May 26, 2008 Research led by the University of Leeds has discovered genetic evidence that overturns existing theories about human migration into Island Southeast Asia (covering the Philippines, Indonesia and Malaysian Borneo) - taking the timeline back by nearly 10,000 years.
Prevailing theory suggests that the present-day populations of Island Southeast Asia (ISEA) originate largely from a Neolithic expansion from Taiwan driven by rice agriculture about 4,000 years ago - the so-called "Out of Taiwan" model.
However an international research team, led by the UK's first Professor of Archaeogenetics, Martin Richards, has shown that a substantial fraction of their mitochondrial DNA lineages (inherited down the female line of descent), have been evolving within ISEA for a much longer period, possibly since modern humans arrived some 50,000 years ago.
Moreover, the lineage can be shown to have actually expanded in the opposite direction - into Taiwan - within the last 10,000 years.
Says Professor Richards: "I think the study results are going to be a big surprise for many archaeologists and linguists on whose studies conventional migration theories are based. These population expansions had nothing to do with agriculture, but were most likely to have been driven by climate change - in particular, global warming and the resulting sea-level rises at the end of the Ice Age between 15,000-7,000 years ago."
At this time the ancient continent known as Sundaland -- an extension of the Asian landmass as far as Borneo and Java -- was flooded to create the present-day archipelago.
Although sea-level rise no doubt devastated many communities, it also opened up a huge amount of new coastal territory for those who survived(1). The present-day coastline is about twice as great as it was 15,000 years ago.
"Our genetic evidence suggests that probably from about 12,000 years ago these people began to recover from the natural catastophes and expanded greatly in numbers, spreading out in all directions, including north to Taiwan, west to the Southeast Asian mainland, and east towards New Guinea. These migrations have not previously been recognised archaeologically, but we have been able to show that there is supporting evidence in the archaeological record too."
The interdisciplinary research team comprised colleagues from Leeds, Oxford, Glasgow, Australia and Taiwan. The study was funded by the Bradshaw Foundation and the European Union Marie Curie Early Stage Training program and is published in the current issue of Molecular Biology and Evolution (MBE).
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