Watching this National Geographic video of two cockroaches duking it out may simultaneously be gross and mesmerizing, and a little like American politics. According to a new study, Madagascar hissing cockroaches, as pictured in the video, either grow to be "lovers" with big testicles, or "fighters" with big horns.Regardless of whether a cockroach is a lover or fighter, they still have to fight in order to impress a potential mate. The fighter may be better built to fight, of course, but ultimately, the lover may be more fertile."After a bit of scrabbling and butting and trying to flip their opponent over, one or the other will back down, and then the female will usually mate with the winner," said Kate Durrant, a biologist at the University of Nottingham. "We measured the aggression of both species, and the big-horned guys were indeed more aggressive, but when we looked at the little-horned guys, their testes were absolutely bigger than the other ones." This held true not only between two species, but also within a single cockroach species.Usually biological factors will decide whether to give the creatures one or the other: bigger horns or bigger testicles. In their final phase of development, an insect can change the size of certain body parts by diverting resources to specific areas, explained Durrant.The video shows us up close the cockroaches' anatomy: what the fighter looks like compared to the lover. We also get to see and hear them scuttle around a tiny container wrestling with one another. It may sound like a disgusting kitchen infestation, but luckily in this case, they'll squash each other before any unfortunate roommate would have to deal with them.Get six of our favorite Motherboard stories every day by signing up for our newsletter.
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