Fossils suggest the mammals that evolved into primates – including humans – arose in Asia not Africa
OUR ANCIENT forebears arose within Africa, or so the evolutionary story goes. New research findings bring this assumption into question however. Our earliest roots could well have been somewhere in Asia.
To a degree, defining our origins could come down to deciding where to draw the line, how far back in time do we want to go. If we allow the clock to wind back a few million years ago then our origins are definitely African.
We have “Lucy”, a 3.2 million year old human ancestor and “Ardi”, even older at 4.4 million years. Older still is “Toumai” found in Chad whose skull dates to between six and seven million years old, but scientists have yet to agree on where it sits on the evolutionary family tree.
The picture changes however when you go back more than 35 million years, a time when our primate ancestors walked on four and not two legs and looked much more like modern lemurs.
Research published in the journal Naturethis morning argues that fossil bits from four early primates dug out of the deserts of Libya point towards an origin in Asia and not Africa.
Dr Jean-Jacques Jaeger and colleagues discovered these previously unknown creatures’ remains at the Dur At-Talah escarpment in central Libya. There wasn’t much left – just teeth – but there was enough to link them to known early anthropoids, the early mammals that can trace a path directly to modern humans.
The thing that surprised the researchers was the fact they all occupied the same restricted area in north Africa at the same time. Fossil discoveries made earlier in Algeria and in Egypt included African anthropoid animals but each region contained only one family of animals. The Libya find was different however, including four different but related animals.
“All four primate [animals] known from Dur At-Talah are remarkably small, ranging from 120g to 470g in estimated adult body mass,” the authors write. That means the largest weighed little more than a bag of sugar.
The find suggests however that a lot of evolutionary change had taken place already to allow this variety of animals to exist. The author’s question is, “Where did this evolution take place?”
The current accepted wisdom is that Africa provided a haven for this, with the significant lack of a fossil record relating to the challenge of finding them rather than the possibility that they didn’t live in ancient Africa.
“The age and diversity of the Dur At-Talah primate fauna indicates substantial gaps in either the African or the Asian fossil record of anthropoid evolution (and possibly both),” the authors argue.
It was not good enough to claim that the missing African history would be filled in after digging out more fossils, they say.
“An alternative hypothesis that now demands serious consideration is that multiple Asian anthropoid [families] may have colonised Africa more or less synchronously during the middle Eocene [38-39 million years ago].”
This view would hold that the diversification seen in these anthropoids took place in Asia and that these animals eventually spread out to colonise Africa along with a host of other mammals including early rodents.
So humans might well be out of Asia, but without doubt, by way of Africa.
