The earliest seafaring ancestors of people
living in South Pacific islands such as Vanuatu and Tonga arrived from Asia, an
analysis of ancient DNA from four skeletons reveals.
Key points
- Earliest
people to arrive in Vanuatu and Tonga are associated with the Lapita
culture
- Analysis
of ancient DNA of skeletons from Vanuatu and Tonga shows these people were
Asian
- All
South Pacific Islanders are a mix of this group from Asia and a second
wave from New Guinea-Solomon Islands.
A wealth of
archaeological evidence, including intricate pottery, indicates people
associated with the Lapita culture were the first to colonise the remote
islands in the Pacific in the last major dispersal of people to unpopulated
lands 3,000 years ago.
But until this
analysis we did not know who these people were, the study's co-author Professor
Matthew Spriggs of the Australian National University said.
"Now that we've
got the DNA of the ancient Lapita people, the big shock is that they are really
like [Aboriginal] people from Taiwan," Professor Spriggs said.
Today, all south
Pacific Islanders have a heritage that includes DNA from both a Papuan and an
East Asian population to varying degrees.
The relationship
between the Lapita people and Papuan people, which dominated the region for
50,000 years, has been long debated.
Linguistically and
culturally the Lapita were similar to Asian groups.
But many
archaeologists thought the Lapita mixed with the Papuan population as they
travelled down through New Guinea and the Solomon Islands before setting out
towards the remote islands 3,000 years ago.
Analysis of skeletons shows first Lapita did not mix
DNA was extracted from this 3,000 year old
skull and mandible from Vanuatu
Supplied: Frederique Valentin
To uncover the origins
of the Lapita people, Professor Spriggs and his colleague Dr Stuart Bedford
worked closely with the Vanuatu Cultural Centre to excavate and extract DNA
from skeletons from the Teouma burial ground in Vanuatu.
"This is in fact
the fourth attempt to extract ancient DNA over the last decade," Professor
Spriggs said.
Finally, a genetic
analysis by a team led by Dr David Reich at Harvard University revealed three
skeletons aged between 3,100 years and 2,700 years contained no traces of
Papuan DNA.
A fourth Lapita
skeleton aged between 2,700 and 2,300 years that was excavated in Tonga by a
second team, led by Dr Geoffrey Clark of the Australian National University,
and analysed at a different lab in Germany, also contained no Papuan DNA.
An additional analysis
of DNA volunteered by 778 present day people from East Asia and Oceania shows
all four skeletons contain unique DNA that no longer exists, but is similar to
that found in Aboriginal groups from Taiwan and some northern Philippine
populations.
"The first people
who got to Vanuatu were not these people who'd been in the region for 50,000
years ... they were these Asian populations," Professor Spriggs said.
The analysis also
showed that the Asian genes in today's Pacific people came from these first
remote Oceanians.
"What we've been
able to say is that Asian inheritance comes from Lapita," Professor
Spriggs said.
He said the finding, reported
in the journal Nature, challenged the use of
labels such as Melanesian and Polynesian to describe peoples from different
parts of the Pacific.
"I'd like to call
them Pasifika people because I think these old categories we inherited from the
19th century don't make much sense biologically or culturally," he said.
"The variation is
simply the percentage of the genetic inheritance from the first people who got
out to these islands 3,000 years ago."
Second wave of Papuan men mixed with Lapita
A loop motif displayed on a shard of Lapita
pottery recovered from Nukuleka in Tonga
Supplied: David Burley
Not only did the
genetic data show the Asian ancestry in today's South Pacific Islanders comes
from the Lapita, but that it was more likely to come from women than men.
This indicated the
first wave of Lapita seafarers was soon followed by a second wave of Papuan
people — mainly men.
"The men tend to
be moving down from the New Guinea-Solomons area and they're marrying the Asian
women, and that's the mixture that's occurring," Professor Spriggs said.
Just when the two
lineages came across each other on the islands spread across the Pacific is
unclear.
"We think for
Vanuatu it is in late Lapita times 2,800 to 2,700 years ago when populations
were small," Professor Spriggs said.
But he said it may
have happened much later for places such as Fiji and Polynesia.
"For Fiji we just
don't know. But for Polynesia we have an absolute date by which it must have
occurred which is 1,000 years ago."
At that time, the
population started moving out from Tonga and Samoa to the eastern Pacific
Islands of Hawaii and Tahiti, then 700 years ago travelled south to become the
Maori population in New Zealand.
"When they leave
1,000 years ago that mixture has already happened."
But more work with
ancient DNA from skeletons of different ages would be needed to clarify exactly
when the mixes happened in various locations, Professor Spriggs said.
A 3,000 year old burial site in Vanuatu with
bones arranged in a triangular pattern.
Supplied: Frederique Valentin
Clues and questions about Pacific ancestry
Commenting on the study, director of the Australian Centre for
Ancient DNA Professor Alan Cooper said the paper provided a lot more
information about the Pacific and Polynesian origins "that was just
conjecture before".
"It clarifies
this whole issue of how you get two groups of people together to form another
one that does the most amazing voyages," Professor Cooper said.
He said the study also
raised questions about when the Papuan mix happened in Tonga and subsequently
in Polynesia, whose people today have 26 per cent Papuan DNA.
"The Tongan
individual carried little or no Papuan ancestry providing confirmation the
ancestral population of Polynesians was not yet fully formed or widespread by
the end of the Lapita," he said.
"So how long
before [the Papuans] catch up? That's a long way out in the Pacific.
"You figure that
the genetic mix that generated the Polynesians happened before they went out
voyaging to the islands."
He said it also raised
questions about the identity of the ancient Papuan people, who had a mix of
Australian Aboriginal and Papuan DNA.
"I'm intrigued by
who that Australian-Papuan group was — where do they come from?
"I'm going to
guess off the top of my head Torres Strait Islands or some coastal group,
possibly trading with the Lapita group."
Want more science from across the ABC?