Today's Quick Peep into the Evo-Psych World: On Mean Girls

It's always a fun place to visit!  This time we learn that there are "mean girls" (hard-wired mean!) because cattiness discourages other woman from putting out and so maximizes the "mean girls'" own reproductive success.  The linked summary says that the paper was not terribly well-received, and also offers a criticism. I'm glad of the criticism being added there.

 This example demonstrates something common in  much of evolutionary psychology:  Anything that exists will* have an evolutionary explanation if you think hard enough and weird enough (within the simple model). 

Or look at it the other way round:  If there were no "mean girls" or no time when any woman behaves like that, then the evolutionary explanation for women's kindness towards each other could be the need to get more alloparents for their children and perhaps to get help in gathering or trapping or fishing.

The behavioral reality is  somewhere in the middle.  We humans all have nasty sides and nice sides, in varying proportions by the individual.  Just as there are "mean boys" there are "mean girls".   ---  The particular way this meanness presents itself may have genetic differences by gender or perhaps not.  But it certainly links to the way girls and boys are brought up, too.  --- And what we are mean about is not limited to just jealousy or envy about sexual partners or romantic partners but to most everything humans do.  To pick girls' meanness in only that context probably biases the research from the beginning.
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*For instance, I've read about evolutionary psychology attempts to explain how suicide might contribute to the reproductive success of one's tribal unit.