For the study, Higham, an assistant professor of anthropology at New York University, and co-author William Allen studied guenon monkeys, which sport all sorts of quirky facial hair, from ear tufts to beards and bushy eyebrows. Both male and female guenon monkeys have these features, to the point that humans looking at them cannot always tell which monkey is a male and which is a female.
The researchers designed a computer algorithm that could assess 500 photographs of 12 species of guenons. The images were collected in various settings, including at U.S. and U.K. zoos and at a wildlife sanctuary in Nigeria. The photos were of both male and female guenons.
"We sought to test a computer's ability to do something close to what a guenon viewing other guenons' faces would do," explained Allen, who is now a post-doctoral researcher at the University of Hull.