Because walking it takes too long.
Ture, but marathons take too damn long too.
So I just do 10k's now.
[ According to evolutionary biologist Daniel Lieberman at Harvard University, our huge bumpers give us the balance that other bipedal animals get from tails, and they also aid in making us superior runners.
Our ability to run apparently helped in our evolution as well because while there is no way we could beat one of the other great apes in a fight we could definitely outrun them.
We also had to run to catch some of the animals we wanted to eat.
Even though many animals, like dogs and cats, run faster than us, as the distances get longer we’re actually able to catch up and beat some of the fastest creatures on the planet.
Add to this the configuration of our ear canals, which give us the incredible balance needed to run on two legs, and you see why we might make ideal marathoners.
Being relatively hairless also helps. It makes it easy to get rid of excess heat. ]
The whole “Out of trees and onto the savhanna” theory is daned brainless, if it were true why would we even lose our body hair, baboons LIVE in the savanna and they have fur, so why not humans....
Not to mention the shape of the nose, and the amount of body fat that would actually make it HARDER to shed excess heat.
If we came down from the trees and started walking upright in the savhanna we would look like bipedal baboons... Not like something entirely different...