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Rushton’s Differential K Theory and Intelligence

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1250 words

This is my 50th post. I plan to cover altruism and ethnocentrism much more extensively, intelligence and race, psycological disease and race, personality and race and so on. A JayMan refutation on his belief of Ethnic Genetic Interests and Group Selection is coming soon.

Differential K Theory explains human behavior on countless variables. Rushton was one the first scientist to use r/K selection theory to explain human behavior. Albeit, it’s on a much smaller scale than what r/K selection theory is used for, it still greatly applies to human populations. On over 6o variables, Blacks (r selected) fall at one end of the continuum, whereas Orientals (K selected) fall at the other end, with Caucasians falling in the middle, consistently on over 60 variables.

Rushton’s theory, which of course is extremely controversial, drew the ire of many researchers because he chose to use r/K selection theory in regards to explaining differences between isolated human populations. But, what they don’t get is this: even if Rushton is wrong with his Differential K theory, you’d still need a way to explain how and why these 3 populations who evolved in genetic isolation came to have such stark and consistent differences between them no matter where in the world you look. Between IQ (Asians 103-4; Europeans 100 and African-Americans 85), rates of 2-egg twinning (Asians 4 for every 1000, Europeans 8 for every 1000, and Africans 16 for every 1000 [I wrote about some evolutionary causes for earlier menstration in black girls with leptin being the cause last week, it also explains how and why blacks have more rates of 2-egg twinning, because the life expectancy is so low it lead to evolutionary pressurses in which Africans evolved mechanisms that have them have more kids and earlier menstral cycle.]), average age of first walk (blacks one week before whites who are one week before Asians) and so on and so forth.

The more intelligent the woman, the less kids she will want to have, on average. One SD increase in childhood IQ leads to a 21-25 percent decrease in a woman’s odds to have children. This is a clear k strategy. Have less kids, but show more care for them. Conversely, blacks have more kids, but show less paternal involvement. This still continues today in America, even though we have an industrial society. The things involved in this discussion are, at its core, evolution in its process, but we don’t see it that way because of the society we live in. With intelligent women not having children, while the less intelligent, r selected women having more children, this will lead to an eventual dysgenisis and the average IQ in America will drop immensely. The birth rate for whites in America was 1.75 in 20132.0 for blacks, 2.4 for Hispanics and 1.77 for Asians. The r/K selection theory perfectly explains this. It’s an evolutionary process that occurs as adaptations to the environment that their ancestors evolved in.

The more K selected peoples had to have less children in their ancestral environment due to food being scarce. This is where the higher intelligence evolved as well as high amounts of altruism, which I theorize that Europeans have a higher amount of the brain hormone oxytocin, which leads to more altruism, but is being taken advantage of by non-Western people who are abnormal to our societies and eventually leads to increased ethnocentrism.

Rushton postulates that Differential K Theory is a cause for group differences in intelligence. With the K selected having less children and the r selected having more, we can see this in birth trends as well as IQ trends in the country. More intelligent women can see that it’d be better to wait to have children as to be more financially able to take care of the baby. While the less intelligent women have more kids due to not thinking into the future and only thinking in the now, wanting their pleasure immediately. This is causing a dysgenic effect on America. The more the average intelligence drops, the more we can expect to see conditions begin to deteriorate, as a country is only as good as the majority of its population, as we can see looking at the average living conditions around the world.

With altruistic behavior being highly correlated with race due to evolution for tens of thousands of  years, we can see that more intelligent people will be more law abiding, more altruistic, commit less crime, have less children, more cooperative and so on. Whereas less intelligent people will be less law abiding, less altruistic, commit more crime, have more children and be less cooperative. This is modeled in communities all over America in their crime rates, graduation rates, IQ scores and so on. One of the most noticeable r selected traits is criminality. This is due to lack of ability to delay gratification and higher testosterone. The reverse is true for lower testosterone Eurasians, as well as numerous other differing physiological factors between the races.

With differing crime rates no matter where you look, the racial disparities are all the same. This is no coincidence; social factors do not account for these differences. Evolution, does, though. Evolution is also the cause for the social factors that do arise within and between populations. Over time, these selection pressures caused these positive traits you see in those who evolved in the Northern, harsher, colder climates and the more negative traits in the more Southerly, hotter climates.

This is why importing more people from differing societies into our countries will not end well. They have differing evolutionary goals different evolutionary reasons for them. They are not normal for our societies; ethnic dissimilarity causes more strife between people due to genetic distance. The more r selected peoples are less intelligent and are also prone to higher rates of criminality as well due to higher testosterone.

These differing evolutionary goals would be fine; if not for forced mass immigrations into Western countries. Since birth rates never remain stable, a lower white birth rate would have been able to rebound eventually. With the introduction of mass immigration into Western Societies, this is causing the birth rate to continue to fall percentage wise, even if the birth rate increases due to the introduction of more r selected peoples. The more educated that women get, the less kids they have. It works in two ways: going for higher degrees and wanting success in life first, some women may be around their mid 30s before deciding to have children and when deciding to have children they then can’t have any due to being too old. Whereas those with lower intelligence and no career prospects would have been having more kids due to their r selected strategy and lack of foresight into the future due to lower intelligence.

Looking at things from an evolutionary lens will make what’s going on around the world clear. Everything you see is evolution in action, though you won’t see its effects and they won’t be noticeable for tens of thousands of years, it’s evolution on a macro level. Negative birth trends always do reverse, as they never remain stable. As more women get educated (and this holds for all women of every age, race, religion and ethnic group), birth rates drop due to less time in the fertile years attempting to get pregnant. If we’d only look at things in an evolutionary scientific way, we’d be better able to understand how and why human populations differ behaviorally cognitively, and a whole multitude of other factors. We’d also better understand how to, on average, deal with the average criminalistic personality. It would make the job for police easier if these evolutionary factors were known and life would be safer in America as a whole.



  1. […] due to evolution in cold climates. The altered intelligence, which then altered personality. This r/K Life History Theory of Rushton’s blend’s beautifully with the GFP and intelligence. Evolution in cold […]


  2. […] Rushton’s Differential K Theory and Intelligence […]


  3. […] testosterone, which makes blacks more extroverted than whites who are more extroverted than Asians (Rushton’s Differential-K Theory). If these racial biases were really to manifest themselves to actually sap 15 to 18 (1 to 1.2 SDs) […]


  4. Jim Dandy says:

    I find Rushton’s “Differential K Theory and Intelligence” a very fascinating topic. I have recently read a interesting theoretical paper by a Micheal Trust titled “Modern Political Thought in the Context of Evolutionary Psychology”, which can be found below. His theory posits that peoples political leanings are influenced by either r or K type genetic predisposition. I would be very interested to hear your thoughts on his work as compared to Rushton’s as well as other related research in this area.


    • RaceRealist says:

      r/K selection in regards to humans is very interesting but I’ve changed my views a bit in the year it’s been since I’ve written this. I don’t agree with everything Rushton says about r/K theory.

      I don’t believe that cold winter theory is valid to explain intelligence differences—I’m now thinking that differences in sexual selection causes ethnic differences in intelligence.

      I have recently read a interesting theoretical paper by a Micheal Trust titled “Modern Political Thought in the Context of Evolutionary Psychology”, which can be found below. His theory posits that peoples political leanings are influenced by either r or K type genetic predisposition. I would be very interested to hear your thoughts on his work as compared to Rushton’s as well as other related research in this area.

      I’ve been meaning to buy AC’s book on evo psych and r/K selection. I never got around to it. I’ll check this paper out this weekend and tell you my thoughts.

      I personally am more interested in anatomic/physiologic differences between the races now. IQ is boring to me.

      By the way, check out this article I wrote a few weeks ago. I believe that what Lynn, Rushton, et al say about cold winters driving higher intelligence is bunk. Cold winters only selects for larger brains. Warmer temperatures select for smaller brains.

      A supposed ‘anomaly’ for the IQ hierarchy is the Inuit and Arctic peoples. Their brain size is the same as East Asians but their IQ is only 91. Lynn explains attempts to explain this away by saying that they have a small population and thus a smaller chance to acquire high IQ alleles. Therefore they have a low IQ with a large brain size.

      Arctic peoples use more tools than tropical peoples. You need a certain expertise to construct usable tools. You also need to pass skills down to future generations in order to construct those tools. Tool-crafting is related to an increase in brain size. There is evidence that expertise is not correlated with IQ, and so to become an expert you don’t need a high IQ. So since Arctic peoples make more tools than tropical peoples, they need a larger brain to store more ‘informational chunks’ and so they got selected for by making complex tools. That, along with cold temperatures, is why brain size increased for Eurasians.

      Also keep in mind that Europeans and East Asians were a single breeding population 10kya.

      People with Erectus-sized brains have had normal intelligence, implying that some Erectus had intelligence on our level. Big-brained babes are harder to birth; mortality rates are high for both women and babes. So there was a reason why large brains evolved, reason being for expertise capacity.

      Brain Size Increased for Expertise Capacity, not IQ


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