Earliest Pacific seafarers were matrilocal society, study suggests

The world's earliest seafarers who set out to colonise remote Pacific islands nearly 3000 years ago were a matrilocal society with communities organised around the female line according to analysis of ancient DNA.

Some of the earliest inhabitants of islands in Oceania had population structures in which women almost always remained in their communities after marriage, according to the research. In ancient populations in Europe and Africa, patrilocal societies were the norm.

David Reich, a professor of genetics at Harvard Medical School, led the work on the peopling of the Pacific.

Traditional communities in the Pacific have both patrilocal and matrilocal populations and there was a debate about what the common practice was in the ancestral populations. The results show that matrilocality was the rule.

The first complete gap-free human genomes have been published.

By 50,000 years ago, the populations of ancient humans had spread through Australia. It wasn't until after 3,500 years ago that people in what is now Taiwan developed long-distance canoes and ventured out into the ocean. About 2,000 small islands north of the equator were included in the region called Micronesia.

A genome-wide analysis of ancient and modern individuals from five islands was published in the journal Science. The genomes of different populations drift apart when they remain isolated. The effect was seen in the ancient Micronesians, but the genetic drift was more pronounced in the mitochondria, part of the genome that is passed on only to females. Women were not moving as much as men.

When females moved to new islands they were part of a joint movement of both males and females. It must have been unique to males.

The work uncovered new evidence of migrations from mainland New Zealand to the islands of Micronesia, which were mostly men.

There is evidence of matrilocality in pre-industrial societies in the Amazon basin, central China and southern India, according to Dr Mark Dyble.

Dyble said that matrilocality shouldn't be compared with matriarchy. He said that matrilocality invokes an image of peaceful relations between islands with men leaving their island to marry and women staying put. The same genetic structure could result from men taking over neighbours by force. This is still considered a matrilocal residence since men and women are dispersed. This is a different situation on the ground.