 Anne Campbell writes that females may thus avoid direct physical aggressiveness and instead use strategies such as "friendship termination, gossiping, ostracism, and stigmatization".Psychologist and professor Mark van Vugt, from VU University at Amsterdam, Netherlands, has argued that males have evolved more aggressive and group-oriented in order to gain access to resources, territories, mates and higher status.His theory the Male Warrior hypothesis explains that males throughout hominid history have evolved to form coalitions or groups in order to engage in inter-group aggression and increase their chances of acquiring resources, mates and territory.