143 General Primate Characteristics

Key Idea: Primates exhibit unique, but quite generalised, morphological, physiological, and behavioural features. Morphological features include five digits on the hands and feet, physiological features include a longer gestation than other mammals, and behavioural features include prolonged infant dependency and keen social behaviour.

The gestation (pregnancy period) in primates is longer than most other mammals. Primates typically have one young per pregnancy (below). Infancy is prolonged with longer periods of infant dependency and a large parental investment in each offspring. This nurturing increases the survival rate of the young and allows cultural development.

The life span of a primate is generally longer than most other mammals and there is a greater dependency on highly flexible learned behaviour. Primates tend to be highly sociable (above). Unusually for mammals, adult males of many primate species often associate permanently with the group.

Chimpanzees and gorillas spend more time out of trees than do either of the Asian apes. The chimpanzee above shows typical knuckle-walking behaviour. Their relatively long arms facilitate this mode of locomotion.

RA The brain is large and generally more complex than in other mammals.

There is an emphasis on vision, the visual areas of the brain are enhanced. Well developed binocular, stereoscopic vision provides overlapping visual fields and good depth perception. Colour vision is probably present in all primates, except specialised nocturnal forms.

A trend towards a reduced snout and flattened face and reduced olfactory regions in the brain. Baboons go against this trend, with a secondary increase in muzzle length.

Primates have a generalised dental pattern particularly in the back teeth. Unspecialised teeth enabled primates to adopt a flexible omnivorous diet.

Primates have a tendency toward erectness, particularly in the upper body, as seen in the gorilla, above. This tendency is associated with sitting, standing, leaping, and (in some) walking. Gibbons are the smallest of the apes and are specialised to use brachiation (a technique of under-branch swinging), in combination with rapid climbing, midair leaps, and bipedal running, to move quickly through the forest. Monkeys walk quadrupedally on the palms of their hands and the soles of their feet. In the trees, they walk along the tops of branches, gripping them with their hands and feet.

2. Humans belong to the order Primates. Describe the features of humans that characterise their primate heritage:

The primate pictured is a white-fronted capuchin monkey (Cebus albifrons) from northern South America. These monkeys inhabit the mid-canopy deciduous, gallery forests.

Vision: Brain size and specialisation:

Face shape and snout: Collarbone:

Teeth shape and dental arrangement: Posture:

Hands and feet:

Limb joints: Reproduction: 3D

Social organisation: