MADAGASCAR is renowned for its unusual animals, particularly its lemurs, a group of primates extinct elsewhere on the planet. Its human population, though, is equally unusual. The island was one of the last places on Earth to be settled, receiving its earliest migrants in the middle of the first millennium AD. Moreover, despite Madagascar’s proximity to Africa (400km, or 250 miles, at the closest point) those settlers have long been suspected of having arrived from the Malay Archipelago—modern Indonesia—more than 6,000km away.
There are three reasons for this suspicion. First, it has been recognised for centuries that the Malagasy language, though distinct, borrows a lot of words from Javanese, Malay and the tongues of Borneo and Sulawesi. Second, the islanders’ culture includes artefacts ranging from boats with outriggers to xylophones, and crops such as bananas and rice, that are (or, rather, were then) characteristically Asian, not African. And third, genetic evidence has linked the modern Malagasy with people living in eastern Indonesia as well as farther off in Melanesia and Oceania.
Now, Murray Cox of Massey University in New Zealand and his colleagues have put the matter beyond doubt by showing not only where the first settlers came from, but also how many of them there were. And the answer is surprisingly few. Though Dr Cox is unable, with the method he used, to work out how many men were in the original party, the number of women was 30.
He drew this conclusion, just published in the Proceedings of the Royal Society, by sampling the DNA of 266 Malagasy people and comparing it with existing samples from 2,745 Indonesians. He concentrated on DNA from mitochondria. These are cellular components involved in energy production that are descended from bacteria which became symbiotic with humanity’s ancestors almost 2 billion years ago, and thus have their own genes. People inherit mitochondria only from their mothers, which is why only the female line of descent can be tracked using them.
The advantage of studying mitochondrial DNA is that it is not shuffled around by sex. Dr Cox and his colleagues were therefore able to make a statistical comparison of Indonesian and Malagasy mitochondrial genomes knowing that any changes which had occurred since they separated would be the result of rare mutations. These can be spotted and accounted for. Indeed, because they can be tracked they add to the information which can be extracted from a sample.
Having confirmed that Malagasy and Indonesian DNA separated about 1,200 years ago, which is statistically close to the date archaeologists suggest Madagascar was colonised, the team then asked their data how many women, drawn at random from the Malay Archipelago of that period, would have been needed to explain the variation in mitochondrial DNA in Madagascar. The answer was about 30.
That answer bears on a second question: was the colonisation of Madagascar a deliberate act or an accident? The first is possible. At the time, much of the Malay Archipelago was in the hands of the Srivijayan empire, an entity that could certainly have sent expeditions across the Indian Ocean, had it so willed. But there is no historical evidence that it did. In any case if it had, it is likely that a successful colonisation by one group would have been followed by others, as happened when Europeans discovered the Americas.
Most likely, then, the first Malagasy were accidental castaways, news of whose adventure never made it back home. But there is still a puzzle. Most ships’ crews are male. Though the number of men in the original party will remain obscure until an analysis like Dr Cox’s is done on the Y-chromosome of Malagasy men (Y-chromosomes include DNA passed exclusively down the male line in the way that mitochondrial DNA is passed down the female line), the presence of women on board a trading vessel would have been unusual. Unless, of course, the women themselves were the objects being traded. Possibly, then, Madagascar was colonised by an errant slave ship. Which would make its history even stranger than anyone had previously thought.