What is THE EVOLUTIONARY ADVANTAGE...

of the ridge atop the PENIS?  I need to know.


Why not cant it just be a smooth transition into the shaft, like a Popsicle?

It is supposed that in pre-historic communities it was typical for females to have had several sexual partners in quick succession. The ridge on the male penis therefore is thought to have evolved to push the contenders' sperm out of the vagina, thus maximizing the chance of fertilization by that specific male's sperm.