My one year old started walking a couple of weeks ago, any parent that has a toddler will know that they don't look very confortable on their feet, in fact, she can still crawl much, much faster than she can walk.

So that begs the question, why does she even bother, why does she not stay on all four? What instinct forces her to get up and walk?

The obvious answer would be to say that she is mearly copying us, but that opens a new chicken and the egg type question, why did we start walking in the first place?

Does anybody know the answer to that one?