There are hundreds of species of primates in the world today — monkeys, lemurs, gorillas, orangutans and more in a vibrant range of shapes, sizes and colors and found in virtually every type of tropical forest.
On the basis of their physical characteristics, primates are traditionally separated into two great clans: the prosimians — generally smaller, nocturnal and possessing more primitive features — and the anthropoids, encompassing all the monkeys and apes.
IN PHOTOS: View a gallery of primates that are endangered around the world.
Geographically, primates are found in four main regions. Those of Central and South America are referred to by scientists as New World primates and are described as Neotropical; those known as Old World primates are divided between the continent of Africa, the "island continent" of Madagascar and the region of Southeast Asia.
With a shared geography comes shared evolutionary history, and the New World primates are a unique and separate group. In the Old World, three broad categories of primates coexist in the African and Asian forests:
- The prosimians, most similar to the nocturnal ancestors of all primates;
- The anthropoid or Old World monkeys, diverse and often brilliantly colored; and
- The apes, divided into the great apes — orangutans, gorillas, chimpanzees and bonobos – and the lighter-bodied "lesser apes," the gibbons and siamangs.
Finally, occupying a realm of their own are the lemurs of Madagascar, ancient and isolated for millions of years.
Want more primates? Try our interactive primate tree for detailed information about specific primates.
"Pro-simians" means "before the monkeys," and although today’s species are by no means primitive, modern prosimians retain many of the physical features that were common to the earliest true primates.
Old World monkeys of Africa and Asia are almost universally adapted to life in the daytime and have acute vision, crucial to daily life.
New World monkeys are not adapted for living on the ground; in general they avoid it, and keep to the trees whenever possible.
Restricted to the deciduous monsoon and evergreen rainforests of Southeast Asia, the lesser apes include gibbons and siamangs.
The great apes are the largest living primates, with opposable thumbs, shaggy coarse hair, and an unfurred, highly expressive face.