Skeletons reveal early settlers' diet
Killer diet Skeletons from the oldest cemetery in the Pacific Islands show a preference for free-range food is not a modern phenomenon.
In a paper published in this week's PLOS One, the international research team, including Australian scientists, reveals insights into the diet of the Lapita people, who colonised Oceania.
The findings are based on an analysis of carbon, nitrogen and sulphur isotopes in bone collagen of 49 adults buried at the Teouma archaeological site on Vanuatu's Efate Island.
It shows the first Lapita colonials ate reef fish, marine turtles, fruit bats, pigs and chickens rather than primarily relying on crops for human food and animal fodder.
Dr Stuart Bedford, from the College of Asia and the Pacific at the Australian National University, says the analysis reveals the broad mix in the diet of the first settlers in the last 10 - 15 years before they died.
Bedford says the finding helps clear up debate about how the early Lapita colonisers sustained themselves as they spread across the Pacific islands around 3000 years ago.
Debate over survival strategy
The Lapita people appeared in the Bismarck Archipelago, on the east coast of Papua New Guinea, around 3000 years ago before moving east to colonise the islands of remote Oceania with a "transported landscape" of domestic plants and animals.
However, debate has long ranged over how the Lapita settlers adapted to the local ecology of each new island in order to obtain enough food for survival.
One theory suggests the transported plants and animals were the critical food items, while competing theories have favoured that the interlopers focused on gathering local resources.
This study, led by Dr Rebecca Kinaston at the University of Otago, reveals the likely truth lies somewhere between.
Bedford says it appears the new colonists practiced a mixed subsistence strategy consuming wild marine and land animals and local flora as well as eating pigs and chickens.
The lack of significant amounts of C3 plants such as tubers in the human diet supports the idea crops were still being established at this time and could not be heavily relied upon.
"It's not a planned strategy," says Bedford. "When they arrive they have to survive off the local fauna and flora while they establish gardens. It's logical, but at the same time having the direct evidence is satisfying."
Analysis of ancient pig bones found at the site suggests the domestic animals foraged for food "reducing the competition between pigs and humans for the limited horticultural plant foods likely being grown", the researchers write.
The researchers add this could be "the first direct evidence of a 'low-cost free-range system' of animal husbandry.
Unpublished data on the site shows the diet of both humans and pigs changes as gardens become established, says Bedford.
Men versus women
The study also reveals males ate more protein than women.
While the paper suggests this indicates males had a higher status in the communities, Bedford says this is just one "potential scenario".
He says because males were the primary hunters, the find might just reflect they had more access to meat.
Bedford points to modern-day hunting practices in island communities to illustrate his point: "Men are the ones that essentially go off and hunt and sometimes when they do that they will sit down and cook what they kill, and eat on the spot."
He says excavation at the site, just 10 minutes north of Port Vila, has uncovered more than 2000 tortoise bones.
Hunting endemic animals to extinction "is a key indicator of first arrival", says Bedford, as the tortoise was not known to be present in the area prior to the discovery of these bones.
He says the discovery of the Teouma site is critical to understanding colonising communities.
"It is extraordinarily rare that these sites are found," says Bedford. "This discovery helps us to understand how these communities arrived, adapted and survived."