A new paper suggests that instead of some primates evolving in Africa and spreading out from there, they colonized it, likely from Asia.   The search for data regarding the origins of man's earliest anthropoid ancestors is obviously one of the most hotly pursued subjects in paleontology.

Anthropoids are the primate group that includes humans, apes, and monkeys and it has been widely accepted that they evolved in Africa but a team of paleontologists say new fossils discovered at the Dur At-Talah escarpment in central Libya presents the case that the diversity of species present, three distinct families of anthropoid primates that lived in North Africa at approximately the same time, means that anthropoids underwent diversification, through evolution, previous to the time of these newly discovered fossils, which date to 39 million years ago.

The sudden appearance in the African fossil record of diverse anthropoid families can be answered in one of two ways, the paper's authors say. It could be the result of a gap in the African fossil record prior to this period, though they state that is unlikely as Northern Africa's Eocene sites have been well sampled over the past century and no diversity of anthropoid fossils has yet been discovered that predates the new Libyan specimens or, the paleontologists suggest, several anthropoid species 'colonized' Africa from another continent 39 million years ago, the middle of the Eocene epoch.

Since diversification would have occurred over extreme lengths of time, and likely leave fossil evidence, the new fossils combined with previous sampling in North Africa leads the paper's authors to surmise an Asian origin for anthropoids. 

An international team of paleontologists  suggests that anthropoids,the primate group which includes humans, apes, and monkeys, migrated into Africa rather than originally evolving in Africa as has been widely accepted.  They say the new fossil discoveries suggest that anthropoids underwent diversification, through evolution, prior to the time of these newly discovered fossils, which date to 39 million years ago.   Photo: Mark A. Klingler/Carnegie Museum of Natural History, Pittsburgh, Pa.

"If our ideas are correct, this early colonization of Africa by anthropoids was a truly pivotal event—one of the key points in our evolutionary history," says Christopher Beard, Curator of Vertebrate Paleontology at Carnegie Museum of Natural History and an author on the paper. "At the time, Africa was an island continent; when these anthropoids appeared, there was nothing on that island that could compete with them. It led to a period of flourishing evolutionary divergence amongst anthropoids, and one of those lineages resulted in humans. If our early anthropoid ancestors had not succeeded in migrating from Asia to Africa, we simply wouldn't exist."

Beard has done extensive research on anthropoid origins, including his work on the primate Eosimias. His book, "The Hunt for the Dawn Monkey", posited Asia, not Africa, as the place of origin for anthropoids. 

"This extraordinary new fossil site in Libya shows us that in the middle Eocene, 39 million years ago, there was a surprising diversity of anthropoids living in Africa, whereas few if any anthropoids are known from Africa before this time," says Beard. "This sudden appearance of such diversity suggests that these anthropoids probably colonized Africa from somewhere else. Without earlier fossil evidence in Africa, we're currently looking to Asia as the place where these animals first evolved."

Citation: Jean-Jacques Jaeger, K. Christopher Beard, Yaowalak Chaimanee, Mustafa Salem, Mouloud Benammi, Osama Hlal, Pauline Coster, Awad A. Bilal, Philippe Duringer, Mathieu Schuster, et al., 'Late middle Eocene epoch of Libya yields earliest known radiation of African anthropoids', Nature 467, 1095-1098 (27 October 2010) doi:10.1038/nature09425