Tyrone Hayes, a biologist at the University of California, Berkeley, has devoted the past fifteen years to studying the herbicide atrazine, which is applied to more than half the corn in the country. During that time scientists around the world have expanded on his findings, suggesting that the herbicide is associated with birth defects in humans as well as in animals. Company documents show that while Hayes was studying atrazine, Syngenta, the agribusiness firm which had originally asked him to conduct experiments on the herbicide, was studying him, as he had suspected for years. Syngenta’s notes reveal that the company’s employees struggled for years to make sense of him.