A nutrient-rich, inexpensive plant that thrives in warm temperatures and can be eaten from root to leaf? It’s called taro, and William & Mary researchers are documenting its sustainability, starting on the small island of Rurutu, Eastern Polynesia, with support from the Interdisciplinary Research Innovation Fund.
W&M anthropologist Jennifer Kahn and biologists Harmony Dalgleish and Joshua Puzey are investigating taro farming on Rurutu at the intersection of environment, genetics and culture. Anthropology graduate students Caroline Donovan M.A. ’24 and Lindsay Bliss M.A. ’25 have already done fieldwork on the island with Kahn and Dalgleish during the past winter break; more students will be involved both in the field and in the lab.
This project is a case study for sustainable agriculture and food security in the context of climate change. It also speaks to the university’s Vision 2026 themes of water (examining wetland systems), democracy (represented by small holder farmers’ practices), data (from genomic analysis) and careers (involving students as well as the local community).
‘A very important species globally’
A starchy tuber native to Southeast Asia, taro (Colocasia esculenta) has long been a staple food in several tropical and subtropical regions. Only edible when cooked, it’s described by Kahn and Dalgleish as tasting similar to a potato or a turnip, but with a hint of carrot and a chewier texture.
“As a foodstuff that could be grown under wet or dry conditions, with climate change taro could be a very important species globally,” said Kahn.
Rurutu is one of the last places in Eastern Polynesia to practice intensive irrigated taro agriculture. On the island, an established tradition of subsistence farming is meeting a shift to commercial farming.
Circa 900 years ago, Polynesian settlers introduced taro (kalo in Hawaiian) to Rurutu: However, as Kahn’s archaeology excavations recently revealed, intensive farming did not start at least until one century later.
This switch might have been sustainable – or not. Analyzing the evolution of soil nutrients through time will help researchers understand whether land was either overused or farmed sustainably.
In Rurutu, taro is still farmed following traditional practices; banana leaves and coconut fronds are used in mulching to prevent weed growth and to retain moisture. However, non-traditional methods have also been introduced, with cardboard, plastic rice bags and large plastic sheets used for mulch.
Dalgleish is interested in testing the effects of these newer cultivation practices on the soil and water. For example, dyes and microplastics leaching from irrigated terraces into the lagoons would have considerable consequences for the islanders, who rely heavily on subsistence fishing.
In the short term, explained Dalgleish, using plastic as mulch may boost productivity by heating up the soil and increasing microbial activity; however, this may lead to reduced productivity in the longer term, with microbes not having as much organic matter to feed on.
“We think about soil as dirt, and dirt is dead matter,” said Puzey. “But soil is living: It has a lot of biological activity, and it’s a very important resource if we think about how we can feed the world.”
Kahn and Dalgleish will return to the island this summer; Puzey is about to start DNA sequencing of the samples they brought back from their winter expedition.
The research team is also examining the genetic variation of taro in combination with historical and archaeological records – including museum samples – and ethnobotanical interviews. This work will help reconstruct patterns of Polynesians’ migration history as well as find out whether heirloom varieties of taro survive on the island.
“It was the number and diversity of types of taro that really struck me,” said Dalgleish. She thought there was an ecological reason for intermixing multiple plants in the same plot but then found out that farmers were just planting what they had.
“It’s really fascinating, and I don’t know what the consequences might be for sustainability in the long term,” she said.
‘A democratizing practice’
Taro, explained Kahn, is not just food for Rurutuans: It’s a part of their identity.
Taro patterns are found on many traditional quilts (tifaifai); the plant is central to a foundational myth starting with Hina – a name attributed to different Polynesian deities – here represented as a witch-like creature stealing taro from the farmers.
Many farmers still plant according to the lunar calendar, for reasons that are more spiritual than biological or ecological.
“Many people on the island describe it as a connection to their ancestors,” said Kahn. “One farmer said that teaching their kids how to farm taro is a direct way of teaching them about their culture.”
Kahn defined taro farming as a democratizing practice: All Rurutuans inherit land through their families and have access to specialized knowledge about taro planting.
“Taro is a plant that requires labor but not any specialized machinery to crop,” she said. “Anyone with the time and inclination can be a taro farmer.”
Taro remains so important for the island’s identity that Rurutuans are developing a dedicated museum, which will directly benefit from findings from this research.
The island’s mayor and Council of Elders are consulting with the team, which also includes Rurutuans who participate in the excavation. Kahn always aims to involve the local community in her research to ensure continued cultural sensitivity. A citizen-science component is also part of the project, as students from a local vocational school will help conduct farmer interviews and taro species surveys this summer.
Engaging with the local community was an unforgettable experience for Bliss, who began research for her thesis in Rurutu.
Donovan, too, cited working with the local community as a highlight. As an early-career researcher, being involved in a multidisciplinary project gave her the opportunity to work on archaeological excavations and learn more about biology but also to see how everything fit together.
“This really shows how interdisciplinary the project is and how we’re each bringing something to the table when we share these interests,” said Kahn. “Working together brings up questions that we wouldn’t have thought of on our own.”
Antonella Di Marzio, Senior Research Writer