The reason women are thought to vary less than men is because that's what nearly all the statistics say.
The only statistics I've actually seen addressing sex differences in standard deviations from the mean are IQ, height, weight, and life expectancy. Do you have links to studies from this perspective on other traits?
There is a fairly straightforward ev-psych explanation for this.
Without disputing the fact that evolutionary psychology may correctly explain some things, the problem with ev-psych exlanations is that they can explain anything. Just as you can finance pundit diametrically opposed stock market data and they'll find some way to fit both sets to their theory, and armchair evolutionary psychologist can explain any behavior in ev-pysch terms, correct or not. Being able to offer a mechanism is, in my view, rather important for corroboration.
the problem with ev-psych exlanations is that they can explain anything.
Um, no. Yes it's possible to rationalize anything if one is creative enough, this isn't limited to ev-psych, but just as some arguments are better then others, some ev-psych explanations are better then others, and this one is pretty straightforward: namely since the number of children an individual female can have is much more limited then an individual male, it makes sense for females to use less risky, i.e., lower variance, strategies. Hence, we should expect males to have a hi...
This is an experiment to use polls to tap into the crowd knowledge probably present on LW.
This is your chance to ask your multiple choice question you always wanted to throw in. Get qualified numeric feedback to your comments. Post fun polls.
There are some rules:
If you don't know how to make a poll in a comment look at the Poll Markup Help.
This being an experiment I do not announce it to be regular. If it is successful I may. Or you may. In that case I recommend the following to make this potentially more usable:
EDIT: Added recommendations from KnaveOfAllTrades.