Female promiscuity gives males big testes and small brains. In bat species noted for female monogamy, males have small testes and big brains; in bat species noted for female promiscuity, males have testicles five times as big, but with smaller brains. Testes in one species are 8.5 percent of the male's body weight. Reason for big testicles: If a female is taking sperm from you and another guy, the best way to pass on your genes instead of his is to deliver more sperm. (This is why chimps have testicles "many times larger than those of gorillas.") Reason for small brains: Male bats that spent their energy making sperm beat out the ones that spent their energy thinking. Researchers' conclusion: "Size does matter."
Absolutely shocking. I never would have guessed this. This is why we need to put chastity belts on all the women. It's for the good of humanity. It'll make us all smarter.