Evolutionary psychology has proposed several evolutionary explanations for gender differences in aggressiveness. Males can increase their reproductive success by polygyny which will lead the competition with other males over females. If the mother died, this may have had more serious consequences for a child than if the father died in the ancestral environment since there is a tendency for greater parental investments and caring for children by females than by males. Greater caring for children also leads to difficulty leaving them in order to either fight or flee. Anne Campbell writes that females may thus avoid direct physical aggressiveness and instead use strategies such as "friendship termination, gossiping, ostracism, and stigmatization".