The remarkable voyage of the sweet potato

A group of scientists recently gathered nearly 200 samples of sweet potato varieties and related species from a host of herbariums and botanical collections.

A group of scientists recently gathered nearly 200 samples of sweet potato varieties and related species from a host of herbariums and botanical collections. (KarepaStock, Shutterstock)


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Estimated read time: 4-5 minutes

SALT LAKE CITY — When the Wampanoag people and Puritan pilgrims shared their famous harvest meal in the autumn of 1621, it's not likely that they had sweet potatoes on the menu like we often do at Thanksgiving.

Although native to Central and South America, the sweet potato hadn't been introduced to New England by the time the first Thanksgiving celebration happened. But like those on the Mayflower, it had nonetheless sailed across the salty seas to other places.

From America, the sweet potato found its way across the Pacific to Polynesia, where it has been known as "kumara" for hundreds of years. Similarly, it is known as "kumar" by the Quechua people of South America where it has been cultivated for the past 4,000 years or so, according to research from the Library of Congress. Some archaeologists believe this is no coincidence. They see the similar names as supporting evidence that seafaring Polynesians expanded their ancient trade routes to South America, arriving at the New World before the Europeans did.

However, the sweet potato's DNA might tell a different version of this story.

A group of scientists recently gathered nearly 200 samples of sweet potato varieties and related species from a host of herbariums and botanical collections. One of the samples was even collected in 1769 by botanists aboard Captain James Cook's expedition to Polynesia. After comparing the genomes of these samples, they reported that the variety of sweet potato found in Polynesia has probably been growing there for thousands of years before the arrival of humans. In other words, seeds or plants might have made that voyage across the Pacific with the help of birds or floating debris – not humans.

Not everyone in the ivory towers of sweet potato research is sold on this explanation, as noted in a 2018 article published in the journal Nature. And so for now, the science on the matter remains unsettled.

What is far more certain is how the sweet potato made its way across the Atlantic. Cultivations of the crop were commonplace in the Caribbean islands when Columbus and his crew arrived. And when they navigated their caravel and carrack ships back to Europe, they brought sweet potatoes along with them. Thus began the introduction of this American staple to the Old World. It quickly spread across Europe, into Africa and Asia, eventually circumnavigating all the way back around to the Pacific and arriving in Japan by 1605, Stripes Okinawa says.

Outside the Caribbean-adjacent southern states — and except for on Thanksgiving — most North Americans ignored the sweet potatoes in the grocery aisle for many years, if they were stocked there at all. But that has changed recently. Data from the USDA shows that farmers are producing more than twice as many sweet potatoes now than they were in the decades prior to 2000.

One might imagine that the American path to sweet potato acceptance was blazed by the regular potato (only a distant relation) when fast food introduced us all to french fries. It wasn't long until julienned sweet potatoes found their way into the deep fryer too, and now many customers of burger joints will gladly pay a dollar more to upgrade their fries to the sweeter orange variety.

There might be a few other reasons why we are eating more sweet potatoes, according to Professor Daniel Drost, a vegetable specialist with the Utah State University agriculture extension.

First, Drost says that more of us are realizing how nutritious sweet potatoes are. "Popularity of the sweet potato is due to its nutritional content," he said, noting that they are high in carbohydrates and also full of vitamins A and C, and high in calcium and iron, too. "So, they are really good for you."

Second, Drost noted that "they are now available year-round." In the past, it was hard to find sweet potatoes regularly except for around the holidays, but now there are even several varieties to choose from.

"Common orange-fleshed varieties include Beauregard, Covington and Jewel," Drost said. Sometimes these are mislabeled as yams, but real yams are from Africa and are less common at most American grocery stores.

And finally, the sweet potato is a convenient and versatile vegetable that also stores well.

"They are easy to prepare, just like regular potatoes," Drost said, adding that he often uses them to add a subtle sweetness to his roasted vegetable mix of onions, brussels sprouts, carrots and parsnips.

There are many other ways that sweet potatoes will be prepared this holiday season. Whether baked, fried, mashed, or in pie, we can all be thankful that this delicious orange root made a remarkable voyage that somehow landed it on our plates.


About the Author: Robert Lawrence

Robert Lawrence is a science editor based in New York. He enjoys his sweet potatoes cubed and sautéed in olive oil with a bit of sea salt. You can find more of his work at: www.robertlawrencephd.com

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