According to philosopher and neuroscientist Nayef Al-Rodhan, fear-induced preventive aggression is a human response to the injustices that threaten survival. It is often the root of the unthinkable brutality and injustice that is immortalized by men. It can occur at any time, even in situations that seem calm and under control. When injustice is perceived as a threat to survival, fear-induced preventive aggression will lead individuals to take all necessary measures to be free from this threat. Most ethologists believe that aggression has biological benefits. Aggression can help an animal secure territory, including resources such as food and water. Aggression between men often occurs to ensure mating opportunities, and leads to the choice of healthier/stronger animal. Assaults can also occur to protect themselves or offspring. [24] Aggressiveness between groups of animals may also have benefits; For example, hostile behaviours may force an animal population to enter a new area where the need to adapt to a new environment may lead to increased genetic flexibility. [25] In humans, there is a seasonal variation in aggressiveness associated with changes in testosterone.

[88] For some primate species such as rhesus monkeys and baboons, for example, females are more likely to be involved in struggles for the ovulation period and just before menstruation. [86] If the results were the same in humans as in rhesus monkeys and baboons, the increase in aggressive behaviours during ovulation is explained by the decrease in estrogen levels. This makes normal testosterone levels more effective. [89] Castrated mice and rats have lower levels of aggression. The castrated males as neo-nenziers show low levels of aggression, even if testosterone is given during their development. Gender is a factor that plays a role in the aggression of humans and animals. Men have historically been considered more physically aggressive than women since they were young[153] and men commit the vast majority of murders (Buss 2005). This is one of the most robust and reliable behavioral differences, and it has been found in many different age groups and cultures. However, some empirical studies have shown that the gap in the aggressiveness of men and women in childhood is more pronounced and that the sex difference in adults is modest when studied in an experimental context.

[50] Yet there is evidence that men are more aggressive (Frey et al. 2003) and that more often women express their aggression physically. [155] When one considers indirect forms of non-violent aggression, such as relational aggression and social rejection, some scientists argue that women can be quite aggressive, although female aggression is rarely expressed physically. [156] [157] [158] With the exception of intimate couple violence that occurs in engaged, married or other intimate couples. In many animals, aggression may be associated with pheromones released between consepenifs. In mice, important urinary proteins (mups) have been detected to promote aggressive congenital behaviour in men[103][104] and can be transmitted through neuromodulatory systems. [105] Mups activate sensory olfactory neurons in the Vomeronasal (VNO) organ, a nasal subsystem known to detect pheromones on specific sensory receptors, mice[104] and rats. [106] The phremones have also been identified in fruit flies detected by neurons in the antenna that send a message to the brain, which de-indoctrinates aggressiveness; Aggressive phemones were found to have not been identified in humans. [107] The frequency of physical aggression in humans peaks at about 2 to 3 years of age.