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Ancient DNA traces the woolly mammoth's disappearance
June 08, 2007Some ancient-DNA evidence has offered new clues to a very cold case: the disappearance of the last woolly mammoths, one of the most iconic of all Ice Age giants, according to a June 7th report published online in Current Biology, a publication of Cell Press.
DNA lifted from the bones, teeth, and tusks of the extinct mammoths revealed a "genetic signature" of a range expansion after the last interglacial period. After the mammoths' migration, the population apparently leveled off, and one of two lineages died out.
"In combination with the results on other species, a picture is emerging of extinction not as a sudden event at the end of the last ice age, but as a piecemeal process over tens of thousands of years involving progressive loss of genetic diversity," said Dr. Ian Barnes, of Royal Holloway, University of London. "For the mammoth, this seems much more likely to have been driven by environmental rather than human causes, even if humans might have been responsible for killing off the small, terminal populations that were left."
Barnes, along with Dr. Adrian Lister of the University College London and the Natural History Museum in London and others, had earlier found evidence that bison, bears, and lions underwent major population shifts twenty-five to fifty thousand years ago. Those results came as a surprise, the researchers said, because scientists tended to think that the major environmental changes happened about fifteen to twenty-five thousand years ago, when the glaciers reached their fullest extent. The findings also offered early human hunters a potential alibi; they didn't come on the scene in large numbers until even later.
In search of a general pattern in the new study, Barnes and Lister's team looked to the extinct woolly mammoth. What they found, however, was an "interesting pattern, not like those of the other species."
Their genetic data indicate that Siberian mammoths expanded from a small base some time before sixty thousand years ago. Moreover, they found two distinct genetic groups, implying that mammoths had diverged in isolation for some time before merging back into a single population. The DNA further suggests that no later than forty thousand years ago, one of the groups died out, leaving only the second alive at the time of the mammoth's last gasp.
"At a time when we should be very concerned about the potential extinction of many existing large mammals, studying those that occurred in the geologically recent past can provide many insights," Lister said. "Our work, together with that of others, shows that the conditions for extinction can be set up long before the actual extinction event."
Cell Press
Barnes, along with Dr. Adrian Lister of the University College London and the Natural History Museum in London and others, had earlier found evidence that bison, bears, and lions underwent major population shifts twenty-five to fifty thousand years ago. Those results came as a surprise, the researchers said, because scientists tended to think that the major environmental changes happened about fifteen to twenty-five thousand years ago, when the glaciers reached their fullest extent. The findings also offered early human hunters a potential alibi; they didn't come on the scene in large numbers until even later.
In search of a general pattern in the new study, Barnes and Lister's team looked to the extinct woolly mammoth. What they found, however, was an "interesting pattern, not like those of the other species."
Their genetic data indicate that Siberian mammoths expanded from a small base some time before sixty thousand years ago. Moreover, they found two distinct genetic groups, implying that mammoths had diverged in isolation for some time before merging back into a single population. The DNA further suggests that no later than forty thousand years ago, one of the groups died out, leaving only the second alive at the time of the mammoth's last gasp.
"At a time when we should be very concerned about the potential extinction of many existing large mammals, studying those that occurred in the geologically recent past can provide many insights," Lister said. "Our work, together with that of others, shows that the conditions for extinction can be set up long before the actual extinction event."
Cell Press
Woolly Mammoth Current Events and Woolly Mammoth News RSSWoolly-Mammoth Gene Study Changes Extinction Theory
A large genetic study of the extinct woolly mammoth has revealed that the species was not one large homogenous group, as scientists previously had assumed, and that it did not have much genetic diversity.
Back to the future: Mastodon extends the time limit on DNA sequencing
In a new paper in the open access journal PLoS Biology, Michael Hofreiter from the Max Planck Institute for Evolutionary Anthropology in Germany, and colleagues from Switzerland and the United States, announce the sequencing of the complete mitochondrial genome of the mastodon (Mammut americanum), a recently extinct relative of the living elephants that diverged about 26 million years ago.
Woolly mammoth genome comes to life
A McMaster University geneticist, in collaboration with genome researchers from Penn State University and the American Museum of Natural History has made history by mapping a portion of the woolly mammoth's genome.
Scientists sequence DNA of woolly mammoth
Experts in ancient DNA from McMaster University (Canada) have teamed up with genome researchers from Penn State University (USA) for the investigation of permafrost bone samples from Siberia.
Small species back-up giant marsupial climate change extinction claim
Thinking small in a time when everything was big has helped Queensland researchers to unearth new evidence that climate change, instead of humans, was responsible for wiping out Australian giant marsupials or megafauna 40,000 years ago.
Old bones unearth new date for giant deer's last stand
A new investigation into extinctions caused by climate change has revealed that the giant deer, previously thought to have been wiped out by a cold spell 10,500 years ago, instead survived well into the modern era.
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