Friday, March 12, 2010

‘WORLD’S MOST USEFULL TREE’ PROVIDES LOW-COST WATER PURIFICATION METHOD FOR DEVELOPING WORLD

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A low-cost water purification technique published in Current Protocols in Microbiology could help drastically reduce the incidence of waterborne disease in the developing world. The procedure, which uses seeds from the Moringa oleifera tree, can produce a 90.00% to 99.99% bacterial reduction in previously untreated water, and has been made free to download as part of access programs under John Wiley & Sons' Corporate Citizenship Initiative.

A billion people across Asia, Africa, and Latin America are estimated to rely on untreated surface water sources for their daily water needs. Of these, some two million are thought to die from diseases caught from contaminated water every year, with the majority of these deaths occurring among children under five years of age. Michael Lea, a Current Protocols author and a researcher at Clearinghouse, a Canadian organisation dedicated to investigating and implementing low-cost water purification technologies, believes the Moringa oleifera tree could go a long way to providing a solution.

“Moringa oleifera is a vegetable tree which is grown in Africa, Central and South America, the Indian subcontinent, and South East Asia. It could be considered to be one of the world’s most useful trees,” said Lea. “Not only is it drought resistant, it also yields cooking and lighting oil, soil fertilizer, as well as highly nutritious food in the form of its pods, leaves, seeds and flowers. Perhaps most importantly, its seeds can be used to purify drinking water at virtually no cost.”

Moringa tree seeds, when crushed into powder, can be used as a water-soluble extract in suspension, resulting in an effective natural clarification agent for highly turbid and untreated pathogenic surface water. As well as improving drinkability, this technique reduces water turbidity (cloudiness) making the result aesthetically as well as microbiologically more acceptable for human consumption.

Despite its live-saving potential, the technique is still not widely known, even in areas where the Moringa is routinely cultivated. It is therefore Lea’s hope that the publication of this technique in a freely available protocol format, a first, will make it easier to disseminate the procedure to the communities that need it.

“This technique does not represent a total solution to the threat of waterborne disease," concluded Lea. "However, given that the cultivation and use of the Moringa tree can bring benefits in the shape of nutrition and income as well as of far purer water, there is the possibility that thousands of 21st century families could find themselves liberated from what should now be universally seen as19th century causes of death and disease. This is an amazing prospect, and one in which a huge amount of human potential could be released. This is particularly mind-boggling when you think it might all come down to one incredibly useful tree.”

John Wiley & Sons, Inc.

UTAH PALEONTOLOGIST PART OF INTERNATIONAL TEAM TO DISCOVER OLDEST KNOWN DINOSAUR RELATIVE

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Until now, paleontologists have generally believed that the closest relatives of dinosaurs possibly looked a little smaller in size, walked on two legs and were carnivorous. However, a research team including Randall Irmis, curator of paleontology at the Utah Museum of Natural History and assistant professor in the Department of Geology and Geophysics at the University of Utah has made a recent discovery to dispel this hypothesis.

The team announced the discovery of a proto-dinosaur (dinosaur-like animal) — a new species called Asilisaurus kongwe (a-SEE-lee-SOAR-us KONG-way), derived from asili (Swahili for ancestor or foundation), sauros (Greek for lizard), and kongwe (Swahili for ancient). The first bones of Asilisaurus were discovered in 2007, and it is the first proto-dinosaur recovered from the Triassic Period in Africa. Asilisaurus shares many characteristics with dinosaurs but falls just outside of the dinosaur family tree—living approximately 10 million years earlier than the oldest known dinosaurs.

The description of the new species Asilisaurus kongwe appears in the March 4 issue of the journal Nature in a paper co-authored by an international team, including Irmis, Sterling Nesbitt, a postdoctoral researcher at the University of Texas at Austin's Jackson School of Geosciences, Christian A. Sidor (Burke Museum and University of Washington), Kenneth D. Angielczyk (The Field Museum, Chicago), Roger M.H. Smith (Iziko South African Museum, South Africa), and Linda A. Tsuji (Museum für Naturkunde and Humboldt-Universität zu Berlin, Germany).

Fossil bones of at least 14 individuals were recovered from a single bone bed in southern Tanzania making it possible to reconstruct nearly the entire skeleton, except portions of the skull and hand. The individuals stood about 1.5 to 3 feet (0.5 to 1 meter) tall at the hips and were 3 to 10 feet (1 to 3 meters) long. They weighed about 22 to 66 pounds (10 to 30 kilograms), walked on four legs, and most likely ate plants or a combination of plants and meat.

"The crazy thing about this new dinosaur discovery is that it is so very different from what we all were expecting, especially the fact that it is herbivorous and walked on four legs, said Irmis, who was involved in the researching the discovery over the past three years.

Asilisaurus kongwe is part of a newly recognized group known as silesaurs. "We knew that there were a number of species from the Triassic that were similar to Asilisaurus," said Irmis, "but we were only able to recognize that they formed this group called silesaurs with the new anatomical information from Asilisaurus." Members of the silesaur group were distributed across the globe during the Triassic, when all of the continents were together in a supercontinent called Pangaea.

Silesaurs are the closest relatives of dinosaurs, analogous to the close relationship of humans and chimps. Even though the oldest dinosaurs discovered so far are only 230 million years old, the presence of their closest relatives 10 million to 15 million years earlier implies that silesaurs and the dinosaur lineage had already diverged from a common ancestor by 245 million years ago. Silesaurs continued to live side by side with early dinosaurs throughout much of the Triassic Period (between about 250 million and 200 million years ago). The researchers conclude that other relatives of dinosaurs, such as pterosaurs (flying reptiles) and small forms called lagerpetids, might have also originated much earlier than previously thought.

Silesaurs have triangular teeth and a lower jaw with a beak-like tip, suggesting that they were specialized for an omnivorous and/or herbivorous diet. These same traits evolved independently in at least two dinosaur lineages (ornithischians and sauropodomorphs). In all three cases, the features evolved in animals that were originally meat-eaters. Although difficult to prove, it's possible that this shift conferred an evolutionary advantage. The researchers conclude that the ability to shift diets may have lead to the evolutionary success of these groups.

"The research suggests that at least three times in the evolution of dinosaurs and their closest relatives, meat-eating animals evolved into animals with diets that included plants," said Irmis. "These shifts all occurred in less than 10 million years, a relatively short time by geological standards, so we think that the lineage leading to silesaurs and dinosaurs might have had a greater flexibility in diet, and that this could be a reason for their success."

This new species (Asilisaurus) is found along with a number of primitive crocodilian relatives in the same fossil beds in southern Tanzania. The presence of these animals together at the same time and place suggests that the diversification of the relatives of crocodilians and dinosaurs was rapid, and happened earlier than previously suggested. It sheds light on a group of animals that later came to dominate terrestrial ecosystems throughout the Mesozoic Era (250 million to 65 million years ago).

"This new research suggests that there are more groups of animals yet to be discovered in this early period of dinosaur relatives," said Irmis. "It's very exciting because the more we learn about the Triassic Period, the more we learn about the origin of the dinosaurs and other groups."

(Photo: Marlene Donnelly, Field Museum)

University of Utah

WOMEN MORE AFFECTED THAN MEN BY AIR POLLUTION WHEN RUNNING MARATHONS

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Poor air quality apparently affects the running times of women in marathons, according to a study by Virginia Tech civil and environmental engineer Linsey Marr.

Marr's findings come from a comprehensive study that evaluated marathon race results, weather data, and air pollutant concentrations in seven marathons over a period of eight to 28 years. The top three male and female finishing times were compared with the course record and contrasted with air pollutant levels, taking high temperatures that were detrimental to performance into consideration.

Higher levels of particles in the air were associated with slower running times for women, while men were not significantly affected, Marr said. The difference may be due to the smaller size of women's tracheas, which makes it easier for certain particles to deposit there and possibly to cause irritation.

"Although pollution levels in these marathons rarely exceeded national standards for air quality, performance was still affected," Marr said.

Her work, done in collaboration with Matthew Ely, an exercise physiologist at the U.S. Army Research Institute of Environmental Medicine, appears in the official journal of the American College of Sports Medicine, Medicine and Science in Sports & Exercise.

Her studies were conducted where major U.S. marathons are located, such as New York, Boston, and Los Angeles, where pollution tends to be highest. Although the person might not be significantly impacted by low-yet-still-acceptable air quality, marathoners are atypical because of their breathing patterns, she said.

"Previous research has shown that during a race, marathon runners inhale and exhale about the same volume of air as a sedentary person would over the course of two full days," Marr said. "Therefore, runners are exposed to much greater amounts of pollutants than under typical breathing conditions."

Particulate matter appeared to be the only performance-altering factor in air quality, with carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide levels not impacting race times.

(Photo: Virginia Tech)

Virginia Polytechnic Institute and State University

CONFIDENCE KEY IN GAUGING IMPRESSIONS WE LEAVE

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The gift of “seeing ourselves as others see us” is particularly beneficial when we judge how we’ve made a first impression – in a job interview, during a sales pitch, on a first date.

Yet many come away from these situations with at best a vague notion of how that first impression was perceived or at worst no clue at all.

Now, psychologists at Washington University in St. Louis and Wake Forest University have tested people in first impression settings in the laboratory and have found that confidence makes all the difference in knowing whether you’ve hit a homerun or struck out.

Erika N. Carlson, Washington University doctoral candidate in psychology, her advisor Simine Vazire, Ph.D., assistant professor of psychology, and Wake Forest University’s R. Michael Furr, engaged some 280 students in opposite-sex pairings from both universities in five-minute conversation after which impressions (your rating of your partner’s personality traits) and meta-perceptions (your rating of how you think your partner rated your personality traits) were recorded on 60 personality items (such as nice, funny, outgoing), which were rated on a scale from 1 to 7.

There was a twist to their study. The researchers asked a confidence question: How confident are you in your estimation of how your partner sees your personality?

“In the past, researchers hadn’t asked whether you know when you’re accurate in first impressions, nor your degree of confidence,” says Carlson.

“We found that people who were poor at making good meta-impressions were less confident than people who made accurate ones. So, after making a first impression, if you’re confident in your judgment, you’re likely to be right.”

The research was recently published in Social Psychological and Personality Science.

At the crux of knowing you’ve made a good impression is something called calibration, or “being confident when you’re right and uncertain when you’re wrong,” says Vazire. “Not well calibrated people are confident when they’re wrong and uncertain when they’re right. The confidence and accuracy questions in our study shed light on participants’ calibration.”

She likens accurate calibration to a sort of internal gauge.

“You think, ‘This is the impression I think I made’. And the internal gauge tells you to go ahead with that impression, you’re probably right. Or, gather more information, you might be wrong. So, well-calibrated people have a good internal gauge.”

The goal of their research is to enable people to trust the confidence of their first impressions and pursue the next step, Carlson says.

When you have misjudged the way others see you, the result is often a bad decision, says Carlson. “You might have thought that the date you went on went well and she liked you, but it went wrong in the date’s eyes and she doesn’t like you. Your next move could be embarrassing and painful.”

We’re sometimes wrong about the impressions we’ve made, Vazire says.

“We might think that obviously the other person could tell that I hated them, or that I obviously liked them, or obviously my brilliance came across, but we’ve all been wrong, so it’s important in any number of social settings when to actually doubt how you’ve come across.”

Future metaperception research will explore videotaped first impression interactions from calibration studies to determine which factors affect calibration, like verbal or non-verbal clues, which might reveal who formed accurate meta-perceptions and who didn’t, who was well-calibrated and who wasn’t, and perhaps more importantly why people understood the impressions they made. Such clues could be in overt behaviors like talking rates, smiles, how close the participants sat to each other, or more subjective things like the intimacy of the conversation.

Carlson says there is some preliminary evidence that when one person is more accurate in metaperceptions their partner also is, suggesting that there might be something unique to relationships that influences whether we can pick up on the impression we’ve made.

With the exception of someone like Michael Scott (the totally clueless boss in the TV sitcom “The Office”), people have a surprising level of self-knowledge in judging their first impressions, says Carlson.

“For the most part, people understand when they’re right and when they’re wrong,” she says. “If you want to know if you’ve made the right impression, trust your gut.”

(Photo: WUSTL)

Washington University in St. Louis

ISLAND OF DWARF DINOSAURS

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The idea of dwarf dinosaurs on Haţeg Island, Romania, was proposed 100 years ago by the colourful Baron Franz Nopcsa, whose family owned estates in the area. He realized that many of the Haţeg dinosaurs had close relatives in older rocks in England, Germany, and North America, but the Romanian specimens were half the size.

In new work by Professor Mike Benton at the University of Bristol, and six other authors from Romania, Germany, and the United States, Nopcsa’s hypothesis is tested for the first time. They found that the Haţeg Island dinosaurs were indeed dwarfs.

One much debated theme among evolutionary ecologists is whether there is an ‘island rule’, the observation that large animals isolated on islands tend to become smaller. There is no doubt that the Haţeg dinosaurs were small, but were they just juveniles?

Three species of the Haţeg dinosaurs – the plant-eating sauropod Magyarosaurus and the plant-eating ornithopods Telmatosaurus and Zalmoxes – are half the length of their nearest relatives elsewhere.

The team examined these three dinosaurs, each represented by many specimens, but they found no evidence of any large bones such as they would expect to find in their normal-sized relatives. More importantly, a close study of the bones confirmed that the dinosaurs had reached adulthood.

As dinosaurs matured, just like humans, their bones lost their growing centres and fused. In addition, detailed studies by Martin Sander in Bonn and his students, show that the bone histology (the microscopic structure) is adult. Traces of earlier growth can be tracked in the core of the bone, and the outer surfaces are solid and show evidence of ‘remodeling’ only seen in adults.

Professor Benton said: "The idea of ‘island dwarfing’ is well established for more recent cases. For example, there were dwarf elephants on many of the Mediterranean islands during the past tens of thousands of years. These well-studied examples suggest dwarfing can happen quite quickly.

The general idea is that larger animals that find themselves isolated on an island either become extinct because there isn’t enough space for a reasonably-sized population to survive, or they adapt. One way to adapt is to become smaller, generation by generation."

The Haţeg dinosaurs date from close to the end of the Cretaceous Period, some 65-70 million years ago, when much of Europe was flooded by great seas. There was an archipelago of islands across eastern Europe and the Mediterranean coastal area and dinosaurs are known from some of these islands.

Haţeg Island was about 80,000 km2 in area and the rich assemblages of fossil plants, insects, fishes, frogs, lizards, birds, and mammals show that the scene was rich and tropical.

How did the dinosaurs get to the island? It’s not certain whether they were marooned there as the seas rose, or whether they swam or drifted there by chance later on. Either way, this research demonstrates that once they arrived they evolved to become dwarfs.

(Photo: Simon Powell)

University of Bristol

ABSOLUTE HUMIDITY, DRY CONDITIONS TIED TO SEASONAL OUTBREAKS OF INFLUENZA

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The seasonal increase of influenza has long baffled scientists but a new study has found that seasonal changes of absolute humidity are the apparent underlying cause of these wintertime peaks.

The study also found that the onset of outbreaks might be encouraged by anomalously dry weather conditions – at least in temperate regions.

The study, published in the science journal PLoS Biology, builds on laboratory research that found influenza virus survival rates increased greatly as absolute humidity decreased. In this new study, the researchers used 31 years of observed absolute humidity conditions to drive a mathematical model of influenza and found that the model simulations reproduced the observed seasonal cycle of influenza throughout the United States.

They also discovered that the start of many influenza outbreaks during the winter was directly preceded by a period of weather that was drier than usual.

“This dry period is not a requirement for triggering an influenza outbreak, but it was present in 55 to 60 percent of the outbreaks we analyzed so it appears to increase the likelihood of an outbreak,” said Jeffrey Shaman, an Oregon State University atmospheric scientist and lead author on both studies. “The virus response is almost immediate; transmission and survival rates increase and about 10 days later, the observed influenza mortality rates follow.”

Scientists have long suspected a link between humidity and seasonal (epidemic) flu outbreaks, but most of the research has focused on relative humidity – the ratio of water vapor content in the air to the saturating level, which varies with temperature.

Absolute humidity quantifies the actual amount of water in the air, irrespective of temperature. Though somewhat counter-intuitive, absolute humidity is much higher in the summer, said Shaman, an assistant professor in the College of Oceanic and Atmospheric Sciences at Oregon State University.

“In some areas of the country, a typical summer day can have four times as much water vapor as a typical winter day – a difference that exists both indoors and outdoors,” Shaman said. “Consequently, outbreaks of influenza typically occur in winter when low absolute humidity conditions strongly favor influenza survival and transmission.”

Shaman, who specializes in the relationship between climate and infectious disease transmission, said anomalously low absolute humidity in much of the continental United States is often associated with excursions of colder air masses from the north. These air masses, which can follow a cold front, bring cloud-free skies, reduced surface temperature and lower humidity levels.

Though the findings by Shaman and his colleagues build a strong case for absolute humidity’s role in influenza outbreaks, they do not constitute a predictive model, he emphasized.

“Certainly absolute humidity may affect the survival of the influenza virus, but the severity of outbreaks also is dependent upon other variables, including the type of virus and its virulence, as well as host-mediated factors such as the susceptibility of a population and rates of population mixing and person-to-person interactions,” Shaman said.

“But what we can do is identify when environmental conditions are rife for transmission, which is the first step toward a predictive model,” he added.

In the modeling portion of their study, the researchers examined influenza in New York, Washington, Illinois, Arizona and Florida, and found that the absolute humidity conditions in those state all produced model-simulated seasonal outbreaks of influenza that correlated well with the observed seasonal cycle of influenza within each state.

Shaman and colleagues then extended their model to the rest of the continental U.S. and were able to reproduce the seasonal cycle of influenza elsewhere. Other potential “drivers” of outbreaks – such as temperature, relative humidity, solar radiation and even school days – were examined, but no variable worked as well as absolute humidity.

The association between the onset of wintertime influenza outbreaks and unusually dry weather conditions was based on state-by-state analysis of nearly 1,500 winters throughout the United States.

“In a few winters, there was little influenza transmission and thus no definable onset,” Shaman pointed out. “In the other winters, outbreaks may have begun as early as November or as late as March. In more than half of these cases, the onset was preceded by a period of drier-than-normal weather.”

“Conditions are already seasonally dry during winter and favorable for influenza virus survival and transmission,” Shaman said. “Drier-than-normal weather conditions appear to additionally amplify the survival rate of the virus.”

Marc Lipsitch, a professor of epidemiology at the Harvard School of Public Health and senior author on the new study, said the new analysis may have implications for other diseases.

"Seasonality of infectious diseases is one of the oldest observations in human health, but the mechanisms – especially for respiratory diseases like flu – have been unclear,” Lipsitch said. “This study, in combination with Shaman and (Melvin) Kohn's earlier analysis of laboratory experiments on flu transmission, points to variation in humidity as a major cause of seasonal cycles in flu.”

“Seasonal variation in flu, in turn, helps to explain variation in other infectious diseases – such as pneumococcal and meningococcal disease – as well as seasonal variation in heart attacks, strokes and other important health outcomes."

Lipsitch directs the Center for Communicable Disease Dynamics, of which Shaman is a member. This study and the center are supported by the Models of Infectious Disease Agent Study, or “MIDAS Program,” of the U.S. National Institute of General Medical Sciences – one of the National Institutes of Health.

"The discovery of a link between influenza outbreaks and absolute humidity could have a major impact on the development of strategies for limiting the spread of infection," said Irene Eckstrand, who oversees the MIDAS program. "Understanding why outbreaks arise is an important first step toward containing or even preventing them, so it is essential for scientists to follow up on this intriguing connection."

Oregon State University

WERE SHORT WARM PERIODS TYPICAL FOR TRANSITIONS BETWEEN INTERGLACIAL AND GLACIAL EPOCHS?

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At the end of the last interglacial epoch, around 115,000 years ago, there were significant climate fluctuations. In Central and Eastern Europe, the slow transition from the Eemian Interglacial to the Weichselian Glacial was marked by a growing instability in vegetation trends with possibly at least two warming events.

This is the finding of German and Russian climate researchers who have evaluated geochemical and pollen analyses of lake sediments in Saxony-Anhalt, Brandenburg and Russia. Writing in Quaternary International, scientists from the Helmholtz Centre for Environmental Research (UFZ), the Saxon Academy of Sciences (SAW) in Leipzig and the Russian Academy of Sciences say that a short warming event at the very end of the last interglacial period marked the final transition to the ice age.

The Eemian Interglacial was the last interglacial epoch before the current one, the Holocene. It began around 126,000 years ago, ended around 115,000 years ago and is named after the river Eem in the Netherlands. The followed Weichselian Glacial ended around 15,000 years ago is the most recent glacial epoch named after the Polish river Weichsel. At its peak around 21,000 years ago, the glaciers stretched as far as the south of Berlin (Brandenburg Stadium).

The researchers studied lake sediments to reconstruct the climate history of the Eemian Interglacial, since deposits on river and lake beds can build up a climate archive over the years. The sediment samples came from lakes that existed at the time, but which have since silted up and been uncovered in the former open cast mines at Gröbern near Bitterfeld, Neumark-Nord in the Geiseltal valley near Merseburg, and Klinge near Cottbus and at Ples on the upper reaches of the Volga, around 400 kilometres north-east of Moscow. Gröbern in Saxony-Anhalt is now seen by experts as one of the most studied places for Eemian Interglacial climate history in Germany. As well as pollen concentrations, the researchers analysed the level and ratios of stable carbon (13C/12C) and oxygen isotopes (18O/16O) in carbonates and organic matter from sediment layers, since these provide information about the vegetation development and an indication of the climate.

The results show a relatively stable climate over most of the time, but with instabilities at the beginning and end of the Eemian Interglacial. "The observed instability with the proven occurrence of short warming events during the transition from the last interglacial to the last glacial epoch could be, when viewed carefully, a general, naturally occurring characteristic of such transition phases," concludes Dr Tatjana Boettger of the UFZ, who analysed the sediment profiles at the UFZ's isotope laboratory in Halle. "Detailed studies of these phenomena are important for understanding the current controversial discussed climate trend so that we can assess the human contribution to climate change with more certainty," explains Dr Frank W. Junge of the SAW.

From reconstructions of climate history, we know that in the Earth's recent history, interglacial epochs occurred only once every 100,000 years or so and lasted for an average of around 10,000 years. The current interglacial epoch – the Holocene – has already lasted more than 10,000 years and reached its highest point so far around 6000 years ago. From a climate history perspective, we are currently at the end of the Holocene and could therefore expect to see a cooling-down in a few thousand years if there had been no human influence on the atmosphere and the resulting global warming.

(Photo: Frank W. Junge/SAW)

Helmholtz Centre for Environmental Research

WIDENING THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE

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The Search for Extraterrestrial Intelligence (SETI) has been dominated for its first half century by a hunt for unusual radio signals. But as he prepares for the publication of his new book The Eerie Silence: Are We Alone?, Paul Davies tells Physics World readers why bold new innovations are required if we are ever to hear from our cosmic neighbours.

Writing exclusively in March's Physics World, Davies, director of BEYOND: Center for Fundamental Concepts in Science at Arizona State University in the US, explains why the search for radio signals is limited and how we might progress.

As Davies writes, "speculation about SETI is bedevilled by the trap of anthropocentrism – a tendency to use 21st-century human civilisation as a model for what an extraterrestrial civilisation would be like... After 50 years of traditional SETI, the time has come to widen the search from radio signals."

Questioning the idea of an alien civilisation beaming radio signals towards Earth, Davies explains that even if the aliens were, say, 500 light years away (close by SETI standards), the aliens would be communicating with Earth in 1510 – long before we were equipped to pick up radio signals.

While SETI activity has been concentrated in radio astronomy, from Frank Drake's early telescope to the more recent Allen Telescope Array, astronomers have only ever been met with an (almost) eerie silence.

Davies suggests that there may be more convincing signs of intelligent alien life, either here on Earth in the form of bizarre microorganisms that somehow found their way to Earth, or in space, through spotting the anomalous absence of, for example, energy-generating particles that an alien life form might have harvested.

"Using the full array of scientific methods from genomics to neutrino astrophysics," Davies writes, "we should begin to scrutinise the solar system and our region of the galaxy for any hint of past or present cosmic company."

(Photo: IoP)

Institute of Physics

ANCIENT DNA FROM RARE FOSSIL REVEALS THAT POLAR BEARS EVOLVED RECENTLY AND ADAPTED QUICKLY

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A paper published in the current issue of the Proceedings of the National Academy of Sciences by researchers at Penn State University, the University at Buffalo, the University of Oslo, and other institutions is filling in key pieces of the evolutionary history of polar bears and brown bears, including their response to past climate changes.

"Our results confirm that the polar bear is an evolutionarily young species that split off from brown bears some 150,000 years ago and evolved extremely rapidly during the late Pleistocene, perhaps adapting to the opening of new habitats and food sources in response to climate changes just before the last interglacial period," says Charlotte Lindqvist, Ph.D., research assistant professor in the UB Department of Biological Sciences and lead author on the paper with Stephan C. Schuster at Penn State's Center for Comparative Genomics and Bioinformatics.

"Very few polar bear fossils have been found, leading to widely varying estimates of exactly when and how polar bears evolved," explains Oystein Wiig, polar bear expert and co-author at the University of Oslo's Natural History Museum. "Because polar bears live on the ice, their dead remains fall to the bottom of the ocean or get scavenged. They don't get deposited in the sediments like other mammals." But in 2004, an Icelandic geologist found a rare, well-preserved, 110,000-to-130,000-year-old, fossil jawbone and canine tooth in the Svalbard archipelago of Norway. This specimen subsequently was sent to Wiig for analysis.

Lindqvist, who was working at Oslo's Natural History Museum as a postdoctoral researcher, extracted DNA from the sample after drilling into the bone and tooth to obtain the powder to analyze. When she arrived at UB in 2008, she obtained tissue samples from modern polar bears and brown bears and began analyzing them at UB's New York State Center of Excellence in Bioinformatics and Life Sciences after starting the collaboration with Schuster at Penn State.

This work resulted in the sequencing of the complete mitochondrial genome of the fossil; the scientists then used that information to develop mitochondrial sequencing of the other bears and to construct phylogenies showing that the ancient polar bear evolved within the lineage of brown bears. "Since the brown bears from Alaska's Admiralty, Baranof, and Chichagof Islands are the polar bears' closest relatives, it was crucial to include them in our study in order to more precisely date when polar bears appeared as a distinct species," Lindqvist explains. "The fact that our ancient polar bear lies almost directly at the splitting point between this unique group of brown bears and polar bears, that is, close to their most recent common ancestor of the two species, was very intriguing. It provided an ideal opportunity to ultimately settle the time of polar bear origin."

"This is, by far, the oldest mammal mitochondrial genome to be sequenced," says Schuster. "It's about twice the age of the oldest mammoth genome that has, to date, been sequenced."

The mitochondrial genome refers to all the DNA in the mitochondrion, the energy-producing component of most eukaryotic (complex) cells. Lindqvist explains that ancient DNA studies have tended to focus on the mitochondrial genome because it generally reveals characteristics useful for evolutionary analyses and allows for DNA to be retrieved from ancient samples most easily.

To conduct their analyses, the researchers used a variety of techniques including isotope analyses, high-throughput genomic sequencing, bioinformatics, and phylogenetic analysis, which traces evolutionary relationships among species. While their data demonstrate how adaptive polar bears have been historically, the scientists caution against assuming that the polar bears, therefore, also will be able to adapt to current and future changes in the Arctic.

"We have found that polar bears actually survived the interglacial warming period, which was generally warmer than the current one," Lindqvist says, "but it's possible that Svalbard might have served as a refugium for bears, providing them with a habitat where they could survive. However, climate change now may be occurring at such an accelerated pace that we do not know if polar bears will be able to keep up." Ultimately, she notes, the polar bear species may prove less adaptive. "The polar bear may be more evolutionarily constrained because it is today very specialized; morphologically, physiologically, and behaviorally well-adapted to living on the edge of the Arctic ice, subsisting on a few species of seals," she says.

Lindqvist and Schuster are seriously considering working on sequencing the nuclear genome of the ancient polar bear, work that they expect will reveal even more about polar bear evolution.

(Photo: U.S. Fish and Wildlife Service)

Penn State University

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