The arboreal theory claims that

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

s evolved from their ancestors by adapting to

arboreal Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...

life.Sussman, R. W. (1991)
Primate origins and the evolution of angiosperms
American Journal of Primatology, 23(4), 209-223. It was proposed by

Grafton Elliot Smith Sir Grafton Elliot Smith (15 August 1871 – 1 January 1937) was an Australian-British anatomist, Egyptologist and a proponent of the hyperdiffusionist view of prehistory. He believed in the idea that cultural innovations occur only once and ...

(1912), a neuroanatomist who was chiefly concerned with the emergence of the primate brain. Primates are thought to have developed several of their traits and

habits A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.

initially while living in trees. One key component to this argument is that primates relied on sight over smell. They were able to develop a keen sense of

depth perception Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsis an ...

, perhaps because of the constant leaping that was necessary to move about the trees. Primates also developed

hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "h ...

s and feet that were capable of grasping. This was also a result of arboreal life, which required a great deal of crawling along branches, and reaching out for fruit and other food. These early primates were likely to have eaten foods found in trees, such as flowers, fruits, berries, gums, leaves, and insects. They are thought to have shifted their diets towards insects in the early

Cenozoic era The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

, when insects became more numerous.

References

{{DEFAULTSORT:Arboreal Theory Theories Evolutionary biology