When it comes to the original migration to the Islands of Southeast Asia (ISEA - namely, the Philippines, Indonesia and Malaysian Borneo), the prevailing theory has been the "out of Taiwan" model - a Neolithic expansion from Taiwan driven by rice agriculture about 4,000 years ago.
Researchers say they have discovered genetic evidence that overturns that theory and takes the timeline back by nearly 10,000 years.
The 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.
Not only were the island populations present far longer than believed, the researchers say, the old theory is backwards - the migration to Taiwan happened in 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).
(1) The importance of this flood-driven dispersal for the region’s local communities was predicted ten years ago by co-author and Oxford scholar Stephen Oppenheimer, in his book Eden in the East.
Article: Molecular Biology and Evolution (MBE): Climate Change and Post-Glacial Human Dispersals in Southeast Asia