Human ancestors originated in Asia, not Africa, says study

WASHINGTON: The earliest ancestors of modern human may have originated in Asia and not Africa as widely believed, according to a new study based on fossil discovery in Myanmar.

Previous fossil finds have long suggested that Africa was the cradle for anthropoids, which include monkeys, apes and humans. Now, an international team in Myanmar has found the tooth of a pre-human ancestor which may prove that anthropoids originated in Asia.

The findings, published in the journal Proceedings of the National Academy of Sciences, could shed light on a pivotal step in primate and human evolution, the researchers said.

The four teeth of the prehistoric human — called afrasia djijidae as it forms a missing link between Africa and Asia — were recovered after six years of hard work. They date back to 37 million years and resemble those of another anthropoid, the 38-million-year-old Afrotarsius libycus, recently found in the Sahara Desert of Libya, LiveScience reported.

The anthropoids in Libya were far more diverse at that early time in Africa than scientists had thought, suggesting they actually originated elsewhere.

And the close similarity between Afrasia and Afrotarsius now suggests that early anthropoids colonised Africa from Asia, the team said.

This migration from Asia ultimately helps set the stage for the later evolution of apes and humans in Africa. "Africa is the place of origin of man, and Asia is the place of origins of our far ancestors," researcher Jean-Jacques Jaeger, a palaeontologist at University of Poitiers in France, said.

However, the researchers said that it remained an open question how early anthropoids actually migrated from Asia to Africa. Back then, the two continents were separated by a more extensive version of the modern Mediterranean Sea, called the Tethys Sea.

Early anthropoids, the team believes, may have either swum from island to island from Asia to Africa, or possibly have been carried on naturally occurring rafts of logs and other material washed out to sea by floods and storms.

"Around 34 million years ago, there was a dramatic glacial event that cooled the world climate and affected Asia more than Africa.

"During that crisis, we suppose that all primitive Asian anthropoids disappeared," Jaeger said.

The anthropoids we see in Asia now, such as gibbons and orangutans, "immigrated from Africa some 20 million years ago," Jaeger added. 

http://www.thehindu.com/sci-tech/article3497505.ece