At http://archaeology.about.com/od/transportation/a/trans-pacific.htm April 27th … About.Com archaeology has an article (and several others in their archive) on contacts between Polynesians and South America. In the mid 20th century the idea of pre-Columbus voyages across the Pacific was part of a rich vein of speculation. Thor Heyerdahl is perhaps the most famous adherents of this idea via his adventures on the balsa raft, Kon Tiki. His books were all the rage – bestsellers that appealed to teenagers and adults alike. However, there were also other suggestions, such as a similarity between Middle Jomon pottery from Japan and South American pottery types. All such ideas went out of fashion when diffusionism became unpopular – indeed, was ‘not mentioned’ as if it was a ‘death knell’ for the ambitious archaeologist.
Things have turned somewhat mellow since then – a new generation of archaeologists that have other, different prejudices to suppress. While the idea of colonisation is still out of the question – contact by small groups of people is back in vogue. It may have crept in through a side door while the tutor was not looking but it obviously is a realistic appraisal of the evidence. For example, sweet potatoes, a New World crop. It became popular around 2500 years ago and it is a fact that some Polynesian communities had the sweet potato long before Columbus or Magellan. Scientists have drawn up computer models to show it is theoretically possible the sweet potato reached the mid Pacific by drifting on ocean currents – but there will always be sceptics.
Chickens on the other hand originated in SE Asia, probably from jungle fowl many thousands of years ago. They became a part of the Polynesian food resources, taken from island to island with the pig – and other easily transportable cultural dependables. The Polynesian adventure began with the Lapita expansion, it is thought, around 1000BC, but Polynesian settlement of islands in the far Pacific came much later. Chicken bones were found at El Arenal in Chile and dated to the 14th century AD – before Columbus. Coconuts growing in Ecuador originated in the Philippines and bottle gourds, from the Americas, are known from Polynesia as early as 1000AD. Evidence such as this is what Heyerdahl was saying in the 1950s and 1960s.