for National Geographic News
The tooth of a mastodon buried beneath Alaska's permafrost for many thousands of years is yielding surprising clues about the history of elephants—and humans.
A team of researchers recently extracted DNA from the tooth to put together the first complete mastodon mitochondrial genome.
The study, published in the journal PLoS Biology, significantly alters the evolutionary timeline for elephants and their relatives.
Comparing the new genome with that of other animals in the elephant family also provides evidence that the elephant family diverged on roughly the same timeline that primates separated, suggesting there may have been a common cause for the splits.
"I think the divergence is the most interesting thing from this study," said lead author Michael Hofreiter, an evolutionary biologist at the Max Plank Institute for Evolutionary Anthropology in Leipzig, Germany.
Reason to Evolve
According to Hofreiter's research, African elephants diverged from mastodons about 7.6 million years ago, about the same time gorillas split from the line that gave rise to humans and chimpanzees.
Mammoths and Asian elephants speciated around 6.7 million years ago, roughly the same time humans and chimps split.
Alfred Roca is a geneticist at the Laboratory of Genomic Diversity in Frederick, Maryland, part of the U.S. National Cancer Institute. He was not involved in the new research.
He called Hofreiter's work "outstanding," noting that the research pushes the previously believed dates for the divergence of elephants by several million years.
He added that several groups of modern animals—not just elephants and humans—went through significant change during that time, the late Miocene period. (Related: "Mastodons Driven to Extinction by Tuberculosis, Fossils Suggest" [October 3, 2006].)
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