Sunday, June 24, 2012

Early Humans In India: Peopling The Planet Special Issue

Ha.. move over Africa. Finally a human evolution mystery that involves India!

Nature has a special issue titled Peopling the Planet. Many of the articles are open access. They deal with what we know now of the migration of Homo sapiens out of Africa  and the peopling of various continents. The essay Eastern Odyssey  is on the controversial question of when Homo sapiens first moved across western Asia and into India.

The stone tool record  typical of modern humans place our species in India by 45 thousand years ago. These tools have been found inland. There may have been an earlier presence but since the first migration routes were likely along coastal areas via Arabia that record is drowned by the Holocene sea level rise. Analysis of mitochondrial DNA suggests a diversification of mitochondrial lineages as early as 60 thousand to 65 thousand years ago, implying modern humans had left Africa and become semi-isolated populations residing in different Asian regions by then.

Now, a group led by Michael Petraglia at the University of Oxford, UK think they have found signs that modern humans may have left Africa and entered Asia and the India subcontinent earlier than 74 thousand years ago, perhaps even 100 thousand years ago. The record of a volcanic eruption at Toba is preserved as an ash deposit in the Jurreru Valley region in Kurnool district , Andhra Pradesh, South India. The eruption is dated to 74 thousand years ago. Dr. Petraglia's team has found tools below this deposit. They have interpreted these tools are belonging to our species, thus implying their presence in India before 74 thousand years ago. Dr. Petraglia thinks that the genetic signal of these first migrant has been lost as populations vanished to be replaced by later migrants.

Other scientists like Paul Mellars are not convinced. They see these tools as the handiwork of another more archaic human species, possibly the descendants of Homo erectus from a much earlier migration.

Confidence that their version of the story is the right one is quite high:

But did these early explorers press on, from Arabia into Iran and India? No, says Mellars. Theirs was a failed expansion, like one documented in Israel, where modern humans were present more than 100,000 years ago but then vanished. When the climate cooled and dried about 75,000 years ago, turning Arabia back into a desert, the Nubian pioneers either died out or retreated to Africa. “There's not a smell, not a whiff [of Nubian technologies] that has ever been detected in India,” says Mellars. “If Mike Petraglia could come to me with one of those Nubian cores and say, 'Look, we found this in India,' I would get down on my knees and say, 'Sorry, Mike, I got it wrong'.”

Anatomically modern humans evolved probably around 200 thousand to 150 thousand years ago in Africa but it is not until 100 thousand years ago that we have an unambiguous record of them outside Africa in the Middle East. Whether these initial migrants went on into India is a mystery.

The story of human evolution in India has not received that much attention until now. One problem is a scarcity of skeletal remains. Why that is so is not clear. Other vertebrate fossil fauna is commonly preserved in fluvial and cave deposits. Maybe human fossils are preserved in very rare contexts. Anthropologist Parth Chauhan suggests that until recently most fossil hunting was being conducted by geologists or archaeologists and not trained physical anthropologists. So we might simply have not recognized skeletal fragments as being of hominin origin. Instead, scientists have had to rely on the tool record which is proving hard to compare across continents and to assign to specific human species.


  1. As a person who had Anthropology in his Graduation course, the post attracted me and I liked what I read. As an animal, however, I have doubts, if we (Indians) are homo-sapiens-sapiens at all. Even if we are, we have to be a very virulent strain of the species.

  2. Suvrat, where in South India was the study conducted?

  3. Kaustubh.. should have clarified that, it is Jurreru valley in Kurnool district Andhra Pradesh.. I have updated the post too.. thanx..

    Umashankar.. thanks for visiting..those are virulent views :)