Just like human women who walk innocuously down the street on two legs, female animals also endure unwanted catcalls (or worse) from their male counterparts. And while other animals haven't developed pepper spray or the vocalization "fuck off," they have their own defenses against unwanted sexual attention.
Some female butterflies, for example, emit an anti–aphrodisiac when a male tries to mate with them after they have already mated with another; the unpleasant substance drives horny males straight away. The female African swallowtail butterfly employs a unique tactic to avoid harassment: it dresses in drag by morphing its usual markings to resemble that of the black and yellow male.
Now, a new paper from UK researchers at the University of Exeter, led by Professor David Hosken, suggests female animals across most species have subtly weaponized their appearance.
Male animals typically attract female mates through flagrant visual displays that signal they're the best reproductive choice, but males can also be discerning about their partner's appearance. In that case, Hosken muses, "Why do females not signal their sexual quality via ornamental secondary sexual traits like males do?"
It's long been observed that females are typically less decorated than their male counterparts—the sexual dimorphism displayed amongst peacocks is an obvious example. Previous explanations for the penchant for drab plumage among female animals have focused on the increased need for females to camouflage from predators and conserve energy for reproduction.
But Hosken theorizes that, "given that selection can favor female signals that reduce male harassment"—such as emitting an anti–aphrodisiac or forming communities away from males entirely—"it is very likely that the costs of male harassment could also select against ornaments that positively signal female quality, even if these ornaments would increase fitness in the absence of sexual harassment."
In other words, Hosken suggests that females look deceptively dull in part to ward off unwanted male attention because the threat of sexual harassment outweighs the potential benefits of being able to attract a better mate. To test his theory, Hosken told Broadly that he is currently doing work to determine if "attractive females are more harassed" than "non-attractive" females.