Scientists debunked a long-held American superfood myth

I yam going to tell you the real story.
I yam going to tell you the real story.
Image: AP Photo/Melissa d'Arabian
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Sweet potatoes have occupied a spot at Thanksgiving dinner tables in the US for more than a century, largely because American history books often cite the root vegetable as one of the country’s native plants. But there’s a good chance the story Americans tell themselves about sweet potatoes is nothing but a myth.

According to a new study published this week in the Proceedings of the National Academy of Sciences, the vegetable may actually be an immigrant from Asia. The sweet potato is part of the morning glory family, and scientists have long believed it originated in North America about 35 million years ago, thanks to plant-fossil evidence. But a research team at Indiana University uncovered and identified 17 much older morning glory leaf-fossil specimens while on a trip to Meghalaya in northeast India, some dating back 57 millions years.

“I think this will change people’s ideas,” one of the researchers said in a statement. “It will be a data point that is picked up and used in other work where researchers are trying to find the time of the evolution of major groups of flowering plants.”

The researchers note the leaves they found are in the genus Ipomoea, which includes sweet potatoes, but also includes hundreds of other plants. So technically scientists can’t yet say for certain that sweet potatoes were growing in that region—or even if they were, that they resembled what we eat today.

Regardless of where it came from, the sweet potato is among the world’s most important crops today. That’s because it packs a nutritious punch and can be easily grown just about anywhere. During the US Great Depression, sweet potatoes rose in popularity because they were cheap and recognized as good for health.

Starting in the 1940s, however, after US soldiers returned home from war, the economy bounced back. People could afford to buy russet potatoes from stores, and the newly-industrialized farming system hit the sweet-potato market hard, sending production plummeting.

The sweet potato caught on again, though, in the 2000s, appearing in many fad diets, including the South Beach (which was created in 2003), paleo, and Atkins eating regimens. Since then, the health community has crowned the sweet potato a superfood, and the US farmers who grow it have enjoyed a sizable market rebound after a decades-long decline. And for now, it doesn’t appear the trend is going to slow anytime soon.