Living primates

The essentials

Primates are an order of mammals that includes lemurs, lorises, tarsiers, monkeys, apes and humans. Most primates evolved as tree-dwellers, and many of their features are adaptations to life in trees.

Key points

• General features: grasping hands and often feet; opposable thumb (and big toe in many); nails instead of claws; forward-facing eyes giving stereoscopic (3-D) vision; colour vision in many species; reduced sense of smell; relatively large and complex brain; long period of infant dependency; usually one offspring at a time; complex social life.
• Prosimians (strepsirrhines): lemurs (Madagascar) and lorises; moist nose (rhinarium), more reliance on smell, often nocturnal.
• Tarsiers: small nocturnal primates of Southeast Asia with very large eyes.
• Anthropoids: monkeys, apes and humans.
• New World monkeys (Platyrrhini): Central and South America; broad nose with nostrils facing sideways; some have a prehensile (grasping) tail.
• Old World monkeys (Catarrhini): Africa and Asia; narrow, downward-facing nostrils; no prehensile tail; e.g. macaques, langurs, baboons.
• Apes (Hominoidea): no tail; larger brains; lesser apes (gibbons) and great apes (orangutan, gorilla, chimpanzee, bonobo). Humans are also hominoids.
• Chimpanzees and bonobos are the closest living relatives of humans.

Exam tips

• Remember the nose rule: platyrrhine = flat/broad nose, New World; catarrhine = narrow nose, Old World.
• Only some New World monkeys have prehensile tails; no Old World monkey does.
• India's primates include the rhesus macaque, the Hanuman langur, the slow loris and the hoolock gibbon (an ape).

Common mistakes

• Calling apes "monkeys": apes lack tails.
• Assuming humans evolved from chimpanzees; both share a common ancestor.