Ursula Moser Cowgill (9 November 1927 – November 27, 2015) was a biologist and anthropologist who worked for Yale University, Dow Chemical Company and the University of Colorado during the second half of the 20th century. Her work includes studies of agricultural practices in pre-Columbian Mesoamerica, seasons of birth in human beings, the relationship between cultural gender bias and infant mortality, and the possible role of selenium in reducing mortality from AIDS. She also looked after four pottos for many years and published a series of observations on their behaviour. Cowgill earned a PhD from Iowa State University in 1956. Later she worked as an analytical chemist for the limnologist G. Evelyn Hutchinson. Her first journal articles, some published jointly with Hutchinson, appeared in the early 1960s. Cowgill was living in Colorado as of 2003. In addition to her scientific research, she was an activist with the American Civil Liberties Union. Work and findings Pottos In 1959, three pairs of pottos from West Africa arrived at Yale's Osborn Zoological Laboratory. At first they lived in the laboratory with a number of other nocturnal prosimians that Cowgill and Hutchinson were studying. In 1964, Cowgill took two of the pairs to live with her. She looked after them until 1981, when she gave the sole surviving male to a colleague. While the pottos were with her, Cowgill published a number of journal articles on their anatomy, diet, reproduction, illnesses and recovery, and social behaviour. These publications constitute one of the few long-term studies of pottos in captivity. Maya agriculture Between 1961 and 1963, Cowgill and Hutchinson made studies of soil in the Petén Basin, Guatemala, with the aim of learning about the effects of agricultural practices of the pre-Columbian Maya civilization. Their findings reported that Maya cultivation methods had gradually robbed the soil of vital elements, meaning that it eventually became unable to sustain crops. Some scholars have linked this exhaustion of the soil to the 10th-century decline of the Maya urban settlements in the Petén region. Sex ratio and childhood mortality Cowgill's research into gender and child mortality covered both historical records in England and contemporary observations in Guatemala. Using birth and death records from the parish registers of York between 1538 and 1812, Cowgill found that throughout the city's history, girls at every stage of childhood had died at a higher rate than boys of the same age. This resulted