT -- "an attempt to represent the Scandinavian name Harthacnut," said Richardson.

Read more at Discovery News

Dec 14, 2011

Tiny Human Hairs Beat Back Bugs

Human body hair, such as the “peach fuzz” on our arms and faces, turns out to be quite useful.

This hair has the ability to enhance the detection of parasites and can even prevent pests from biting.

A study, published in the latest Royal Society Biology Letters, helps to explain why the human body looks relatively hairless compared to that of other furrier apes, but yet still has the same density of hair follicles as would be expected of a chimp or gorilla of the same size.

The fine hair consists of types known as “vellus” and “terminal.” The former is the aforementioned peach fuzz, while the latter refers to head hair as well as to pubic hair that develops in the armpits and around the genitals.

“All these hairs have nerves attached to them and provide us with the ability to detect displacement of the hair,” co-author Michael Siva-Jothy told Discovery News. “By simultaneously forming a barrier and providing detection, these hairs prolong search time and make detection more likely because the bug has to spend more time clambering over them.”

Siva-Jothy, a professor of entomology in the University of Sheffield’s Department of Animal & Plant Sciences, and colleague Isabelle Dean came to these conclusions after conducting an experiment that was both figuratively and literally hair raising.

The researchers placed bed bugs on shaved and unshaved arm areas belonging to 10 women and 19 men who were student volunteers from the university. Each bed bug was hungry and ready to feast on its potential victim.

The volunteers had to remain still throughout the experiments, so participation in the study was not suitable for potentially bug-squeemish people.

The scientists took note of how hairy the students were and how long it took for the bed bug to get ready to eat. While the volunteers were warned that they might be bitten during the experiment, no one was.

Siva-Jothy explained, “Just before it begins to feed, the bed bug swings its proboscis from a ‘stowed’ position to a ‘ready for action’ position. We stopped the trial as soon as that second position was adopted.”

The bugs aren’t looking for veins, but instead disrupt the capillaries and subsequently feed on the pool of blood under the skin.

Host detections of the parasite were more frequent on unshaved arms of both men and women. Bed bug search times took significantly longer on the unshaved arms of men. Men simply have a lot more body hair, so their bodies present challenging obstacle courses for bugs.

“Men tend to have more terminal hairs because of the effects of testosterone,” he said.

The researchers believe human body hair foils not only bed bugs, but also other parasites, such as mosquitoes, ticks and leeches.

Humans have retained this useful peach fuzz and other body hair, but have lost their heavy, thick coat of fur over evolutionary time. Thick fur provides warmth and protection, but it can also aid parasites, by giving them a place to hide and making it harder to remove and crush them.

Prior research has determined that human body hair aids in sweat gland maintenance. Other as-of-yet undiscovered functions could also exist.

Read more at Discovery News

Most Complete Example of Commandments on Display

The most complete and best preserved ancient example of the Ten Commandments‭, a 2,000 year old ‬leather parchment scroll discovered in a cave at the Dead Sea in 1952, will go on display on Friday in New York's Discovery Times Square Exposition. The scroll is an important, although brief, addition to the show "Dead Sea Scrolls: Life and Faith in Biblical Times."

The largest collection of biblical artifacts ever displayed outside Israel, the exhibit, which opened October 28 and will run through April 15, is already featuring 20 Dead Sea Scrolls, with sections from the biblical books of Genesis, Psalms, Exodus, Isaiah, and others.

The Ten Commandments scroll will be added to the show from Dec. 16 through Jan. 2.

Dating from 50 BCE to 1 BCE, the scroll was found in Cave 4, one of the 11 caves near the site of Khirbet Qumran on the northwestern shores of the Dead Sea where a highly fragmented collection of documents in Hebrew, Greek and Aramaic writing was discovered between‭ ‬1947‭ ‬and‭ ‬1956.

Written in Hebrew, the scroll contains the text of the Ten Commandments from Deuteronomy (the fifth book of the Old Testament) and is the best preserved of all the Deuteronomy manuscripts.

It features four complete and two partially damaged columns and was likely intended as a prayer leaflet.

Owned by the Israel Antiquities Authority, the scroll is believed to be the second-oldest version of the commandments, after the Nash Papyrus, which dates to‭ ‬150‭–‬100‭ ‬BCE. However, this‭ manuscript, which‬ was discovered in Egypt and is now in the Cambridge University Library, is less complete‭ ‬and more fragmented.

In Toronto, where it was displayed at the Royal Ontario Museum for just 80 hours due to its fragile conditions and sensitivity to light and humidity, the Ten Commandments scroll attracted a large number of visitors.

Lines for what was hailed as "a once-in-a-lifetime opportunity to see one of the greatest archaeological finds of the 20th century" were indeed a couple of miles deep.

According to Risa Levitt Kohn, professor of Hebrew Bible and Judaism at San Diego State University and one of the exhibition's curators, ancient religious relics like the Ten Commandments scroll exert a unique fascination.

"You can actually see, up close, the oldest parchment copy of laws that have influenced so much of western religious and secular culture," Levitt Kohn told Discovery News.

Read more at Discovery News

Isaac Newton's Writings Go Online

More than 4,000 pages of the pioneering scientist and mathematician Sir Isaac Newton (1642-1727) are now publicly available online, Cambridge University has announced.

Holding the world's largest and most significant collection of Newton's scientific works, the University Library decided to embark on the huge digital project in 2010.

Up to 200 pages were captured each day, although significant conservation work had to be undertaken on several of the manuscripts and notebooks before they were considered robust enough to be digitized.

"Anyone, wherever they are, can now see at the click of a mouse how Newton worked and how he went about developing his theories and experiments," said Grant Young, digitisation manager.

The collection includes Newton's own annotated copy of his 1687 masterwork, "Philosophiæ naturalis principia mathematica," in which he described his laws of motion and gravitation.

Containing Newton's own edits and notes, the digitized copy shows how methodically the scientist worked through his text, "marking alterations, crossing out and annotating his work in preparation for the second edition," Young said.

In addition to Newton's Principia, notebooks and early papers, the University has included the "Waste Book," a very large notebook the scientist inherited from his stepfather. He filled it with notes and calculations when he was forced to leave his studies in Cambridge during the Great Plague.

"With plenty of time and paper to hand, Newton was able to make significant breakthroughs, particularly in his understanding of calculus," Young said.

But not all Newton's contemporaries would have approved the online publication.

Several manuscripts in the collection contain the handwritten line "not fit to be printed," scrawled by Thomas Pellet, a Fellow of the Royal Society, who had been asked to go through Newton's papers after his death and decide which ones should be published.

Read more at Discovery News

Rattlesnakes Can't Keep Up With Climate Change

As the Earth's climate changes over the next century, rattlesnakes will have to adapt as much as 1,000 times more quickly than they have in the past to find habitats that they can tolerate.

Some species may be flexible enough to handle the rapidly changing conditions. But many will be unable to slither away fast enough to survive. And the same is likely true for other kinds of creatures, including mammals and other reptiles.

"I'm not sure how species will be able to follow the climate so quickly," said Michelle Lawing, a paleobiologist at Indiana University in Bloomington. "In some cases, it might be better for conservationists to move them or create managed corridors where they could be assisted to better, more suitable habitats."

"Even when we make a big effort, the world will still look very different," Lawing added. "We're going to have different combinations of species in different places that we've never seen before."

To predict where animals might be able to live in the coming decades, plenty of studies have taken into account the physical traits of various species and how those traits might limit their future ranges.

To add more context to these kinds of projections, Lawing and colleague David Polly looked to the past to see how rattlesnakes have adapted to previous climate shifts. They chose to study rattlesnakes because these reptiles have lived and moved throughout North America for a long time.

For the first part of the study, the researchers used evidence from fossils and elsewhere to created maps of the ranges of 11 rattlesnake species at 4,000-year intervals over the last 320,000 years. Then, they analyzed all sorts of details about each era's climate conditions, including things like mean annual temperature and maximum temperature of the warmest quarter of the year. That allowed them to see how temperature and precipitation has affected the suitable ranges of the snakes over the millennia.

In the past, rattlesnakes have responded to changes in climate by moving to new places. Those geographic movements happen 100 to 1,000 times faster than the animals can adapt to physically. In the face of major climatic changes, in other words, evolution is not an option. And the snakes won't be able to move fast enough to get to a new, more habitable place.

The researchers used accepted climate projections from the Intergovernmental Panel on Climate Change to look at how climate changes might affect rattlesnakes through the year 2100.

Their results, published in the journal PLoS One, showed that rattlesnakes are going to have to move an average of between 100 and 1,000 times more quickly than they have over the last 300 millennia to reach acceptable places for them to survive. And that's without threats from predators, competitors, parasites, human developments and other obstacles.

"Based on what they've been doing over the past 320,000 years, they probably cannot adapt that quickly in 90 years to different climate tolerances," Lawing said. "They will have to physically move."

Even though rattlesnakes are often vilified, they play important roles in the ecosystems where they live, said Jesse Meik, an evolutionary biologist at the University of Texas, Arlington.

The new study adds insight into what the future holds for these and many other animals that are sensitive to changes in climate, he added. Some species may be able to physically adapt, but some will likely need to shift their home ranges to avoid extinction, and that might not always be possible.

Read more at Discovery News

Dec 13, 2011

Catch the Fever: It'll Help You Fight Off Infection, Evidence Shows

With cold and flu season almost here, the next time you're sick, you may want to think twice before taking something for your fever. That's because scientists have found more evidence that elevated body temperature helps certain types of immune cells to work better. This research is reported in the November 2011 issue of the Journal of Leukocyte Biology.

"An increase in body temperature has been known since ancient times to be associated with infection and inflammation," said Elizabeth A. Repasky, Ph.D., a researcher involved in the work from the Department of Immunology at the Roswell Park Cancer Institute in Buffalo, New York. "Since a febrile response is highly conserved in nature (even so-called cold blooded animals move to warmer places when they become ill) it would seem important that we immunologists devote more attention to this interesting response."

Scientists found that the generation and differentiation of a particular kind of lymphocyte, known as a "CD8+ cytotoxic T-cell" (capable of destroying virus-infected cells and tumor cells) is enhanced by mild fever-range hyperthermia. Specifically, their research suggests that elevated body temperature changes the T-cells' membranes which may help mediate the effects of micro-environmental temperature on cell function. To test this, researchers injected two groups of mice with an antigen, and examined the activation of T-cells following the interaction with antigen presenting cells. Body temperature in half of the mice was raised by 2 degrees centigrade, while the other half maintained a normal core body temperature. In the warmed mice, results showed a greater number of the type of CD8 T-cells capable of destroying infected cells.

"Having a fever might be uncomfortable," said John Wherry, Ph.D., Deputy Editor of the Journal of Leukocyte Biology, "but this research report and several others are showing that having a fever is part of an effective immune response. We had previously thought that the microbes that infect us simply can't replicate as well when we have fevers, but this new work also suggests that the immune system might be temporarily enhanced functionally when our temperatures rise with fever.

Read more at Science Daily

World's Smallest Frogs Discovered in New Guinea

Field work by researcher Fred Kraus from Bishop Museum, Honolulu has found the world's smallest frogs in southeastern New Guinea. This also makes them the world's smallest tetrapods (non-fish vertebrates). The frogs belong to the genus Paedophryne, all of whose species are extremely small, with adults of the two new species -- named Paedophryne dekot and Paedophryne verrucosa -- only 8-9 mm in length.

The study was published in the open access journal ZooKeys.

Previous research had led to the discovery of Paedophryne by Kraus in 2002 from nearby areas in New Guinea, but the genus was not formally described until last year (Kraus 2010, also in Zookeys). The two species described earlier were larger, attaining sizes of 10-11 mm, but the genus still represents the most miniaturized group of tetrapods in the world.

"Miniaturization occurs in many frog genera around the world," said the author, "but New Guinea seems particularly well represented, with species in seven genera exhibiting the phenomenon. Although most frog genera have only a few diminutive representatives mixed among larger relatives, Paedophryne is unique in that all species are minute." The four known species all inhabit small ranges in the mountains of southeastern New Guinea or adjacent, offshore islands. Their closest relatives remain unclear.

The members of this genus have reduced digit sizes that would not allow them to climb well; all inhabit leaf litter, and their reduced digits may be a corollary of a reduced body size required for inhabiting leaf litter and moss. Habitation in leaf litter and moss is common in miniaturized frogs and may reflect their exploitation of novel food sources in that habitat.

Read more at Science Daily

Trillion-Frame-Per-Second Video

MIT researchers have created a new imaging system that can acquire visual data at a rate of one trillion exposures per second. That's fast enough to produce a slow-motion video of a burst of light traveling the length of a one-liter bottle, bouncing off the cap and reflecting back to the bottle's bottom.

Media Lab postdoc Andreas Velten, one of the system's developers, calls it the "ultimate" in slow motion: "There's nothing in the universe that looks fast to this camera," he says.

The system relies on a recent technology called a streak camera, deployed in a totally unexpected way. The aperture of the streak camera is a narrow slit. Particles of light -- photons -- enter the camera through the slit and pass through an electric field that deflects them in a direction perpendicular to the slit. Because the electric field is changing very rapidly, it deflects late-arriving photons more than it does early-arriving ones.

The image produced by the camera is thus two-dimensional, but only one of the dimensions -- the one corresponding to the direction of the slit -- is spatial. The other dimension, corresponding to the degree of deflection, is time. The image thus represents the time of arrival of photons passing through a one-dimensional slice of space.

The camera was intended for use in experiments where light passes through or is emitted by a chemical sample. Since chemists are chiefly interested in the wavelengths of light that a sample absorbs, or in how the intensity of the emitted light changes over time, the fact that the camera registers only one spatial dimension is irrelevant.

But it's a serious drawback in a video camera. To produce their super-slow-mo videos, Velten, Media Lab Associate Professor Ramesh Raskar and Moungi Bawendi, the Lester Wolfe Professor of Chemistry, must perform the same experiment -- such as passing a light pulse through a bottle -- over and over, continually repositioning the streak camera to gradually build up a two-dimensional image. Synchronizing the camera and the laser that generates the pulse, so that the timing of every exposure is the same, requires a battery of sophisticated optical equipment and exquisite mechanical control. It takes only a nanosecond -- a billionth of a second -- for light to scatter through a bottle, but it takes about an hour to collect all the data necessary for the final video. For that reason, Raskar calls the new system "the world's slowest fastest camera."

Doing the math

After an hour, the researchers accumulate hundreds of thousands of data sets, each of which plots the one-dimensional positions of photons against their times of arrival. Raskar, Velten and other members of Raskar's Camera Culture group at the Media Lab developed algorithms that can stitch that raw data into a set of sequential two-dimensional images.

The streak camera and the laser that generates the light pulses -- both cutting-edge devices with a cumulative price tag of $250,000 -- were provided by Bawendi, a pioneer in research on quantum dots: tiny, light-emitting clusters of semiconductor particles that have potential applications in quantum computing, video-display technology, biological imaging, solar cells and a host of other areas.

The trillion-frame-per-second imaging system, which the researchers have presented both at the Optical Society's Computational Optical Sensing and Imaging conference and at Siggraph, is a spinoff of another Camera Culture project, a camera that can see around corners. That camera works by bouncing light off a reflective surface -- say, the wall opposite a doorway -- and measuring the time it takes different photons to return. But while both systems use ultrashort bursts of laser light and streak cameras, the arrangement of their other optical components and their reconstruction algorithms are tailored to their disparate tasks.

Because the ultrafast-imaging system requires multiple passes to produce its videos, it can't record events that aren't exactly repeatable. Any practical applications will probably involve cases where the way in which light scatters -- or bounces around as it strikes different surfaces -- is itself a source of useful information. Those cases may, however, include analyses of the physical structure of both manufactured materials and biological tissues -- "like ultrasound with light," as Raskar puts it.

As a longtime camera researcher, Raskar also sees a potential application in the development of better camera flashes. "An ultimate dream is, how do you create studio-like lighting from a compact flash? How can I take a portable camera that has a tiny flash and create the illusion that I have all these umbrellas, and sport lights, and so on?" asks Raskar, the NEC Career Development Associate Professor of Media Arts and Sciences. "With our ultrafast imaging, we can actually analyze how the photons are traveling through the world. And then we can recreate a new photo by creating the illusion that the photons started somewhere else."

"It's very interesting work. I am very impressed," says Nils Abramson, a professor of applied holography at Sweden's Royal Institute of Technology. In the late 1970s, Abramson pioneered a technique called light-in-flight holography, which ultimately proved able to capture images of light waves at a rate of 100 billion frames per second.

But as Abramson points out, his technique requires so-called coherent light, meaning that the troughs and crests of the light waves that produce the image have to line up with each other. "If you happen to destroy the coherence when the light is passing through different objects, then it doesn't work," Abramson says. "So I think it's much better if you can use ordinary light, which Ramesh does."

Read more at Science Daily

Has the Elusive Higgs Boson Been Spotted?

Researchers working at the world's largest atom smasher in Geneva have found tantalizing hints of the tiny, elemental bit of matter that has been labeled "the brick that built the universe" and "the god particle" -- but stopped short of announcing the discovery of the tiny particle.

The Higgs Boson is believe to have emerged from the Big Bang 13.7 billion years ago and have brought much of the rest of the flying debris together to form galaxies, stars and planets. The element is a crucial component of the "Standard Model" -- the all-encompassing physics theory of how the cosmos as we know it works at its basic level -- one that scientists have spent decades and billions of dollars hunting for.

Yet no one has convincingly claimed to have glimpsed the Higgs Boson, let alone proved that it actually exists.

"ATLAS sees a small excess at a Higgs mass of 126 GeV [Giga electron volts] coming from 3 channels," CERN scientists wrote on Twitter. Put simply, the scientists have greatly narrowed the area they are studying in the hunt for the Higgs Boson.

"This is the region where, if you see an excess, there's a hint that something's up," said Guido Tonelli, a spokesman for the CMS experiment, at a seminar discussing the findings. CMS, or the Compact Muon Solenoid experiment, is one of the largest international scientific collaborations in history.

But Fabiola Gianotti, the scientist in charge of the ATLAS experiment at the Large Hadron Collider near Geneva, said the signal they have detected may or may not be the Higgs.

"I think it would be extremely kind of the Higgs boson to be here," she said during the seminar. "But it is too early" for final conclusions, she said. "More studies and more data are needed. The next few months will be very exciting ... I don't know what the conclusions will be."

Tonelli agreed, noting that there are still other signals the scientists are peering at in the quest for the Higgs Boson beyond the 126 GeV mark that ATLAS scientists highlighted.

"We cannot exclude the presence of the Standard Model Higgs between 115 and 127 GeV because of a modest excess of events in this mass region that appears, quite consistently, in five independent channels,” Tonelli said. “As of today what we see is consistent either with a background fluctuation or with the presence of the boson."

Both concluded that further experiments in 2012 will help refine this analysis. Gianotti remained hopeful that next year, the quest may be resolved.

"Given the outstanding performance of the LHC this year, we will not need to wait long for enough data and can look forward to resolving this puzzle in 2012."

Researchers believe data about the so-called Higgs boson could help explain many scientific mysteries. British physicist Peter Higgs theorized its existence more than 40 years ago to explain why atoms have weight.

"These results will be based on the analysis of considerably more data than those presented at the summer conferences, sufficient to make significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or non-existence of the Higgs," CERN scientists said prior to the announcement.

Read more at Discovery News

Dec 12, 2011

Disappearance of the Elephant Caused Rise of Modern Humans

Elephants have long been known to be part of the Homo erectus diet. But the significance of this specific food source, in relation to both the survival of Homo erectus and the evolution of modern humans, has never been understood -- until now.

When Tel Aviv University researchers Dr. Ran Barkai, Miki Ben-Dor, and Prof. Avi Gopher of TAU's Department of Archaeology and Ancient Near Eastern Studies examined the published data describing animal bones associated with Homo erectus at the Acheulian site of Gesher Benot Ya'aqov in Israel, they found that elephant bones made up only two to three percent the total. But these low numbers are misleading, they say. While the six-ton animal may have only been represented by a tiny percentage of bones at the site, it actually provided as much as 60 percent of animal-sourced calories.

The elephant, a huge package of food that is easy to hunt, disappeared from the Middle East 400,000 years ago -- an event that must have imposed considerable nutritional stress on Homo erectus. Working with Prof. Israel Hershkovitz of TAU's Sackler Faculty of Medicine, the researchers connected this evidence about diet with other cultural and anatomical clues and concluded that the new hominids recently discovered at Qesem Cave in Israel -- who had to be more agile and knowledgeable to satisfy their dietary needs with smaller and faster prey -- took over the Middle Eastern landscape and eventually replaced Homo erectus.

The findings, which have been reported in the journal PLoS One, suggest that the disappearance of elephants 400,000 years ago was the reason that modern humans first appeared in the Middle East. In Africa, elephants disappeared from archaeological sites and Homo sapiens emerged much later -- only 200,000 years ago.

The perfect food package

Unlike other primates, humans' ability to extract energy from plant fiber and convert protein to energy is limited. So in the absence of fire for cooking, the Homo erectus diet could only consist of a finite amount of plant and protein and would have needed to be supplemented by animal fat. For this reason, elephants were the ultimate prize in hunting -- slower than other sources of prey and large enough to feed groups, the giant animals had an ideal fat-to-protein ratio that remained constant regardless of the season. In short, says Ben-Dor, they were the ideal food package for Homo erectus.

When elephants began to die out, Homo erectus "needed to hunt many smaller, more evasive animals. Energy requirements increased, but with plant and protein intake limited, the source had to come from fat. He had to become calculated about hunting," Ben-Dor says, noting that this change is evident in the physical appearance of modern humans, lighter than Homo erectus and with larger brains.

To confirm these findings, the researchers compared archaeological evidence from two sites in Israel: Gesher B'not Yaakov, dating back nearly 800,000 years and associated with Homo erectus; and Qesem Cave, dated 400,000 to 200,000 years ago. Gesher B'not Yaakov contains elephant bones, but at Qesem Cave, which is bereft of elephant bones, the researchers discovered signs of post-erectus hominins, with blades and sophisticated behaviors such as food sharing and the habitual use of fire.

Evolution in the Middle East

Modern humans evolved in Africa 200,000 years ago, says Dr. Barkai, and the ruling paradigm is that this was their first worldwide appearance. Archaeological records tell us that elephants in Africa disappeared alongside the Acheulian culture with the emergence of modern humans there. Though elephants can be found today in Africa, few species survived and no evidence of the animal can be found in archaeological sites after 200,000 years ago. The similarity to the circumstances of the Middle East 400,000 years ago is no coincidence, claim the researchers. Not only do their findings on elephants and the Homo erectus diet give a long-awaited explanation for the evolution of modern humans, but they also call what scientists know about the "birth-place" of modern man into question.

Read more at Science Daily

Ten Years After the Attacks On the World Trade Center, Human Health Cost Is Still Being Counted

The World Trade Center disaster exposed nearly half a million people to hazardous chemicals, environmental toxins, and traumatic events. According to research published in the December 2011 issue of Elsevier-published journalPreventive Medicine, this has resulted in increased risk of developing physical and mental health conditions after 9/11.

"The New York City Health Department's volunteer and heart disease studies in this issue ofPreventive Medicine reinforce the importance of tracking the long-term physical and mental health effects of 9/11 and help inform planning for future 9/11-related health care needs," said New York City Health Commissioner Dr. Thomas Farley.

A study of volunteers who turned out in the thousands to assist the 9/11 rescue operation, shows they, along with others who were directly exposed to the events of the 9/11 disaster, are now suffering from a range of physical and mental illnesses. At particular risk for poorer health outcomes are volunteers not affiliated with groups such as the American Red Cross, whose earlier arrival at the WTC sites and day-to-day work left them less prepared for the horrific events and injuries of 9/11.

Volunteers not affiliated with an organization were more highly exposed to the WTC disaster than volunteers affiliated with recognized organizations and were at greater risk for developing physical and mental health conditions after 9/11, according to the volunteer study. The study showed the need to provide volunteers with long-term screening and treatment for 9/11-related conditions that resulted from hazardous exposures.

A study of adults exposed to 9/11 found that being in the dust cloud, being injured on 9/11, or developing posttraumatic stress disorder increased the risk of developing heart disease years after the disaster.

"This exploratory heart disease study suggests that adults who were directly exposed to the World Trade Center disaster and its aftermath have an increased risk for heart disease," said Dr. Hannah Jordan, first author of the study. "It will be important to confirm and expand upon these findings so that appropriate steps can be taken to prevent heart disease in this population."

Read more at Science Daily

Baby Sloth Orphanage: The Cutest Place on Earth

Baby sloths are completely irresistible. Perhaps it's because their faces are shaped in a permanent smile. Or maybe it's because they love to hug -- stuffed animals, trees, other sloths, people. It could simply be their signature comical slowness.

And orphan baby sloths? Well, If you think you can resist them, try watching this video only once.

The trailer is just a taste of the new documentary, "Too Cute! Baby Sloths," airing Saturday Dec. 17 at 8 p.m. ET on Animal Planet. The show is filmmaker Lucy Cooke's follow-up to her wildly popular internet video "Meet the Sloths." Both were shot at the Aviarios Sloth Sanctuary in Costa Rica.

The sanctuary takes in any sloth in need, but is mostly populated by orphaned baby sloths who lost their mothers to power lines or road traffic or other accidents. There are currently around 160 sloths there. I can attest that it's an amazing place, and well worth a visit (or a donation). Cooke spent a year filming the lives of the sloths there, from potty-training to pole-climbing class. The new documentary follows five main stars, and according to Cooke, uncovers a surprisingly active (though slow) lifestyle filled with love, loss, lust and humor. (There is even footage of some super slow sloth sex.)

Read more at Wired Science

Razor-Toothed Meat-Eater Was Mammal Relative

A newly identified primitive mammal-like animal was agile, sleek and had a voracious appetite for meat.

The animal, identified as a varanopid pelycosaur and part of the genus Aerosaurus, looked like today's Komodo dragons, but was actually more closely related to mammals, according to a study published in the journal Naturwissenschaften (The Science of Nature).

"Our varanopid was probably about the size of an adult Nile monitor found in Africa," co-author Sean Modesto told Discovery News.

"It would have looked superficially like one too. The curvature of the teeth (the tips curve back towards the throat) and the serrations on the cutting edges of these teeth suggest that the animal was equipped to rip flesh from vertebrate prey."

One of the world's most successful fossil hunters, Roger Smith, found and collected the specimen, which consists of a partial skull and jaw. Smith, another co-author, discovered the remains in rocks from the Pristerognathus Assemblage Zone of the Beaufort Group, South Africa.

The carnivore is the youngest known primitive mammal-like mammal. It lived about 260 million years ago during the Permian Period and was part of "the first wave of creatures on the evolutionary line to mammals," said Modesto, an associate professor of biology at Cape Breton University.

Modesto and his team studied the fossils. The remains, along with prior finds, indicate the mammal-like predators survived for more than 35 million years and, toward the end of their time on Earth, co-existed with more advanced animals.

"Advanced" in this case refers to mammal-like characteristics that evolved to varying degrees in species of the period.

Christian Sidor, curator of vertebrate paleontology and an associate professor of biology at the University of Washington, agrees that the fossils belonged to a varanopid.

Sidor told Discovery News that the newly discovered protomammal "represents an upward extension for varanopids." He wishes more fossils for the predator existed.

As it stands, Modesto and his team can still tell that the new Aerosaurus had a more primitive body design. It's a design that proved to be successful.

"These animals were the most agile predators of their time, sleek-looking when compared to their contemporaries," co-author Robert Reisz from the University of Toronto Mississauga said. "They seem to have survived a major change in the terrestrial fauna that occurred during the Middle Permian, a poorly understood extinction event in the history of life on land."

Aerosaurus's razor sharp teeth, with their finely serrated cutting edges, are typical of hypercarnivores. These are animals with a diet consisting of more than 70 percent meat. It's doubtful then that the new mammal-like predator sunk its specialized choppers into plants very often.

The body plan survives to this day to some extent in Komodo lizards. Aerosaurus wasn't even related to these monitor lizards, according to the researchers.

Read more at Discovery News

Dec 11, 2011

Brain-Controlled Computer Tracks Attention

Controlling computers –- or anything else -– with the brain has been done using electroencephalograms (EEGs) but they require a skullcap on the head. Now a small company in North Carolina says it has a way around that, and in the process created an tool for training people to stay alert when involved in important tasks.

Freer Logic (named for its founder and CEO Peter Freer) came up with a system called BodyWave. It’s not dissimilar to an ordinary EEG, except it works with sensors that can be put around an arm rather than the head.

While it is harder to pick up signals from further away form the head, Freer told Discovery News that the signal strength per se isn’t too much of a problem. “You wouldn’t use this for clinical applications,” he said. So this wouldn’t be any good for a scientist or doctor trying to get a picture of brain activity. But it is fine when trying to detect the activity, called beta waves, that indicates attention.

BodyWave can detect when someone is paying attention to something. Freer noted that the system was used to train nuclear power plant workers as well as help understand the best way to design control systems. (For example: knowing what grabs a person’s attention can tell you where to put an alarm display).

Connected to a computer, BodyWave can tell when someone is paying attention and sound an alarm when they aren’t. Something like this can also be used in cars -– for instance sounding an alarm if a drivers’ attention drifts.

Read more at Discovery News

Savanna Chimps Exhibit Human-Like Sharing Behavior, Anthropologists Say

Sharing food has widely been considered by scholars as a defining characteristic of human behavior. But a new study by Iowa State University anthropology professor Jill Pruetz now reports that chimpanzees from her Fongoli research site in Senegal also frequently share food and hunting tools with other chimps.

Co-authored by ISU anthropology graduate student Stacy Lindshield, their study is posted online in Primates and will be published in a future issue of the journal.

The researchers witnessed 41 cases of Fongoli chimpanzees willingly transferring either wild plant foods or hunting tools to other chimpanzees. While previous research by primatologists had documented chimps transferring meat among other non-relatives, this is the first study to document non-meat sharing behavior.

"They're [the Fongoli chimps] not the only chimps that share, but in terms of the resources that we cover here, that is unique," said Pruetz (left), who was named a 2008 National Geographic Emerging Explorer for her research on savanna chimpanzees in Senegal. "I guess all chimps share meat, but they don't share plants or tools. Yet they do here, in addition to meat. It was intriguing when we first started seeing these events."

Breaking new ground on chimp sharing

The researchers document a frequency of sharing previously unreported for chimpanzees. The chimps commonly transferred meat and wild plant foods, but they also transferred tools, honey and soil. Most of the transfer behavior was classified as recovery or passive sharing, with females commonly taking food from males -- with much of that taking place from dominant to subordinate recipients.

Of the 41 witnessed events, Fongoli male chimps transferred wild foods or tools to females 27 times. While Christina Gomes and Christopher Boesch from the Max Planck Institute for Evolutionary Anthropology authored a 2009 study proposing that males and females exchange meat for sex -- resulting in males increasing their mating success and females increasing their caloric intake to overcome the energy costs and potential injury from hunting -- Pruetz contends that's not all that's going on in the cases she's witnessed.

"It's a different set of relationships within the social group [at the Fongoli site], and I tend to think again that it ties back to the environment and the fact that the resources are distributed differently," said Pruetz, who is also ISU's Walvoord Professor in the College of Liberal Arts and Sciences. "They have a big home range -- about 10 times bigger than Jane Goodall's range in Gombe at 86 square kilometers -- and that forces them to stay together. If they split up like chimps normally do, it could be days or weeks or months before they may see someone again -- and chimps are more social than that. So I think they stay together like monkeys and they move around their home range together."

Pruetz sees some of the sharing behavior between males and females as a product of the "food for sex" theory. The ISU researchers found that both adult females in estrus [the period of maximum sexual receptivity of the female] and adolescent females cycling to estrus were more likely to receive food from adult male chimps. Pruetz says that the male chimps may use food transfer as a future mating strategy with the adolescent females, particularly since there are a relatively small number of females in the Fongoli community.

"It may be used as a strategy [by the male chimps], anticipating a long-term gain on their behavior," she said. "We see that in baboons who have special friends."

Read more at Science Daily