An Evolutionary Advantage of the Human Glans Penis

To account for the bell- or acorn-shaped glans penis, in 1995 Baker and Bellis put forward their ‘semen-displacement hypothesis’. They argued that the existence of the glans penis is indicative of a promiscuous phase in our evolutionary past, in which females would commonly mate with several males in rapid succession. They argued that within this promiscuous scenario the distinctive shape of the glans penis evolved so as to enable the displacement of rival males’ semen. The idea that there was an influential promiscuous phase in our evolutionary past has faced several powerful criticisms that are here briefly reviewed. However, the critics of the semen-displacement hypothesis have not put forward an alternative evolutionary explanation of the glans penis. I try to redress that here, albeit speculatively. I suggest an alternative hypothesis that may more convincingly account for the shape and texture of the human glans penis.