Big testicles, fellas? She'll cheat on you. Tiny balls? She won’t, say scientists
According to scientists at the University of Oslo, big balls are more likely to mean a fella has an unfaithful partner.
There is only one male in troops of gorillas, unlike fellow apes bonobos, who mate in large groups.
As such, bonobos have particularly large testicles with the aim of increasing their sperm count, giving them a greater chance of becoming dads.