Carbon dating of rat bones and seeds the rats had chewed on puts human arrival somewhere between 1280 and 1300.
“East Polynesian islands preserve exceptionally detailed records of the initial prehistoric impacts on highly vulnerable ecosystems, but nearly all such studies are clouded by persistent controversies over the timing of initial human colonization, which has resulted in proposed settlement chronologies varying from 200 BC to 1000 AD or younger,” write study author Janet Wilmshurst and her colleagues at Landcare Researc, in PNAS.
“…Radiocarbon dates on distinctive rat-gnawed seeds and rat bones show that the Pacific rat was introduced to both main islands of New Zealand 1280 AD, a millennium later than previously assumed.”
Actually, as the PNAS paper itself notes, there are two models for human arrival in New Zealand, a ‘short model’ saying reasonably recently and a ‘long model’ saying longer ago. The short model is probably more accepted, so this backs this up, rather than radically overturning an existing theory.
However, as AP notes:
The study, published Tuesday in the U.S. journal Proceedings of the National Academy of Sciences, contradicts findings from a previous radiocarbon dating study of rat bones, published in Nature magazine in 1996. That study found evidence that man was in New Zealand from around 200 BC.
That Nature paper states that rats were established in New Zealand 2,000 years ago, carried by humans. However it does note that these humans “either left immediately or quickly died out”.
The new PNAS paper mentions a number of points raised regarding the Nature paper by later authors , including inadequate pre-treatment of bones and arguments that bones may have appeared older than they are due to dietary uptakes of carbon, and notes “Subsequent dating … failed to duplicate the early series of old rat bone dates”.
But TV3 says the author of that 1996 study isn’t happy. Richard Holdaway is sticking to his guns and saying the Landcare Research team “misconstrued his study by implying he believes someone else arrived before the Maori and settled here”.
“If rats arrived [2000 years ago], people obviously arrived,” he says. “Whether they’ve stayed, I’ve consistently said they didn’t.”
Image: New Zealand / Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC