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humans in:
Primates
Primates are a part of the order Mammalia or mammals. Basically, they exist in two groups:
1) The prosimians - the lemurs, loris, and the tree shrew
2) The anthropoids - the apes, monkeys and humans
In the evolution of the tree-dwelling prosimians, the eyes of the animals moved to the front of the head, permitting binocular vision. They also developed hands with separate fingers and opposing thumbs
that could grasp and hold onto branches.
Lemurs stay mostly in the trees. The big-eyed loris and the tarsier are found in Asia. Their large eyes are set in a fixed position so that the animals must turn their heads to look to the side; their heads can rotate 180° .
About 30 million years ago a more advanced type of primate, the monkey, appeared in Africa and began to replace the lemur, with which it competed for living space and food. (The lemurs avoidedextinction as they lived in Madagascar, which was an island). A monkey's valued characteristic is its vision, which is better than that of the tree dwelling prosimians. It has three-dimensional vision like us, and its color vision is excellent.
Throughout primate evolution, a trend toward size increase is evident. Many monkeys use their tail to grip the branches, while others like the baboon live on the ground. When the apes became too large to walk along a branch safely, they began swinging under it on their arms. The most acrobatic is the gibbon. Among the great apes, however, the orangutan stays mostly in the trees. As the higher primates became larger, so did their brains. The first hominids (prehuman apes) appeared about 3 million years ago. Read about human evolution to know more.
