The stories in old bones

12 October 2016

Fiona and Katy

Katy Anderson and Dr Fiona Petchey, contributing to ground-breaking Pacific research.

Academics from Harvard, University College Dublin and the Max Planck Institute for the Science of Human History released some major Pacific research earlier this month, and they couldn’t have done it without input from the University of Waikato.

The research involved DNA sequencing which has helped them find out more about the Solomon Islanders who more than 3,000 years ago set out along the southwestern edge of the Pacific Ocean and steered their outrigger canoes toward the horizon, with no land as far as their eyes could see. These people and their descendants were to be the first to cross more than 350 kilometre stretches of open ocean into a region known as Remote Oceania.

The researchers analysed DNA from people who lived in Tonga and Vanuatu between 2,500 and 3,100 years ago, and were among the first people to live in these islands. The results overturn the leading genetic model for this last great movement of humans to unoccupied but habitable lands.

To their great surprise—that the ancient sailors carried no trace of ancestry from people who settled Papua New Guinea more than 40,000 years ago, in contrast to all present-day Pacific islanders who derive at least one-quarter of their ancestry from Papuans. This means that the Remote Oceanian pioneers swept past the archipelago that surrounds New Guinea without much mating with local people.

So where does Waikato come into this research?

Dr Fiona Petchey from the University’s Radiocarbon Dating Laboratory has been investigating the tricky problem of dating bone from these early Pacific colonists for the last 10 years. Her research has included the investigation of the age of 10 different Lapita burial grounds, including the sites of Teouma and Talasiu which were studied as part of the ancient genome research.

“When it comes to obtaining accurate dates, context is one of the most important considerations, and directly dating the human remains often gives us the best context possible,” she says.

“Disturbance is a common problem in archaeological sites and by dating the burials we could be sure that the scientists were testing the first settlers.”

However, not only is it necessary to remove contamination from bones that have been sitting in the ground for a long time. “What the individual ate can also impact on the age since 14C is not evenly distributed between the ocean and terrestrial environments. Incorrect interpretation of the dietary 14C input can shift the ages by hundreds of years – this is where my research comes in,” Dr Petchey says.