Subject: Did the Rift Valley separate the apes from the humans?

I've read that the Great Rift Valley appeared about 7 million years ago, 
separating the eastern portion of Africa from the western part. This 
geographical change caused the eastern part to become a drier, more 
savannah-like climate while the western part remained tropical. The 
divergence of the would-be great apes and the would-be humans occured around 
this time (7 million years ago). Did the appearance of the Rift Valley cause 
this divergence? Did human ancestors evolve (from the common ape/human 
ancestor) on the eastern side of the drift, isolated from the western 
primates that eventually became the great apes?

Re: Did the Rift Valley separate the apes from the humans?