I’m not just talking about “G-d told Abraham to do so.” I’m looking for historical reasons. For example, could male circumcision have been an influence from Zoroastrianism? Did ancient Jews somehow find that sex was made easier, and therefore, women could have more babies for the population to grow?
Also, does the Tanakh or Talmud say anything about the health benefits of circumcision (better protection against AIDS, higher prevention of yeast infections, etc.)?