The evolutionary benefits of war are that land and resources which benefit survival can be gained and also increased access to females, thereby improving a mans chances of reproducing and passing on his genes.
HOWEVER warfare is a risky strategy as it can end in serious injury or death. Forming coalitions with others is therefore seen as an adaptive response as it reduces these risks. Groups are more powerful and offer more protection therefore increasing chances of survival. Not only can resources be acquired, they can be protected more easily by friightening of potential attackers. Furthermore, men who are more aggressive and strong are more likely to win fights and therefore survive to pass on genes. Also, men who are successful in battle may appear more attractive to females increases chances of reproduction.
RESEARCH - Chagnon observed behaviour in the Yanonomo tribe from the amazon and found that the need for more increased access to women was a common cause of warfare between groups. he also found that successful warriors had more wives and children.
pinker found that abusing women from an opposing side was commonplace in WW2 concentration camps among Muslim women in bosnia, thereby supporting gene survival as driving force. However - according to evolutionary theory this should not be the case as they would want genes to survive, which is unlikely in concentration camp.
It has been claimed that tribal warfare has been replaced in the modern day by sports events where different teams can be seen as opposing tribes. Competitive sports such as football and rugby are therefore seen as ritualised forms of aggression. An example of this can be seen in the performance of the Haka by the new zealand rugby team. The Haka is a dance originally performed by warriors before going into battle.
Many aspects of good play in team games are indications of strenght (e.g. scrum, tackling) and athletisism (speed etc). These abilities are seen as attractive to females as they indicate a mans ability to protect and provide for them as well as making his genes attractive. Being a good team player also indicates the ability to co-operate with other which is very beneficial in times of war. The better a player is the more resources are available to him thorugh higher earnings and greater access to females as they are seen as more attractive.
RESEARCH - Cialdini - found that when a team was successful people were more likely to wear team colours in order to associate themselves with that success. Was also found that team supporters were more likely to use the term 'we' when describing the teams successes. They also more likely to use the term 'they' when their team lost. These behaviours show an attempt to increase attractiveness through association.
You cannot form a testable hypothesis as it is an evolutionary theory- therefore you cannot compare past and present aggression. However you can observe varying level of aggression in groups. This reduces effectiveness as we can't falsify the theory and diminishes psychology as a science.
DEBATES - Deterministic - it is an evolutionary theory which states that group displays of aggression are an inevitable adaptive response determined by genes and the evolutionary need to pass on genes and survive. However it cannot explain the behaviour of conscientious objectors that will not participate in war and so this reduces the effectiveness of the theory.
One problem with tribe research is that theri behaviour was observed by an outsider- so experimentor bias may affect the results as they may not know enough about the tribe.