April 13 (UPI) -- The sweet potato made its way to Polynesia without human assistance, new research suggests, colonizing the islands prior to the arrival of the first humans.
When European explorers first visited Polynesia, they found an abundance of sweet potatoes, a root vegetable native to the Americas. Researchers led by a team at Britain's University of Oxford have interpreted their discovery as proof of early contact between Polynesians and Americans prior to the arrival of European explorers and colonists.
New genomic evidence, however, undermines such an interpretation. Analysis of the remains of Polynesian sweet potatoes collected by Captain Cook in 1769 showed the vegetables were of a variety that colonized before the arrival of the earliest Polynesia peoples.
Researchers sequenced the genomes of several varieties of sweet potatoes, both planted and wild varieties, using historic and modern samples. Their analysis, published this week in the journal Current Biology, linked the historic wild varieties with the cultivated crop.
The research suggests that wild sweet potatoes came to Polynesia through natural means. It's possible the seeds were carried to the islands by migrating birds. Scientists also determined that several other species of morning glories closely related to wild sweet potatoes colonized Polynesia during pre-human times.
"The sweet potato's early presence in Polynesia has been widely interpreted as strong evidence for human contact between Polynesia and America in the Pre-Columbian era," Pablo Muñoz-Rodríguez, a researcher at Oxford, said in a news release. "However, our finding is that the plant probably reached the Pacific Islands through natural dispersal by birds, wind or sea currents in pre-human times, as did several other species of morning glory."