People or sweet potatoes: What came first?
Tampa, April 13: The bulbous, colourful sweet potato has long been seen as an artifact of mankind’s first ocean voyages, ferried from its home in South America all the way to Polynesia centuries ago.
But a controversial new study on Thursday questions that assumption, using the most extensive genetic analysis yet to suggest that the sweet potato was widespread on Earth long before humans came into the picture.
Researchers at the University of Oxford say their findings show that sweet potatoes ( Ipomoea batatas) originated in South America some 800,000 years ago, and that the plant likely made its way to the Pacific island simply by seeds traveling on the wind.
“We show there is no need to invoke humanmediated transport,” said co- author Tom Carruthers, a PhD student at the University of Oxford.
“Sweet potato evolved before humans so the origin of sweet potato hasn’t got anything to do with humans.”
However, some experts questioned the findings, saying they ignore an ample amount of archeological and linguistic evidence that suggests early Polynesian marine navigators travelled to South America and brought the sweet potato back with them as early as 1000- 1100 AD.
The far- flung sweet potato has long been seen as a sign that indigenous people were capable of crossing the oceans long before Christopher Columbus’s 1492 journey.
But the notion has stoked debate as far back at the 19th century. Could such voyages really have been possible?
The study in the journal Current Biology takes a molecular biology approach to answering the riddle of how the sweet potato made it to the Pacific before Europeans.
Using the latest advances in genetic technology, researchers analyzed 199 specimens of modern and historical sweet potato worldwide, along with its wild relatives.
One sample, housed at the Natural History Museum of London, came from the Captain James Cook’s original expedition to New Zealand and the Society Islands in 1769.
By extracting DNA from various specimens, then analyzing how much they differ from each other, scientists can figure out how long ago they diverged, or had a common ancestor.
The earliest specimen of sweet potato collected from Polynesia has “a unique genetic signature suggesting that it diverged from its other samples on the American continent more than 100,000 years ago,” said the study, describing the evidence as “extremely strong” that humans had nothing to do with it.
Therefore, Carruthers, student at the University of Oxford, said it’s more likely that wind dispersal, or seeds hitching a ride on a bird or a clump of sea debris, helped the sweet potato become so widespread on Earth.