Broadly, there are two types of monkey, which can be distinguished by which side of the Atlantic Ocean – or, indeed, the Pacific – they live on. Old World monkeys are native to Africa, Asia and Europe, whereas New World monkeys all live in South and Central America.
The terms Old World and New World were coined by Europeans after Christopher Columbus’s famous voyages of discovery. But he wasn’t the first primate to cross the Atlantic.
There was a time when all monkeys lived in the Old World. But about 50 million years ago, some of them made it to South America, perhaps on a raft of vegetation (the Atlantic wasn’t as wide as it is now), where they gave rise to the sakis, howlers, uakaris, capuchins, squirrel monkeys, spider monkeys, marmosets and tamarins we see there today.
Meanwhile, the Old World lineage produced the baboons, vervets, langurs, colobus, mangabeys and macaques, among others. It also gave rise, about 30 million years ago, to the apes, which means that Old World monkeys are more closely related to chimps, gorillas and ourselves than they are to New World monkeys.