An extensive study of sweet potato DNA led by Oxford scientists controversially suggests that sweet potato tuber evolved before humans.

The results support that the sweet potato, a plant of American origin, likely arrived in Polynesia due to the natural dispersal of its seeds – challenging the long-standing view that the widely-used tuber was transported by humans in pre-European times.

Pablo Muñoz-Rodríguez, a DPhil candidate at the Oxford Department of Plant Sciences, was a member of the sweet potato research team, which conducted the biggest survey of sweet potato DNA yet.

Muñoz-Rodríguez told Cherwell: “This finding calls into question the alleged contacts between Polynesians and Americans in pre-European times, because sweet potato was the only remaining biological evidence of these contacts.

“This finding is likely to be controversial because it contradicts predominant theories that suggest ancient contacts between both sides of the Pacific Ocean.

“However, the molecular results we present are robust and have been thoroughly tested; we are confident they are accurate and therefore there is strong evidence against human-mediated transport of the sweet potato to Polynesia in ancient times.”

Muñoz-Rodríguez says he and his team plan to continue their sweet potato research.

“There is one other question pertaining to the origin of the sweet potato that remains unresolved, and that will be the focus of our research now: what was the evolutionary path that led from the wild species to the sweet potato?”