Men have been designed with an internal factory that creates and disseminates naturally occurring steroids (Testosterone) into the bodies of men, causing them to be naturally bigger, faster, and stronger. It gives us more body mass and heavier bone structure as a framework for the muscle. I saw the statement in the article
"...It's already known that males' upper bodies, on average, have 75% more muscle mass and 90% more strength than females'. But it's not known why..." That is why. Our naturally supplied, legal (so far) steroid call Testosterone.