I'm amazed at how little both men and women understand about penile function and sensitivity. I was circumcised as an adult and know both sides of the story so listen up...

First off, those studies that compare sensitivity are quite correct - the glans penis' sensitivity does not change after being circumcised. But there's a caveat. Despite intuitive expectations, the glans is not all that sensitive in the first place - and for good reason.

The penis is first and foremost a conduit for ejaculate. The closer it gets to the cervix, the better the chances of procreation. If the head of the penis was very sensitive one would prefer shorter, shallower thrusts near the vaginal opening. If on the other hand the inner foreskin, or what's left of it, is the real source of stimulation, it would encourage deeper thrusts - deeper thrusts by virtue of the fact that the sensitive inner foreskin (or what's left of it) extends behind the penis head.

I would also add that the mushroom shape of the head functions to mechanically squeegy away competitors' semen. Going flaccid quickly after ejaculation prevents one from squeegying away one's own semen.

As for the differences I've experienced, I must confess I prefer being circumcised. Although I've lost most of my foreskin, there's still more than enough left to give me tremendous pleasure. Sex is different though. The stretched tight skin during an erection is sensitive in a way that it never was with a bunched up foreskin behind the head. To demonstration, try tickling the palm of your hand when it's relaxed, then try again with your hand spread open so that the skin on your palm is tight. You'll probably find it's more ticklish when stretched out. Ditto for our penises. Here's another test guys can try. Try masturbating by tickling only the head of your penis. Can you climax? Try again only tickling the band of skin behind your head and back to your circumcision scar. Does that work better?

Why isn't what I've said above common knowledge? I believe this is because there's a sensory illusion of sorts. It feels like the head is the source of stimulation but in fact it's that inner foreskin. Our eyes are similar. It's our inner eyelids that feel a piece of grit, not the eyeball itself.

Although I prefer my new penis, I still believe it should be his decision. There are psychological elements to all this - both in terms of body image, social approval, and physiologically. I remember a time when my uncircumcised penis craved to get out of its foreskin jacket and experience the satisfying tactile touch of clothes brushing against it. Going about my day with my foreskin drawn back helped a bit, but the bunched up foreskin still didn't expose much inner foreskin to stimulation. At the same time many circumcised guys I knew wanted their foreskins back. I didn't understand this until I became one like them. When you're circumcised, your penis is constantly being stimulated - often to distraction. Sometimes one just wants to turn down the volume as it were. There doesn't seem to be a middle ground. Either your uncircumcised penis craves stimulation, or your circumcised penis craves some peace and quiet.

Finally, why do we have foreskins? What evolutionary advantage do they give us? My guess is this - there was a time in human history when we went around naked and foreskins provided protection. Evolutionary pressures did not remove the foreskin when we started wearing clothes because we short-circuited evolution by cutting off foreskins ourselves.