Nuts Confirm Maori Were First N. Zealanders

Nuts Confirm Maori Were First N. Zealanders
Anna Salleh, ABC Science Online

June 3, 2008 -- Remains of nuts nibbled by ancient rats is among new evidence that settles a debate over whether Maori people were New Zealand's first inhabitants, say researchers.

Paleontologist Trevor Worthy of the University of Adelaide in Australia and colleagues report their findings in this week's issue of the Proceedings of the National Academy of Sciences.

Worthy says the research settles a controversy triggered in 1996 when researchers reported in Nature they had found evidence for a human presence in New Zealand 2,000 years ago.

He said the report, by Richard Holdaway from the University of Canterbury and colleagues, caused a controversy since most people at the time accepted evidence that Maori were the first humans in New Zealand, and arrived much later.

"The Holdaway paper opened the door to Maori not being the people of the land which is central to their being," says Worthy.

Since then the idea that there were people in New Zealand before the Maori has gained broader acceptance, said Worthy, although scientific debate has raged over the accuracy of the dates reported in Nature.

Holdaway's 1996 paper relied on radiocarbon dating of rat bones, from the species Rattus exulans, which is generally taken as a proxy for early human presence in New Zealand, said Worthy.

"They could only get to New Zealand by human transport," said Worthy, who was involved in the Holdaway excavation in two caves on the South Island, rich with rat bones deposited by owls.

Worthy and colleagues dated bones taken from the same layers of soil excavated in the Holdaway study, as well as digging deeper to recover even older bones.

They found the oldest bones to be just 650 years old.

Worthy and colleagues confirmed their findings using a completely independent line of evidence, by dating 150 tree nuts from other sites, which were attractive food for ancient rats.

"Some of the tree seeds are nearly a centimeter long and you can clearly tell whether they've been chewed by a rat or not," he said.

Grooves in the nut match the width of the teeth of the rats, said Worthy, which were the only gnawing mammal in New Zealand at the time.

"The seeds that were not chewed extended in age back to 3,000 years ago, but there was no evidence of rats prior to about 650 years ago."

Worthy said the findings suggest Holdaway's dates were wrong due to errors in radiocarbon dating.

At the time, he said, radiocarbon dating was not capable of accurately date small amounts of material, which is all Holdaway had.

Worthy said the "cleaner technology" being used today, together with the more numerous samples of bones and confirmation from the chewed nuts all adds up to a more convincing argument.

The date humans -- and rats -- arrived in New Zealand is also relevant to debates over conservation policy.

New Zealand's fauna is threatened by rats and more recently introduced mammals requiring management by conservation authorities.

But, Worthy said, these authorities have adopted Holdaworthy's dates, which suggests destruction of New Zealand fauna by rats occurs slowly.

The latest paper confirms that destruction can happen quite quickly and should emphasize the urgency of controlling fauna destruction by such animals.

Related Links:
ABC Science Online
Discovery News blog: Born Animal
The Hall of Human Ancestors
Early Human Phylogeny

Copyright © 2008 Discovery Communications, LLC. The number-one nonfiction media company.