Arboreal theory Arboreal theory This theory is proposed by Grafton Elliott-Smith (1912) who was a neuroanatomist who was chiefly concerned with the emergence of the primate brain. The arboreal theory claims that primates evolved from their ancestors by adapting to arboreal life. Primates are thought to have developed several of their traits and habits 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, perhaps because of the constant leaping that was necessary to move about the trees. Primates also developed hands
Sexual dimorphism in non-human primates to the likelihood of higher vulnerability to predators. Another hypothesis suggests that arboreal primates have limitations on their upper body size, given that larger body size could disrupt their usage of terminal branches for locomotion. However, among some species of guenons ("Cercopithecus"), arboreal blue monkeys ("C. mitis") appear to be more sexually dimorphic than terrestrial vervet monkeys ("C. aethiops"). It has been hypothesized that niche divergence between the sexes attributes to the evolution of size dimorphism in primates. Males and females are known to have different preferences for ecological habitat due to different reproductive activities, which could possibly lead to