Sweet potatoes exhibit a notable versatility as a tuber, serving various culinary purposes such as roasting, baking into pies, and being made into french fries. Recent research also highlights their significant role in the colonization of Polynesian islands.
Though not native to Polynesia—originating instead from Central and South America—sweet potatoes have become a fundamental component of Polynesian cuisine. While it has been established that sweet potatoes arrived in eastern Polynesia after human settlement around 900 CE and subsequently spread westward towards New Zealand, the exact methods and timelines of their arrival have been a matter of scientific debate. Some hypotheses suggest that natural means like birds, wind, and sea currents transported sweet potato seeds to the region. Current research, however, indicates that the crop’s introduction was crucial for human expansion across the Polynesian islands.
A research team led by Professor Ian Barber from the University of Otago conducted an archaeological study on the New Zealand island of Te Wāhipounamu, in search of ancient kūmara, the Maori term for sweet potatoes. The team discovered sweet potato granules in the sand of Triangle Flat, a site formerly home to a Maori farming complex, and performed carbon dating on them.
The results revealed that the crop may have been cultivated as early as 1290 CE, predating previous estimates by over 100 years and coinciding with the initial colonization of the southernmost Polynesian islands. In a study published in the journal Antiquity, Barber argued that sweet potatoes might have been among the first crops planted by colonizers, significantly contributing to the feasibility of island settlement.
Sweet potatoes are known for their resilience and rapid growth rate. Given Polynesia’s expansive network of over 1,000 islands, settlers required robust crops to sustain themselves, especially when migrating to cooler climates. Barber suggested in a press release that the availability of sweet potatoes may have encouraged Polynesians to venture across cooler waters toward southern Polynesian islands.
"American sweet potato resilience, as bequeathed by continental evolution, may have helped motivate early migrants to cross cooler waters for southern Polynesian islands where kūmara would outperform," Barber stated.
Barber’s research may have broader implications. According to the International Potato Center, sweet potato production reaches over 105 million metric tons globally each year, ranking it as the world’s fifth largest crop. However, climate change poses a threat to this production, with significant warming anticipated by 2070 in key producing regions. Barber hopes that understanding the historical spread of sweet potatoes could lead to strategies for enhancing the crop’s resilience in the face of climate change.