Thursday, 30 August 2012

A Sudden Twist In The Story Of Human Migration

Our species is a mere 200,000 years old. We moved out of Africa around 60,000 years ago, but despite this, the exact details of the global diaspora which we would undertake still remains mystery. Large parts of the story are sketchy or almost non existent. Evidence is fragmentary and dates do not seem to match up. There is our migration out of Africa around 60,000 years ago yet the oldest signs of human habitation in Australia, on the other side of the world, is of the same age.

The 63,000 year old skull from the Annamite Mountains in Laos
This means that our species would have had to cross deserts, mountains and oceans in an impossibly short space of time to reach the southern continent. Now, a fossil has been discovered which may resolve this problem. A team of palaeontologists, led by anthropologist Laura Shackelford from the University of Illinois, were excavating in the Annamite Mountains in Laos - the first team since digs in the early 1900s - when they uncovered a single skull.

The cranium was found 2.5 metres below the soil in a cave. Analysis revealed that the sediment was around 43,000 years old. Yet the skull was far older. Not only was it a member of our species, it was an incredible 63,000 years old, making it older than both the oldest human fossils in Australia and the youngest proposed boundary for our migration out of Africa. This single discovery neatly re-aligns the dates of the diaspora, clearing up the question of how we became a global species.

The proposed route out of Africa
The geographical and temporal gaps between many other links in the chain of fossil evidence show that we spread like wildfire across the surface of the planet. Even so, this skull still pushes the date of the exodus closer to the 70,000 year mark. The composition of the sediment and the difference between its age and that of the skull showed that the remains had been washed into the cave. The absence of artifacts in the cave supports the idea that the cave was uninhabited.

The skull's owner, however, must have been part of a family group.The fossil evidence matches the clues left in our genetics so it is very possible that more remains will be recovered from the region. 'This find supports an 'Out-of-Africa' theory of modern human origins rather than a multi-regionalism model,' said Shackelford.

'Given its age, fossils in this vicinity could be direct ancestors of the first migrants to Australia. But it is also likely that mainland Southeast Asia was a crossroads leading to multiple migratory paths. This fossil find indicates that the migration out of Africa and into East and Southeast Asia occurred at a relatively rapid rate, and that, once there, modern humans weren't limited to environments that they had previously experienced.'

This new find is perhaps one of the most important anthropological discoveries of the past few years. The problem with dating the colonization of Oceania has been a long standing one. With more fossil and archaeological evidence this will become clearer. The Laos skull is a start.