Researchers working in the swamplands of Myanmar have discovered several fossilized teeth from a new species of primate that lived 37 million years ago. If this turns out to be for real, their findings could rewrite the book on the evolutionary origins of monkeys, apes — and even humans.
The discovery was made by an international team of scientists led by paleontologist Jean-Jacques Jaeger. It took Jaeger and his colleagues six years to collect the popcorn-kernel-sized molars; and while the team has only found four teeth so far, the specimens are already shedding considerable light on a number of hotly debated subjects, namely: the origins and evolution of so-called anthropoid primates (aka higher primates) — the ancestors of all monkeys, apes and humans.
Jaeger and his team believe the teeth came from a previously undiscovered species of anthropoid, which they've since named Afrasia djijidae. Afrasia now joins a growing body of evidence that suggests anthropoids arose in Asia 37-45 million years ago, before colonizing Africa. But these four molars have offered the researchers something two decades of other discoveries in Asia have not: unprecedented insight into the murky story of anthropoid migration.
Until now, writes Science Magazine's Ann Gibbons, paleontologists have lacked the fossils to show when and how these anthropoids trekked from Asia to Africa. But these four molars "were enough to show [Jaeger's team] that Afrasia was closely related to another primitive anthropoid that lived at about the same time, but in Africa — Afrotarsius libycus from Libya." Gibbons continues:
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... 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.
On closer examination, however, the team noticed that the new molars from the Asian Afrasia were more primitive than those of Afrotarsius from Libya, particularly in the larger size of a tiny bulge at the back of its last lower molar. These primitive traits, as well as the greater diversity and age of early, or "stem," anthropoids in Asia rather than Africa suggest that this group arose in Asia and migrated to Africa 37 million to 39 million years ago. "Anthropoids didn't arrive in Africa until right before we find their fossils in Libya," says Jaeger.
"We've all heard about Out-of-Africa for human origins," adds vertebrate paleontologist K. Christopher Beard, a co-author on the paper describing the team's findings. "Now we think there was an Out-of-Asia migration into Africa first."