Migration clues from fruit and veg

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 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 they "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. He expected that 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 called amplified fragment length polymorphism to construct a "family tree" for kumara in Oceania.

Mr Clarke was working on bottle gourds in the Pacific when he joined 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. The work showed that bottle gourds, widely used as containers before modern times, were taken to the Americas thousands of years ago.

- NZPA