"There’d been studies over the years supporting the proposition that groups composed exclusively of women usually made intelligent decisions, that exclusively male groups did a bit less well, and that mixed groups did most poorly of all, by a substantial margin. It appeared that, when women were present, testosterone got the upper hand and men took greater risks than they might otherwise. Correspondingly, women in the mixed group tended to revert to roles, becoming more passive, and going along with whatever misjudgment the males might perpetrate."