How Evolution Gave Humans the Ability to Throw a Fastball

As babies, it doesn't take long for us to realize that--as fun as it is to grab on to everything within our reach--it's even more fun to chuck those things as far and as hard as we can. And now, thanks to a new study, we know the reason behind that delightfully destructive pitcher's instinct--and it all started with Homo erectus almost two million years ago.