Evolutionary scientists accept the theory that humans first evolved from primates in Africa, and hundreds of unearthed fossils support this idea.

However, there are still gaps in the gigantic puzzle that is the Asia-Africa human evolution. For instance, how did the transition occur between species in Asia and in Africa? Were prehistoric ancestors automatically "residents" of Africa?

Now, newly discovered fossils in China strengthen the case that primates first emerged in Asia millions of years ago. But what happened? Scientists say the effects of a changing climate got in the way.

Had there been no extensive global cooling — which was a climate event that helped alter the course of history — human evolution could have continued in Asia instead of transitioning to Africa, experts say.

The Extinction Of Primate Species

The six newly found primate species were forms of extinct animals that had been identified from jaw and tooth fragments, researchers say.

These primate species were estimated to have roamed the Earth 34 million years ago, or during the transition between the Eocene and Oligocene eras.

Unfortunately, as climate all over the world rapidly transformed and became cooler, several regions became uninhabitable for these primates, which liked environments that were warm and wet.

K. Christopher Beard, co-author of the report and senior curator at the Biodiversity Institute at University of Kansas, says primates became extinct in Europe and North America, but not all of them. Several primates survived in Southern Asia and Africa.

"An Enigma"

Anthropoid primates — the ancestors of modern apes, monkeys and humans — had first appeared in Asia.

Beard says understanding the arc of early primate and human evolution in Asia has always been an enigma.

The ancient primates in Asia were tropical tree-dwellers. One of the newfound species was somehow incredibly similar to a species in the Philippines and Indonesia known as the tarsier.

At some point, the evolution of primates shifted from Asia to Africa, but Beard says that was something they never understood until now.

The climate crisis during the Eocene and Oligocene transition ultimately wiped out anthropoids in Asia.

The surviving species could only move to Africa in order to evolve into apes, monkeys and humans. When they arrived in Africa, they began to spread. This resulted in the birth of new species.

Implications Of The Findings

The study, which is featured in the journal Science, emphasizes the vulnerability of primates to climate change.

Although the Eocene-Oligocene was the opposite of global warming, it was kind of a mirror image, says Beard.

"This is the flip side of what people are worried about now," adds Beard.

Photo: Roberto Verzo | Flickr