Female lice grow penises, demand 70 hours of sex: study

In an international head-scratcher of a development, female bark lice — the tree-feeding branch of the itchy insect family — are engaged in what scientists are dubbing a penis-growing arms race.

Females from two breeds on different continents — the Neotrogla in South America and the Afrotrogla in southern Africa — have evolved male sex organs, according to a new study published in Biology Letters.

And now they are weaponizing their new appendages, says lead study author Kazunori Yoshizawa, an associated professor at Hokkaido University in Japan.

Despite seemingly having it all, these gals are hungry: they live in caves where food is extremely scarce. Switching into sexual survival mode, the female lice stalk males to acquire their “seminal gifts,” which are rich with nutrients.

Often, sperm cravings come before consent, and the females force themselves on the men in marathon sex sessions, Yoshizawa says.

These insatiable women “grasp and stimulate” their men for as long as 70 hours, he says. Male species have, in turn, developed vaginas.

It is this “coercion” mating which is believed to cause the curious co-evolution of female penises and male vaginas, the study suggests.

“Under typical sexual selection in which females are choosy and males are courting, the male penis has evolved many times independently, probably for active and sometimes coercive mating,” Yoshizawa says. “A simple reversal of gender roles in sexual selection, however, cannot simply cause the reversed genital organs.”

The takeaway: Scientists don’t know exactly why this is happening, but continued research is necessary, says Yoshizawa. “[Because] the study of female penises could also shed light on the evolution of male penises.”

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