This is my sexist, misogynistic generalization but I think women can be meaner than men for the most part, and when we work together as all-women groups that tendency comes to light more. I noticed it in my army barracks & in my marketing team too (we were mostly women).

It doesn't mean we are mean individuals but just female social dynamics kind of use meanness as a catalyst for order & function.

I think men can be very mean too, but not as often or as punitively. However, when men are mean, I have seen them be truly cruel more often than I see women be cruel.

Again these are all blanket statements & in no way applicable to all men and women. And I have been in work groups of mostly women where we have all supported and encouraged each other, just not as often as I have been in groups where we bullied each other.