Changes

The foreskin and the glans have similar functions. Both are designed to trigger nerve impulses that lead to [[erection ]] and ejaculation. The glans detects deep pressure and movement. The foreskin detects movement through the accordion-like action of the ridged band; in addition, the outer, true [[skin]] of the foreskin has an exquisite ability to detect light touch and pin-prick. The glans lacks these abilities because it relies on the covering foreskin to provide them.

The double-layered design of the foreskin does indeed permit smooth penetration and a sliding action. The [[skin]] of the penis, including the foreskin, becomes rougher during [[erection]]. This roughness is brought about by a mechanism similar to that which raises goosebumps. The extra frictional resistance brought about in this way reduces slippage of penile [[skin]] against female tissues. The double-layering of the foreskin is designed to offset the frictional effect of erect penile [[skin]] and allow for easy vaginal penetration.