A team of researchers with the Lester E. Fisher Center for the Study and Conservation of Apes and the Urban Wildlife Institute, Lincoln Park Zoo, has found that two species of great apes tend to look longer at unfamiliar human faces than those of people they know. In their paper published in the journal Proceedings of the Royal Society B, the group describes experiments they conducted with chimpanzees and gorillas at the Lincoln Park Zoo in Chicago and what they learned about the interests of great apes.