Why do human males have a foreskin?

I'm not really interested in circumcision

Well, do you think that identifying the effect of destroying something is indicative of what that thing did?

Like the clitoral hood, the primary purpose of the foreskin is most likely just that it feels good. I was citing research that supported that point.

Here is other research you might find interesting. Cold & McGrath (1999) wrote:

It was not until 1991 that the ridged bands of the male prepuce were identified as a concentrated area of corpuscular receptors. At that time, it was unknown whether the ridged band existed in the female prepuce or in other non-human primates. A later histologic study of the penile and clitoral prepuce, carried out on human and non-human primates, showed that corpuscular receptors are concentrated at the prepuce/glans penis and the prepuce/glans clitoridis interface in humans and rhesus monkeys. Surprisingly different patterns of innervation, however, are seen between human and non-human male primates.

The rhesus monkey has fewer corpuscular receptors in the prepuce and more corpuscular receptors in the glans. In humans, however, the glans penis has few corpuscular receptors and predominant free nerve endings, consistent with protopathic sensibility. Protopathic simply refers to a low order of sensibility (consciousness of sensation), such as to deep pressure and pain, that is poorly localised. The cornea of the eye is also protopathic, since it can react to a very minute stimulus, such as a hair under the eyelid, but it can only localise which eye is affected and not the exact location of the hair within the conjunctival sac. As a result, the human glans penis has virtually no fine touch sensation and can only sense deep pressure and pain at a high threshold. … While the human glans penis is protopathic, the prepuce contains a high concentration of touch receptors in the ridged band.

The results of this study demonstrate that the human prepuce is not "vestigial" but is, in fact, an evolutionary advancement over the prepuce of other primates. This is most clearly seen in the evolutionary increase in corpuscular innervation of the human prepuce and the concomitant decrease in corpuscular receptors of the human glans relative to the innervation of the prepuce and glans of lower primates.

This shows that circumcision alters the sensitivity pattern of the head of the human penis to make it more like that of lower primates.

Why do humans have a considerably more complex pattern of penile sensitivity than lower primates? That seems like a good question, doesn't it?

/r/askscience Thread