Stephen Wooding

2018 Hellman Fellow

Assistant Professor, Public Health
UC Merced

Project Title:

Genetics and domestication of cassava (Manihot esculenta) a key Amazonian crop

Project Description: Plant domestication was a pivotal event in human history. By providing ample, readily available sources of food such as corn, rice, and wheat, it triggered a shift from ancient hunter-gatherer lifestyles to permanent settlement. The cultural and biological processes that led to domestication are numerous, and difficult to disentangle; however, unraveling them can reveal some of the most important chapters in modern civilization.

The Wooding laboratory is investigating the domestication of a key tropical crop, cassava. Cassava, which produces starch rich roots similar to potatoes, is little known in western nations but is an integral part of diets in the tropics. Wild cassava, which originated in the Amazon, is notoriously toxic – consumption is fatal without extensive processing. However, indigenous Amazonian peoples cultivate myriad varieties with distinct names, forms, and nutritional characteristics, including reduced toxicity, making them easy to grow, harvest, and eat. The diversity of modern cassava varieties raises numerous questions about the domestication process: How are different varieties related? Which traits were selected for and against during domestication? Was low toxicity always preferred? How do growers decide which to use, and when?

The project supported by Dr. Wooding’s Hellman Fellowship is investigating cassava domestication in the Amazon using ethnography, field experiments, and genetic analyses. On two expeditions to the upper Amazon river in PerĂº, Dr. Wooding will visit indigenous populations growing cassava to learn about traditional perspectives on diversity, analyze nutritional traits and toxicity using laboratory techniques, and collect specimens for long term study. After returning to UC Merced, he will use genetic methods to pinpoint ancient relationships among varieties, shedding light on the paths taken in the derivation of productive modern cassava types from primitive ancestors.