I think men are naturally more competitive too. There aren't tons of studies on human competition, but when male dogs go through puberty they become more competitive and aggressive, hence a reason why neutering is so popular (to curb the behavior).
Also a lot of the top contributors to these equality / affirmative action posts seem ignorant of biochemistry. They always sight testosterone and estrogen as the only chemical differences, which is very high-school level understanding of the real gender differences.
You need to look at many androgens (androsenediol, androstenendione, dehydroepiandrosterone, dihydrotestosterone, testosterone), estrogens (estradiol, estetrol, estriol, estrone), progestogens (e.g. progesterone) and other biomarkers like DHEA, adrenals, prolactin to get the full picture.
This is also why the people claiming transgenders are identical hormonally to the gender they are swapping to frustrate me. It's just not the case. There are a huge array of sex hormones aside from testosterone and estrogen (usually referring to e2 or estradiol) that have large impact on an individual. I don't really care what you do with your body, but don't be ignorant to the science of what you are changing / not changing.
Anyway, I am not suggesting in anyway that we discriminate against one group or another. But we should all do our part and try to learn the differences between eachother to better understand these issues.
EDIT: I am quite liberal and don't hate anyone. I just am frustrated at other liberals who opt to ignore science to push their own agendas.
EDIT2: It's really sad that I feel the need to actually have to post the first edit.