Researchers from New Zealand's University of Otago studying 3000-year-old skeletons from the oldest known cemetery in the Pacific Islands are casting new light on the diet and lives of the enigmatic Lapita people, the likely ancestors of Polynesians.

Their results -- obtained from analysing stable isotope ratios of three elements in the bone collagen of 49 adults buried at the Teouma archaeological site on Vanuatu's Efate Island -- suggest that its early Lapita settlers ate reef fish, marine turtles, fruit bats, free-range pigs and chickens, rather than primarily relying on growing crops for human food and animal fodder.

The findings are newly published in the journal PLOS ONE. Study lead author Dr Rebecca Kinaston and colleague Associate Professor Hallie Buckley at the Department of Anatomy carried out the research in collaboration with the Vanuatu National Museum and researchers from the University of Marseilles and CNRS (UMR 7269 and UMR 7041) in France and The Australian National University, Canberra.

Dr Kinaston says the study is the most detailed analysis of Lapita diet ever undertaken and provides intriguing insights into the socio-cultural elements of their society.

"It was a unique opportunity to assess the lifeways of a colonising population on a tropical Pacific island," she says.

The researchers analysed the isotopic ratios of carbon, nitrogen and sulphur in adult human bone collagen and compared these with ratios in ancient and modern plants and animals from the location, which provided a comprehensive dietary baseline.

"Examining these ratios gave us direct evidence of the broad make-up of these adults' diets over the 10-20 years before they died, which helps clear up the long-running debate about how the Lapita settlers sustained themselves during the early phases of colonising each island during their eastward drive across the Pacific."

Dr Kinaston says it appears that the new colonists, rather than relying mainly on a "transported landscape" of the crop plants and domesticated animals they brought with them, were practicing a mixed subsistence strategy.

"The dietary pattern we found suggests that in addition to eating pigs and chickens, settlers were also foraging for a variety of marine food and consuming wild animals -- especially fruit bats -- and that whatever horticultural food they produced was not heavily relied on," she says.

Isotopic analysis of the ancient pig bones found at the site also suggests that they were free-ranging rather than penned and given fodder from harvested crops.

Study of the human bones revealed a sex difference in diet compositions, showing that Lapita men had more varied diets and greater access to protein from sources such as tortoises, pigs and chicken than women did.

"This may have resulted from unequal food distribution, suggesting that males may have been considered of higher status in Lapita society and treated preferentially," Dr Kinaston says.