Why did we start walking upright?

One thing that has bothered me is when and why 'Hominids' started walking upright. One point is so that they could free up the limbs to 'make tools' and so they could stand and 'see' over the tall grass for approaching predators and also so that it would be easier for them to 'run' away as they could move a bit faster on two legs rather than four. Another one is Owen Lovejoys theory being it was the 'sexual strategy' that forced them into it. A brief outline of what Owen said is that an 'animal has two fundamantaly different ways in which an animal can function sexually. It can produce a great many eggs, with an investment in very little energy in any one egg. Or it can produce very few eggs, but put a large investment in each. These are known as the "r" and "k" strategy. An extreme example of "r" would be the Oyster who can produce as many as five hundred million eggs a year. The most extreme example of "k" are the Great apes-the Gorilla, Chimpanzee and Orangutan'. So he is saying that because they had saved energy by becoming "k" related they were able to concentrate on becoming Bipedal and learning the other things so we could evolve into what we are today.
What do you think?

Do you believe?

G'day everyone its been awhile since last time and everythings well. Now I am a believer in the spirits and the afterlife so ill just give you a taste of one of my experiences. My elder brother and I used to do everything together from partying and fighting to womanising we were unseperable. Anyway he and I were involved in a car accident and he died while I was hospitalised for two months upon my return to home life I felt alone in a way and didn't go out I always felt his presence at our house. A few years later our second child was born and we had a swinging cradel that the baby would lay in sometimes he would cry in his crib but when we would check on him the cradel would be rocking and he would be getting back to sleep. Now all the usual things would be checked such as open windows, doors, any wind blowing but nothing. Another time a friend of my wifes would visit and sleep over one tiome she told us that a man was standing beside the bed looking at her, she didn't know my brother but described him after the visit. Our lates son is five and talks about a man that he talks to and points to a photo we have of him saying thats him. I have no worries about our visitor its been eleven years since the accident and I think that he still worries about me and like to check in. What does everyone think?

G'day

Howdy people
First time member and am fascinated so far. Any tips on where to go and waht to look for?