Dan Colman points to the earliest known illustration of circumcision, from a tomb in Sakkara, Egypt, that dates to 2400 B.C.E.:
The origins of circumcision remain unclear. According to this online essay, a stele (carving on stone) from the 23rd century B.C.E. suggests that an author named “Uha” was circumcised in a mass ritual. He wrote:
“When I was circumcised, together with one hundred and twenty men, there was none thereof who hit out, there was none thereof who was hit, and there was none thereof who scratched and there was none thereof who was scratched.”
By the time you get to 4,000 B.C.E., you start to find exhumed Egyptian bodies that show signs of circumcision. And then come the artistic depictions. The Sakkara depiction comes with the perhaps helpful written warning,“Hold him and do not allow him to faint.”
One of the other reasons often cited for opposing circumcision — decreased penile sensitivity in circumcised men — is not borne out by science. …
One inquiry included thousands of Kenyan men who were split into two random groups, only one of which would have its participants circumcised. With a large sample of previously uncircumcised men now willing to be circumcised for the study, scientists finally had a basis for comparing sensitivities re: circumcision, and their findings belied the conventional wisdom. “Overall, the circumcised men actually report that their penises are more sensitive [after circumcision], and that they have an easier time reaching orgasm,” the authors wrote.
Further, in a collective review of 10 studies using almost 20,000 men as subjects, scientists “did not see any differences between circumcised and uncircumcised men in terms of sexual desire, pain during sex, premature ejaculation, problems with erections, or problems with orgasms.”