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Research gives new clues to Madagascar settlement

Thursday, March 22, 2012

Research gives new clues to Madagascar settlement

New research from a Massey University computational biologist has found 30 Indonesian women first settled the island of Madagascar.

The finding sheds light on one of the strangest evolutionary events in human history. The people of Madagascar, off the east coast of Africa, are descended from Indonesians, quarter of a world away. How this happened has never been fully explained.

Dr Murray Cox, of the Institute of Molecular Biosciences, led a team that screened the DNA of Madagascans and Indonesians to reconstruct the island’s early history.

“It has been known for a very long time that there is a really clear Asian signature in the DNA of Madagascans,” Dr Cox says. “What we’ve done is developed a computer model to find out more about that very early settlement history. Our research suggests that around 30 Indonesian women came to the island about 1200 years ago, around the 9th century AD.”

Almost all Madagascans today are related to those 30 founding women. “There has been trading along the Indian Ocean for millennia, and people have assumed that Indonesians settled there as a result of lots of people using this trading route,” he says. “But if it is only 30 individuals, that theory doesn’t make sense. So it appears more likely that this may have been an accidental event – it certainly wasn’t a big, planned movement of people.”

To conduct the research, Dr Cox and his team took DNA from 300 Madagascans and almost 3000 Indonesians and used the specially developed computer model to simulate evolution under various parameters. A year and a half of computer time was needed to run the simulations.

Dr Cox says simulations are needed to discover the details of the settlement. “Just looking at the DNA itself will tell you some things, like the fact there is an Asian connection,” he says. “But what it won’t tell you is how many people came and when that happened and what the population size is today. To get that you have to run simulations to figure out what has happened in the past.

“We simulated under a whole range of different demographic models and found one that matched the actual outcome. That gives us a measurement of what the most likely settlement model is.”

Dr Cox worked with a team that included researchers from the Eijkman Institute in Indonesia, the University of Arizona and the University of Toulouse. The research was published in the Proceedings of the Royal Society B and was funded by the Royal Society of New Zealand through a Rutherford Fellowship.


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