It is usually thought that female organisms in the animal kingdom have only two dire choices when attacked by coercive and aggressive sexual behavior from their male counterparts: acquiesce, or resist (by fighting).

But IAST research fellow Samuel Snow and his co-author Richard Prum present, in their new paper – just published at Evolution  – an intriguing third possibility: females of certain species might have been able to actively “remodel” their male counterparts’ capacity to sexually coerce them through evolution, by selecting mates and male mating practices that enhance female autonomy and protect them from violent sexual attacks.

This, as Sam and Richard’s work shows, is a co-evolutionary process: females evolve new preferences for autonomy-enhancing traits because they benefit from freedom of choice; thereafter, males evolve those traits because there is a population of females that prefer them.

Sam and Richard’s paper was inspired by their observation of bowerbirds, a group of bird species from Australasia. The males of many bowerbird species build peculiar characteristic structures out of sticks, called “bowers,” which are special courtship display arenas that seemingly allow the female to be courted while remaining physically protected from aggressive male attack, and while also being able to escape easily if threatened https://youtu.be/1EN9k6LEulg

Sam and Richard hypothesize that female bowerbirds may have evolved preferences for mates that can build bowers that better protect them from coercive mating, and allow them a freer, non-coerced, mate choice. If females can evaluate the structure of the bower from far away, these “autonomy-enhancing” traits can evolve, even though the structure interferes with a male’s own ability to coerce.

The male, in short, has no choice but to build a bower that will attract and satisfy a female, if he wants a female to visit him!

This is not only about birds!

Other autonomy-enhancing traits could be things like noticeably smaller body or tooth size (which makes it harder to commit violence effectively). The fact that human males are less violent and smaller relative to females than chimpanzee males, our closest relatives in the animal kingdom, suggests that the kind of “remodelling” that Sam and Richard write about here might have occurred among humans as well.

To learn more, check out the paper here: https://doi.org/10.1093/evolut/qpad074

and see Sam’s blog about it here: https://samsnowscience.com/2023/06/01/new-paper-out-remodeling-male-coercion/