What do cat-callers and men with annoyingly loud motorbikes have in common? Well, these types of men have tiny balls—literally speaking.
A recent study conducted on Howler monkeys with louder roars are overcompensating for having smaller testicles “and by extension, less sperm for reproduction,” according to US News and World Report.
Lead researcher at the University of Cambridge’s Division of Biological Anthropology, Jacob Dunn, reported, “In evolutionary terms, all males strive to have as many offspring as they can; but when it comes to reproduction, you can’t have everything.”
He added, “When males invest in large bodies, bright colors, or weaponry such as horns or long canines, they are unable to also invest in reproductive traits.”
Considered one of the loudest living creatures on the planet who emit a boisterous noise that can be heard from three miles away, you won’t believe that the Howler monkeys only weigh about 15 pounds.
“It may be that investment in developing a large vocal organ, and roaring is so costly that there is simply not enough energy left to invest in testes,” Dunn said.