A primate is any mammal belonging to the group that includes lemurs , lorises , tarsiers , monkeys , apes , and humans . The order Primates contains more than 500 species and is the third most diverse order of mammals, after rodents and bats. Primates share characteristics, including a large brain (relative to body weight) and a fissure unique to primates that separates the visual areas in the brain. While other mammals have claws or hooves, primates have flat nails, and most have grasping feet. Primates are mainly tropical, found in Africa, India, Southeast Asia, and South America. However, the numbers of many primate species are declining, with over 70% in Asia and roughly 40% in South America and Africa listed as endangered.

How are primates different from other mammals?

Primates share key traits, setting them apart from other mammals. Most mammals rely on smell, but primates emphasize sight and touch, leading to brain changes. The primate brain is larger relative to body size, with a unique fissure separating visual areas. Unlike other mammals, primates have flat nails instead of claws or hooves. Most have grasping hands and feet, with the big toe diverging to grip objects. Catarrhines (Old World monkeys, apes, and humans) have opposable thumbs for precise manipulation. These features support an arboreal lifestyle, which is common among primates.

What are some examples of primates?

Primates are mammals that include more than 500 species, such as lemurs , lorises , tarsiers , monkeys , and apes (including humans). Examples of primates: * Old World Monkeys Baboons, guenons, macaques, drills, and mandrills * New World Monkeys Marmosets, capuchins, and howler monkeys * Apes Gibbons, chimpanzees, orangutans, gorillas and humans Primates share traits like forward-facing eyes, grasping feet, and larger brains relative to body weight compared to other terrestrial mammals.

Where do most primates live?

Most nonhuman primates live in the tropical latitudes of Africa, India, Southeast Asia, and South America. Rainforests are the ancestral home and principal habitat of nonhuman primates. These forests have evergreen broad-leaved trees that form a closed canopy, thick-stemmed lianas, and three strata: an understory, a middle story, and an upper story. Primates also live in tropical grasslands, or savannas, in Africa and Asia. Some primates inhabit tropical montane forests or tropical rainforests at high altitudes in Africa, Asia, and South America. However, many primate species' numbers are declining steeply. More than 70 percent of primates in Asia and roughly 40 percent of primates in South America, mainland Africa, and Madagascar are listed as endangered.

What special features help primates survive in their habitats?

Primates exhibit a combination of traits that enable them to thrive in their habitats. Their unspecialized structure coupled with behavioral adaptability allows them to exploit various ecological opportunities. Key features include: * Grasping hands and feet Primates have sensitive, grasping hands and feet with opposable thumbs and big toes, which aid in climbing and ensure stability on branches. * Stereoscopic vision Forward-facing eyes provide accurate depth perception, crucial for arboreal life. * Brain structure Primates possess brains that are large relative to their body size, with a complex cerebral cortex that processes sensory information and converts it into motor actions. * Dietary Adaptations While many primates are omnivorous, their diet is a factor of their ecology and has played a role in their dispersion and adaptive radiation, as well as in the development of their teeth, jaws, and digestive system. * Social Living Most apes live in groups, giving them advantages when it comes to raising young, protection, and overall survival.

How are humans related to other primates?

Humans are classified within the order Primates, a diverse group of mammals that includes lemurs , lorises , tarsiers , monkeys , and apes . The evolutionary lineage leading to modern humans diverged from that of chimpanzees, their closest living relatives, around 7 million years ago. Primate characteristics include a relatively large brain compared to body weight, specialized nerve endings increasing tactile sensitivity, and flat nails instead of claws. The most distinctive feature of primates is the grasping hands (and feet except in humans), which have opposable thumbs that enable a precision grip.

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Images & Videos

Illustration comparing the body plans of representative anthropoids, showing a male western lowland gorilla, a male human, a male bonobo, a female Bornean orangutan, and male and female northern white-cheeked gibbons, all labeled and depicted to scale.

The video thumbnail image shows two black and white photos of monkey and ape heads, surrounded by blue and pink circles.

Illustration of a male western lowland gorilla (Gorilla gorilla gorilla) standing on all fours, showing its muscular build, dark fur, and prominent brow ridge, with a scale bar below for size reference.

A common chimpanzee (Pan troglodytes) sits on a rock holding a long blade of grass in its mouth, with dense green foliage in the background.

mountain gorilla (Gorilla gorilla beringei)

Two Japanese macaques at Jigokudani Monkey Park in Nagano, Japan, with one grooming the other's fur as they sit close together.

At a Glance

primate summary

primate

mammal

Also known as: Primates

Written by

J.R. NapierAll

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Britannica Editors

Last updated

Oct. 30, 2026 •History

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primate, in zoology, any mammal of the group that includes the lemurs, lorises, tarsiers, monkeys, apes, and humans. The order Primates, including more than 500 species, is the third most diverse order of mammals, after rodents (Rodentia) and bats (Chiroptera).

Although there are some notable variations between some primate groups, they share several anatomic and functional characteristics reflective of their common ancestry. When compared with body weight, the primate brain is larger than that of other terrestrial mammals, and it has a fissure unique to primates (the Calcarine sulcus) that separates the first and second visual areas on each side of the brain. Whereas all other mammals have claws or hooves on their digits, only primates have flat nails. Some primates do have claws, but even among these there is a flat nail on the big toe (hallux). In all primates except humans, the hallux diverges from the other toes and together with them forms a pincer capable of grasping objects such as branches. Not all primates have similarly dextrous hands; only the catarrhines (Old World monkeys, apes, and humans) and a few of the lemurs and lorises have an opposable thumb. Primates are not alone in having grasping feet, but as these occur in many other arboreal mammals (e.g., squirrels and opossums), and as most present-day primates are arboreal, this characteristic suggests that they evolved from an ancestor that was arboreal. So too does primates’ possession of specialized nerve endings (Meissner’s corpuscles) in the hands and feet that increase tactile sensitivity. As far as is known, no other placental mammal has them. Primates possess dermatoglyphics (the skin ridges responsible for fingerprints), but so do many other arboreal mammals.

The eyes face forward in all primates so that the eyes’ visual fields overlap. Again, this feature is not by any means restricted to primates, but it is a general feature seen among predators. It has been proposed, therefore, that the ancestor of the primates was a predator, perhaps insectivorous. The optic fibres in almost all mammals cross over (decussate) so that signals from one eye are interpreted on the opposite side of the brain, but, in some primate species, up to 40 percent of the nerve fibres do not cross over.

Primate teeth are distinguishable from those of other mammals by the low, rounded form of the molar and premolar cusps, which contrast with the high, pointed cusps or elaborate ridges of other placental mammals. This distinction makes fossilized primate teeth easy to recognize.

Fossils of the earliest primates date to the Early Eocene Epoch (56 million to 41.2 million years ago) or perhaps to the Late Paleocene Epoch (59.2 million to 56 million years ago). Though they began as an arboreal group, and many (especially the platyrrhines, or New World monkeys) have remained thoroughly arboreal, many have become at least partly terrestrial, and many have achieved high levels of intelligence. It is certainly no accident that the most intelligent of all forms of life, the only one capable of constructing the Encyclopædia Britannica, belongs to this order.

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By the 21st century the populations of approximately 75 percent of all primate species were falling, and some 60 percent were considered either threatened or endangered species. Habitat loss and fragmentation from logging, mining, urban sprawl, and the conversion of natural areas to agriculture and livestock raising are the primary threats to many species. Other causes of widespread population declines include hunting and poaching, the pet trade, the illegal trade in primate body parts, and the susceptibility of some primates to infection with human diseases.

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