How the penis lost its spikes

Zoë Corbyn in Nature:

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.

“It is a small but fascinating part of a bigger picture about the evolution of human-specific traits,” said Gill Bejerano, a developmental biologist at Stanford who led the work along with colleague David Kingsley. “We add a molecular perspective to a discussion that has been going on for several decades at least.”

Published in Nature today¹, the research also suggests a molecular mechanism for how we evolved bigger brains than chimpanzees and lost the small sensory whiskers that the apes — who are amongst our closest relatives and with whom it has been estimated we share 96% of our DNA — have on their face.

More here.