Why did an ape evolve into Man and the other apes not?

Answer 1

It is inaccurate to say that humans were once other similar apes such as gorillas or chimpanzees. Instead, evolutions states that our species and other species of great apes share a common ancestor. That means at some point a long time ago, our three species were one species and over time, we diverged into what we are today. It is exceedingly unlikely for any of the current species of great apes to retrace millions of years of evolution back to that common ancestor and begin to evolve on the exact same path as humans. Instead, they will continue on their own evolutionary path that is parallel to others and will not converge.

Answer 2

Both the great apes and humans have a common ancestor who lived around 7 million years ago. One group of this ancestor population stayed in the trees and became modern apes, while another ventured further and further afield of the forest to become humans. The need to walk over savannah while our arms were full of various food stuffs or weapons lead to our current foot structure and bipedal locomotion. We lost our hair as a way to cool our bodies, and we gained darker skin to keep it from getting burnt by the sun. Our brains grew so we could better adapt to the ever changing environment of ancient Africa. Eating more cooked meat contributed to this growth. Our once ape-like flat nose grew to its current proportions to deal with colder temperatures. A good book that explains all of this is Before the Dawn (2006) by Nicholas Wade.