The world’s earliest navigators who set out to colonize remote Pacific islands nearly 3,000 years ago formed a matri-local society with communities organized around the female line, analysis of ancient DNA suggests.
The study, based on genetic sequencing of 164 ancient individuals from 2,800 to 300 years ago, suggested that some of the earliest inhabitants of Oceania islands had a population structure in which women almost always remained in their community after marriage, while men left the community of their own. left their mother to live with their wives. This pattern differs markedly from that of patrilocal societies, which seemed to be the norm in ancient populations in Europe and Africa.
“The population of the Pacific is a long-standing and important mystery because it is the last major expansion of humans into unoccupied areas,” said David Reich, a professor of genetics at Harvard Medical School who led the work.
“Today, Pacific traditional communities have both patrilocal and matrilocal population structures, and there has been a debate about what was the common practice in the ancestral populations,” he said. “These results suggest that matrilocality was the rule in the earliest seafarers.”
50,000 years ago, populations of ancient humans had arrived and spread across Australia, New Guinea, and the Solomon Islands. But it wasn’t until 3,500 years ago that humans, probably in what is now Taiwan, developed long-distance canoes and ventured into the open ocean, arriving in remote Oceania. This expansion included the region called Micronesia – about 2,000 small islands north of the equator, including Guam, the Marshall Islands, the Caroline Islands, Palau, and the Northern Mariana Islands.
The latest findings, published in the journal Science, include a genome-wide analysis of 164 ancient individuals from five islands from 2,800 to 300 years ago and 112 modern individuals. When individual populations remain isolated over time, for example on islands, their genomes drift apart. This effect was seen in the ancient Micronesians, but the genetic drift was significantly greater in the mitochondrial DNA, a portion of the genome that is only passed down the female line. This strongly suggests that women did not move through communities as often as men.
“Women certainly moved to new islands, but when they did, they were part of joint movements of both women and men,” Reich said. “This pattern of community abandonment must have been almost unique for men.”
The work also uncovered new evidence of migrations — again almost exclusively males — from mainland New Guinea, which contributed Papuan ancestry to those living on some islands in Micronesia today.
dr. Mark Dyble, an anthropologist at University College London, who was not involved in the study, said matrilocal societies were “unusual but certainly not unique,” with evidence of matrilocality in pre-industrial societies in the Amazon Basin, central China and southern China. India.
Matrilocality should not necessarily be equated with matriarchy, Dyble emphasized. “Matrilocality conjures up a picture of peaceful inter-island relations, with men leaving their islands to get married and women staying,” he said. “However… the same genetic structure on islands could presumably result from men taking over neighboring communities by force. No doubt this still counts as matrilocal residence, as males disperse and females remain on their native island. But in practice this is a very different scenario.”