As apes have emerged in the monkey group as sister of the old world monkeys, characteristics that describe monkeys are generally shared by apes as well. Williams et al outlined evolutionary features, including in stem groupings, contrasted against the other primates such as the tarsiers and the lemuriformes.The many species of monkey have varied relationships with humans. Some are kept as pets, others used as model organisms in laboratories or in space missions. They may be killed in monkey drives or used as service animals for the disabled.
