However, one of the most significant behavioural patterns that occurred in the evolving primates was bipedalism. Moving on to two legs, would free the upper limbs, and particularly the hands to explore objects which eventually lead to the use of tools by ape-men. To trace the origins of these animals, we have to go back some thirty million years.
At that time, one group of lower primates were increasing in size. This brought a change in the way they moved through the trees. Instead of balancing on the top of a branch and running along it, they began to swing along beneath it. Swinging successfully involves physical changes. Arms lengthened, a tail that was used for balancing, disappeared; and the musculature and skeleton of the body changed so that the backbone and abdomen was supported in vertical rather than a horizontal plane. Those changes produced the members of the Family Hominidae and include Gibbons (Hylobates); and the Great Apes which includes the Orang-Utan (Pongo pygmaeus) from Asia, the Gorilla (Gorilla gorilla), the Chimpanzee (Pan troglodytes), the Bonobo (Pan paniscus) from Africa and Humans (Homo sapiens).