Primates range from a 30-gram mouse lemur to a 200-kilogram gorilla
The primate order spans Madame Berthe's mouse lemur, lighter than a letter, and the eastern gorilla, heavier than two grown men. Scientists count between 376 and 524 living species depending on the system, and they keep finding more: 36 new species were described in the 2010s alone.
Primates emerged between 74 and 63 million years ago from small ground-dwelling mammals that took to tropical forests. Life in the treetops shaped their signature features: big brains for their body size, forward-facing eyes with depth and colour vision, flexible shoulders, and in most species opposable thumbs for gripping. Compared with most mammals, they lean on sight rather than smell, a trend strongest in monkeys and apes and weaker in lemurs and lorises. Even ground dwellers such as gorillas, baboons and humans keep adaptations for climbing.
The order divides into strepsirrhines, the lemurs, galagos and lorises, and haplorhines, the tarsiers plus monkeys and apes. Movement styles vary from leaping and arm-over-arm swinging called brachiation to knuckle-walking and upright walking. Primates are highly social, living in pairs, harems or large mixed groups, and they grow slowly, mature late and live long for their size. Non-human species use tools and communicate with gestures, scents and calls.
The name comes from Latin for first or chief; Linnaeus chose it because he considered primates the highest animals. Everyday labels cause confusion. Terms like prosimian, monkey and ape describe groups that leave out some descendants of a shared ancestor. Monkeys, for instance, exclude apes, which evolved from the same lineage, and apes exclude humans unless the word is stretched, as the palaeontologist Michael Benton did in 2005 by including people among the apes.
Close contact between people and other primates can spread viruses such as herpes, measles, Ebola and rabies, and thousands are used in research because they resemble humans. About 60 percent of species face extinction, chiefly from forest clearance for agriculture, along with hunting for food, medicine and the pet trade.
Source: Primate
