The pain of evolution: a big toothache for reptiles - Study reveals infection in the jaw of 275-million-year-old reptile, highlighting the high cost of having permanent teeth
Springer Select - New York / Heidelberg, 4/18/11
Our susceptibility to oral infection has some parallels to those of ancient reptiles that evolved to eat a diet incorporating plants in addition to meat. That's according to Robert Reisz from the University of Toronto and his colleagues who found evidence of bone damage due to oral infec-tion in Paleozoic reptiles as they adapted to living on land. Their findings, published online in Springer's journal Naturwissenschaften - The Science of Nature, predate the previous record for oral and dental disease in a terrestrial vertebrate by nearly 200 million years.
The researchers investigated the jaws of several well-preserved specimens of Labidosaurus hama-tus, a 275-million-year-old terrestrial reptile from North America. One specimen stood out because of missing teeth and associated erosion of the jaw bone. With the aid of CT-scanning, Reisz and colleagues found evidence of a massive infection. This resulted in the loss of several teeth, as well as bone destruction in the jaw in the form of an abscess and internal loss of bone tissue.
As the ancestors of advanced reptiles diversified to life on land, many evolved dental and cranial specializations to feed more efficiently on other animals and to incorporate high-fiber plant leaves and stems into their diet. The primitive dental pattern in which teeth were loosely attached to the jaws and continuously replaced, changed in some lineages to be strongly attached to the jaw, with little or no tooth replacement. This was clearly advantageous to some early reptiles, allowing them to chew their food and thus improve nutrient absorption. The abundance and global distribution of Labidosauris and its kin attest to the evolutionary success of this strategy.
However, Reisz and his colleagues suggest that as this reptile lost the ability to replace teeth, the likelihood of infections of the jaw, resulting from damage to the teeth, increased substantially. This is because prolonged exposure of the dental pulp cavity of heavily worn or damaged teeth to oral bacteria was much greater than in other animals that quickly replaced their teeth.
The authors conclude: "Our findings allow us to speculate that our own human system of having just two sets of teeth, baby and permanent, although of obvious advantage because of its ability to chew and process many different foodstuffs, is more susceptible to infection than that of our distant ancestors that had a continuous cycle of tooth replacement."
Reference
Reisz R R et al (2011). Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance. Naturwissenschaften - The Nature of Science. DOI 10.1007/s00114-011-0792-1
Showing posts with label prehistoric life. Show all posts
Showing posts with label prehistoric life. Show all posts
Friday, April 29, 2011
Friday, September 3, 2010
Rockies fossils yield 8 new species
This is the claw of Stanleycaris, a predatory species newly discovered at the Stanley Glacier fossil field. It was a primitive arthropod, the group of jointed-legged animals that includes insects, spiders and crabs. The claw is about 3 centimetres long and the entire animal was probably less than 20 centimetres in size. (Jean-Bernard Caron/Royal Ontario Museum)A surprise fossil field at a glacier in B.C.'s Kootenay National Park contains at least eight new species that lived 505 million years ago.
Jean-Bernard Caron, curator of invertebrate paleontology at Toronto's Royal Ontario Museum, said the new arthropods (the group to which crabs and insects belong) and worms were found in an environment where paleontologists previously believed fossils could not be preserved or found.
The discovery means paleontologists might be able to find new fossils in similar environments that they had previously ignored.
"It opens up, I guess, a new terrain to explore," said Caron, who returned Thursday from a followup expedition to similar sites. "I think the chance to find new fossils in the future … will expand dramatically."
Descriptions of the new fossil field and the new species collected two years ago were published in the September issue of the journal Geology.
Fossils were first collected by a hiker walking on a trail near the Stanley Glacier in the park in the 1990s. The hiker contacted the Royal Ontario Museum, which sent researchers to collect fallen rock debris in the park in 1996.
Caron examined the rocks when he began working at the museum in 2006 and noticed that the fossils seemed to appear in a type of Rocky Mountain shale rock that hadn't been known for fossils before.
The rock dates back 505 million years ago, to the Middle Cambrian period — the same one represented by the Burgess Shale, which is located in the Rockies of Yoho National Park and considered one of the most important fossil fields in the world.
The Burgess Shale, located 40 kilometres northwest of the new fossil field, was once at the foot of an undersea cliff in tropical waters. Researchers believed the cliff provided an ideal environment for a diverse community of animals, and its harder rock prevented the fossil in the softer mud of the sea floor from being crushed by geological forces in hundreds of millions of years that followed.
The Stanley Glacier site represents a similar undersea environment, but with no evidence of any cliff nearby. It seems to have been above the Burgess Shale cliff.
Caron led a two-week expedition to the site in 2008, where researchers collected 2,000 specimens. Many of the species were previously known from other sites like the Burgess Shale, although some specimens were better preserved than any known before. However, eight were new, including a primitive arthropod predator that would have grabbed prey with its claws. It was named Stanleycaris after the glacier.
Caron said that's a lot of new species, considering that just 200 species have been discovered among more than 200,000 specimens collected from the Burgess Shale. He suggested the newly discovered animals may have been specifically adapted to that environment.
This August, Caron and his team went to look for similar sites along the same geological formation in the Rockies that yielded the Stanley Glacier site. They didn't find any new fossils this time, but plan to go back in the future.
Read more: http://www.cbc.ca/technology/story/2010/09/03/bc-kootenay-fossil-stanley-glacier.html#ixzz0yU4HvkOL
Rockies fossils yield 8 new species
This is the claw of Stanleycaris, a predatory species newly discovered at the Stanley Glacier fossil field. It was a primitive arthropod, the group of jointed-legged animals that includes insects, spiders and crabs. The claw is about 3 centimetres long and the entire animal was probably less than 20 centimetres in size. (Jean-Bernard Caron/Royal Ontario Museum)A surprise fossil field at a glacier in B.C.'s Kootenay National Park contains at least eight new species that lived 505 million years ago.
Jean-Bernard Caron, curator of invertebrate paleontology at Toronto's Royal Ontario Museum, said the new arthropods (the group to which crabs and insects belong) and worms were found in an environment where paleontologists previously believed fossils could not be preserved or found.
The discovery means paleontologists might be able to find new fossils in similar environments that they had previously ignored.
"It opens up, I guess, a new terrain to explore," said Caron, who returned Thursday from a followup expedition to similar sites. "I think the chance to find new fossils in the future … will expand dramatically."
Descriptions of the new fossil field and the new species collected two years ago were published in the September issue of the journal Geology.
Fossils were first collected by a hiker walking on a trail near the Stanley Glacier in the park in the 1990s. The hiker contacted the Royal Ontario Museum, which sent researchers to collect fallen rock debris in the park in 1996.
Caron examined the rocks when he began working at the museum in 2006 and noticed that the fossils seemed to appear in a type of Rocky Mountain shale rock that hadn't been known for fossils before.
The rock dates back 505 million years ago, to the Middle Cambrian period — the same one represented by the Burgess Shale, which is located in the Rockies of Yoho National Park and considered one of the most important fossil fields in the world.
The Burgess Shale, located 40 kilometres northwest of the new fossil field, was once at the foot of an undersea cliff in tropical waters. Researchers believed the cliff provided an ideal environment for a diverse community of animals, and its harder rock prevented the fossil in the softer mud of the sea floor from being crushed by geological forces in hundreds of millions of years that followed.
The Stanley Glacier site represents a similar undersea environment, but with no evidence of any cliff nearby. It seems to have been above the Burgess Shale cliff.
Caron led a two-week expedition to the site in 2008, where researchers collected 2,000 specimens. Many of the species were previously known from other sites like the Burgess Shale, although some specimens were better preserved than any known before. However, eight were new, including a primitive arthropod predator that would have grabbed prey with its claws. It was named Stanleycaris after the glacier.
Caron said that's a lot of new species, considering that just 200 species have been discovered among more than 200,000 specimens collected from the Burgess Shale. He suggested the newly discovered animals may have been specifically adapted to that environment.
This August, Caron and his team went to look for similar sites along the same geological formation in the Rockies that yielded the Stanley Glacier site. They didn't find any new fossils this time, but plan to go back in the future.
Read more: http://www.cbc.ca/technology/story/2010/09/03/bc-kootenay-fossil-stanley-glacier.html#ixzz0yU4HvkOL
Wednesday, August 25, 2010
Study shows carnivore species shrank during global warming event
August 24, 2010 by Leeann Bright
A new University of Florida study indicates extinct carnivorous mammals shrank in size during a global warming event that occurred 55 million years ago.
The study, scheduled to appear in the December print edition of the Journal of Mammalian Evolution and now available online, describes a new species that evolved to half the size of its ancestors during this period of global warming.
The hyena-like animal, Palaeonictis wingi, evolved from the size of a bear to the size of a coyote during a 200,000-year period when Earth's average temperature increased about 15 degrees Fahrenheit. Following this global warming event, Earth's temperature cooled and the animal evolved to a larger size.
"We know that plant-eating mammals got smaller during the earliest Eocene when global warming occurred, possibly associated with elevated levels of carbon dioxide," said lead author Stephen Chester, a Yale University doctoral student who began the research at UF with Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History. "Surprisingly, this study shows that the same thing happened in some carnivores, suggesting that other factors may have played a critical role in their evolution."
Researchers discovered a nearly complete jaw from the animal in Wyoming's Big Horn Basin in 2006 during a fossil-collecting expedition, led by Bloch, a co-author on the study. Bloch said the new findings could help scientists better understand the impact of current global warming.
"Documenting the impact of global climate change in the past is one of the only real experiments that can inform us about what the effects global warming might have on mammals in the near future," said Bloch, who has studied this climate change event for nearly a decade.
Scientists think the Earth experienced increased levels of carbon dioxide and a drier environment during the warmer time period, but they do not completely understand what caused mammals to shrink.
One theory is that carbon dioxide levels reduced plant nutrients, causing herbivorous mammals to shrink. The newly described species primarily consumed meat, meaning plant nutrients couldn't have been the only factor, Bloch said.
Mammals in warmer climates today tend to be smaller than mammals in colder climates, Chester said. For example, brown bears in Montana are generally smaller than those found in Alaska.
The study's other authors are Ross Secord, assistant professor at the University of Nebraska, and Doug Boyer, assistant professor at Brooklyn College.
Bloch said a tooth from this animal was described in a paper about 20 years ago, but scientists did not have enough information to name the new species until finding the jaw.
The species was named after Scott Wing, a paleobotanist at the Smithsonian National Museum of Natural History. He studies the impact the global warming event had on forests in the past, and has played an important role in the collaborative research in the Big Horn Basin, Bloch said.
Thursday, May 27, 2010
Ancient cephalopod identified
SQUID'S IN: A 500 million-year-old cephalopod fossil shows modern squids have a much older ancestry than previously thought. Nectocaris pteryx was about 5cm long and resembled a cuttlefish with two long, grasping tentacles. Scientists have analysed 91 new Nectocaris fossils and Yoho National Park in British Columbia, Canada, and concluded it was a primitive cephalopod.
http://e-edition.metro.co.uk/2010/05/27/ - p23.
http://e-edition.metro.co.uk/2010/05/27/ - p23.
Thursday, March 25, 2010
DNA identifies new ancient human dubbed 'X-woman'
Thursday, 25 March 2010
By Paul Rincon
Science reporter, BBC News
Scientists have identified a previously unknown type of ancient human through analysis of DNA from a finger bone unearthed in a Siberian cave.
The extinct "hominin" (human-like creature) lived in Central Asia between 48,000 and 30,000 years ago.
An international team has sequenced genetic material from the fossil showing that it is distinct from that of Neanderthals and modern humans.
Details of the find, dubbed "X-woman", have been published in Nature journal.
Ornaments were found in the same ground layer as the finger bone, including a bracelet.
Professor Chris Stringer, human origins researcher at London's Natural History Museum, called the discovery "a very exciting development".
"This new DNA work provides an entirely new way of looking at the still poorly-understood evolution of humans in central and eastern Asia."
The discovery raises the intriguing possibility that three forms of human - Homo sapiens, Neanderthals and the species represented by X-woman - could have met each other and interacted in southern Siberia.
The tiny fragment of bone from a fifth finger was uncovered by archaeologists working at Denisova Cave in Siberia's Altai Mountains in 2008.
An international team of researchers extracted mitochondrial DNA from the bone and compared the genetic code with those from modern humans and Neanderthals.
Origin unknown
Mitochondrial DNA comes from the cell's powerhouses and is passed down the maternal line only.
The analysis carried out by Johannes Krause from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues revealed the human from Denisova last shared a common ancestor with modern humans and Neanderthals about one million years ago.
This is known as the divergence date; essentially, when this human's ancestors split away from the line that eventually led to Neanderthals and ourselves.
The Neanderthal and modern human evolutionary lines diverged much later, around 500,000 years ago. This shows that the individual from Denisova is the representative of a previously unknown human lineage that derives from a hitherto unrecognised migration out of Africa.
"Whoever carried this mitochondrial genome out of Africa about a million years ago is some new creature that has not been on our radar screens so far," said co-author Professor Svante Paabo, also from the Max Planck Institute for Evolutionary Anthropology.
The divergence date of one million years is too young for the Denisova hominin to have been a descendent of Homo erectus, which moved out of Africa into Asia some two million years ago.
And it is too old to be a descendent of Homo heidelbergensis, another ancient human thought to have originated around 650,000 years ago. However, for now, the researchers have steered away from describing the specimen as a new species.
Dr Krause said the ground layer in which the Denisova hominin fragment was found contain tools which are similar to those made by modern humans in Europe.
Slice of time
"We have ornaments, there is a bracelet, so there are several elements in the layers that are usually associated with modern human archaeology," he told BBC News.
"That's quite interesting, but of course, it is hard to prove that the bone is strongly associated to this archaeology, because it is possible that bones could have moved within the site.
"We are also not sure how exactly the excavation was done. It could have come from a deeper layer, so that's hard to say."
Professor Clive Finlayson, director of the Gibraltar Museum, said the find presented a number of questions, such as to what extent culture could continue to be used as a proxy for different prehistoric human groups.
Referring to his research on Neanderthals and modern humans in southern Iberia, he told BBC News: "The assumption is that when one group - the moderns - arrives the other group disappears. Here you have a very clear example of co-existence for long periods.
"Where is the rule that says you can have only one species in an area? Especially if they're at low density... the implications are big."
The research contributes to a more complex picture that has been emerging of humankind during the Late Pleistocene, the period when modern humans left Africa and started to colonise the rest of the world.
Professor Finlayson has previously argued: "A time slice at a point in the late Pleistocene would reveal a range of human populations spread across parts of Africa, Eurasia and Oceania.
"Some would have been genetically linked to each other, behaving as sub-species, while the more extreme populations may well have behaved as good species with minimal or no interbreeding."
It was long known that modern humans overlapped with Neanderthals in Europe, apparently for more than 10,000 years.
But in 2004, researchers discovered that a dwarf species of human, dubbed "The Hobbit", was living on the Indonesian island of Flores until 12,000 years ago - long after modern humans had colonised the region.
Difficult classification
Neanderthals appear to have been living at Okladnikov Cave in the Altai Mountains some 40,000 years ago. And a team led by Professor Anatoli Derevianko, from the Russian Academy of Sciences, has also found evidence of a modern human presence in the region at around the same time.
Professor Stringer commented: "Another intriguing question is whether there might have been overlap and interaction between not only Neanderthals and early moderns in Asia, but also, now, between either of those lineages and this newly-recognised one.
"The distinctiveness of the mitochondrial DNA patterns so far suggests that there was little or no interbreeding, but more extensive data will be needed from other parts of the genome, or from the fossils, for definitive conclusions to be reached."
Experts have been wondering whether X-woman might have links with known fossil humans from Asia, which have controversial classifications.
"Certain enigmatic Asian fossils dated between 250,000-650,000 years ago such as Narmada (in India), and Yunxian, Dali and Jinniushan (in China) have been considered as possible Asian derivatives of Homo heidelbergensis, so they are also potential candidates for this mystery non-erectus lineage," said Prof Stringer.
"However, there are other and younger fragmentary fossils such as the Denisova ones themselves, and partial skulls from Salkhit in Mongolia and Maba in China, which have been difficult to classify, and perhaps they do signal a greater complexity than we have appreciated up to now."
Other experts agreed that while the Siberian specimen may be a new species, this has yet to be shown.
"We really don't know," Ian Tattersall of the American Museum of Natural History in New York, told the Associated Press news agency.
Dr Tattersall, who wasn't involved in the new research, added: "The human family tree has got a lot of branchings. It's entirely plausible there are a lot of branches out there we don't know about."
http://news.bbc.co.uk/1/hi/sci/tech/8583254.stm
(Submitted by Liz R)
By Paul Rincon
Science reporter, BBC News
Scientists have identified a previously unknown type of ancient human through analysis of DNA from a finger bone unearthed in a Siberian cave.
The extinct "hominin" (human-like creature) lived in Central Asia between 48,000 and 30,000 years ago.
An international team has sequenced genetic material from the fossil showing that it is distinct from that of Neanderthals and modern humans.
Details of the find, dubbed "X-woman", have been published in Nature journal.
Ornaments were found in the same ground layer as the finger bone, including a bracelet.
Professor Chris Stringer, human origins researcher at London's Natural History Museum, called the discovery "a very exciting development".
"This new DNA work provides an entirely new way of looking at the still poorly-understood evolution of humans in central and eastern Asia."
The discovery raises the intriguing possibility that three forms of human - Homo sapiens, Neanderthals and the species represented by X-woman - could have met each other and interacted in southern Siberia.
The tiny fragment of bone from a fifth finger was uncovered by archaeologists working at Denisova Cave in Siberia's Altai Mountains in 2008.
An international team of researchers extracted mitochondrial DNA from the bone and compared the genetic code with those from modern humans and Neanderthals.
Origin unknown
Mitochondrial DNA comes from the cell's powerhouses and is passed down the maternal line only.
The analysis carried out by Johannes Krause from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues revealed the human from Denisova last shared a common ancestor with modern humans and Neanderthals about one million years ago.
This is known as the divergence date; essentially, when this human's ancestors split away from the line that eventually led to Neanderthals and ourselves.
The Neanderthal and modern human evolutionary lines diverged much later, around 500,000 years ago. This shows that the individual from Denisova is the representative of a previously unknown human lineage that derives from a hitherto unrecognised migration out of Africa.
"Whoever carried this mitochondrial genome out of Africa about a million years ago is some new creature that has not been on our radar screens so far," said co-author Professor Svante Paabo, also from the Max Planck Institute for Evolutionary Anthropology.
The divergence date of one million years is too young for the Denisova hominin to have been a descendent of Homo erectus, which moved out of Africa into Asia some two million years ago.
And it is too old to be a descendent of Homo heidelbergensis, another ancient human thought to have originated around 650,000 years ago. However, for now, the researchers have steered away from describing the specimen as a new species.
Dr Krause said the ground layer in which the Denisova hominin fragment was found contain tools which are similar to those made by modern humans in Europe.
Slice of time
"We have ornaments, there is a bracelet, so there are several elements in the layers that are usually associated with modern human archaeology," he told BBC News.
"That's quite interesting, but of course, it is hard to prove that the bone is strongly associated to this archaeology, because it is possible that bones could have moved within the site.
"We are also not sure how exactly the excavation was done. It could have come from a deeper layer, so that's hard to say."
Professor Clive Finlayson, director of the Gibraltar Museum, said the find presented a number of questions, such as to what extent culture could continue to be used as a proxy for different prehistoric human groups.
Referring to his research on Neanderthals and modern humans in southern Iberia, he told BBC News: "The assumption is that when one group - the moderns - arrives the other group disappears. Here you have a very clear example of co-existence for long periods.
"Where is the rule that says you can have only one species in an area? Especially if they're at low density... the implications are big."
The research contributes to a more complex picture that has been emerging of humankind during the Late Pleistocene, the period when modern humans left Africa and started to colonise the rest of the world.
Professor Finlayson has previously argued: "A time slice at a point in the late Pleistocene would reveal a range of human populations spread across parts of Africa, Eurasia and Oceania.
"Some would have been genetically linked to each other, behaving as sub-species, while the more extreme populations may well have behaved as good species with minimal or no interbreeding."
It was long known that modern humans overlapped with Neanderthals in Europe, apparently for more than 10,000 years.
But in 2004, researchers discovered that a dwarf species of human, dubbed "The Hobbit", was living on the Indonesian island of Flores until 12,000 years ago - long after modern humans had colonised the region.
Difficult classification
Neanderthals appear to have been living at Okladnikov Cave in the Altai Mountains some 40,000 years ago. And a team led by Professor Anatoli Derevianko, from the Russian Academy of Sciences, has also found evidence of a modern human presence in the region at around the same time.
Professor Stringer commented: "Another intriguing question is whether there might have been overlap and interaction between not only Neanderthals and early moderns in Asia, but also, now, between either of those lineages and this newly-recognised one.
"The distinctiveness of the mitochondrial DNA patterns so far suggests that there was little or no interbreeding, but more extensive data will be needed from other parts of the genome, or from the fossils, for definitive conclusions to be reached."
Experts have been wondering whether X-woman might have links with known fossil humans from Asia, which have controversial classifications.
"Certain enigmatic Asian fossils dated between 250,000-650,000 years ago such as Narmada (in India), and Yunxian, Dali and Jinniushan (in China) have been considered as possible Asian derivatives of Homo heidelbergensis, so they are also potential candidates for this mystery non-erectus lineage," said Prof Stringer.
"However, there are other and younger fragmentary fossils such as the Denisova ones themselves, and partial skulls from Salkhit in Mongolia and Maba in China, which have been difficult to classify, and perhaps they do signal a greater complexity than we have appreciated up to now."
Other experts agreed that while the Siberian specimen may be a new species, this has yet to be shown.
"We really don't know," Ian Tattersall of the American Museum of Natural History in New York, told the Associated Press news agency.
Dr Tattersall, who wasn't involved in the new research, added: "The human family tree has got a lot of branchings. It's entirely plausible there are a lot of branches out there we don't know about."
http://news.bbc.co.uk/1/hi/sci/tech/8583254.stm
(Submitted by Liz R)
Fossil finger points to new human species
DNA analysis reveals lost relative from 40,000 years ago.
24 March 2010
Rex Dalton
In the summer of 2008, Russian researchers dug up a sliver of human finger bone from an isolated Siberian cave. The team stored it away for later testing, assuming that the nondescript fragment came from one of the Neanderthals who left a welter of tools in the cave between 30,000 and 48,000 years ago. Nothing about the bone shard seemed extraordinary.
Its genetic material told another story. When German researchers extracted and sequenced DNA from the fossil, they found that it did not match that of Neanderthals — or of modern humans, which were also living nearby at the time. The genetic data, published online in Nature, reveal that the bone may belong to a previously unrecognized, extinct human species that migrated out of Africa long before our known relatives.
"This really surpassed our hopes," says Svante Pääbo, senior author on the international study and director of evolutionary genetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "I almost could not believe it. It sounded too fantastic to be true."
Researchers not involved in the work applauded the findings but cautioned against drawing too many conclusions from a single study. "With the data in hand, you cannot claim the discovery of a new species," says Eske Willerslev, an evolutionary biologist and director of the Centre for GeoGenetics at the University of Copenhagen.
If further work does support the initial conclusions, the discovery would mark the first time that an extinct human relative had been identified by DNA analysis. It would also suggest that ice-age humans were more diverse than had been thought. Since the late nineteenth century, researchers have known that two species of Homo — Neanderthals and modern humans — coexisted during the later part of the last ice age. In 2003, a third species, Homo floresiensis, was discovered on the island of Flores in Indonesia, but there has been no sign of this tiny 'hobbit' elsewhere. The relative identified in Siberia, however, raises the possibility that several Homo species ranged across Europe and Asia, overlapping with the direct ancestors of modern people.
The Siberian site in the Altai Mountains, called Denisova Cave, was already known as a rich source of Mousterian and Levallois artefacts, two styles of tool attributed to Neanderthals. For more than a decade, Russian scientists from the Institute of Archaeology and Ethnology in Novosibirsk have been searching for the toolmakers' bones. They discovered several bone specimens, handling each potentially important new find with gloves to prevent contamination with modern human DNA. The bones' own DNA could then be extracted and analysed.
When the finger bone was discovered, "we didn't pay special attention to it", says archaeologist Michael Shunkov of the Novosibirsk institute. But Pääbo had established a relationship with the Russian team years before to gather material for genetic testing from ice-age humans. After obtaining the bone, the German team extracted the bone's genetic material and sequenced its mitochondrial DNA (mtDNA) — the most abundant kind of DNA and the best bet for getting an undegraded sequence from ancient tissue.
After re-reading the mtDNA sequences an average of 156 times each to ensure accuracy, the researchers compared them with the mtDNA genomes of 54 modern humans, a 30,000-year-old modern human found in Russia and six Neanderthals. The Denisova Cave DNA fell into a class of its own. Although a Neanderthal mtDNA genome differs from that of Homo sapiens at 202 nucleotide positions on average, the Denisova Cave sample differed at an average of 385 positions.
The differences imply that the Siberian ancestor branched off from the human family tree a million years ago, well before the split between modern humans and Neanderthals. If so, the proposed species must have left Africa in a previously unknown migration, between that of Homo erectus 1.9 million years ago and that of the Neanderthal ancestor Homo heidelbergensis, 300,000 to 500,000 years ago.
Study author Johannes Krause, also at the Max Planck Institute in Leipzig, says that the researchers are now generating nuclear DNA sequences from the bone with the hope of sequencing its entire genome. If they are successful, it would be the oldest human genome sequenced, eclipsing that of the 4,000-year-old Eskimo from Greenland that Willerslev and his colleagues reported last month2.
A complete genome might also enable the researchers to give the proposed new species a formal name. They had originally planned to do so on the basis of the mtDNA genome. But they opted to wait until more bones are found — or until the DNA gives a clearer picture of its relationship to modern humans and Neanderthals.
Willerslev emphasizes that, on its own, the mtDNA evidence does not verify that the Siberian find represents a new species because mtDNA is inherited only from the mother. It is possible that some modern humans or Neanderthals living in Siberia 40,000 years ago had unusual mtDNA, which may have come from earlier interbreeding among H. erectus, Neanderthals, archaic modern humans or another, unknown species of Homo. Only probes of the nuclear DNA will properly define the position of the Siberian relative in the human family tree.
Anthropologists also want to see more-refined dating of the sediments and a better description of the finger bone itself. "I haven't seen a picture of the bone, and would like to," says Owen Lovejoy, an anthropologist at Kent State University in Ohio. "The stratigraphic age for the bone is 30,000 to 48,000 years old, but the mtDNA age could be as old as H. erectus," says Lovejoy. "That doesn't tell us much about human evolution unless it truly represents a surviving ancient species."
The cave has yielded few clues about the culture of the Siberian hominin, although a fragment of a polished bracelet with a drilled hole was found earlier in the same layer that yielded the bone3.
Pääbo suspects that other human ancestors — and new mysteries — may emerge as geneticists grind up more ancient bones for sequencing. "It is fascinating that molecular studies make a contribution in palaeontology where there is little or no morphology preserved," he says. "It is clear we stand just in the beginning of many fascinating developments."
http://www.nature.com/news/2010/100324/full/464472a.html
(Submitted by Michael and Sue Watson)
24 March 2010
Rex Dalton
In the summer of 2008, Russian researchers dug up a sliver of human finger bone from an isolated Siberian cave. The team stored it away for later testing, assuming that the nondescript fragment came from one of the Neanderthals who left a welter of tools in the cave between 30,000 and 48,000 years ago. Nothing about the bone shard seemed extraordinary.
Its genetic material told another story. When German researchers extracted and sequenced DNA from the fossil, they found that it did not match that of Neanderthals — or of modern humans, which were also living nearby at the time. The genetic data, published online in Nature, reveal that the bone may belong to a previously unrecognized, extinct human species that migrated out of Africa long before our known relatives.
"This really surpassed our hopes," says Svante Pääbo, senior author on the international study and director of evolutionary genetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "I almost could not believe it. It sounded too fantastic to be true."
Researchers not involved in the work applauded the findings but cautioned against drawing too many conclusions from a single study. "With the data in hand, you cannot claim the discovery of a new species," says Eske Willerslev, an evolutionary biologist and director of the Centre for GeoGenetics at the University of Copenhagen.
If further work does support the initial conclusions, the discovery would mark the first time that an extinct human relative had been identified by DNA analysis. It would also suggest that ice-age humans were more diverse than had been thought. Since the late nineteenth century, researchers have known that two species of Homo — Neanderthals and modern humans — coexisted during the later part of the last ice age. In 2003, a third species, Homo floresiensis, was discovered on the island of Flores in Indonesia, but there has been no sign of this tiny 'hobbit' elsewhere. The relative identified in Siberia, however, raises the possibility that several Homo species ranged across Europe and Asia, overlapping with the direct ancestors of modern people.
The Siberian site in the Altai Mountains, called Denisova Cave, was already known as a rich source of Mousterian and Levallois artefacts, two styles of tool attributed to Neanderthals. For more than a decade, Russian scientists from the Institute of Archaeology and Ethnology in Novosibirsk have been searching for the toolmakers' bones. They discovered several bone specimens, handling each potentially important new find with gloves to prevent contamination with modern human DNA. The bones' own DNA could then be extracted and analysed.
When the finger bone was discovered, "we didn't pay special attention to it", says archaeologist Michael Shunkov of the Novosibirsk institute. But Pääbo had established a relationship with the Russian team years before to gather material for genetic testing from ice-age humans. After obtaining the bone, the German team extracted the bone's genetic material and sequenced its mitochondrial DNA (mtDNA) — the most abundant kind of DNA and the best bet for getting an undegraded sequence from ancient tissue.
After re-reading the mtDNA sequences an average of 156 times each to ensure accuracy, the researchers compared them with the mtDNA genomes of 54 modern humans, a 30,000-year-old modern human found in Russia and six Neanderthals. The Denisova Cave DNA fell into a class of its own. Although a Neanderthal mtDNA genome differs from that of Homo sapiens at 202 nucleotide positions on average, the Denisova Cave sample differed at an average of 385 positions.
The differences imply that the Siberian ancestor branched off from the human family tree a million years ago, well before the split between modern humans and Neanderthals. If so, the proposed species must have left Africa in a previously unknown migration, between that of Homo erectus 1.9 million years ago and that of the Neanderthal ancestor Homo heidelbergensis, 300,000 to 500,000 years ago.
Study author Johannes Krause, also at the Max Planck Institute in Leipzig, says that the researchers are now generating nuclear DNA sequences from the bone with the hope of sequencing its entire genome. If they are successful, it would be the oldest human genome sequenced, eclipsing that of the 4,000-year-old Eskimo from Greenland that Willerslev and his colleagues reported last month2.
A complete genome might also enable the researchers to give the proposed new species a formal name. They had originally planned to do so on the basis of the mtDNA genome. But they opted to wait until more bones are found — or until the DNA gives a clearer picture of its relationship to modern humans and Neanderthals.
Willerslev emphasizes that, on its own, the mtDNA evidence does not verify that the Siberian find represents a new species because mtDNA is inherited only from the mother. It is possible that some modern humans or Neanderthals living in Siberia 40,000 years ago had unusual mtDNA, which may have come from earlier interbreeding among H. erectus, Neanderthals, archaic modern humans or another, unknown species of Homo. Only probes of the nuclear DNA will properly define the position of the Siberian relative in the human family tree.
Anthropologists also want to see more-refined dating of the sediments and a better description of the finger bone itself. "I haven't seen a picture of the bone, and would like to," says Owen Lovejoy, an anthropologist at Kent State University in Ohio. "The stratigraphic age for the bone is 30,000 to 48,000 years old, but the mtDNA age could be as old as H. erectus," says Lovejoy. "That doesn't tell us much about human evolution unless it truly represents a surviving ancient species."
The cave has yielded few clues about the culture of the Siberian hominin, although a fragment of a polished bracelet with a drilled hole was found earlier in the same layer that yielded the bone3.
Pääbo suspects that other human ancestors — and new mysteries — may emerge as geneticists grind up more ancient bones for sequencing. "It is fascinating that molecular studies make a contribution in palaeontology where there is little or no morphology preserved," he says. "It is clear we stand just in the beginning of many fascinating developments."
http://www.nature.com/news/2010/100324/full/464472a.html
(Submitted by Michael and Sue Watson)
Meet Digit, the new type of human
NICKY PHILLIPS
March 25, 2010 - 6:10AM
THE human family has a new member.
A previously unknown type of ancient human, who lived about 40,000 years ago, has been identified using DNA from a finger bone found in Siberia.
The extraordinary find brings to four the number of human species thought to have roamed the earth at that time.
Six years ago only two were known: Neanderthals and modern humans. Then, in 2004, scientists announced the discovery of a hobbit-sized species of extinct human on the Indonesian island of Flores.
"Forty thousand years ago, the planet was more crowded than we thought," said Terence Brown, of the University of Manchester.
A team led by Johannes Krause, of the Max Planck Institute in Germany, discovered the finger – thought to be a "pinky" – in a cave in the Altai Mountains of southern Siberia. Dr Krause said the DNA it contained was different to that of both Neanderthals and modern humans.
He carried out extensive testing to confirm the mitochondrial DNA, passed from mothers to their offspring, was authentic and had not been contaminated by DNA from other sources.
"[It] was from what seemed to be a new hominin lineage," said Dr Krause, whose findings are published in the journal Nature.
Dr Krause was so shocked he called his colleague Svante Paabo – who sequenced the DNA of Neanderthals last year – to tell him about the find.
"At first I didn't really believe him, I thought he was pulling my leg," said Professor Paabo.
This is the first time a new human ancestor has been identified by its DNA sequence rather than from the study of its bones.
With only DNA evidence to go by, the researchers have said it is impossible to tell what the species would have looked like. And although they could not determine the sex of the individual to whom the finger belonged, the researchers have nicknamed the prehistoric person "X-woman".
The first human group to leave Africa, about 2 million years ago, was Homo erectus. They were followed by Neanderthals around 500,000 years ago, and modern humans around 50,000 years ago.
Professor Paabo said the x-woman type of human would have developed much later than Homo erectus but long before Neanderthals. Modern humans shared a common ancestor with the unknown hominin about a million years ago, he said.
The X-woman humans seem to have lived alongside Neanderthals and modern humans.
http://www.smh.com.au/world/science/meet-digit-the-new-type-of-human-20100325-qx2i.html
(Submitted by Paul Cropper)
March 25, 2010 - 6:10AM
THE human family has a new member.
A previously unknown type of ancient human, who lived about 40,000 years ago, has been identified using DNA from a finger bone found in Siberia.
The extraordinary find brings to four the number of human species thought to have roamed the earth at that time.
Six years ago only two were known: Neanderthals and modern humans. Then, in 2004, scientists announced the discovery of a hobbit-sized species of extinct human on the Indonesian island of Flores.
"Forty thousand years ago, the planet was more crowded than we thought," said Terence Brown, of the University of Manchester.
A team led by Johannes Krause, of the Max Planck Institute in Germany, discovered the finger – thought to be a "pinky" – in a cave in the Altai Mountains of southern Siberia. Dr Krause said the DNA it contained was different to that of both Neanderthals and modern humans.
He carried out extensive testing to confirm the mitochondrial DNA, passed from mothers to their offspring, was authentic and had not been contaminated by DNA from other sources.
"[It] was from what seemed to be a new hominin lineage," said Dr Krause, whose findings are published in the journal Nature.
Dr Krause was so shocked he called his colleague Svante Paabo – who sequenced the DNA of Neanderthals last year – to tell him about the find.
"At first I didn't really believe him, I thought he was pulling my leg," said Professor Paabo.
This is the first time a new human ancestor has been identified by its DNA sequence rather than from the study of its bones.
With only DNA evidence to go by, the researchers have said it is impossible to tell what the species would have looked like. And although they could not determine the sex of the individual to whom the finger belonged, the researchers have nicknamed the prehistoric person "X-woman".
The first human group to leave Africa, about 2 million years ago, was Homo erectus. They were followed by Neanderthals around 500,000 years ago, and modern humans around 50,000 years ago.
Professor Paabo said the x-woman type of human would have developed much later than Homo erectus but long before Neanderthals. Modern humans shared a common ancestor with the unknown hominin about a million years ago, he said.
The X-woman humans seem to have lived alongside Neanderthals and modern humans.
http://www.smh.com.au/world/science/meet-digit-the-new-type-of-human-20100325-qx2i.html
(Submitted by Paul Cropper)
Sunday, March 21, 2010
“Hobbit” island's deeper history
March 20, 2010
Jonathan Amos
Long before a ‘hobbit' species of human lived on Indonesia's Flores island, other human-like creatures colonised the area.
That much was clear.
But scientists have now been able to date their presence to at least one million years ago — some 120,000 years earlier than previously recognised.
The team reports the discovery of these humans' tools in the journal Nature.
The group says the finds bring a new dimension to our understanding of the history of Flores.
Lead author Adam Brumm told BBC News that the location and circumstances of the tools' preservation meant human occupation of the island could extend deep into the past.
“What's really exciting about this is that we effectively have no idea how long hominids have been on Flores,'' said University of Wollongong, Australia.
The remains of the hobbit, known to science as Homo floresiensis, were discovered five years ago at Liang Bua cave.
The diminutive creature's unearthing was a sensation because it indicated a separate human species was living alongside us just 18,000 years ago. Flores has witnessed intensive paleontological investigation ever since.
The famous H. floresiensis cave is located in the west of the island. The new discoveries come from the Soa Basin, an area in central-west Flores.
A dig site there, known as Mata Menge, had already revealed tools dated to 880,000 years ago. Now, just 500m away but much deeper in the sediments, an international team has identified even older artefacts.
The site, referred to as Wolo Sege, has yielded more than 40 stone flakes.
These were hand tools, probably used to butcher meat among other tasks.
Many show evidence of being swept along in a stream before being laid down.
Critically, however, their burial is capped by a layer of volcanic ash that has been accurately dated to just over one million years ago.
The scientists can say nothing about who used these tools.
There is an insufficient number at this stage to assess which culture produced them.
But their mere discovery raises some interesting issues.
For example, the Mata Menge discoveries are associated with the disappearance in the deposition record of a number of animal species, such as a pygmy elephant and a giant tortoise.
The conclusion that had been drawn from their extinction was that human hunters arriving on the island had hunted them out of existence.
But the Wolo Sege findings put a new perspective on this story because they show humans must have been living side by side with the animals for at least 120,000 years.
Brumm and colleagues tell Nature that it may be difficult to find artefacts in the Soa Basin that are older than the Wolo Sege flakes. The reason is that the tools were lying just on top of what is the rock base in the area (the flank of a volcano).
“Anything inside that bedrock, or within any layers we identify in the bedrock, if they contain stone tools they must be at least 1.86 million years old,'' said Dr. Brumm.
The notion that Flores may have a very deep history of occupation will feed into the debate over H. floresiensis' origins.
Many scientists believe the creature evolved from a much larger-bodied species, Homo erectus, that became isolated and shrunk over time.
Others point to features in the hobbit's body — such as the length its feet to the shape of its shoulder girdle — that are very primitive and not what one would expect in dwarfed H. erectus.
These researchers have put forward the idea that H. floresiensis may have evolved from more archaic creatures that left Africa to colonise Asia even before erectus. “Our discovery at Wolo Sege will certainly open the door to this contentious theory," said Dr Brumm. — © BBC News/Distributed by the New York Times Syndicate
http://beta.thehindu.com/arts/history-and-culture/article258675.ece
(Submitted by Chad Arment)
Jonathan Amos
Long before a ‘hobbit' species of human lived on Indonesia's Flores island, other human-like creatures colonised the area.
That much was clear.
But scientists have now been able to date their presence to at least one million years ago — some 120,000 years earlier than previously recognised.
The team reports the discovery of these humans' tools in the journal Nature.
The group says the finds bring a new dimension to our understanding of the history of Flores.
Lead author Adam Brumm told BBC News that the location and circumstances of the tools' preservation meant human occupation of the island could extend deep into the past.
“What's really exciting about this is that we effectively have no idea how long hominids have been on Flores,'' said University of Wollongong, Australia.
The remains of the hobbit, known to science as Homo floresiensis, were discovered five years ago at Liang Bua cave.
The diminutive creature's unearthing was a sensation because it indicated a separate human species was living alongside us just 18,000 years ago. Flores has witnessed intensive paleontological investigation ever since.
The famous H. floresiensis cave is located in the west of the island. The new discoveries come from the Soa Basin, an area in central-west Flores.
A dig site there, known as Mata Menge, had already revealed tools dated to 880,000 years ago. Now, just 500m away but much deeper in the sediments, an international team has identified even older artefacts.
The site, referred to as Wolo Sege, has yielded more than 40 stone flakes.
These were hand tools, probably used to butcher meat among other tasks.
Many show evidence of being swept along in a stream before being laid down.
Critically, however, their burial is capped by a layer of volcanic ash that has been accurately dated to just over one million years ago.
The scientists can say nothing about who used these tools.
There is an insufficient number at this stage to assess which culture produced them.
But their mere discovery raises some interesting issues.
For example, the Mata Menge discoveries are associated with the disappearance in the deposition record of a number of animal species, such as a pygmy elephant and a giant tortoise.
The conclusion that had been drawn from their extinction was that human hunters arriving on the island had hunted them out of existence.
But the Wolo Sege findings put a new perspective on this story because they show humans must have been living side by side with the animals for at least 120,000 years.
Brumm and colleagues tell Nature that it may be difficult to find artefacts in the Soa Basin that are older than the Wolo Sege flakes. The reason is that the tools were lying just on top of what is the rock base in the area (the flank of a volcano).
“Anything inside that bedrock, or within any layers we identify in the bedrock, if they contain stone tools they must be at least 1.86 million years old,'' said Dr. Brumm.
The notion that Flores may have a very deep history of occupation will feed into the debate over H. floresiensis' origins.
Many scientists believe the creature evolved from a much larger-bodied species, Homo erectus, that became isolated and shrunk over time.
Others point to features in the hobbit's body — such as the length its feet to the shape of its shoulder girdle — that are very primitive and not what one would expect in dwarfed H. erectus.
These researchers have put forward the idea that H. floresiensis may have evolved from more archaic creatures that left Africa to colonise Asia even before erectus. “Our discovery at Wolo Sege will certainly open the door to this contentious theory," said Dr Brumm. — © BBC News/Distributed by the New York Times Syndicate
http://beta.thehindu.com/arts/history-and-culture/article258675.ece
(Submitted by Chad Arment)
Saturday, March 6, 2010
Dinosaur-eating snake discovered
Tuesday, 2 March 2010Scientists say they have identified the fossilised remains of a snake that dined on dinosaur eggs.
The 67-million-year-old skeleton was found in a dinosaur nest.
The study, published in the journal Plos Biology, is said to show the first direct evidence of feeding behaviour in a fossilised primitive snake.
This 3.5m fossil snake is believed to have fed on the hatchlings of sauropods, as it was found wrapped around a baby titanosaur.
Fully grown, the plant-eating titanosaurs weighed up to 100 tonnes. Many people have a fear of snakes and this research indicates that even giant dinosaurs may have been scared of them, too.
"It was such a thrill to discover such a portentous moment frozen in time," said Dr Dhananjay Mohabey from the Geological Survey of India, who unearthed the fossil.
Experts at the University of Michigan and University of Toronto Mississauga studied and identified the find.
Ancient gape
According to researchers, the fossil would have lacked the mobile jaws of modern snakes and would have struggled to eat dinosaur eggs. However, the hatchlings of these dinosaurs would have been just the right size.
The fossil was first uncovered in India in 1987 but it was not until 2001 that American scientists were able to detect that there was a snake among the dinosaur eggshells.
The researchers now believe that the snake was attacking a hatchling that had just emerged from the egg. The event was then overcome by a natural disaster, possibly a storm, and the whole scene was frozen in time.
The snake, one of the few animals that preyed on giant dinosaurs, has been named Sanajeh indicus, meaning "ancient gaped one from India" in Sanskrit.
http://news.bbc.co.uk/1/hi/sci/tech/8545450.stm
Mystery Behind Dinosaur Demise 'Revealed'
1:00pm UK, Friday March 05, 2010
Lulu Sinclair, Sky News Online
A massive asteroid was to blame for the demise of the dinosaur, and not a volcanic eruption, scientists have finally agreed.
The team of 41 international scientists came to their conclusion after analysing the past 20 years of research.
The mass extinction wiped out more than half of all species on the planet, including the dinosaurs and some large marine reptiles, the scientists decided.
They concluded the impact, that happened around 65 million years ago, cleared the way for mammals to become Earth's dominant species.
The 15-kilometre wide asteroid is believed to have hit the planet with a force one billion times more powerful than the atomic bomb at Hiroshima.
It resulted in the crater known as the Chicxulub crater buried underneath the Yucatan Peninsula.
The asteroid - about the size of the Isle of Wight - would have blasted material at high speed into the atmosphere.
That set off a chain of events that caused a global winter, wiping out much of life on Earth in a matter of days, the review says.
Scientists had previously argued about whether the so-called Cretaceous-Tertiary (KT)extinction was caused by the asteroid or by volcanic activity in India over 1.5 million years.
For the new study, scientists analysed 20 years of work by palaeontologists, geochemists, climate modellers, geophysicists and sedimentologists.
They concluded that geological records show the event that triggered the extinction destroyed marine and land ecosystems rapidly, meaning an asteroid impact was the only plausible explanation.
See videos at: http://news.sky.com/skynews/Home/World-News/Asteroid-To-Blame-For-Demise-Of-Dinosaurs-International-Science-Team-Decides/Article/201003115567004?f=rss
Lulu Sinclair, Sky News Online
A massive asteroid was to blame for the demise of the dinosaur, and not a volcanic eruption, scientists have finally agreed.
The team of 41 international scientists came to their conclusion after analysing the past 20 years of research.
The mass extinction wiped out more than half of all species on the planet, including the dinosaurs and some large marine reptiles, the scientists decided.
They concluded the impact, that happened around 65 million years ago, cleared the way for mammals to become Earth's dominant species.
The 15-kilometre wide asteroid is believed to have hit the planet with a force one billion times more powerful than the atomic bomb at Hiroshima.
It resulted in the crater known as the Chicxulub crater buried underneath the Yucatan Peninsula.
The asteroid - about the size of the Isle of Wight - would have blasted material at high speed into the atmosphere.
That set off a chain of events that caused a global winter, wiping out much of life on Earth in a matter of days, the review says.
Scientists had previously argued about whether the so-called Cretaceous-Tertiary (KT)extinction was caused by the asteroid or by volcanic activity in India over 1.5 million years.
For the new study, scientists analysed 20 years of work by palaeontologists, geochemists, climate modellers, geophysicists and sedimentologists.
They concluded that geological records show the event that triggered the extinction destroyed marine and land ecosystems rapidly, meaning an asteroid impact was the only plausible explanation.
See videos at: http://news.sky.com/skynews/Home/World-News/Asteroid-To-Blame-For-Demise-Of-Dinosaurs-International-Science-Team-Decides/Article/201003115567004?f=rss
Thursday, February 4, 2010
Close encounters with Japan's 'living fossil'
Thursday, 4 February 2010By Richard Black
Environment correspondent, BBC News
It soon becomes clear that the giant salamander has hit Claude Gascon's enthusiasm button smack on the nose.
"This is a dinosaur, this is amazing," he enthuses.
"We're talking about salamanders that usually fit in the palm of your hand. This one will chop your hand off."
As a leader of Conservation International's (CI) scientific programmes, and co-chair of the Amphibian Specialist Group with the International Union for the Conservation of Nature (IUCN), Dr Gascon has seen a fair few frogs and salamanders in his life; but little, he says, to compare with this.
Fortunately for all of our digits, this particular giant salamander is in no position to chop off anything, trapped in a tank in the visitors' centre in Maniwa City, about 800km west of Tokyo.
But impressive it certainly is: about 1.7m (5ft 6in) long, covered in a leathery skin that speaks of many decades passed, with a massive gnarled head covered in tubercles whose presumed sensitivity to motion probably helped it catch fish by the thousand over its lifetime.
If local legend is to be believed, though, this specimen is a mere tadpole compared with the biggest ever seen around Maniwa.
A 17th Century tale, related to us by cultural heritage officer Takashi Sakata, tells of a salamander (or hanzaki, in local parlance) 10m long that marauded its way across the countryside chomping cows and horses in its tracks.
A local hero was found, one Mitsui Hikoshiro, who allowed the hanzaki to swallow him whole along with his trusty sword - which implement he then used, in the best heroic tradition, to rend the beast from stem to stern.
It proved not to be such a good move, however.
Crops failed, people started dying in mysterious ways - including Mr Hikoshiro himself.
Pretty soon the villagers drew the obvious conclusion that the salamander's spirit was wreaking revenge from beyond the grave, and must be placated. That is why Maniwa City boasts a shrine to the hanzaki.
The story illustrates the cultural importance that this remarkable creature has in some parts of Japan.
Its scientific importance, meanwhile, lies in two main areas: its "living fossil" identity, and its apparently peaceful co-existence with the chytrid fungus that has devastated so many other amphibian species from Australia to the Andes.
Close family
"The skeleton of this species is almost identical to that of the fossil from 30 million years ago," recounts Takeyoshi Tochimoto, director of the Hanzaki Institute near Hyogo.
"Therefore it's called the 'living fossil'."
The hanzaki (Andrias japonicus) only has two close living relatives: the Chinese giant salamander (A. davidianus), which is close enough in size and shape and habits that the two can easily cross-breed, and the much smaller hellbender (Cryptobranchus alleganiensis) of the south-eastern US.
Creatures rather like these were certainly around when dinosaurs dominated life on land, and fossils of the family have been found much further afield than their current tight distribution - in northern Europe, certainly, where scientists presumed the the lineages had gone extinct until tales of the strange Oriental forms made their way back to the scientific burghers of Vienna and Leiden a couple of centuries ago.
"They are thought to be extremely primitive species, partly due to the fact that they are the only salamanders that have external fertilisation," says Don Church, a salamander specialist with CI.
The fertilisation ritual must be quite some sight.
Into a riverbank den that is usually occupied by the dominant male (the "den-master") swim several females, and also a few other males.
The den-master and the females release everything they have got, turning incessantly to stir the eggs and spermatozoa round in a roiling mass.
Maybe the lesser males sneak in a package or two as well; their function in the ménage-a-many is not completely clear.
When the waters still, everyone but the den-master leaves; and he alone guards the nest and its juvenile brood.
It is not an ideal method of reproduction.
Research shows that genetic diversity among the hanzaki is smaller than it might be, partly as a result of the repeated polygamy, which in turn leaves them more prone to damage through environmental change.
But for the moment, it seems to work.
Outside the breeding season, the salamander's life appears to consist of remaining as inconspicuous as possible in the river (whether hiding in leaves, as the small ones do, or under the riverbanks like their larger fellows) and snapping whatever comes within reach, their usual meandering torpor transformed in an instant as the smell of a fish brushes by.
The adults' jaws are not to be treated lightly.
Among Dr Tochimoto's extensive collection of photos is one of bloodied human hands; and as he warns: "you may be attacked and injured; please be careful".
When the chytrid fungus was identified just over a decade ago, indications were that Japan would be an unlikely place to look for its origins.
With the discovery of chytrid on museum specimens of the African clawed frog (Xenopus laevis), an out-of-Africa migration spurred by human transportation of amphibians once seemed the simple likelihood.
But just last year, a team of researchers led by Koichi Goka from Japan's National Institute for Environmental Studies published research showing that certain strains of chytrid were present on Japanese giant salamanders, and only on Japanese giant salamanders, including museum specimens from a century or so back; and that the relationship seemed benign.
The hanzaki-loving strains of chytrid appear to differ from those that are proving so virulent to amphibians now.
Unravelling all that, says Don Church, might tell us something about the origins and spread of chytrid - and there is so much diversity among Japanese chytrid strains that the country is now being touted as a possible origin, as diversity often implies a long evolutionary timeframe.
More importantly, the discovery might also provide options for treating the infection.
"In the case of the North American salamanders, what was found was that they have bacteria living on their skin that produce peptides that are lethal to the amphibian chytrid fungus," says Dr Church.
"And those bacteria might be able to be transplanted to other species that can't fight off the fungus."
This is a line of research that is very much in play in laboratories around the world.
It appears likely now that studies of the Japanese giant salamander can expand the number of chytrid-fighting bacteria known to science, and so extend the options for developing treatments for an infection that currently cannot be controlled in the wild.
But that can only come to pass if the giant salamanders endure; something that is not guaranteed, with the challenges they face in modern Japan including, perhaps, new strains of chytrid itself.
There is as yet no modern hero able to still the pace of habitat loss or prevent invasion from rival species.
Richard Black will examine threats to the Japanese giant salamander, and what is being done to combat those threats, in a second article.
See videos at: http://news.bbc.co.uk/1/hi/sci/tech/8497330.stm
(Submitted by Tim Chapman)
Wednesday, February 3, 2010
Aznalcóllar disaster compared with Cretaceous mass extinction
02 February 2010 Plataforma SINC
Researchers from the University of Granada (UGR) have compared the disaster caused by the Aznalcóllar spillage in the Doñana National Park in Andalusia 11 years ago with the biggest species extinction known to date. What do these two disasters have in common? The scientists say that carrying out comparisons of this kind will make it possible to find out how ecosystems recover following mass extinctions.
Until now, scientists used to study the fossil record in order to analyse how organisms responded to major environmental changes in the past, such as the mass extinction of species during the Cretaceous period (65 million years ago) and their subsequent recovery.
Now a team of scientists from the UGR has proposed a different methodology: "Another way of looking at this issue is to compare present day disasters that have also caused an abrupt ecological change, and which have therefore also had a major impact on organisms", Francisco Javier Rodríguez-Tovar, lead author of the study and a researcher at the UGR's Department of Stratigraphy and Palaeontology, tells SINC.
The study, published recently in the journal Geobiology, was based on "one of the worst environmental disasters to have happened in Spain over recent decades".
The pyrite mine at Aznalcóllar, in the Doñana National Park, burst on 25 April 1988, spilling four million cubic metres of acidic water and one million cubic metres of waste material containing high levels of toxic compounds, which affected more than 4,500 hectares of the rivers Agrio and Guadiamar and the land around them.
The researchers carried out a detailed analysis of how the pollution from Aznalcóllar evolved, and how the local plant and animal communities responded following the event, by studying the affected soil. "Comparing this with what happened 65 million years ago could help to better interpret this past event", explains Rodríguez-Tovar.
The similarities are obvious - sudden impact, high levels of toxic compounds, and the existence of a polluted layer covering the affected area. However, the scientist also points out some of the most significant differences, such as recovery following the impact, which was "much faster after the disaster at Aznalcóllar", and in terms of the area affected, which was "global for the Cretaceous- Tertiary boundary event", says Rodríguez-Tovar.
In search of signs of life
The scientists were able to carry out a range of experiments on the layers of mud that have not been removed from Doñana. Geochemical analysis showed that "there is still significant contamination, with high concentrations of toxic elements, and high acidity levels", stresses the palaeontologist. However, less than 10 years after the disaster, the scientists could identify trails and nests made by Tapinoma nigérrima, an aggressive and opportunistic species of ant. "We even found this ant's larvae just below the layer of highly- contaminated mud", explains the expert.
This ant's opportunism, aggressiveness and high levels of independence were compared with the organism that created Chondrites, a trace fossil that scientists have recorded near the red layer associated with the Chixulub crater in Mexico, generated by the impact of the meteorite that caused the Cretaceous-Tertiary extinction. Previous ichnological studies (on trace fossils) have shown that "the Chondrites-generati ng organism was able to inhabit the substrate immediately after the event, due to its opportunistic and independent nature", says Rodríguez-Tovar.
Using the data on trace fossils and on comparisons with present day disasters, the scientists were able to prove that "the community started to recover fairly rapidly following the mass extinction caused by the impact 65 million years ago, possibly within hundreds or thousands of years", concludes the palaeontologist.
http://plataformasinc.es/index.php/esl/Noticias/Comparan-el-desastre-de-Aznalcollar-con-la-extincion-masiva-del-Cretacico
(Submitted by Tim Chapman)
Researchers from the University of Granada (UGR) have compared the disaster caused by the Aznalcóllar spillage in the Doñana National Park in Andalusia 11 years ago with the biggest species extinction known to date. What do these two disasters have in common? The scientists say that carrying out comparisons of this kind will make it possible to find out how ecosystems recover following mass extinctions.
Until now, scientists used to study the fossil record in order to analyse how organisms responded to major environmental changes in the past, such as the mass extinction of species during the Cretaceous period (65 million years ago) and their subsequent recovery.
Now a team of scientists from the UGR has proposed a different methodology: "Another way of looking at this issue is to compare present day disasters that have also caused an abrupt ecological change, and which have therefore also had a major impact on organisms", Francisco Javier Rodríguez-Tovar, lead author of the study and a researcher at the UGR's Department of Stratigraphy and Palaeontology, tells SINC.
The study, published recently in the journal Geobiology, was based on "one of the worst environmental disasters to have happened in Spain over recent decades".
The pyrite mine at Aznalcóllar, in the Doñana National Park, burst on 25 April 1988, spilling four million cubic metres of acidic water and one million cubic metres of waste material containing high levels of toxic compounds, which affected more than 4,500 hectares of the rivers Agrio and Guadiamar and the land around them.
The researchers carried out a detailed analysis of how the pollution from Aznalcóllar evolved, and how the local plant and animal communities responded following the event, by studying the affected soil. "Comparing this with what happened 65 million years ago could help to better interpret this past event", explains Rodríguez-Tovar.
The similarities are obvious - sudden impact, high levels of toxic compounds, and the existence of a polluted layer covering the affected area. However, the scientist also points out some of the most significant differences, such as recovery following the impact, which was "much faster after the disaster at Aznalcóllar", and in terms of the area affected, which was "global for the Cretaceous- Tertiary boundary event", says Rodríguez-Tovar.
In search of signs of life
The scientists were able to carry out a range of experiments on the layers of mud that have not been removed from Doñana. Geochemical analysis showed that "there is still significant contamination, with high concentrations of toxic elements, and high acidity levels", stresses the palaeontologist. However, less than 10 years after the disaster, the scientists could identify trails and nests made by Tapinoma nigérrima, an aggressive and opportunistic species of ant. "We even found this ant's larvae just below the layer of highly- contaminated mud", explains the expert.
This ant's opportunism, aggressiveness and high levels of independence were compared with the organism that created Chondrites, a trace fossil that scientists have recorded near the red layer associated with the Chixulub crater in Mexico, generated by the impact of the meteorite that caused the Cretaceous-Tertiary extinction. Previous ichnological studies (on trace fossils) have shown that "the Chondrites-generati ng organism was able to inhabit the substrate immediately after the event, due to its opportunistic and independent nature", says Rodríguez-Tovar.
Using the data on trace fossils and on comparisons with present day disasters, the scientists were able to prove that "the community started to recover fairly rapidly following the mass extinction caused by the impact 65 million years ago, possibly within hundreds or thousands of years", concludes the palaeontologist.
http://plataformasinc.es/index.php/esl/Noticias/Comparan-el-desastre-de-Aznalcollar-con-la-extincion-masiva-del-Cretacico
(Submitted by Tim Chapman)
New Research Rejects 80-Year Theory of 'Primordial Soup' as the Origin of Life
ScienceDaily (Feb. 3, 2010) — For 80 years it has been accepted that early life began in a 'primordial soup' of organic molecules before evolving out of the oceans millions of years later. Today the 'soup' theory has been over turned in a pioneering paper in BioEssays which claims it was the Earth's chemical energy, from hydrothermal vents on the ocean floor, which kick-started early life.
"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent -- one that is riddled with tiny interconnected compartments or pores."
The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.
"Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life," said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."
In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides which may have given rise to the first true cells.
The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today -- a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.
"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation -- positive outside and negative inside -- as the inorganic vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.
"Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."
This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved -- and they could not have evolved without it," said Martin.
"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis," concluded Lane. "It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' -- an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."
http://www.sciencedaily.com/releases/2010/02/100202101245.htm
(Submitted by Tim Chapman)
"Textbooks have it that life arose from organic soup and that the first cells grew by fermenting these organics to generate energy in the form of ATP. We provide a new perspective on why that old and familiar view won't work at all," said team leader Dr Nick lane from University College London. "We present the alternative that life arose from gases (H2, CO2, N2, and H2S) and that the energy for first life came from harnessing geochemical gradients created by mother Earth at a special kind of deep-sea hydrothermal vent -- one that is riddled with tiny interconnected compartments or pores."
The soup theory was proposed in 1929 when J.B.S Haldane published his influential essay on the origin of life in which he argued that UV radiation provided the energy to convert methane, ammonia and water into the first organic compounds in the oceans of the early earth. However critics of the soup theory point out that there is no sustained driving force to make anything react; and without an energy source, life as we know it can't exist.
"Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life," said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. "But soup has no capacity for producing the energy vital for life."
In rejecting the soup theory the team turned to the Earth's chemistry to identify the energy source which could power the first primitive predecessors of living organisms: geochemical gradients across a honeycomb of microscopic natural caverns at hydrothermal vents. These catalytic cells generated lipids, proteins and nucleotides which may have given rise to the first true cells.
The team focused on ideas pioneered by geochemist Michael J. Russell, on alkaline deep sea vents, which produce chemical gradients very similar to those used by almost all living organisms today -- a gradient of protons over a membrane. Early organisms likely exploited these gradients through a process called chemiosmosis, in which the proton gradient is used to drive synthesis of the universal energy currency, ATP, or simpler equivalents. Later on cells evolved to generate their own proton gradient by way of electron transfer from a donor to an acceptor. The team argue that the first donor was hydrogen and the first acceptor was CO2.
"Modern living cells have inherited the same size of proton gradient, and, crucially, the same orientation -- positive outside and negative inside -- as the inorganic vesicles from which they arose" said co-author John Allen, a biochemist at Queen Mary, University of London.
"Thermodynamic constraints mean that chemiosmosis is strictly necessary for carbon and energy metabolism in all organisms that grow from simple chemical ingredients [autotrophy] today, and presumably the first free-living cells," said Lane. "Here we consider how the earliest cells might have harnessed a geochemically created force and then learned to make their own."
This was a vital transition, as chemiosmosis is the only mechanism by which organisms could escape from the vents. "The reason that all organisms are chemiosmotic today is simply that they inherited it from the very time and place that the first cells evolved -- and they could not have evolved without it," said Martin.
"Far from being too complex to have powered early life, it is nearly impossible to see how life could have begun without chemiosmosis," concluded Lane. "It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' -- an idea that dates back to a time before anybody in biology had any understanding of how ATP is made."
http://www.sciencedaily.com/releases/2010/02/100202101245.htm
(Submitted by Tim Chapman)
Tuesday, February 2, 2010
Polish scientists say 3 Neanderthal teeth found
By VANESSA GERA, Associated Press Writer Vanessa Gera, Associated Press Writer – Mon Feb 1, 2:54 pm ET
WARSAW, Poland – A team of Polish scientists said Monday they have discovered three Neanderthal teeth in a cave, a find they hope may shed light on how similar to modern humans our ancestors were.
Neanderthal artifacts have been unearthed in Poland before. But the teeth are the first bodily Neanderthal remains found in the country, according to Mikolaj Urbanowski, an archaeologist with Szczecin University and the project's lead researcher.
Urbanowski said the teeth were unearthed in the Stajnia Cave, north of the Carpathian Mountains, along with flint tools and the bones of the woolly mammoth and the woolly rhinoceros, both extinct Ice Age species.
The researchers also found a hammer made of reindeer antler and bones of cave bears bearing cut marks, indicating they were eaten by the Neanderthals, Urbanowski said.
"The cave bears were big, dangerous animals and this supports the view the Neanderthals were really efficient hunters," he said.
The findings were reported by the German science journal Naturwissenschaften in an online article dated Jan. 28.
The article focused mainly on one of teeth, providing evidence for the claim that it is the molar of a Neanderthal who died around age 20.
Urbanowski said that tooth has undergone the most analysis but the team is nearly certain the other two also belonged to Neanderthals who lived 100,000 to 80,000 years ago.
The placement of the teeth along with flint tools has led the team to hypothesize that the site could have been some kind of primitive burial site, which would point to a belief in the afterlife.
Jeffrey Schwartz, a professor of physical anthropology with the University of Pittsburgh, said the find is significant because it establishes that Neanderthals lived in a region where so far little evidence has been found. However, he said there is not enough evidence at this point to draw any conclusions about a possible burial site.
"No one ceremoniously buries one human tooth," said Schwartz, who was not involved in the research, but reviewed an early version of the paper.
http://news.yahoo.com/s/ap/20100201/ap_on_re_eu/eu_poland_neanderthal_teeth
(Submitted by Ben Blake)
WARSAW, Poland – A team of Polish scientists said Monday they have discovered three Neanderthal teeth in a cave, a find they hope may shed light on how similar to modern humans our ancestors were.
Neanderthal artifacts have been unearthed in Poland before. But the teeth are the first bodily Neanderthal remains found in the country, according to Mikolaj Urbanowski, an archaeologist with Szczecin University and the project's lead researcher.
Urbanowski said the teeth were unearthed in the Stajnia Cave, north of the Carpathian Mountains, along with flint tools and the bones of the woolly mammoth and the woolly rhinoceros, both extinct Ice Age species.
The researchers also found a hammer made of reindeer antler and bones of cave bears bearing cut marks, indicating they were eaten by the Neanderthals, Urbanowski said.
"The cave bears were big, dangerous animals and this supports the view the Neanderthals were really efficient hunters," he said.
The findings were reported by the German science journal Naturwissenschaften in an online article dated Jan. 28.
The article focused mainly on one of teeth, providing evidence for the claim that it is the molar of a Neanderthal who died around age 20.
Urbanowski said that tooth has undergone the most analysis but the team is nearly certain the other two also belonged to Neanderthals who lived 100,000 to 80,000 years ago.
The placement of the teeth along with flint tools has led the team to hypothesize that the site could have been some kind of primitive burial site, which would point to a belief in the afterlife.
Jeffrey Schwartz, a professor of physical anthropology with the University of Pittsburgh, said the find is significant because it establishes that Neanderthals lived in a region where so far little evidence has been found. However, he said there is not enough evidence at this point to draw any conclusions about a possible burial site.
"No one ceremoniously buries one human tooth," said Schwartz, who was not involved in the research, but reviewed an early version of the paper.
http://news.yahoo.com/s/ap/20100201/ap_on_re_eu/eu_poland_neanderthal_teeth
(Submitted by Ben Blake)
Saturday, January 9, 2010
Neanderthal 'make-up' discovered
Saturday, 9 January 2010
Scientists claim to have the first persuasive evidence that Neanderthals wore "body paint" 50,000 years ago.
The team report in Proceedings of the National Academy of Sciences (PNAS) that shells containing pigment residues were Neanderthal make-up containers.
Scientists unearthed the shells at two archaeological sites in the Murcia province of southern Spain.
The team says its find buries "the view of Neanderthals as half-wits" and shows they were capable of symbolic thinking.
Professor Joao Zilhao, the archaeologist from Bristol University in the UK, who led the study, said that he and his team had examined shells that were used as containers to mix and store pigments.
Black sticks of the pigment manganese, which may have been used as body paint by Neanderthals, have previously been discovered in Africa.
"[But] this is the first secure evidence for their use of cosmetics," he told BBC News. "The use of these complex recipes is new. It's more than body painting."
The scientists found lumps of a yellow pigment, that they say was possibly used as a foundation.
They also found red powder mixed up with flecks of a reflective brilliant black mineral.
Some of the sculpted, brightly coloured shells may also have been worn by Neanderthals as jewellery.
Until now it had been thought by many researchers that only modern humans wore make-up for decoration and ritual purposes.
There was a time in the Upper Palaeolithic period when Neanderthals and humans may have co-existed. But Professor Zilhao explained that the findings were dated at 10,000 years before this "contact".
"To me, it's the smoking gun that kills the argument once and for all," he told BBC News.
"The association of these findings with Neanderthals is rock-solid and people have to draw the associations and bury this view of Neanderthals as half-wits."
Professor Chris Stringer, a palaeontologist from the Natural History Museum in London, UK, said: "I agree that these findings help to disprove the view that Neanderthals were dim-witted.
But, he added that evidence to that effect had been growing for at least the last decade.
"It's very difficult to dislodge the brutish image from popular thinking," Professor Stringer told BBC News. "When football fans behave badly, or politicians advocate reactionary views, they are invariably called 'Neanderthal', and I can't see the tabloids changing their headlines any time soon."
Hybrid boy?
Another study published in the same issue of PNAS provides intriguing evidence about the relationship between humans and Neanderthals.
An international team of researchers examined teeth from the skeleton of a human child that was discovered in Portugal in the late 1990s.
It was suggested by some scientists at the time that this skeleton, which dates from the Upper Palaeolithic period - between 10,000 and 40,000 years ago - might have been the product of human and Neanderthal interbreeding.
The researchers found that the skeleton's teeth shared some features with Neanderthals rather than modern humans.
Although this does not settle the argument of whether the child was a hybrid, it does indicate, the researchers write, that "these earlier Upper Palaeolithic humans are not simply older versions of [today's] humanity".
http://news.bbc.co.uk/1/hi/sci/tech/8448660.stm
(Submitted by D.R. Shoop)
Scientists claim to have the first persuasive evidence that Neanderthals wore "body paint" 50,000 years ago.
The team report in Proceedings of the National Academy of Sciences (PNAS) that shells containing pigment residues were Neanderthal make-up containers.
Scientists unearthed the shells at two archaeological sites in the Murcia province of southern Spain.
The team says its find buries "the view of Neanderthals as half-wits" and shows they were capable of symbolic thinking.
Professor Joao Zilhao, the archaeologist from Bristol University in the UK, who led the study, said that he and his team had examined shells that were used as containers to mix and store pigments.
Black sticks of the pigment manganese, which may have been used as body paint by Neanderthals, have previously been discovered in Africa.
"[But] this is the first secure evidence for their use of cosmetics," he told BBC News. "The use of these complex recipes is new. It's more than body painting."
The scientists found lumps of a yellow pigment, that they say was possibly used as a foundation.
They also found red powder mixed up with flecks of a reflective brilliant black mineral.
Some of the sculpted, brightly coloured shells may also have been worn by Neanderthals as jewellery.
Until now it had been thought by many researchers that only modern humans wore make-up for decoration and ritual purposes.
There was a time in the Upper Palaeolithic period when Neanderthals and humans may have co-existed. But Professor Zilhao explained that the findings were dated at 10,000 years before this "contact".
"To me, it's the smoking gun that kills the argument once and for all," he told BBC News.
"The association of these findings with Neanderthals is rock-solid and people have to draw the associations and bury this view of Neanderthals as half-wits."
Professor Chris Stringer, a palaeontologist from the Natural History Museum in London, UK, said: "I agree that these findings help to disprove the view that Neanderthals were dim-witted.
But, he added that evidence to that effect had been growing for at least the last decade.
"It's very difficult to dislodge the brutish image from popular thinking," Professor Stringer told BBC News. "When football fans behave badly, or politicians advocate reactionary views, they are invariably called 'Neanderthal', and I can't see the tabloids changing their headlines any time soon."
Hybrid boy?
Another study published in the same issue of PNAS provides intriguing evidence about the relationship between humans and Neanderthals.
An international team of researchers examined teeth from the skeleton of a human child that was discovered in Portugal in the late 1990s.
It was suggested by some scientists at the time that this skeleton, which dates from the Upper Palaeolithic period - between 10,000 and 40,000 years ago - might have been the product of human and Neanderthal interbreeding.
The researchers found that the skeleton's teeth shared some features with Neanderthals rather than modern humans.
Although this does not settle the argument of whether the child was a hybrid, it does indicate, the researchers write, that "these earlier Upper Palaeolithic humans are not simply older versions of [today's] humanity".
http://news.bbc.co.uk/1/hi/sci/tech/8448660.stm
(Submitted by D.R. Shoop)
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