ABSTRACT
When most people go to the zoo, they have two visits in mind: first to the big cats—the lions, leopards, and tigers—and second to “see the monkeys.” Here “monkeys” means primates in general, including the prosimians, small apes, orangutans, chimpanzees, and gorillas as well as true monkeys. As we stand in front of their cages or look at them from outside their enclosures, we can’t help but compare their outer appearance and behavior with our own. More so than the big cats or any other animal in or outside the zoo, the primates look a lot like us. And even more tantalizing, they behave a lot like us. Of course, this is for good reason—we humans are primates, too. All primates had a common ancestor some 63 myr ago but diverged into different lineages at that point, with many groups eventually becoming extinct and the successful ones evolving into modern times.
