How much does circumcision alter what a man ultimately feels? Scientific studies aiming to answer this question have been inconclusive.

Now researchers prodding dozens of male penises with a fine-tipped tool have found that the five areas most receptive to fine-touch are routinely removed by the surgery.

The finding, announced today, was detailed in the April issue of the British Journal of Urology (BJU) International.

Circumcision surgery involves the removal of the skin that covers the tip of the penis, called the foreskin. Infant male circumcision is the most common medical procedure in the United States, with an estimated 60 percent of male newborns undergoing the surgery.

Morris Sorrells of National Organization of Circumcision Information Resources Center and colleagues created a “penile sensitivity map” by measuring the sensitivity of 19 locations on the penises of 159 male volunteers. Of the participants, 91 were circumcised as infants and none had histories of penile or sexual dysfunction.

For circumcised penises, the most sensitive region was the circumcision scar on the underside of the penis, the researchers found. For uncircumcised penises, the areas most receptive to pressure were five regions normally removed during circumcision—all of which were more sensitive than the most sensitive part of the circumcised penis.

Circumcision is a procedure practiced in several countries for medical as well as cultural reasons. Most scientists agree that the surgery confers some protection against infection and the risk of contracting sexual diseases. Recent studies have also shown that circumcision can lower the risks of HIV infection by as much as 60 percent in sex between males and females.

But Robert Van Howe, a study team member at Michigan State University, thinks such claims are somewhat overblown. “The [health benefits] that have been consistently shown are very small, and there are less aggressive, less invasive, less expensive ways of dealing with the problems [circumcision] is supposed to address,” Van Howe told LiveScience.

Other practices, such as choosing sexual partners wisely and using condoms consistently, are far more effective in protecting against diseases, he added.

Circumcision is opposed by some groups on the grounds that it is painful and not a life-saving procedure, and that it also makes sex less pleasurable by exposing and numbing the tip of the penis, called the glans. Some have gone so far as recommending foreskin restoration.

Some previous studies found that circumcision led to little, if any, decrease in penile sensitivity, but Sorrells and his colleagues say such findings are suspect because many are based on self-reports from men who were circumcised to correct medical problems.