Things I never knew about birds

From MA’OZ TZ-URL by Scott Alexander.

The Greater Male Variability Hypothesis says that men will have more variability on most traits than women, and therefore the highest and lowest performers in lots of areas will be disproportionately male. It goes along with a neat genetic explanation: males don’t have a backup for the X chromosome and so small mutations there have more effect – and a neat evolutionary explanation: men have more variability in their reproductive success and so should pursue higher-risk strategies. A 2013 study gives the theory an interesting test – what about birds, where females are (bird equivalent of) XY and males XX? Here the female birds have more variability, suggesting the genetic principle is sound but casting doubt on the evolutionary explanation. Unless I’m misunderstanding something.