Over thousands of generations, human brains have evolved to fulfil the evolutionary goals of survival and reproduction.

To fulfil them, two fundamental qualities are required:

1) Craving Attitude for copulation, which helps in the goal of reproduction by ensuring healthy human propagation and

2) Caring Attitude for others, which helps in the goal of survival by ensuring quality upbringing of the offspring thereafter.

As processing for craving attitude in the brain is solely about the desire of copulation, it requires direct logic processing.

As processing for caring attitude for others in the brain is about making decisions in context with other people, it requires contextual logic processing.

As both attitudes have different execution strategies at their core, it is not possible to execute them in the same brain – the way a miser cannot be a spendthrift. For the same reason, the optimizing aspect of natural selection has distributed their execution between left and right hemispheres of the brain respectively. 

As a result, direct logic processing is typically processed in the interaction processing areas of left hemisphere, which I call “System 1”, and contextual logic processing is processed in the interaction processing areas of right hemisphere, which I call “System 2”.  

Furthermore, as craving attitude for copulation and caring attitude for others are equally important for the evolutionary goals of survival and reproduction, to distribute them equally among the overall human population, the optimizing aspect of natural selection has distributed them between male and female genders respectively.

Such distribution is achieved by hard-wiring the attribute of confidence levels in the system 1, which is the non-conscious part of decision making, as follows. 

High confidence levels are hard-wired in male brains to favour decisions provided by system 1, which results in the unconscious part of their decision making (i.e. their inner feeling) to favour direct logic processing of system 1 in their interactions, resulting into them being more suitable for mechanisms designed to boost craving attitude.

Conversely, low confidence levels are hard-wired in female brains to favour decisions provided by system 1, which results in the unconscious part of their decision making to favour contextual logic processing of system 2 in their interactions, resulting into them being more suitable for mechanisms designed to boost caring attitude.

The same is the reason why typically male brains are geared towards logical, analytical, objective, rule based, systematic, etc. processing, all of which are based on system 1 processing and female brains are geared towards emotional, social, creative, empathizing, thoughtful, artistic, etc. processing, all of which are based on system 2 processing. 

Differences in male and female personalities, behaviours, capabilities, etc. are a result of the same. 

As it is achieved at operational level and not structural level; it is not possible to detect such distribution by structural studies. 

Institution of Marriage

Since time immemorial, a majority of people in the world have spent more than half their lives in the bonding of marriage, but the core reasoning for the institution of marriage is not known. Following is the first ever explanation of the same.

With qualities of craving in male brains satisfying the reproduction aspect and caring attitude in female brains ensuring the survival aspect of the evolutionary process, males may haphazardly copulate with multiple females and vice versa, leaving little support for their offspring.

It is beneficial for those responsible for the offspring to enter into a bond to optimize their care, which can also address other aspects of caring, e.g., earning livelihood, which cannot be optimally done while personally taking care of the offspring. The institution of marriage is designed to optimize such fundamental goals of the evolutionary process.

Monogamy: Furthermore, if a person marries multiple partners, the possibility of clash between such multiple partners and their offspring may fail the purpose of providing good care to them. To further optimize goals of the evolutionary process, the system of monogamous marriage is followed.

Pregnancy: Caring attitude for others in females and craving attitude in males is the reason why the evolutionary process has awarded pregnancy to the female gender and causing it to the male gender.

Craving for copulation in males is also the driving force behind rapes and violence against women.

Without a fully causal account of workings of the human brain, it is not possible for the sciences of mind and brain to causally explain differences between male and female brains, as I have explained using the simple logic of natural selection.