The Amazing Ingredient That Helped Polynesians Conquer the Pacific

Sweet potatoes are a versatile tuber. You can grill. You can bake them into a pie. You can turn them into the third best type of stir fry. And obviously, you can make them an integral part of combining the Polynesian islands.

Sweet potatoes are not native to Polynesia, having originated thousands of miles away in Central and South America. Nevertheless, the tasty root vegetable has become a staple of the islands. Although it was known that the plant had arrived in eastern Polynesia sometime after human settlement in 900 CE, and then spread westward to New Zealand, scientists have debated how and when it got there. Some evidence shows that sweet potato seeds reached the region by natural means, such as birds, wind, and ocean currents. Now, new research shows that the presence of the plant was a major factor in allowing the population to expand throughout the Polynesian islands.

A team of archaeologists, led by University of Otago professor Ian Barber, explored the New Zealand island of Te Wāhipounamu in search of the remains of the ancient kūmara, as the Maori call the sweet potato. They found what they were looking for at Triangle Flat, a former Maori farm. In the sand, they found sweet potato granules, which they labeled with carbon.

The results showed that this plant may have been cultivated since 1290 CE, 100 years earlier than previously believed on the island, and at the same time when settlers began to collect the southern islands of Polynesia. As Barber wrote in his next study, published Wednesday in the journal Agefindings suggest that the sweet potato was among the first crops cultivated by the colonies. In fact, the discovery of the sweet potato as a crop may have been one of the factors that led to the settlement of the islands in the first place.

Vegetables are known for their hardiness, and the speed at which they grow. Polynesia is a vast chain of over 1,000 islands, and settlers needed hardy plants to sustain themselves as they spread to new areas with cooler climates than the islands near the equator. In a press release, Barber suggested that Polynesians may have been strengthened by the knowledge that they had a solid food source that they lacked.

“The robustness of the American sweet potato, as determined by the evolution of the continent, may have helped to encourage the first migrants to cross the cooler waters to the islands of southern Polynesia where the kūmara would pass,” he said.

There may be other major implications of Barber’s research. According to the International Potato Center, more than 105 million tons of the crop are produced worldwide each year, making it the fifth largest crop in the world. Climate change, however, threatens to affect production, as the regions that produce the largest amount of products could be significantly warmer by 2070. Barber expressed hope that studying the spread of sweet potatoes could reveal new ways to improve the crop’s resilience. When that happens, you’ll know who to thank for saving your favorite Thanksgiving meal.