In SciAm:

If you’ve ever had a good, long look at the human phallus, whether yours or someone else’s, you’ve probably scratched your head over such a peculiarly shaped device. Let’s face it—it’s not the most intuitively shaped appendage in all of evolution. But according to evolutionary psychologist Gordon Gallup of the State University of New York at Albany, the human penis is actually an impressive “tool” in the truest sense of the word, one manufactured by nature over hundreds of thousands of years of human evolution. You may be surprised to discover just how highly specialized a tool it is. Furthermore, you’d be amazed at what its appearance can tell us about the nature of our sexuality.

Via William Gibson.