Primates in U.S. zoos

Two branches of one family tree

Primates divide into two suborders. The strepsirrhines are the lemurs, galagos and lorisids; the haplorhines are the tarsiers plus the simians, which are the monkeys and apes. The group arose 74 to 63 million years ago from small mammals that adapted to life in tropical forest canopies.

Many of the traits shared across the order are tree-living adaptations: large brains for body size, binocular and color vision, flexible shoulders and, in most species, opposable thumbs. Monkeys and apes rely more on sight and less on smell than lemurs and lorises do. The ring-tailed lemur of Madagascar and the pygmy slow loris, a nocturnal climber from Southeast Asia with a toxic bite, belong to the strepsirrhine branch.

Telling apes from monkeys

Apes have no tail and more mobile shoulder joints and arms than Old World monkeys, the result of a broad, flat ribcage and a shorter, stiffer spine. The great apes are the largest, from the bonobo at 30 to 40 kg (66 to 88 lb) up to the eastern gorilla. Gibbons are the "lesser apes": the gibbon swings arm over arm through the canopy, a movement called brachiation, at up to 55 km/h (34 mph).

Monkeys fall into two groups. New World monkeys from Central and South America mostly have long tails, and in the howler and spider monkey family those tails are prehensile. The black-handed spider monkey uses its tail as a fifth limb. Old World monkeys from Africa and Asia have tails that cannot grip, or no visible tail. They include the mandrill, the largest monkey, and the Japanese macaque, which lives farther north than any other non-human primate.

Social lives worth watching

Primates are among the most social of all animals. Depending on the species, they live in pairs, family groups, groups with one breeding male or large groups with many males and females. They develop more slowly than other mammals of similar size, mature later and live longer. Non-human primates communicate with facial expressions, hand gestures, smells and calls, and several species use tools in the wild.

On a visit, look for social grooming, which in many species removes skin parasites and cleans wounds, and for food sharing. Listen as well: the siamang inflates a throat pouch as large as its head to produce loud, resonating calls.

A largely threatened order

About 60% of primate species are threatened with extinction, including 87% of species in Madagascar, 73% in Asia, 37% in Africa and 36% in South and Central America. Large-scale tropical forest clearing, mainly for farming, is the leading threat. Hunting for bushmeat, medicine and the pet trade adds pressure, and populations of large primates over 5 kg (11 lb) recover especially slowly because they mature late and give birth at long intervals. All primate species are listed under CITES, most in Appendix II.

Breeding in human care can help. The golden lion tamarin recovered from a few hundred animals to roughly 4,800, helped by releases of zoo-born tamarins, translocations and reforestation. Programs such as the Species Survival Plan manage zoo populations of threatened species as one shared population.