[s_tec]

I'm not the OP, but I'll bite.

For many species, males have a higher standard deviation across a variety factors. There are biological reasons for this, since males are more disposable than females for reproduction. Think of one rooster for a dozen hens - this is still a viable flock, even if the other roosters get eaten. Nature can experiment more with males simply because the stakes are lower, and sometimes those experiments are worthwhile. [edit: Turns out this is not true for birds, so I learned something!]

Now, if you have two normal distributions with the same average and area but a tiny difference in the standard deviation... well, let's not go there because the math is too politically incorrect. [edit: And besides, many other factors affect outcomes besides genetics, so I do believe we should keep policies gender-unbiased as a matter of principle].

[SamReidHughes]

> There are biological reasons for this, since males are more disposable than females for reproduction. Think of one rooster for a dozen hens - this is still a viable flock, even if the other roosters get eaten.

Note that birds do not have mammalian sex chromosomes - males have ZZ and females have ZW - and females have been measured to have greater variability in birds.

So there is not really a biological reason as you say -- it just happened to go one way or the other in the past, and now different trees of species are stuck that way.

[ponow]

If we can repeatedly find differences in variance despite similarity of mean for different sexes within a species or other groupings, then that would be a kind of thing that would be reported in biology research.

[james-bcn]

I've not come across this before ("males have ZZ and females have ZW - and females have been measured to have greater variability in birds"). Do you have some references/books you can recommend? I'd like to find out more.

[SamReidHughes]

For example there is this paper on repeated differences in variance for different sexes in different groupings:

https://onlinelibrary.wiley.com/doi/10.1111/evo.12224

[spzb]

Intelligence, as measured by IQ tests, exam results etc, is not just a product of genetics.