Human Origins and the Great Apes

Evolution of human origins

Human origin is widely portrayed as a fairly straightforward and unproblematic story of evolution from a common ancestor shared with the chimpanzee and bonobo in Africa about 6-7 million years ago. This model is principally based on the greater DNA base similarity shared between humans, chimpanzees, and bonobos compared with gorillas and orangutans. I

It is widely assumed and accepted that this molecular similarity is proof of their being most closely related to each other. But the molecular assumption is contradicted by the numerous phenotypic features uniquely shared by living and fossil hominids and orangutans. The nature of this contradiction is presented in the following web page on the evolution of humans and orangutans. 

Humans and Orangutan origins
 

Fossil apes and hominids

 Terrestrial or arboreal?

Many models of evolution have argued that major evolutionary developments in the human or hominid lineage occured after the first human ancestors adopted a fully terrestrial mode of living. Various features of early hominids are now recognized as being functionally correlated with arboreal living even after the evolution of obligate bipedalism. This raises the question as to whether hominids lived and built their shelters on the ground was an early or late development.

Canopy ecologist Donald Perry argues that many evolutionary developments in humans owe their origin to arboreal, rather than terrestrial, living, and the trasition from arboreal to terrestrail living may have occured comparatively late in human evolution.

Perry, D.R. 2010. Interpreting evidence. In 21st Century Anthropology, Ed. by H. James Birx. Thousand Oaks, SAGE Publications, Vol. 2, pp. 361-369. pdf