A Little Sexual Evolution
Sex would be a very different proposition for humans if — like some animals including chimpanzees, macaques and mice — men had penises studded with small, hard spines.
Now researchers at Stanford University in California have found a molecular mechanism for how the human penis could have evolved to be so distinctly spine-free. They have pinpointed it as the loss of a particular chunk of non-coding DNA that influences the expression of the androgen receptor gene involved in hormone signalling.
That explains why humans are so fascinated with rings and studs. Must be a genetic “leftover.”