An Asian Origin for Human Ancestors?
By ANN GIBBONS - SCIENCE
Added: Mon, 04 Jun 2012 23:56:55 UTC
Thanks to Hans for the link
Researchers agree that our immediate ancestors, the upright walking apes, arose in Africa. But the discovery of a new primate that lived about 37 million years ago in the ancient swamplands of Myanmar bolsters the idea that the deep primate family tree that gave rise to humans is rooted in Asia. If true, the discovery suggests that the ancestors of all monkeys, apes, and humans—known as the anthropoids—arose in Asia and made the arduous journey to the island continent of Africa almost 40 million years ago.
Until 18 years ago, fossils of every suspected early anthropoid were found in Egypt and dated to about 30 million years ago. Then, starting in the 1990s, researchers began discovering the remains of petite primates that lived 37 million to 45 million years ago in China, Myanmar, and other Asian nations. This suggested that anthropoids may have actually arisen in Asia and then migrated to Africa a few million years later. But paleontologists have lacked the fossils to show when and how these anthropoids trekked from Asia to Africa, says paleontologist K. Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.
In 2005, Beard and an international team of researchers sifting fossils of early fish, turtle, and ancestral hippo teeth from fossil beds near the village of Nyaungpinle in Myanmar found a molar the size of a kernel of popcorn. The tooth, dated to about 38 million years ago, belonged to a new species of ancient primate, which would have been the size of a small chipmunk. After several more years of arduous fieldwork, the team has collected just four molars of this primitive anthropoid, which they named Afrasia djijidae. "It's a difficult place to work; it took us 6 years to find four teeth," says Beard.
The four molars were enough to show Beard and team leader Jean-Jacques Jaeger of the University of Poitiers in France that Afrasia was closely related to another primitive anthropoid that lived at about the same time, but in Africa—Afrotarsius libycus from Libya. When the researchers examined the teeth from the two primates under a microscope, they were so similar in size, shape, and age that they could have belonged to the same species of primate, says Beard. Such close resemblance between an Asian and African fossil anthropoid has "never been demonstrated previously," the authors write online today in the Proceedings of the National Academy of Sciences.
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