An article has come out in Current Biology in which the authors report the sequencing of over 650,000 SNPs (single nucleotide polymorphisms) from 27 Rapa Nui individuals. I don't have access to the full article, but I've read the abstract and a discussion of it from today's issue of Science (Lawler, Andrew, 2014, Epic pre-Columbian Voyage Suggested by Genes, Science Vol. 346, No. 6208, p. 406). Native American DNA composed about 8% of the Rapanui genome. They explain this by invoking pre-Columbian trans-Pacific journeys from Easter Island to the Americas and back. They argue that the introgression took place in pre-Columbian times, rather than in recent or historical times, because the Native American DNA segments are fragmented and scattered. The degree of fragmentation and dislocation allow the authors to infer a date of AD 1280–1495 for the contact.
Of course, these issues--Easter Island and trans-Pacific contact--are popular and therefore controversial questions. So, naturally some Norwegians have to defend Thor Heyerdahl by saying that this means that the South Americans sailed to Easter Island. Right. And just happened to get there at the same time as the Polynesians. Sure. That's more likely than the Polynesians, who'd been sailing around the Pacific for thousands of years and who had developed unique maritime technology and navigational knowledge, sailing to South America. Nothing against the South Americans, but dude, this was the Polynesians' thing. In fact, it's hard to imagine that the Polynesians, who, over a period of two or three thousand years, had found and settled virtually all the tiny Polynesian islands, would suddenly stop at Hawaii and Easter Island. Right. You sail all over the Pacific for millennia and find all the little islands, but miss the giant continent in front of you. Yeah, that's really likely.
Of course, the South Americans did have boats and sailed around some, but there's little evidence that they crossed the open ocean to Polynesia. Sure, a boat might have drifted there, as they occasionally do today, but that's not really in the same league.
Added to the pre-Columbian chicken bones from Chile with (possibly) Polynesian chicken DNA in them and the evidence that the yam diffused to Polynesia from South America, and the evidence for pre-Columbian trans-Pacific contact is getting stronger.
The citation for the article is:
Moreno-Mayar, J. Víctor, Simon Rasmussen, Andaine Seguin-Orlando, Morten Rasmussen, Mason Liang, Siri Tennebø Flåm, Benedicte Alexandra Lie, Gregor Duncan Gilfillan, Rasmus Nielsen, Erik Thorsby, Eske Willerslev, and Anna-Sapfo Malaspinas. (2014).
Genome-wide Ancestry Patterns in Rapanui Suggest Pre-European Admixture with Native Americans. Current Biology In press. DOI: http://dx.doi.org/10.1016/j.cub.2014.09.057
Who needs an osteologist? (Installment 19)
2 days ago