Why Is the Penis Shaped Like That?

Why do testicles hang the way they do? Is there an adaptive function to the female orgasm? What does it feel like to want to kill yourself? Does "free will" really exist? And why is the penis shaped like that anyway?

In Why Is the Penis Shaped Like That?, the research psychologist and award-winning columnist Jesse Bering features more than thirty of his most popular essays from Scientific Amer...