The battle trance is an altered state of consciousness that humans enter in the most critical of moments in their lives. In this state, individual needs and the instinct of self-survival gives way to the needs and interests of the larger group, for family members and relatives, members of a combat unit, members of the same nation or religious affiliation, etc. Most importantly, in this altered state combatants do not feel fear and pain, and are religiously dedicated to the group’s interests. In this state they can accomplish the most altruistic of deeds (like sacrificing their life for others), or on the contrary can be involved in violent and heinous acts (like massacring civilians, including children). In this state combatants are totally devoid of rational thinking and they follow the orders or the behaviour of their group members, sometimes suffering partial or total amnesia of their actions in the process.
I proposed that the phenomenon of the battle trance was developed by the forces of natural selection, as individual hominids were too weak to withstand the major land predators of Africa once they had descended to the ground from the trees. In this state participants lose their personal identity and instead obtain a collective identity, where they feel like a small element of something much larger. Both men and women go into this state of mind instantly when their children are in a mortal danger. This state can also be induced by rhythmic collective actions, repetition of verbal formulas, or group singing and dance.
Despite being one cornerstone of human psychology and the basis of such human sentiments as nationalism, religious affiliation, altruism and aggression, the phenomenon of the battle trance is virtually neglected in scholarly literature. Even in military science, where the battle trance still plays the same evolutionary role it played millions of years ago, any serious discussions of this phenomenon is absent.