Dec 2, 2011

Rembrandt painting identified by X-rays

The small panel, "Old Man with a Beard", dating from about 1630, was brought to art historians in Amsterdam by a private collector who believed it bore striking similarities to the Dutch master's work.

Unable to confirm the painter's identify despite several tantalising clues, the experts became convinced there was a second image lying underneath the surface which could solve the problem once and for all.

They took the painting to two X-ray imaging laboratories, the European Synchrotron Radiation Facility in Grenoble, France, and the Brookhaven National Laboratory in New York in the hope of uncovering the hidden layers of paint.

The imaging technology, which highlights pigments concealed beneath the surface, has previously thrown up new discoveries in works by Van Gogh and Goya.

A variety of different X-ray techniques to identify pigments in flesh tone colours such as lead white and vermilion, and concentrations of elements such as copper which did not correlate with the paint on the surface.

The tests uncovered the outlines of a younger, beardless man sporting a beret, an image that strongly resembled other works by Rembrandt, leading Prof Ernst van der Wetering, an art historian at the Rembrandt House in Amsterdam, to conclude that the new painting had been done on top of an unfinished self-portrait.

Prof Koen Janssens, of Antwerp University, who helped carry out the X-rays, said: "We did not realise at first that this particular shape was so meaningful.

Read more at The Telegraph

Moral Dilemma: Would You Kill One Person to Save Five?

Imagine a runaway boxcar heading toward five people who can't escape its path. Now imagine you had the power to reroute the boxcar onto different tracks with only one person along that route.

Would you do it?

That's the moral dilemma posed by a team of Michigan State University researchers in a first-of-its-kind study published in the research journal Emotion. Research participants were put in a three dimensional setting and given the power to kill one person (in this case, a realistic digital character) to save five.

The results? About 90 percent of the participants pulled a switch to reroute the boxcar, suggesting people are willing to violate a moral rule if it means minimizing harm.

"What we found is that the rule of 'Thou shalt not kill' can be overcome by considerations of the greater good," said Carlos David Navarrete, lead researcher on the project.

As an evolutionary psychologist, Navarrete explores big-picture topics such as morality -- in other words, how do we come to our moral judgments and does our behavior follow suit?

His latest experiment offers a new twist on the "trolley problem," a moral dilemma that philosophers have contemplated for decades. But this is the first time the dilemma has been posed as a behavioral experiment in a virtual environment, "with the sights, sounds and consequences of our actions thrown into stark relief," the study says.

The research participants were presented with a 3-D simulated version of the classic dilemma though a head-mounted device. Sensors were attached to their fingertips to monitor emotional arousal.

In the virtual world, each participant was stationed at a railroad switch where two sets of tracks veered off. Up ahead and to their right, five people hiked along the tracks in a steep ravine that prevented escape. On the opposite side, a single person hiked along in the same setting.

As the boxcar approached over the horizon, the participants could either do nothing -- letting the coal-filled boxcar go along its route and kill the five hikers -- or pull a switch (in this case a joystick) and reroute it to the tracks occupied by the single hiker.

Of the 147 participants, 133 (or 90.5 percent) pulled the switch to divert the boxcar, resulting in the death of the one hiker. Fourteen participants allowed the boxcar to kill the five hikers (11 participants did not pull the switch, while three pulled the switch but then returned it to its original position).

The findings are consistent with past research that was not virtual-based, Navarrete said.

The study also found that participants who did not pull the switch were more emotionally aroused. The reasons for this are unknown, although it may be because people freeze up during highly anxious moments -- akin to a solider failing to fire his weapon in battle, Navarrete said.

Read more at Science Daily

They Call It 'Guppy Love': Biologists Solve an Evolution Mystery

Guppies in the wild have evolved over at least half-a-million years -- long enough for the males' coloration to have changed dramatically. Yet a characteristic orange patch on male guppies has remained remarkably stable, though it could have become redder or more yellow. Why has it stayed the same hue of orange over such a long period of time?

Because that's the color female guppies prefer.

"Sometimes populations have to evolve just to stay the same," said Greg Grether, a UCLA professor of ecology and evolutionary biology and co-author of a study published Nov. 23 in the online edition of the journal Proceedings of the Royal Society B: Biological Sciences, a major journal for research in evolutionary biology.

"In this case, the males have evolved back over and over again to the color that females prefer," said Grether, who noted that there are many examples in which there is less variation among populations of a species than life scientists would expect.

The new study, funded by the National Science Foundation, "provides a neat solution to a mystery that has puzzled me for years," he said.

The orange patches on male guppies are made up of two pigments: carotenoids (which they ingest in their diets and are yellow) and drosopterins (which are red and which their bodies produce). Carotenoids are the same pigments that provide color to vegetables and fruits. Plants produce carotenoids, but animals generally cannot; guppies obtain most of their carotenoids from algae.

UCLA's Kerry Deere, the lead author of the study, conducted experiments in which she presented female guppies (Poecilia reticulata) with a choice of males with low, medium and high levels of drosopterin to see which males they preferred. In her experiments, the females were given a wider range of pigment choices than they would find in the wild. Deere, who was a graduate student of ecology and evolutionary biology in Grether's laboratory at the time and is currently a UCLA postdoctoral scholar in human genetics, conducted more than 100 mate-choice trials.

The females strongly preferred the intermediate males, those whose patches, or spots, were the right hue of orange -- not too red and not too yellow.

"The females preferred the males with an intermediate drosopterin level by a highly significant margin," Deere said.

"Males that are closer to this preferred hue probably have more offspring," Grether said.

If guppies were dependent only on carotenoids for their orange coloration, one would expect to find large changes in the color of their orange patches because the availability of algae varies by location. Guppies are native to Trinidad and Venezuela; the ones in this study were from Trinidad.

(Unlike the colorful guppies sold in pet stores, female guppies in the wild do not have bright coloration like the orange patches. Males are not as ornate, or as large, as the pet-store variety either.)

"A pattern I discovered 10 years ago, which was mysterious at first, is that in locations where more carotenoids are available in their diet, guppies produce more of the drosopterins," Grether said. "There is a very strong pattern of the ratio of these two kinds of pigments staying about the same.

"To human eyes at least, as the proportion of carotenoids in the spots goes up, the spots look yellower, and as the proportion of drosopterins goes up, the spots look redder. By maintaining a very similar ratio of the two pigments across sites, the fish maintain a similar hue of orange from site to site. What is maintaining the similar pigment ratio across sites and across populations? The reason for the lack of variation is that genetic changes counteract environmental changes. The males have evolved differences in drosopterin production that keep the hue relatively constant across environments. As a result of Kerry's experiment, we now have good evidence that female mate choice is responsible for this pattern."

While there are many cases in nature in which genetic variation in a trait masks environmental variation, there are very few examples where the cause is known.

"I originally assumed if there was variation among populations in drosopterin production, it would be the populations where carotenoid availability was lowest that were producing more of these synthetic pigments to compensate for the lack of carotenoids in their diet. But we found the opposite pattern," Grether said. "They're not using drosopterins as a carotenoid substitute; they're matching carotenoid levels with drosopterins. Why they are doing that was a mystery. The answer appears to be that it enables them to maintain the hue that female guppies prefer."

Read more at Science Daily

Embryonic Turtles Communicate to Coordinate Hatching

Murray River turtles communicate with their siblings while they are still in their shells, buried under the soil, in order to coordinate when they hatch.

Achieving this synchronicity isn’t easy. Although the eggs are always laid at the same time in the same nest, those at the top of the nest near the sun-drenched soil develop much faster than those buried deeper in the cooler soil. However, Murray River turtles are able to tell whether their fellow hatchlings are more or less advanced and adapt their pace of development accordingly, allowing the slow-coaches to play catch-up.

Ricky-John Spencer from the University of Western Sydney has been studying the turtles for years. In 2003 he collected dozens of batches of wild turtle eggs, split them into two groups and incubated them at either 25C or 30C. He then reunited the eggs and discovered that they still hatched together. At this point he wasn’t sure whether the colder batch were hatching prematurely or speeding up their development.

To follow this up, his team got hold of pregnant Murray River turtles and let them lay their eggs in a lab environment. They split each lot of eggs into two groups — incubating one group at 26C and the other at 30C. Other batches of turtles eggs were split into two groups but both incubated at 26C. After a week of development, the batches were reunited. Spencer’s student Jessica McGlashan monitored each of the embryo’s metabolism by measuring the heart rate and carbon dioxide emissions.

McGlashan discovered that if embryos were incubated with the more developed peers, they sped up their development. In the weeks running up to hatching, their heart rates sped up and they exhaled 67 percent more carbon dioxide than the control group of turtles whose siblings had stayed at 26C.

Once they hatched, it became clear that these turtles had used up more of their yolk supplies in order to catch up, but they were found to be just as strong as their less rushed counterparts.

Read more at Wired Science

Dec 1, 2011

Archaeologists Find New Evidence of Animals Being Introduced to Prehistoric Caribbean

An archaeological research team from North Carolina State University, the University of Washington and University of Florida has found one of the most diverse collections of prehistoric non-native animal remains in the Caribbean, on the tiny island of Carriacou. The find contributes to our understanding of culture in the region before the arrival of Columbus, and suggests Carriacou may have been more important than previously thought.

The researchers found evidence of five species that were introduced to Carriacou from South America between 1,000 and 1,400 years ago. Only one of these species, the opossum, can still be found on the island. The other species were pig-like peccaries, armadillos, guinea pigs and small rodents called agoutis.

Researchers think the animals were used as sources of food. The scarcity of the remains, and the few sites where they were found, indicate that the animals were not for daily consumption. "We suspect that they may have been foods eaten by people of high status, or used in ritual events," says Dr. Scott Fitzpatrick, an associate professor of anthropology at NC State and co-author of a paper describing the research.

"Looking for patterning in the distribution of animal remains in relation to where ritual artifacts and houses are found will help to test this idea," said Christina Giovas, lead author and a Ph.D. student at the University of Washington.

The team, which also included Ph.D. student Michelle LeFebvre of the University of Florida, found the animal remains at two different sites on the island, and used carbon dating techniques to determine their age. The opossum and agouti were the most common, with the latter remains reflecting the longest presence, running from A.D. 600 to 1400. The guinea pig remains had the shortest possible time-frame, running from A.D. 985 to 1030.

These dates are consistent with similar findings on other Caribbean islands. However, while these species have been found on other islands, it is incredibly rare for one island to have remains from all of these species. Guinea pigs, for example, were previously unknown in this part of the Caribbean. The diversity is particularly surprising, given that Carriacou is one of the smallest settled islands in the Caribbean, though the number of remains is still not that large -- a pattern seen on other islands as well.

This combination of small geographical area and robust prehistoric animal diversity, along with evidence for artifact trade with other islands and South America, suggests that Carriacou may have had some significance in the pre-Columbian Caribbean as a nexus of interaction between island communities.

The animal remains are also significant because they were found in archaeological digs at well-documented prehistoric villages -- and the remains themselves were dated, as opposed to just the materials (such as charcoal) found near the remains.

"The fact that the dates established by radiocarbon dating are consistent with the dates of associated materials from the villages means the chronology is well established," says Fitzpatrick, who has been doing research on Carriacou since 2003. "In the future we'd like to expand one of the lesser excavated sites to get more information on how common these species may have been, which could shed light on the ecological impact and social importance of these species prehistorically."

Read more at Science Daily

Why Evolutionarily Ancient Brain Areas Are Important

Different brain structures control eye reflexes in the course of life RUB scientists report in the Journal of Neuroscience.

Structures in the midbrain that developed early in evolution can be responsible for functions in newborns which in adults are taken over by the cerebral cortex. New evidence for this theory has been found in the visual system of monkeys by a team of researchers from the RUB. The scientists studied a reflex that stabilizes the image of a moving scene on the retina to prevent blur, the so-termed optokinetic nystagmus. They found that nuclei in the midbrain initially control this reflex and that signals from the cerebral cortex (neocortex) are only added later on. PD Dr. Claudia Distler-Hoffmann from the Department of General Zoology and Neurobiology and Prof. Dr. Klaus-Peter Hoffmann from the Department of Animal Physiology report in the Journal of Neuroscience.

Why the neocortex needs help

To control sensorimotor functions (e.g. eye movements), the adult brain is equipped with different areas in the neocortex, the evolutionarily youngest part of the cerebrum. "This raises the question, why older subcortical structures in the brain have not lost the functions that can also be controlled by the neocortex" says Hoffmann. The neocortex of primates is, however, not fully functional shortly after birth and therefore cannot control the optokinetic nystagmus. "This is most probably also the case with people" says Distler-Hoffmann. Nevertheless, this reflex works directly after birth.

First the brain stem, then the cerebral cortex

The researchers examined what information controls the optokinetic nystagmus in the first weeks after birth. During the first two weeks, the reflex is controlled by signals from the retina, which are transmitted to two nuclei in the midbrain. The neocortex then adds its information and takes over during the first months of life. The optokinetic reflex, which was studied by the researchers also at the behavioural level, is almost identical under the control of the midbrain and the neocortex. It occurs, for example, when watching a moving scene. First the eyes follow the passing scene, then they move quickly in the opposite direction back to their original position. On this reflex, monkeys and humans build their slow eye tracking movements with which they keep "an eye" on moving objects.

Read more at Science Daily

A Step Towards a Vaccine for AIDS

Tests on lab mice have opened up a new path towards a vaccine against HIV, one of the most frustrating quests in the 30-year history of AIDS, scientists reported.

Genetically modified mice fought back the human immunodeficiency virus (HIV) after they had been injected with genes to make antibodies, the first line of defense in the immune system, the report said in the journal Nature.

First identified in 1981, AIDS has claimed at least 25 million lives, although the annual toll is falling sharply from the peak of the pandemic in response to drug treatment.

But AIDS campaigners say the pandemic will only be crushed once a vaccine emerges. So far, in clinical trials, only one candidate formula has had even a modest effect, providing a shield of only 31 percent against the risk of HIV infection.

This has prompted researchers to return to the drawing board, to look for "broadly neutralising antibodies" -- Y-shaped proteins that are the immune system's foot soldiers -- among the tiny number of people with an innate ability to resist HIV.

So far, this trawl has turned up around 20 so-called "bNAbs," but there are big unknowns as to how they work and, if so, whether they can be made into a deliverable vaccine.

Delving into this, a team led by David Baltimore at the California Institute of Technology (Caltech) says it has developed a way to deliver bNAb-making genes to lab mice.

The rodents were engineered to carry human cells that allow HIV to penetrate and reproduce.

The approach, called Vectored ImmunoProphylaxis, or VIP, entails using a harmless virus as a "Trojan horse" in which they tucked the genes able to turn out specific bNAbs.

They then injected the virus into the leg muscles of the mice, where it holed up in cells, enabling the bNAb genes to produce antibodies in response to HIV.

The mice were first challenged with just one nanogram of AIDS virus -- enough to infect most non-treated mice that received it -- but the dose was eventually cranked up to 125 nanograms without problems. There were no signs of any side effects.

"VIP has a similar effect to a vaccine but without ever calling on the immune system to do any of the work," said Alejandro Balazs, lead author of the study, in a press release issued by Caltech.

"Normally, you put an antigen or killed bacteria or something into the body, and the immune system figures out how to make an antibody against it. We've taken that whole part out of the equation."

The team stressed that the jump from mice to humans is large.

"We're not promising that we've actually solved the human problem," said Baltimore. "But the evidence for prevention in these mice is very clear."

He added the team was drawing up plans to cautiously test the method in small-scale human clinical trials.

Baltimore co-won the 1975 Nobel Prize for Medicine at the age of 37 for his work on reverse transcriptase, a key enzyme in the reproduction of retroviruses -- the family that includes HIV.

In an email exchange with AFP, he said VIP was "like gene therapy, but distinct."

Gene therapy entails slotting a gene into the patient's DNA that corrects a flawed, disease-causing counterpart.

Hopes for this field of research were clouded by several reverses, notably the death of a young volunteer, Jesse Gelsinger, in 1999.

Read more at Discovery News

Wasps Never Forget a Face

Certain wasps have a remarkable ability to recognize the faces of other wasps. And much like humans, these stinging insects are more attuned to those faces than they are to any other shape, including the caterpillars they eat, a new study has found.

The findings, which adds to the list of amazing abilities social insects have, offer insight into how animals become good at specialized tasks. The study also touches on a raging debate about how and why humans are so attuned to sets of eyes, noses and mouths.

The wasps are "phenomenally better at learning wasp faces than anything else we tested them on," said Michael Sheehan, a graduate student in evolutionary biology at the University of Michigan in Ann Arbor. "They're not just good at faces. Like people, the way they learn faces is different from the way they learn other images."

To a set of untrained and fearful human eyes, all wasps may look alike. But, if you're willing to get close enough to a variety of paper wasps called Polistes fuscatus, there are obvious differences in the colors and patterns that cover their faces.

Previous studies have shown that these wasps can both recognize faces and remember them for at least a week. Because this species lives in communities with multiple queens who must follow a strict hierarchy, the theory is that they developed facial recognition skills in order to more accurately know their place in line.

To find out just how good the wasps are at recognizing faces compared to other objects, Sheehan and colleague Elizabeth Tibbetts recruited a dozen wild female wasps to perform a simple T-shaped maze.

Individually, each wasp flew from the bottom of the T to the fork, where they could view an image on either side before picking one to touch. One of the two images delivered a mild and unpleasant shock. For each pair of images, wasps had 40 chances to learn which was a safer bet.

When wasps were shown two distinct wasp faces, it only took about 10 trials before they learned to consistently choose the right one, the researchers report today in the journal Science. For the next 30 trials, they picked right about 75 to 80 percent of the time.

The insects were eventually able to perform as well when shown two different black shapes on a white background, but it took them a lot longer. It wasn’t until close to the end of 40 trials that they were scoring right with the same success rate. When asked to distinguish between caterpillars, the wasps were hopeless.

To look deeper into what it was about faces that mattered, the researches tested wasps on faces that were either lacking antennae or had scrambled parts so that, for example, eyes were on the wrong part of the head. In both cases, wasps struggled to distinguish between images.

A different species of paper wasp with a social structure that doesn’t favor face learning failed the face-recognition task completely.

All together, Sheehan said, the results suggest that facially oriented paper wasps learn faces in a way that is different from the way they learn other shapes.

Plenty of studies have shown an affinity for this kind of facial recognition in sheep, non-human primates and people, said Fred Dyer, a zoologist at Michigan State University in East Lansing. Researchers continue to debate what it all means.

One of the biggest lingering questions, Dyer said, is whether our brains have become equipped through evolution to specialize on faces in a unique way. Alternatively, it’s possible that we are born with a more general ability to distinguish between shapes and that we learn early on that faces are an important kind of shape.

It's a classic nature vs. nurture debate, and wasps could help provide some answers. By showing that such distantly related animals as people and wasps have developed similar skills, the researchers say their study suggests that the need to distinguish between faces has driven the evolution of both groups.

On the other hand, Dyer pointed out, there's still a possibility that the wild wasps used in the study had already built up expertise in faces from their life experiences, which could have boosted their performance. In studies of human aficionados, people who get a lot of practice looking at cars, postage stamps or even cheeses can distinguish between those objects as well as they can between faces. Those kinds of results imply that our sense of faces is learned instead of inborn.

Read more at Discovery News

Nov 30, 2011

Earthquakes: Water as a Lubricant

Geophysicists from Potsdam have established a mode of action that can explain the irregular distribution of strong earthquakes at the San Andreas Fault in California. As the science magazine "Nature" reports in its latest issue, the scientists examined the electrical conductivity of the rocks at great depths, which is closely related to the water content within the rocks. From the pattern of electrical conductivity and seismic activity they were able to deduce that rock water acts as a lubricant.

Los Angeles moves toward San Francisco at a pace of about six centimeters per year, because the Pacific plate with Los Angeles is moving northward, parallel to the North American plate which hosts San Francisco. But this is only the average value. In some areas, movement along the fault is almost continuous, while other segments are locked until they shift abruptly several meters against each other releasing energy in strong earthquakes. After the San Francisco earthquake of 1906, the plates had moved by six meters.

The San Andreas Fault acts like a seam of the Earth, ranging through the entire crust and reaching into the mantle. Geophysicists from the GFZ German Research Centre for Geosciences have succeeded in imaging this interface to great depths and to establish a connection between processes at depth and events at surface. "When examining the image of the electrical conductivity, it becomes clear that rock water from depths of the upper mantle, i.e. between 20 to 40 km, can penetrate the shallow areas of the creeping section of the fault, while these fluids are detained in other areas beneath an impermeable layer," says Dr. Oliver Ritter of the GFZ. "A sliding of the plates is supported, where fluids can rise."

Read more at Science Daily

Transplanted Cells Repair the Brain in Obese Mice

Without neurons reacting to the blood leptin level, the brain does not control the feeling of hunger and fullness. This type of genetic defects results in severe obesity in humans and animals. Scientists from Harvard University (HU), Massachusetts General Hospital (MGH) and the Nencki Institute of Experimental Biology of the Polish Academy of Sciences (Nencki Institute) in Warsaw have demonstrated in their experiments on mice that it is possible to restore brain functions by transplantation of small numbers of new neurons into the damaged area of the brain.

"A spectacular effect in the brain repair that we were able to achieve was significantly reduced weight of genetically defective obese mice and further significant reduction of adverse symptoms accompanying diabetes," says Dr. Artur Czupryn (Nencki Institute, HU, MGH), first author of a paper published in the latest issue of Science.

Already for some time medicine has attempted to repair damaged brain fragments through transplants of stem cells. These interventions are risky. Transplanted cells often develop in an uncontrolled manner, which frequently leads to cancer.

The aim of the research carried out for the past five years at HU, MGH and the Nencki Institute was to show that transplantation of small numbers of cells could restore the missing neuronal circuits and restore the lost brain functions. Genetically defective mice, deficient in leptin receptor, have been used in these experiments. Leptin is a protein secreted from cells of the fat tissue into the blood when eating. When it reaches the hypothalamus, it reacts with specific neurons and its presence or its low level cause the feeling of fullness or hunger, respectively. Leptin receptor deficient mice do not know the feeling of fullness. They weigh up to twice more than healthy individuals and suffer from advanced diabetes.

The team from Harvard University and Nencki Institute focused on the transplants of immature neurons (neuroblasts) and progenitors, which are specific stem cells with already determined developmental direction. Cells isolated from small regions of developing embryonic brains of healthy mice were used for transplantations. Thus, the probability increased that cells introduced into recipients' brains will transform into neurons or accompanying glial cells.

Millions of cells are usually transplanted. In this project, however, scientists injected a suspension of barely several thousand progenitors and neuroblasts into the hypothalamus of mice. About 300 nanolitres of cell suspension was injected into the mouse hypothalamus in the course of low invasive method -- by a thin micropipette with a diameter only several times larger than individual cells.

"The suspension was introduced into strictly defined region of the hypothalamus of mice, measuring about 200-400 micrometres in length. We were able to locate it thanks to unique high-frequency ultrasound microscopic guidance available at Harvard University. It allowed us to carry out complex non-invasive microtransplants with unprecedented precision, because we were able to carry out high resolution imaging of both the brain structures as well as the introduced micropipette," says Dr. Czupryn.

All transplanted cells have been marked with a fluorescent protein, which made possible to follow them in the recipients' brains. Observations carried out 20 or more weeks after the procedure have shown that almost half of transplanted cells transformed into neurons with typical morphology, producing proteins characteristic for normal neurons. By applying sophisticated research techniques, it was possible to demonstrate that the entire range of missing types of neurons was restored in the brain centre for controlling hunger and fullness. Moreover, the new neurons have already formed synapses and communicated with other neurons in the brain, as well as reacted properly to changes in levels of leptin, glucose, and insulin.

The final proof for restoration of proper functioning of the hypothalamus in mice was brought by measurements of body weight and blood metabolic factors. Unlike control population of genetically defective obese mice, the weight of mice with transplanted neurons resembled normal weight. Reversal of unfavourable changes of the blood metabolic parameters has also been observed.

"Many attempts have been described in the literature to date of transplanting cells into the brain. We have shown that a really small transplant of neuroblasts and progenitors was able to reconstitute damaged brain areas and influence the whole organism. We have shown that it is possible to introduce new neurons, which function properly, integrate well into the recipient nervous tissue and restore missing brain functions. Moreover this method turned out to be low invasive and safe, since it did not lead to tumour formation," sums up Dr. Czupryn.

Read more at Science Daily

The Secret of Super-Fast Shark Swimming

Researchers have discovered what makes the shark almost impossible to outswim. By using an engineering imaging technique, researchers have discovered that as a shark’s tail swings from side to side, it creates twice as many jets of water as other fishes’ tails, smoothing out the thrust and likely making swimming more efficient. Sharks do this by stiffening the tail midswing, a strategy that might one day be applied to underwater vehicles to improve their performance.

“The authors have made a persuasive argument that muscles in the fin are modifying the shape and possibly the texture of the fin to modify the [water] flow” throughout the stroke cycle, says Frank Fish, a biomechanist at West Chester University in Pennsylvania.

For fish to move forward, they have to push water backward. And sharks have an added burden: they sink when they stop swimming, so they must be in constant motion. To help generate lift to keep midwater, the top of the tail extends farther back than the bottom, creating a slant along the back edge. Most other fish have tails that are essentially symmetrical from top to bottom.

Curious about how the shark tail works, Harvard University biomechanist Brooke Flammang has been examining its structure and function. In 2005, she discovered a tail muscle that seemed to activate at peculiar times during the tail’s swing back and forth. To understand the muscle’s role, she decided to track in fine detail how the shark pushes water backward.

To do this, researchers typically put a lot of small particles in the water. As the tail swings, the water moves and drags the particles along. The particles reflect light from flashing lasers, so they can be tracked using high-speed cameras. A computer program uses the images to generate pictures of water flow. The jets of water are hard to see, but these jets create rings or vortices of water that resemble smoke rings and can be readily detected.

Typically, this imaging technique employs two cameras to track the particles in the horizontal and vertical directions, and based on that data, researchers estimate how the particles move along the third dimension, depth. But Flammang wanted to see directly how particles moved in three dimensions. So she adapted a more advanced imaging system, one that use three cameras, that until now had only been used to study water flow coming off cylinders with pistons generating the force. “Engineers have employed this technique for years, but its application is new to biology,” Fish notes.

Flammang and her colleagues tested two spiny dogfish and two chain dogfish by putting them in a water tank with a constant water flow so the sharks swam in place. She also looked at the water flow coming off a shark “robot” that had a flexible plastic tail. (For more, see these videos of a spiny dogfish swimming and a robotic fin.) Most fish create a ring of water at the end of each tail flick. The tail pushes the water as it moves to the side, then sends the water twirling away as it stops to change direction. Sharks were thought to produce two rings at that point, one small and one large one because of the shape of the tail, and that’s what happens with the robotic tail.

But in reality, a shark’s tail spins off the second ring right as it reaches the midline of the animal, Flammang and her colleagues report in the 22 December issue of the Proceedings of the Royal Society B. That ring is larger and connects to the ring generated at the end of the tail flick. “That provides a big advantage,” Flammang says. Instead of just getting a push as the tail reaches the extent of its bend, the shark has added thrust midswing. “It may be allowing the animal to produce almost continuous thrust.” Flammang thinks the shark uses the muscle she characterized to stiffen the tail midswing, changing its shape slightly, to throw off the extra vortex.

Read more at Wired Science

Oscar Wilde's Tomb Shielded From Kisses

Oscar Wilde's renovated Paris tomb was unveiled on Wednesday, complete with a new glass barrier to shield the monument to the quintessential dandy's life from a torrent of admiring kisses.

Kiss upon lipsticked kiss in honor of Wilde, who died penniless aged 46 in a Paris hotel room in 1900, had worn down the elegant tomb in Pere Lachaise cemetery, as grease from tourist lips sank into the stonework.

Wilde's only grandson Merlin Holland and British actor Rupert Everett accompanied French and Irish officials at the ceremony, held under bright winter sunshine on the tree-lined alleys of the famous burial ground.

The tomb, designed by modernist sculptor Jacob Epstein with a flying Assyrian-style angel, survived almost unscathed until 1985, except for the angel's notoriously prominent genitals being hacked off.

Then, the expense of cleaning operations to deal with increasing graffiti on the tomb led the descendants of Wilde and of his friend and executor Robert Ross to try, successfully, to get it listed as a historic monument.

The hope was that fines of thousands of euros for defacing the tomb would deter fans of the author of "The Importance of Being Earnest".

But in 1999 the graffiti was replaced by a much more worrying phenomenon when someone had the idea of planting a large, lipsticked kiss on the tomb, sparking a craze for Wilde's many admirers visiting Paris.

The glass should now shield the tomb, with well-wishers already having planted rosy red kisses on a nearby tree.

Holland, whose grandmother changed the family name to avoid public scorn after Oscar was jailed by a London court for the Victorian "crime" of homosexuality, said he would have loved all the fuss.

"I cannot express in words my gratitude to the Irish government and the people of Ireland for what they've done," Holland said.

"The royalties on Oscar Wilde's works disappeared many many years ago, and there's no way I could possibly have raised the money to do this myself."

"If my grandfather had been here he would have loved the attention. The attention has always been given over the last 30 years with notes and then lipstick but now art has to triumph over what the French call 'degradation'.

"Maybe one day we can take it down when the memory of kissing Oscar is gone," he said.

Everett, who came out as gay in the 1980s and starred in the 2002 film version of "The Importance of Being Earnest", described the dandy Irishman as his "patron saint" and "one of the last great vagabonds" of the 19th century.

"I find him very inspiring and touching, not just for his genius, also for his stupidity, in a way. He was a human being, and made mistakes like everyone else," Everett said.

He related Wilde's trial and how he was caught out trying to explain his attitude to the lips of boys and men before being convicted of homosexuality in 1895 and sentenced to two years prison with hard labor.

"Kisses for Oscar Wilde were not just signs of love, he associated them with danger, even death," said Everett, who has written a screenplay about Wilde's final years with which he hopes to make a directorial debut next year.

"He has the perfect blend of brilliance and silliness, of pride and humility ... from the dress circle to the drains, his life was his greatest work of art and an inspiration to anyone who's ever felt outcast."

Wilde left London in 1897 after finishing his prison term and never regained the creative impetus that had made him a hugely popular, if controversial, playwright.

As he died of meningitis in a Paris hotel, he famously remarked: "My wallpaper and I are fighting a duel to the death. One of us has got to go." He was initially given a "sixth class burial" outside Paris.

Read more at Discovery News

Nov 29, 2011

Madagascar Dinosaur Bone Is Most Massive Osteoderm Ever Found

What more can we learn about long-necked dinosaurs that we don't already know? A Macalester professor and her colleagues have found that Madagascar dinosaurs carried giant, hollow bones in their skin that may have helped them survive the harsh environments they inhabited. This discovery has shed new light on the anatomy and function of these bones in the biggest animals to ever walk on land.

Biology/Geology Prof. Kristi Curry Rogers is the lead author of a paper in Nature Communications about bizarre, gigantic bones that grow in the skin of Rapetosaurus, a species of huge plant-eating dinosaur from the island country located in the Indian Ocean off the southeastern coast of Africa.

"This is the biggest osteoderm ever found for any backboned-animal," said Curry Rogers, "The fact that it's hollow debunks all sorts of ideas about how these bones functioned in long-necked dinosaurs."

Osteoderms are bones embedded within the skin and are common among reptiles and some mammals. They create the unique pattern on the backs of crocodiles, the armor body covering on armadillos, and the distinctive plates of dinosaurs like Stegosaurus and Ankylosaurus.

Among the long-necked dinosaurs called sauropods, osteoderms are found in one globally distributed subgroup -- the Titanosauria. For more than a century, paleontologists have been trying to figure out how these weird bones were distributed in the skin of the long-necked titanosaurs and what they might have been used for. Were they for protection, like in armadillos and crocodiles? Were they for display? Could they have helped regulate body temperature?

"Knowing something about the lives of these dinosaurs, particularly in the context of the drought-prone paleoenvironment they lived in, tells us that osteoderms may have been important for storing minerals, which allowed Rapetosaurus to survive the rough times," said Curry Rogers.

Instead of the hundreds of interlocking plates in living animals with osteoderms, Rapetosaurus had only a few osteoderms in its skin. This means that they were less likely to serve as protection or as body temperature regulators.

"The discovery of these giant osteoderms provides new insights into what these bizarre structures may have done for the dinosaurs that had them," said Curry Rogers. "It helps us clarify what these Madagascar dinosaurs looked like with their skin on. Our sample also includes both adult and juvenile osteoderms, which tells us how the osteoderms changed over the lifespan of the dinosaur," said Curry Rogers.

Read more at Science Daily

Poop-Throwing Chimps Provide Hints of Human Origins

Pick up an object that’s close at hand. Throw it at something, or even someone (but gently, of course!) You’ve just reenacted what appears to be a pivotal stage in human evolution, when a propensity for projectiles shaped cognitive powers that later became language and symbolic thought.

That, at least, is one hypothesis for how humans became so smart. And now researchers have found support in chimpanzees, among whom the ability to throw goes hand-in-hand with increased intelligence and brain development.

“Imagine you’re an early hominid throwing at a rabbit. There’s increased selection for the cognitive demands of throwing, and that has some consequences for the development of the brain,” said psychologist Bill Hopkins of Emory University. “That’s where the throwing part becomes really interesting.”

In a study published in the January Philosophical Transactions of the Royal Society B, Hopkins and colleagues tracked several years’ worth of throwing behaviors in captive chimpanzees. (“If I was going to get s–t thrown at me, I was going to get something out of it,” said Hopkins.) Chimps are the closest living ancestor to humans, and the only species aside from ourselves in which throwing is regularly seen.

The researchers were especially interested in relationships between throwing, cognition and lateralization, or the way certain activities are concentrated in the left or right hemispheres of our brains. Language processing occurs in the left side, which also controls our right hands; and most people use their right hands to throw, as do chimpanzees.

While throwing at first might not seem demanding, coordinating it requires intensive, on-the-fly calculations. An equation for throwing a ball, for example, would include the distance to a target, the ball’s heaviness and the thrower’s strength. A moving target makes it even harder. Other psychologists and anthropologists have put throwing at the beginning of a cognitive cascade into higher-order thought, but Hopkins said his team is the first to test this proposition.

From brain scans of chimps that threw most often and accurately, Hopkins found heightened development in and connections between the motor cortex, where physical actions are coordinated, and the Broca’s area, which in humans is central to speech production. Better throwing meant more sophisticated, left hemisphere-reliant brains.

“It supports the idea that these areas could have been selected for as a consequence of throwing,” said Hopkins. “If you imagine that throwing started off as left hemisphere-dominant, before the emergence of speech, then speech and language would have co-opted that side of the brain.”

In behavioral tests, true-throwing chimps also proved especially apt in social intelligence and communication. Intriguingly, they fared no better than poor-throwing chimps on physical problem-solving tests, suggesting that throwing behaviors emerged not for hunting, as is commonly assumed, but to interact with peers.

“Why did these chimps learn to throw in a captive context? I’ve never in my life seen a chimp be given a banana for throwing s–t at someone,” said Hopkins. “The reward is not something food-based. The reward is that they can control a person’s behavior. They get a pile of something to throw, and usually the person tries to run. The chimp learns, ‘If I can do this, I can have some control over the world outside my cage.’”

Read more at Wired

Stonehenge Reveals New Clues of Ancient Worship

Stonehenge may have been a place for sun worship long before the iconic stones were erected more than 5,000 years ago, according to archaeologists who are carrying out the biggest-ever virtual excavation.

Using non invasive technologies such as ground-penetrating radar and geophysical imaging, a team from the University of Birmingham's IBM Visual and Spatial Technology Centre (VISTA) and the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology in Vienna, discovered evidence of two huge pits positioned on a celestial alignment at Stonehenge.

Measuring more than 16 feet across and at least 3 feet deep, the pits lie within the Cursus, a large enclosure north of Stonehenge which pre-dates the prehistoric monument by up to 500 years.

"This is the first time we have seen anything quite like this at Stonehenge," said project leader Vince Gaffney, an archaeologist from the University of Birmingham.

"When viewed from the Heel Stone, a rather enigmatic stone which stands just outside the entrance to Stonehenge, the pits effectively mark the raising and setting of the sun at midsummer days," he said.

According to the archaeologists, the pits may have contained tall stones, wooden posts or even fires to mark the sun rising and setting. Most likely, they defined a processional route used to celebrate the passage of the sun across the sky at the summer solstice.

"It is possible that processions within the Cursus moved from the eastern pit at sunrise, continuing eastwards along the Cursus and, following the path of the sun overhead, and perhaps back to the west, reaching the western pit at sunset to mark the longest day of the year," said Gaffney.

The hypothesis gained more weight when the researchers measured the walking distance between the two pits.

They discovered that the procession would reach exactly half-way at midday, when the sun would be directly on top of Stonehenge.

"This is more than just a coincidence, indicating that the exact length of the Cursus and the positioning of the pits are of significance," said Henry Chapman, senior lecturer in archaeology and visualization at the University of Birmingham.

According to the researchers, the presence of the pits within the Cursus suggest that the Stonehenge area, which features England's densest complex of Neolithic and Bronze Age monuments, was already sacred before construction work began to build the enigmatic stone circle.

"Even though Stonehenge was ultimately the most important monument in the landscape, it may at times not have been the only, or most important, ritual focus," said Gaffney.

"The area of Stonehenge may have become significant as a sacred site at a much earlier date. Other activities were carried out at other ceremonial sites only a short distance away," he said.

The researchers have already found a henge-like monument, several other small monuments, and a new horseshoe arrangement of large pits north-east of Stonehenge which may have also contained posts.

They believe that these structures functioned as minor shrines, perhaps serving specific communities visiting the ceremonial centre.

The team is confident that the project will produce new discoveries soon.

Read more at Discovery News

Chimpanzees Self-Medicate With Food

An extensive look at what chimpanzees consume each day reveals that many of the plants they consume aren't for nutrition but are likely ingested for medicinal purpose.

The findings, published in the journal Physiology & Behavior, indicate that the origins of medicine go way back, beyond the human species.

"We conclude that self-medication may have appeared in our ancestors in association with high social tolerance and lack of herbivorous gut specialization," lead author Shelly Masi and her colleagues write.

Masi, a researcher at the National Museum of Natural History in Paris, and her team recorded the items consumed by a community of over 40 wild chimpanzees at Kibale National Park, Uganda. They also documented the availability of the foods, as well as the social interactions between the chimps.

They also documented the same information for about a dozen wild western gorillas in Dzanga-Ndoki National Park, Central African Republic.

Unusual food consumption in chimpanzees, meaning foods not normally associated with nutritional needs, was twice as high as it was for gorillas. Gorillas turn out to have more specialized guts that are better capable of detoxyifying harmful compounds, making them have have less of a need to self-medicate than chimps and humans may need to.

Chimpanzees and people are extremely social and both learn from each other, including what to eat.

"Older and more successful individuals (such as those that are high ranking) are expected to be the best model to copy, and are mainly responsible for generating and transmitting food traditions," according to the authors.

Analysis of the mostly non-nutritional and sometimes slightly toxic foods consumed determined that most had medicinal properties. Based on the study, the chimpanzee medicine chest appears to include the following: Antiaris toxicaria leaves (anti-tumor), Cordia abyssinica pith (anti-malarial and anti-bacterial), Ficus capensis (anti-bacterial), Ficus natalensis bark (anti-diarrheal), Ficus urceolaris leaves (de-worming agent), and many more.

The primates seemed to strategically go for the medicinal parts of these plants, and would consume them even when other more nutritious and palatable foods were available.

While chimps and humans appear to be the world's most self-medicating animals, another new study, accepted for publication in the journal Small Ruminant Research, documents how both wild and domesticated herbivores also consume plants for medical reasons.

Juan Villalba of Utah State University's Department of Wildland Resources, and co-author Serge Landau of Israel’s Volcani Center explain how goats sometimes nibble on the anti-parasitic plant Albizia anthelmintica. This was "followed by expulsion of worms in the feces and alleviation" of the worm problem.

Stacy Lindshield, an Iowa State University researcher, also identified a medicated body scratcher invented by wild spider monkeys.

"Spider monkeys have been observed rubbing crushed and chewed leaves on their bodies," Lindshield told Discovery News, explaining that "some primates select plants or invertebrates with chemical properties." In addition to medicinal purposes, she said the resulting smelly ointment might also facilitate olfactory communication.

Read more at Discovery News

Nov 28, 2011

Study Debunks Stereotype That Men Think About Sex All Day Long

Men may think about sex more often than women do, but a new study suggests that men also think about other biological needs, such as eating and sleep, more frequently than women do, as well.And the research discredits the persistent stereotype that men think about sex every seven seconds, which would amount to more than 8,000 thoughts about sex in 16 waking hours. In the study, the median number of young men's thought about sex stood at almost 19 times per day. Young women in the study reported a median of nearly 10 thoughts about sex per day.

As a group, the men also thought about food almost 18 times per day and sleep almost 11 times per day, compared to women's median number of thoughts about eating and sleep, at nearly 15 times and about 8 1/2 times, respectively.

The college-student participants carried a golf tally counter to track their thoughts about either eating, sleep or sex every day for a week. Each student was assigned to just one type of thought to record. Before receiving the tally counter, they had completed a number of questionnaires and were asked to estimate how often they had daily thoughts about eating, sleeping and sex.

Overall, a participant's comfort with sexuality was the best predictor for which person would have the most frequent daily thoughts about sex.

"If you had to know one thing about a person to best predict how often they would be thinking about sex, you'd be better off knowing their emotional orientation toward sexuality, as opposed to knowing whether they were male or female," said Terri Fisher, professor of psychology at Ohio State University's Mansfield campus and lead author of the study. "Frequency of thinking about sex is related to variables beyond one's biological sex."

Correcting this stereotype about men's sexual thoughts is important, Fisher noted.

"It's amazing the way people will spout off these fake statistics that men think about sex nearly constantly and so much more often than women do," she said. "When a man hears a statement like that, he might think there's something wrong with him because he's not spending that much time thinking about sexuality, and when women hear about this, if they spend significant time thinking about sex they might think there's something wrong with them."

The study appears online and is scheduled for publication in the January issue of the Journal of Sex Research.

The study involved 163 female and 120 male college students between the ages of 18 and 25 who were enrolled in a psychology research participation program. Of those, 59 were randomly assigned to track thoughts about food, 61 about sleep and 163 about sex. Most students were white and self-identified as heterosexual. The college-student sample made it comparable to previous research and involved an age group at which gender differences in sexuality are likely at their peak.

Before the thought-tracking began, the participants completed a number of questionnaires. These included a sexual opinion survey to measure a positive or negative emotional orientation toward sexuality (erotophilia vs. erotophobia); a sociosexual orientation inventory measuring attitudes about sex and tracking sexual behavior and levels of desire; a social desirability scale to measure respondents' tendency to try to appear socially acceptable; and an eating habits questionnaire and sleepiness scale. They also were asked to estimate how many times in an average day that they thought about sleeping, eating and sex.

Researchers then gave each student a tally counter device and told those assigned to the sexual thoughts condition to click the device to maintain a count their of thoughts about sex. They were told to count a thought about any aspect of sex: sexual activity of any kind, fantasies and erotic images, sexual memories and any arousing stimuli.

Others were instructed to use the device to record thoughts about eating that included food, hunger, cravings, snacking or cooking, and thoughts about sleep that included dreaming, sleeping, napping, going to bed or needing rest.

The questions about food and sleep were designed to mask the true intent of the study's focus on thoughts about sex, Fisher said. However, the results about these additional thoughts provided important information about differences in thinking among males and females.

"Since we looked at those other types of need-related thoughts, we found that it appears that there's not just a sex difference with regard to thoughts about sex, but also with regard to thoughts about sleep and food," she said. "That's very significant. This suggests males might be having more of these thoughts than women are or they have an easier time identifying the thoughts. It's difficult to know, but what is clear is it's not uniquely sex that they're spending more time thinking about, but other issues related to their biological needs, as well."

And when all of those thoughts were taken into account in the statistical analysis, the difference between men and women in their average number of daily thoughts about sex wasn't considered any larger than the gender differences between thoughts about sleep or thoughts about food.

In raw numbers, male participants recorded between one and 388 daily thoughts about sex, compared to the range of female thoughts about sex of between one and 140 times per day.

"For women, that's a broader range than many people would have expected. And there were no women who reported zero thoughts per day. So women are also thinking about sexuality," Fisher said.

The questionnaire data offered some additional clues about the influences on sexual thoughts. When all participants were analyzed together, those measuring the highest in erotophilia -- or comfort with their sexuality -- were the most likely to think more frequently about sex.

But when the analysis considered males and females separately, no single variable -- erotophilia score, unrestrictive attitudes about sex or a lack of desire to be socially acceptable -- could be defined as a predictor of how often men think about sex.

But for women, the erotophilia score remained a good predictor of more frequent sexual thoughts. On the other hand, women who scored high on the desire to be socially acceptable were more likely to think less frequently about sex.

"People who always give socially desirable responses to questions are perhaps holding back and trying to manage the impression they make on others," Fisher explained. "In this case, we're seeing that women who are more concerned with the impression they're making tend to report fewer sexual thoughts, and that's because thinking about sexuality is not consistent with typical expectations for women."

The participants' estimates about how often they thought each day about eating, sleeping and sex were all much lower than the actual number of thoughts they recorded. This suggested to Fisher that previous research in this area -- especially on thoughts about sex -- was weak because almost all previous studies were based on participants' retrospective estimates about how often they thought about sex.

"There's really no good reason that our society should have believed that men are thinking so much more about sex than women. Even the research that had been done previously doesn't support the stereotype that men are thinking about sex every seven seconds," she said.

Read more at Science Daily

First Dogs Came from East Asia, Genetic Study Confirms

Researchers at Sweden's KTH Royal Institute of Technology say they have found further proof that the wolf ancestors of today's domesticated dogs can be traced to southern East Asia -- findings that run counter to theories placing the cradle of the canine line in the Middle East.

Dr Peter Savolainen, KTH researcher in evolutionary genetics, says a new study released Nov. 23 confirms that an Asian region south of the Yangtze River was the principal and probably sole region where wolves were domesticated by humans.

Data on genetics, morphology and behaviour show clearly that dogs are descended from wolves, but there's never been scientific consensus on where in the world the domestication process began. "Our analysis of Y-chromosomal DNA now confirms that wolves were first domesticated in Asia south of Yangtze River -- we call it the ASY region -- in southern China or Southeast Asia," Savolainen says.

The Y data supports previous evidence from mitochondrial DNA. "Taken together, the two studies provide very strong evidence that dogs originated in the ASY region," Savolainen says.

Archaeological data and a genetic study recently published in Nature suggest that dogs originate from the Middle East. But Savolainen rejects that view. "Because none of these studies included samples from the ASY region, evidence from ASY has been overlooked," he says.

Peter Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyse DNA from male dogs around the world. Their study was published in the scientific journal Heredity.

Approximately half of the gene pool was universally shared everywhere in the world, while only the ASY region had the entire range of genetic diversity. "This shows that gene pools in all other regions of the world most probably originate from the ASY region," Savolainen says.

"Our results confirm that Asia south of the Yangtze River was the most important -- and probably the only -- region for wolf domestication, and that a large number of wolves were domesticated," says Savolainen.

In separate research published recently in Ecology and Evolution, Savolainen, PhD student Arman Ardalan and Iranian and Turkish scientists conducted a comprehensive study of mitochondrial DNA , with a particular focus on the Middle East. Because mitochondrial DNA is inherited only from the mother in most species, it is especially useful in studying evolutionary relationships.

"Since other studies have indicated that wolves were domesticated in the Middle East, we wanted to be sure nothing had been missed. We find no signs whatsoever that dogs originated there," says Savolainen.

Read more at Science Daily

Early Humans Were Skilled Deep-Sea Fishermen

Prehistoric humans living more than 40,000 years ago had mastered the skills needed to catch fast-moving, deep ocean fish such as tuna, a remarkable new archaeological find has revealed.

In a small cave at the eastern end of East Timor, north of Australia, archaeologist Sue O'Connor from the Australian National University has unearthed the bones of more than 2,800 fish, some of which were caught as long as 42,000 years ago.

The find shows that the people living in the region had the sophisticated cognitive skills needed to haul in such a difficult catch, O'Connor says.

Her findings appeared in the journal Science.

"What the site has shown us is that early modern humans in island Southeast Asia had amazingly advanced maritime skills," she said.

"They were expert at catching the types of fish that would be challenging even today -- fish like tuna. It's a very exciting find."

It isn't clear exactly what techniques the people living in the area at the time used to catch these fish.

Tuna can be caught using nets or by trolling hooks on long lines through the water, O'Connor said.

"Either way it seems certain that these people were using quite sophisticated technology and watercraft to fish offshore."

The site where the discoveries were made, known as Jerimalai cave, is a small rock overhang hidden behind in foliage, a few hundred meters from the shore.

"When I discovered it in 2005, I didn't think that Jerimalai would tell us about the very early occupation of Timor," O'Connor said. "I was quite surprised when I found all these fish bones and turtle bones."

So far, she and her colleagues have only excavated two small test pits at the cave, which contained a number of stone artifacts, bone points, animal remains, shell beads and fish hooks.

In just one of those pits, 1 meter square and 2 meters deep, they found 39,000 fish bones.

They also unearthed another rare find -- a small piece of fishing hook made from a shell, which dates to between 23,000 and 16,000 years ago.

Read more at Discovery News

Gold-Flecked Stars Give Hint to Past Lives

With only hydrogen, helium and a bit of lithium to work with initially, the earliest generations of stars kept things simple. So how to explain abnormally high concentrations of gold, platinum, uranium and other heavy elements in a handful of the Milky Way's senior residents?

One theory is that they could have been enriched when a partner star exploded nearby, giving the survivor a rich dusting in heavy elements.

A new study however unhinges that theory.

By tracking the orbital motions of the metal-rich ancient stars, scientists realized the vast majority of them are traveling solo in a halo above and below the galaxy's flat central disc.

"A companion star -- if there was one -- would have left behind an optically undetectable black hole, neutron star, or faint white dwarf," astrophysicist Terese Hansen, with the Niels Bohr Institute at the University of Copenhagen, told Discovery News.

But the remnant companion would have a gravitational influence on the visible star's orbit, which would be detectable, she added.

The other explanation for why 1 to 2 percent of the galaxy's most ancient stars are flush with heavy metals is that they formed from a cloud of molecular gas enriched with the exploded remains of earlier stars.

"The great thing about these stars is that there has only been one generation of stars before then. So by looking at these stars we see clear footprints from the first generation of stars and can hence look even further back in time," Hansen wrote in an email.

Read more at Discovery News

Nov 27, 2011

Worms Reveal Secrets of Wound-Healing Response

The lowly and simple roundworm may be the ideal laboratory model to learn more about the complex processes involved in repairing wounds and could eventually allow scientists to improve the body's response to healing skin wounds, a serious problem in diabetics and the elderly.

That's the conclusion of biologists at the University of California, San Diego who have discovered genes in the laboratory roundworm C. elegans that signal the presence of surface wounds and trigger another series of chemical reactions that allow the worms to quickly close cuts in their surfaces that would turn fatal if left unrepaired.

The scientists report in the December 6 issue of the journal Current Biology that these two findings and a third discovery they made in the worms, involving genes that inhibit wound healing, could allow scientists one day to design ways to improve the healing of cuts and sores by possibly blocking the action of these inhibitory genes or finding ways to enhance the chemical signaling and wound healing process. An advance copy of their paper is being published online this week by the journal.

"What we've shown in this paper is that a biochemical pathway is activated by wounding in the worms that involves calcium," said Andrew Chisholm, a professor of biology at UC San Diego, who headed the research effort. "It's been known for some time that one of the things that happens when you damage a cell is that calcium levels within the cell increase."

But in a series of experiments with C. elegans, Chisholm and postdoctoral fellow Suhong Xu found out much more. They took time-lapse movies of areas around the transparent worms where they punctured the skin with a needle or laser. Then they monitored the calcium with a fluorescent protein so they could see how the calcium molecules spread from the point of injury. They also developed genetic screens to pinpoint the specific calcium pathway or "channel" that is signaling the presence of the wound and stimulating the healing process.

"We think the channel is playing an important role in either sensing damage or responding to some other receptor that senses damage," said Chisholm. "Is it sensing a change in the tension of the cell? Is it sensing some kind of change in electrical potential? We don't know."

While biomedical scientists have made great strides in understanding how the body responds to infections and chemically rebuilds the skin when the wound healing process is underway, very little is known about what happens within the cell or the body in the minutes or hours following injury. "That's still a big, big question," Chisholm said. "But we think we've made a start that will help us answer that question."

He thinks the lowly roundworms may be the ideal animals to probe that question and others involving wound healing for a variety of reasons: they are small, transparent, have a delicate surface susceptible to injury and a rapid wound response mechanism that keeps their surface wounds from being fatal.

"They have a hydrostatic skeleton in which the skin and muscles are under pressure to allow the animal to stay semi-rigid, so when you jab a worm with a needle it will, in effect, explode," he said. "But remarkably, they don't die when you do that because they have evolved ways to very rapidly close wounds to survive in the wild. In their natural environment, their predators try to exploit the worm's vulnerable exoskeleton. There are a whole group of fungi with tiny spikes that just sit around waiting for the worms to crawl over them so they can poke holes through their cuticle."

"For us, they are easy to work with, because worms are small, easy to grow and they're transparent, so when you put them on a slide, you can see the calcium clearly," he said.

The transparent worms also allowed Chisholm and Xu to get their first glimpse of how the worms rapidly close their wounds. In a time lapse movie and in a series of photographs detailed in the paper, the researchers show how actin, a protein found in all cells that plays a role in muscle contraction, is recruited to and surrounds the wound, then closes the cut by tightening the actin like a purse string.

"We think that calcium is regulating this process," said Chisholm, "because if you knock out calcium with a drug that chelates calcium, essentially locking it up, you don't get the ring. If you have a genetic mutant worm with low levels of calcium, you don't get the ring. But if you bathe this mutant in calcium, you can restore this ring."

In addition, the researchers discovered in roundworms that a protein called DAPK-1 acts to inhibit the closure of wounds, raising the possibility that drugs that inhibit the action of this protein could improve the wound healing process in humans.

Read more at Science Daily

Child Abuse in Birds: Study Documents 'Cycle of Violence' in Nature

For one species of seabird in the Galápagos, the child abuse "cycle of violence" found in humans plays out in the wild.

The new study of Nazca boobies by Wake Forest University researchers provides the first evidence from the animal world showing those who are abused when they are young often grow up to be abusers. The study appears in the October issue of the ornithology journal, The Auk.

"We were surprised by the intense interest that many adults show in unrelated young, involving really rough treatment," said Wake Forest Professor of Biology Dave Anderson, who led the study with Wake Forest graduate student Martina Müller. "A bird's history as a target of abuse proved to be a strong predictor of its adult behavior."

In Nazca boobies, traumatic abuse of developing young significantly increases the chances those maltreated individuals will exhibit the same maltreatment later in life as adults, Müller said. She is now at the University of Groeningen in the Netherlands.

The ocean-going seabirds live in colonies in the Galápagos Islands off the coast of Ecuador. Among Nazca boobies, victimization by adults on other birds' chicks is widespread. They raise solitary nestlings on the ground and frequently leave their offspring unattended while foraging at sea. So, there is much opportunity for adult birds to bully and beat up neighbor nestlings.

The abusive adults patrol the breeding colony, searching for unguarded chicks. They frequently bite and peck the chicks, and even make sexual advances, sometimes leaving the chicks bleeding and stressed. Female adults show more aggressive behavior than males do, on average.

The young birds nest years later in the colony where they were born, making them ideal models for studying the effects of "chick" abuse on lifelong behavior.

The researchers collected data during three breeding seasons documenting which nestlings suffered abuse or neglect, then several years later evaluated their behavior as adults in the same colony. They tracked the birds and identified them using leg bands.

The findings shed important light on animal behavior. "This is not some contrived experimental situation with freaked out captive animals. This is an animal in a natural situation experiencing natural stressors when young. And, the outcome is their behavior later is influenced by the social stress they experienced," Anderson said. "As we determine how similar the physiology of this response is to the human situation, we may find opportunities for research on this stress response that are not possible to do with humans."

Co-authors on the study included Wake Forest graduate students Elaine T. Porter, Jacquelyn K. Grace, Jill A. Awkerman, and Mark A. Westbrock and technicians Kevin T. Birchler, Alex R. Gunderson, and Eric G. Schneider.

The Wake Forest team of researchers is already exploring physiological responses to abuse and have found a dramatic increase in corticosterone, the primary avian stress hormone, after a chick has experienced abuse. The surge in stress hormone may influence adult bird behavior. The study, led by doctoral student Jacquelyn Grace, was published recently in the journal, Hormones and Behavior.

Read more at Science Daily