It looks like males with larger testicles kill their babies more often so females became more promiscuous to confuse the males. Interesting fact! https://www.t

It looks like males with larger testicles kill their babies more often so females became more promiscuous to confuse the males. Interesting fact! https://www.tremr.com/Duck-Rabbit/primate-testicle-size-determines-sexual-norms-say-researchers https://www.tremr.com/Duck-Rabbit/primate-testicle-size-dete... Everything from elephant seals, to fruit bats, to gorillas, form harems. Monogomy seems the rarest of all bi-gender mating strategys.