Wellington, Dec 15; NZ Press Association
Research into bottle gourds by a Massey University scientist may have produced new evidence of significant Polynesian contact with America.
Andrew Clarke said genetic comparisons of modern bottle gourds around the world with gourds found at archaeological sites in the Western Hemisphere have shown that the gourds used in the Americas came from Asia.
"The Polynesian gourds are really interesting," said Mr Clarke.
"The shape of the Asian ones is quite different to the American ones… but people growing New Zealand gourds thought they might have come from both directions".
Other scientists have said the Polynesian ancestors migrated from Taiwan about 5500 years ago, through Sulawesi, past the islands north of Papua New Guinea, through the Bismarck Archipelago, reaching Central Polynesia by 3200 years ago, with colonisation of Hawaii and New Zealand about 1000 years ago.
The idea that Pacific voyagers might have "discovered" or even settled in the Americas was popular among researchers in the 19th century but lost favour because in the Pacific, sailors from the west would have faced contrary currents and winds that would tend to push them in the wrong direction.
Evidence that ancient Polynesians ate kumara, native to South America, and linguistic similarities between Polynesia and some American Indian tribes in California has revived the debate in recent decades.
Mr Clarke, from Massey’s Allan Wilson Centre for Molecular Ecology, is studying the spread of bottle gourds and kumara through the Pacific for his doctorate. He said research showed the American gourds came from Asia "when everybody thought it had come floating over from Africa".
Mr Clarke said it was difficult to be definitive about how the gourds travelled between continents, because they could also float.
Over the next couple of months. he hoped to analyse his data on kumara, building a "family tree" of the cultivars in Oceania, which could show how they had spread out of South America and into Polynesia. He expected this to give a better picture because kumara had to be carried by people.
According to Mr Clarke, the kumara was probably introduced by Polynesian voyagers who visited the coast of South America about 1000 years ago.
He has used a DNA technique, amplified fragment length polymorphism (AFLP) to construct a "family tree" for kumara in Oceania. The research is seeking the patterns of sweet potato dispersal in Pacific: how many cultivars entered the Pacific and to which islands they were introduced.
Mr Clarke was working on bottle gourds in the Pacific when he joined with American researchers trying to find how domesticated cultivars of gourds native to Africa and used in Asia and the eastern Pacific could have spread to modern-day Florida, Kentucky, Mexico and Peru. He spent three months at the Smithsonian natural history museum in Washington DC.
The work showed that bottle gourds, widely used as containers before modern times, were taken to the Americas thousands of years ago.
"It’s going to be quite hard to dissect out the truth," said Mr Clarke, a specialist in plant DNA at Massey. His study, with anthropologists and biologists from Harvard University, the Smithsonian, and the University of Maine, appeared today on the US web site of the Proceedings of the National Academy of Sciences.
The researchers used a mix of DNA detective work and archaeology, to test a collection of ancient remnants of bottle gourds from across the Americas. They identified key genetic markers from the DNA of both the ancient gourds and their modern counterparts in Asia and Africa and compared the plants’ genetic make-up to determine the origins of the New World gourds.
NZPAWGTkcabmccw 15/12/05 11-57NZ