The origins of Vanuatu and Tonga's first inhabitants has been revealed in a surprise discovery made by ANU archaeologists in the first major study of ancient DNA (aDNA) from the Pacific Islands.
The study, published in the scientific journal Nature, reveals Vanuatu's first people arrived 3,000 years ago from Taiwan and northern Philippines, and not from the neighbouring Australo-Papuan populations of Australia, New Guinea and the Solomon Islands that had been in the region for between 40,000 and 50,000 years.
Researcher Professor Matthew Spriggs said the discovery was confirmed after aDNA analyses were carried out on three skeletal samples excavated from the oldest known cemetery of the Pacific Island Lapita culture near Port Vila in Vanuatu.
"The people of Vanuatu today are descended from Asia first of all. Their original base population is Asian. They were straight out of Taiwan and perhaps the northern Philippines," said Professor Spriggs of the ANU School of Archaeology and Anthropology in the College of Arts and Social Sciences.
"They travelled past places where people were already living, but when they got to Vanuatu there was nobody there. These are the first people.
"Only some time later did they intermarry with Papuan peoples to produce the genetic mix we see today in Vanuatu, and indeed across the Pacific. Today all Pacific Islanders are a mixture of these Asian and Papuan populations. The differences are simply in the percentages."
Ancient DNA of a sample from a Tongan cemetery confirmed that the same group of people became the first inhabitants of Tonga only slightly later.
"We know this because testing conducted by two different laboratories in the United States and Germany confirm that the samples are of the same people," he said.
The skeletal samples from Vanuatu were excavated as part of an Australian Research Council funded excavation project co-directed by Professor Spriggs and Dr Stuart Bedford of the School of Culture, History and Language (CHL), College of Asia-Pacific at the ANU, run jointly with the Vanuatu Cultural Centre. The Tongan excavation was directed by Associate Professor Geoffrey Clark, also of CHL, ANU.
Dr Bedford said "this is a truly remarkable discovery. Debates relating to the origins of Pacific Islanders have been on-going literally for centuries and particularly those relating to Lapita peoples, those who first colonised islands from Vanuatu across to Tonga. It demonstrates the enormous potential for these sorts of studies but these data have already provided an extremely important piece of the puzzle."
A team led by researchers at Harvard Medical School, University College Dublin, and the Max Planck institute for the Science of Human History led the DNA analysis.
"This is the first genome-wide data on prehistoric humans from the hot tropics, and was made possible by improved methods for preparing skeletal remains," says Dr Ron Pinhasi at University College Dublin, a senior author of the study.
"The unexpected results about Oceanian history highlight the power of ancient DNA to overthrow established models of the human past."
"A particularly striking finding is the different ancestry observed on the X-chromosome, which is inherited mainly from females," said lead author Dr Pontus Skoglund of Harvard Medical School and Stockholm University.
"This reveals that the vast majority of the ancestry from these open water pioneers that survives today is derived from females, showing how DNA information can provide insights into cultural processes in ancient societies".