What’s the Difference Between New World and Old World Monkeys?

New World monkeys are found from southern Mexico to central South America, except in the high mountains. They are more primitive than Old World monkeys. Their brains are less complex, their thumbs, when present, are not opposable, and their nostrils are further apart and tend to point outward. Most have 36 teeth. They have slender bodies and limbs with long narrow hands. Most have a prehensile or partially prehensile tail.

New World monkeys include marmosets, tamarins, capuchins, spider monkeys, woolly monkeys, howler monkeys, squirrel monkeys, owl monkeys, the saki, and the auakari.

Old World monkeys are found in southern Asia, with a few species as far north as Japan and northern China, and in all of Africa except the deserts. The tails of Old World monkeys are never prehensile. Their nostrils are close together and tend to point downward. Many species have cheek pouches to hold food, and many have thick pads on their buttocks. They have 32 teeth. Old World monkeys are more closely related to the apes and humans than they are to the new world monkeys.

Old World monkeys include the many species of macaque, baboons, mandrills, mangabeys, colobus monkeys, langurs, leaf monkeys, proboscis monkeys, and guenons.