Man has quite naturally developed skill of walking on two legs. It requires a great sense of balance and correct control of the muscles.
If we compare the human foot with the foot of an ape (ex-gorilla), we can see two differences.
Firstly, contrary to the ape’s foot, all human’s foot have a flat base.
Secondly, the ape has a big toe, which can be moved in opposite direction, so that it can grip curved surfaces like tree branches. In human foot, the big toe is not moveable.
So, man can stand erect and walk, while the apes can grip branches of the tree and leap from one branch to another.
Below Walking info from Wikipedia (Read More):-
Walking (also called ambulation) is the main form of animal locomotion on land, distinguished from running and crawling.[1][2] When carried out in shallow waters, it is usually described as wading and when performed over a steeply rising object or an obstacle it becomes scrambling or climbing. The word walk is descended from the Old English wealcan "to roll".
Walking is generally distinguished from running in that only one foot at a time leaves contact with the ground; for humans and other bipeds, running begins when both feet are off the ground with each step. (This distinction has the status of a formal requirement in competitive walking events, resulting in disqualification at the Olympic level.) For horses and other quadrupedal species, the running gaits may be numerous, and while walking keep three feet at a time on the ground.
http://en.wikipedia.org/wiki/Walking
