'Mother Lode' Fossils In China Show That Primates Shifted Completely From Asia To Africa

The "mother lode" of primate fossils was discovered in southern China by University of Kansas researchers. Recording the impact of ancient climate change on the six new species, they noted that the fossils originated approximately 34 million years ago, just after the Eocene-Oligocene transition. A huge global cooling had made the continent inconducive to primates, thus reducing their population.

"At the Eocene-Oligocene boundary, because of the rearrangement of Earth's major tectonic plates, you had a rapid drop in temperature and humidity," said K. Christopher Beard of the University of Kansas and co-author of the study. "Primates like it warm and wet, so they faced hard times around the world - to the extent that they went extinct in North America and Europe."

"Of course, primates somehow survived in Africa and Southern Asia, because we're still around to talk about it," he added.

Though earlier evidence indicated the earliest anthropods, ie monkeys, apes and humans, as originating in Asia, it was not clear why they landed in Africa. However, it is now evident that severe climate change had erased Asian anthropods, so that the only place left for evolution was Africa.

The study was due to a decade of fieldwork by scientists at southern China. This was a region to which the primates emigrated when it was warmer. The jaw and tooth segments of the fossils lasted because of the tough enamel surfaces.

"The fossil record usually gives you a snapshot here or there of what ancient life was like," Beard said. "You typically don't get a movie."

"We have so many primates from the Oligocene at this particular site because it was located far enough to the south that it remained warm enough during that cold, dry time that primates could still survive there," he continued. "They crowded into the limited space that remained available to them."

Scientists are clear that without the intense global cooling of the Eocene-Oligocene era, the primates would have continued to live in Asia instead of shifting to Africa and evolving into humans.

Hence, primates were vulnerable to climate change even millions of years ago.

"This is the flip side of what people are worried about now," Beard said. "The Eocene-Oligocene transition was the opposite of global warming - the whole world was already warm, then it cooled off. It's kind of a mirror image. The point is that primates then, just like primates today, are more sensitive to a changing climate than other mammals."

The findings were published in the May 6 issue of the journal Science.