Climate change influenced nonhuman primate evolution by forcing the evolution of species and creating new environments that allowed for primates to live. "A rapid temperature increase around 55 mya ... led to an expansion of evergreen tropical forests, the environment that made possible many mammalian groups, including primates." (pg. 260). As rapid temperature increase created new environments a rapid cooling in the beginning of the Oligocene limited the range of habitats greatly. Due to this reduction a majority of the primates during this time lived around the fayum region in northeast Africa. As seen by looking at the geologic time scale it is clear that different environments allow for different evolution to occur.

The three theories