Primates

A primate is a member of the biological order Primates, the group that contains lemurs, the Aye-aye, lorids, galagos, tarsiers, monkeys, and apes, with the last category including humans. With the exception of humans, who now inhabit every continent on Earth, most primates live in tropical or subtropical regions of the Americas, Africa and Asia Primates range in size from the 30-gram (1 oz) Pygmy Mouse Lemur to the 200-kilogram (440 lb) Mountain Gorilla. According to fossil evidence, the primitive ancestors of primates may have existed in the late Cretaceous period around 65 mya (million years ago), and the oldest known primate is the Late Paleocene Plesiadapis, c. 55–58 mya. Molecular clock studies suggest that the primate branch may be even older, originating in the mid-Cretaceous period around 85 mya

Primate species move by brachiation(swinging in between trees), bipedalism (moving on the two hindlimbs), leaping, quadrupedalism (moving on all four limbs), climbing, knuckle-walking or by a combination of these methods. Several prosimians are primarily vertical clinger and leapers. These include many bushbabies, all indriids (i.e., sifakas, avahis and indris), sportive lemurs, and all tarsiers. Other prosimians are arboreal quadrupeds and climbers. Some are also terrestrial quadrupeds, while some are leapers. Most monkeys are both arboreal and terrestrial quadrupeds and climbers. Gibbons, muriquis and spider monkeys all use brachiation extensively. Woolly monkeys also sometimes brachiate. Orangutans use a similar form of locomotion called quadramanous climbing, in which they use their arms and legs to carry their heavy bodies through the trees. Chimpanzees and gorillas knuckle walk, and can move bipedally for short distances. Although numerous species, such as the Australopithecines and early hominids, have exhibited fully bipedal locomotion, humans are the only extant species with this trait.

Lemurs, lorises, tarsiers, and New World monkeys rely on olfactory signals for many aspects of social and reproductive behavior. Specialized glands are used to mark territories with pheromones(chemicals), which are detected by the vomeronasal organ; this process forms a large part of the communication behavior of these primates. Primates also use vocalizations, gestures, and facial expressions to convey psychological state.

Primates have slower rates of development than other mammals. All non-human primate infants are breastfed by their mothers and rely on them for grooming and transportation. In some species, infants are protected and transported by males in the group, particularly males who may be their fathers. Other relatives of the infant, such as siblings and aunts, may participate in its care as well. Most primate mothers cease ovulation while breastfeeding an infant; once the infant is weaned(introduced to its adult diet) the mother can reproduce again. This often leads to weaning conflict with infants who attempt to continue breastfeeding.Primates have a longer juvenile period between weaning and sexual maturity (being able to reproduce) than other mammals of similar size. During the juvenile period, primates are more susceptible than adults to predation and starvation; they gain experience in feeding and avoiding predators during this time They learn social and fighting skills, often through playing.Primates, especially females, have longer lifespans than other similarly sized mammals.

Primates exploit a variety of food sources. Most primates include fruit in their diets to obtain easily digested carbohydrates and lipids for energy. However, they require other foods, such as leaves or insects, for amino acids, vitamins and minerals. Many primates have anatomical specializations that enable them to exploit particular foods, such as fruit, leaves, gum or insects. For example, leaf eaters such as howler monkeys, black-and-white colobuses and sportive lemurs have extended digestive tracts to enable them to absorb nutrients from leaves that can be difficult to digest. Marmosets, which are gum eaters, have strong incisor teeth, enabling them to open tree bark to get to the gum, and claws rather than nails, enabling them to cling to trees while feeding. The Aye-aye combines rodent-like teeth with a long, thin middle finger to fill the same ecological niche as a woodpecker. It taps on trees to find insect larvae, then gnaws holes in the wood and inserts its elongated middle finger to pull the larvae out. Some species have additional specializations. For example, the Grey-cheeked Mangabey has thick enamel on its teeth, enabling it to open hard fruits and seeds that other monkeys cannot.The Gelada is the only primate species that feeds primarily on grass. Tarsiers are the only carnivorous primates, exclusively eating insects, crustaceans, small vertebrates and snakes (including venomous species). Capuchin monkeys, on the other hand, can exploit many different types of food, including fruit, leaves, flowers, buds, nectar, seeds, insects and other invertebrates, bird eggs, and small vertebrates such as birds, lizards, squirrels and bats. The Common Chimpanzee has a varied diet that includes predation on other primate species, such as the Western Red Colobus monkey.

Primates evolved from arboreal animals, and many species live most of their lives in trees. Most primate species live in tropical rain forests. The number of primate species within tropical areas has been shown to be positively correlated to the amount of rainfall and the amount of rain forest area. Accounting for 25% to 40% of the fruit-eating animals (by weight) within tropical rainforests, primates play an important ecological role by dispersing seeds of many tree species.Some species are partially terrestrial, such as baboons and Patas Monkeys, and a few species are fully terrestrial, such as Geladas and Humans. Non-human primates live in a diverse number of forested habitats in the tropical latitudes of Africa, India, Southeast Asia, and South America, including rainforests, mangrove forests, and montane forests. There are some examples of non-human primates that live outside of the tropics; the mountain-dwelling Japanese Macaque lives in the north of Honshu where there is snow-cover eight months of the year; the Barbary Macaque lives in the Atlas Mountains of Algeria and Morocco. Primate habitats span a range of altitudes: the Black Snub-nosed Monkey has been found living in the Hengduan Mountains at altitudes of 4,700 meters (15,400 ft), the Mountain Gorilla can be found at 4,200 meters (13,200 ft) crossing the Virunga Mountains, and the Gelada has been found at elevations of up to 5,000 meters (16,400 ft) in the Ethiopian Highlands. Although most species are generally shy of water, a few are good swimmers and are comfortable in swamps and watery areas, including the Proboscis Monkey, De Brazza's Monkey and Allen's Swamp Monkey, which has developed small webbing between its fingers. Some primates, such as the Rhesus Macaque and gray langurs, can exploit human-modified environments and even live in cities.

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