Life in prehistoric times was difficult; resources were limited, and killing the competitors (neighbours, other tribes) was the only way to survive.
So, stronger and more violent people would acquire more resources and, therefore, survive.
This meant offspring of stronger, more violent people got to live and carry forward such genes.*This cycle continued generation after generation, moving more and more in favour of aggressive and violent people.
And to carry forward genes, the mother’s survival is more critical than that of the father, i.e., if a mother wants her offspring to survive, she must be equally concerned with her own survival.
Since engaging in violence risked survival, women evolved psychologically in favour of childbearing to avoid dangers from combats.
And men evolved to have higher propensities for violence, which were further supported by their physiological evolution.
E.g., men gained more muscle mass (fighting, throwing, lifting, running), more lung volume & haemoglobin (greater oxygen-carrying capacity), and more vitamin K (clotting and faster healing of wounds) than women.
When agriculture came in, this physical strength gave men an upper hand in labour-intensive tasks (ploughing, handling bulls, herding) and women started to depend on them economically as well.
This created a power imbalance, which became a social norm, and any man who couldn’t fit this norm was perceived as weak; research has found “overcoming this perception” to be one of the main reasons for intense anger and violence among men.
Factor 2: Genetic inferiority
A human body has 1 trillion cells (1 followed by 12 zeros), and each cell has 20,000 genes or instructions.
One of these instructions (MAOA gene) is “how to use and recycle chemicals*Serotonin, epinephrine, norepinephrine, and dopamine. that regulate mood & emotion and reduce stress?”.
Some men & women, especially those with any history in the family of having faced oppression, abuse, or war-like situations, have low-activity MAOA (denoted MAOA-L), which means mood-regulating chemicals are not recycled quickly enough and, therefore, upon provocation, these people can become violent.
Females have two copies of MAOA, so even if their MAOA was MAOA-L, they have an extra copy to compensate for low activity.
On the other hand, males have only one copy of MAOA, and if that MAOA happens to be MAOA-L*Because of its contribution to aggression, MAOA-L has been labelled as the Warrior Gene, men are likely to respond to negative experiences extremely or violently.
