Female Brain Size and Male Genitalia Length [new study]

Researchers in Sweden and Australia published a new study exploring how the length of males’ genitalia affects the size of females’ brains. Anyone who reads the study discovers that

1. it’s about a species of tiny fish; and
2. the effect, if it happens, occurs over the span of many generations, possibly not so much with individual females and individual males.

The study is: “Artificial Selection on Male Genitalia Length Alters Female Brain Size,” Séverine D. Buechel [pictured here], Isobel Booksmythe, Alexander Kotrschal, Michael D. Jennions, and Niclas Kolm, Proceedings of the Royal Society B, vol. 283, no. 1843, November 2016, 20161796. The authors, at Stockholm University, Sweden and The Australian National University, report:

“We analysed the brains of eastern mosquitofish (Gambusia holbrooki), which had been artificially selected for long or short gonopodium, thereby mimicking selection arising from differing levels of male harassment. By analogy to how prey species often have relatively larger brains than their predators, we found that female, but not male, brain size was greater following selection for a longer gonopodium.”

Here’s further detail from the study: