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. Vugt argues that this evolved male social dynamic explains the human history of war to modern day gang rivalry which is under a process of male on male competition in order to gain resources and potential mates.