To lay down some groundwork for context before I begin:
- First of all, I suspect that the reason why SJs represent 40% of the population is because Si as a function lends itself to traditional and ‘safe’ behaviors. SJs don’t really want to venture too far outside of their comfort zone; the caution-seeking component of Si would much rather be safe than sorry. This type of built-in aversion to risk would have led to SJs being much more likely to survive long enough to propagate their genes, and pass on their Si tendencies (assuming that personality traits can, at least to some extent, be passed on genetically).
- Likewise, the same logic that explains why high Si users (SJs) would have been more likely to survive environmental risks can also be used to explain why low Se users (NJs) are four of the rarest types. Se is the function that notices and responds to external sensory stimuli - like, for example, an angry tiger defending her young; and higher-order Se users (SPs) process and react to this input much more quickly than lower-order Se users (NJs) do. My younger brother and one of my best friends are both Se-doms (ESTP and ESFP, respectively), and in the time I can even begin stumbling my way through trying to figure out what’s going on around me, they’ve already managed to both process and respond to whatever it is that’s just happened. In humanity’s early world of survival based on the ability to adapt and respond to threats, it’s not hard to imagine how being cognitively less aware of your environment could put you at a disadvantage when it comes to avoiding danger. I suspect that a huge part of the reason why Ni-doms are so rare comes down to the fact that we just simply aren’t as efficient as other types are when it comes to being aware of life-threatening situations.
- Contrary to NJs, SPs - who are high Se users - thrive in environments that necessitate a quick response. ‘High risk, high reward’ is the name of the game for Se; because the same adventurous spirit that helps them find new resources while they roam far and wide can also contribute to their downfall in the form of their compunction for diving head-first into novel - yet potentially dangerous - sensory experiences. This trait is helpful during times of scarcity, but it can also make them impulsive, and prone to placing themselves in harm’s way. Personally, I suspect this is the reason why ESTPs are the rarest sensor type - their foolhardy and devil may care attitude towards risk sees them placing themselves in harm’s way more than any other type.
- I think the large disparity between thinking and feeling functions for men and women (75% of women are feelers, compared to only 45% of men - despite the fact that all other dichotomies (I/E, N/S, and P/J) are relatively even) can be explained by how they’ve adapted differently in response to selective pressures.
Women have always had a greater incentive for learning and displaying pro-social behavior: getting along with other women (and members of your tribe in general) was imperative to early humans, who used to raise their children communally (a tendency which can still be observed in non-Western cultures even today). Women are also, and always have been, the primary caregivers when it comes to child-rearing - it isn’t hard to figure out why it would’ve been advantageous for them to have a more natural and inborn capacity for emotional intelligence when they essentially have to devote half of their entire existence to interpreting and responding to the needs of another person (especially when that person is a small child who depends upon you entirely for their survival, all while trying to learn how to human). The much greater female requirement for being empathetic, nurturing, and understanding is, I think, why 3 in 4 women are feelers.
At the same time, if you bothered to take a look at the second chart that I posted above, you may have noticed that the type ratio for men is much more even than the type ratio for women. Yes, some types are more common than others (although I think that can mostly be explained by type-specific strengths and weaknesses), but it’s clearly much more evened out. Personally, I think this phenomenon can be explained by two different things: a) the fact that men (who are generally the “doers” of the human race) probably require a broader skillset in order to venture out in search of resources to bring home for the group, and b) because natural diversity in men likely increases their individual chances of finding a mate, since they won’t be competing with each other over women who all have a preference for the exact same type of men.
- This is kind of a random and subjective (and mostly unfounded) observation, but based on distribution- and gender-related type statistics, it seems like the most “ideal” type to be (in terms of social and environmental survival) is ISFP. Most of the reason why I think this is because of how evenly balanced the type seems to be among both men and women - ISFPs represent about 7.6% of men, and 9.9% of women.
- People seem to gravitate towards romantic partners who “complete” them, in the sense of having strengths in the areas where they’re weak. For some reason, though, there seems to be a different pattern here for sensors and iNtuitives: sensors tend to stick to dating within their Kiersey temperament cluster (ex. SJs date other SJs, and SPs date other SPs), whereas iNtuitives seem to cross the aisle between NTs and NFs more often than not. I’m not really sure why this is (outside of a post I wrote about the symbiosis between Ne users (NPs) and Ni users (NJs); here it is, if you want to read it), so it’s hard for me to speculate; but my Se-dom brother (ESTP) and closest female friend (ESFP) joke together all the time about how complementary our skill sets are, despite how dramatically different we are on the outside. I’ve also noticed the same thing when it comes to introversion and extroversion, and (tentatively) enneagram types as well - there seems to be a natural affinity there for being attracted to people who naturally complement our personalities.
- I could be completely wrong about this (if interacting with other people online has given me the false impression that iNtuitives are more common in this day and age than they’ve been at any other point in human history), but it seems to me like the population (at least in Western countries) is starting to become more evenly proportionate in terms of the balance between sensors and iNtuitives. If this perception is correct, then this phenomenon may just come down to the fact that mankind has NEVER been as peaceful and prosperous as we are at this point in history. Our current quality of life as a species is completely unprecedented - medical, technological, social, and agricultural advances mean that more people are surviving into adulthood than ever before, and the types that would have been less likely to avoid the culling process of natural selection (i.e. iNtuitives in general) are now surviving much more easily in the modern world of comforts and conveniences. If I’m right about this, then the historical and biological tide may be shifting towards evolution favoring iNtuitives over sensors in future generations.
- Cultural shifts traditional gender roles may also influence the type ratios between men and women.