The evolutionary explanations of human aggression derive from the changes in species over millions of years. This means that it is based on the premise that the human brain is a product of evolution through natural selection.
These changes in species work to increase each and every species’ (humans in this case) likelihood for guaranteed reproduction and survival, hence are also known as characteristics naturally selected to be passed onto offspring. This is due to the reasons that aggression is a strategic approach in resolving adaptive problems among early civilisations, examples such as gaining resources, intimidating or eliminating male rivals for females, deterring mates from sexual infidelity and solving territorial disputes, thus enhancing the survivorship and procreation of individuals, resulting in the mental module and evolution that spread into the gene pool.
Explanation 1. Sexual competition
Ancestral males seeking attention and accessing females in the past would have led to competitions between other males, hence resulting in sexual competition. One form of eliminating the competition would have been through aggressive measures, or in the form of physical opposition. This means successful males in securing and acquiring a mate through the means and methods of aggression, would have most likely passed on their genes to offspring, thus developing the genetically transmitted tendency for males to be more aggressive to other male counterparts.
Evidence for such explanation:
Lassek and Gaulin 2009 states that men have 75% more muscle mass than women, hence higher chances of dying violently because of the difficulty in feeling/ being indebted to others, according to Buss 2015. Additionally, archeological findings show that universally, men have thicker jawbones; this contributes to the reasoning that men hit and fought each other in the past, allowing the thickest boned men to survive and pass on their genes to future generations.
Explanation 2. Sexual jealousy
Male aggression, over the years also mainly stems from sexual jealousy which is rooted in the uncertainty of paternity. Due to the differences between human males and females in biology, men would have a harder time confirming the true parental heritage of their children compared to women, since fertilization occurs inside a woman. This results in the risks of men experiencing cuckoldry, which can then result in a man unwittingly investing his assets and resources in offsprings that are not his. To conclude, an adaptive function of sexual jealousy is to deter a mate or partner from infidelity, thus reducing the risks of cuckoldry.
Evidence for such explanation:
Sexual jealousy accounts for 17% of all murders in the UK.
According to Dobash and Dobash 1984, the primary cause of violence directed and inflicted on women mainly centers around sexual jealousy; hence those who are perceived by their partner to be unloyal or threatening infidelity are usually more at risk for sexual aggression than those who are not.
Explanation 3. Aggression in warfare
Aggressive behavior associated with combats and battles seem to have evolved in adaptive benefits for oneself and their offsprings. This is due to the origins of aggression in early civilizations to extract and obtain valuables, attract mates and form intergroup bonds. Moreover, aggression in combat increases and raises one’s (social) status. This results in the respect and admiration for an individual warrior while strengthening the bond between them and their intragroup. Displays of aggression also point to the likelihood that benefits can be shared with status.
Final Note. Aggressive behavior could also be ineffective, potentially leading to social ostracism, injury and even death in certain cases. For example, violent males may be rejected as mates, and warriors may die in battles.
Psychology A Levels Year 2 AQA 5th Edition