Think about the most trash bro person you know, the person with a penchant for less-than-subtle sexism and gigantic monster trucks with obnoxious engines and (how could we forget?) a grotesquely misguided tendency to catcall. For a new wrinkle in this most unfortunate of human offshoots, the Overcompensator, we turn to a new study published in Current Biology involving monkeys.

"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," lead researcher Jacob Dunn of Cambridge’s Division of Biological Anthropology tells U.S. News. "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."

Researchers studied so-called Howler monkeys, one of the loudest species on the planet with a remarkable average weight of just 15 pounds. When a female wanders into their presence, males start to engage in a roaring wave of screaming not unlike the aforementioned catcalling. The louder the monkey, the smaller the testicles.

"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 proposes. "Alternatively, using a large vocal organ for roaring may be so effective at deterring rival males that there is no need to invest in large testes."

So, trash men, the secret's out. Small balls.