Researchers looked into how the bottle gourd was a staple of New World culture a thousand years ago, despite the fact that it did not naturally grow in the region.
The hard fruit was used as both a canteen and backpack in prehistoric America, USA Today reported. New genetic data suggests the gourd floated over from Africa and started growing before humans domesticated it around 10,000 years ago.
"The bottle gourd's always been an anomaly. It's been puzzling people for a long time," Bruce Smith, an expert in American plant domestication at the Smithsonian Institution's National Museum of Natural History told USA Today. "The bottle gourd is no longer an anomaly."
The research team collected domestic gourds from across the Americas as well as a number of samples of ancient gourds found on archaeological digs. They compared the DNA of these gourds with both current and ancient samples found in Africa, the Los Angeles Times reported.
In the past researchers believed the gourds were brought over by Asian travelers, but in this scenario the gourd-carriers would have crossed a land bridge to Alaska that no longer exists; this region is too cold for the gourds to have survived, USA Today reported.
African and Eurasia gourds diverged from each other genetically over thousands of years; the team found both archeological and modern American gourds were genetically similar to those in Africa, the Los Angeles Times reported.
The researchers looked at data on ocean currents to determine how the gourds could have made their way to the Americas.
Bottle gourd seeds can remain fertile for over a year if floating in ocean water. The team was able to determine that a gourd would be able to travel from Africa to the Americas in anywhere from 248 to 331 days, the Los Angeles Times reported.
"It's so widespread so early on, and it's used so cross-culturally," Study author Logan Kistler, a post-doctoral researcher at Pennsylvania State University told USA Today. "We have much more to learn about this species."
The study was published in the Proceedings of the National Academies of Science (PNAS).