Primatologists' subjects are typically APES, which are a group of mammals that includes gorillas, chimpanzees, orangutans, and bonobos. Primatology is the scientific study of primates, which are a group of mammals that includes monkeys, APES, and humans. Primatologists study the behavior, ecology, and evolution of these animals in their natural habitats. Primatologists' subjects can also include other species of primates such as lemurs, lorises, and tarsiers.