Home » Black-White IQ » Devestating Objections to the Rushton-Lynn Cold Winters Theory

Devestating Objections to the Rushton-Lynn Cold Winters Theory

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Cold winters theory (CWT) attempts to explain the variation in IQ scores between countries. According to the theory, what explains a suite of observed differences is differential evolution by natural selection in different environments. Due to the exodus out of Africa, this led to the colonization of new biomes with novel things that early Man would not have been accustomed to. Thus, they would then need to be able to adapt their actions and behavior to their new environment. Since they were in novel environments, early man would then need to acquire new skills to survive. So those who could not, had a lower chance to reproduce, and so, there was selection-for and selection-against certain traits. So, over time, this led to differences in the phenotype between groups that evolved in different environments, and the driver of this was natural selection. Hereditarians have said as much, and this theory is a cornerstone to their thinking. The observed differences, in order to be of any use to hereditarians, must be due to evolution, particularly due to evolution by natural selection.

However, although natural selection isn’t itself a mechanism (Fodor, 2008; Fodor and Piattelli-Palmarini, 2010), it is generally understood that natural selection actually decreases genetic variation in a trait (Howe, 1997: 70; Richardson, 2017: 46) . Thus, if the differences in IQ between races were due to natural selection, then there would be decreased, not increased, variability in IQ/intelligence between races.

Emil Kirkegaard has a good overview of the history of this theory. Nevertheless, I myself have made critiques of CWT, which rely on the fact that it makes no risky, novel predictions (contra Lynn). In this article, I will mount some more arguments against CWT, and I will further show how the logic for the theory crumbles due to the use of shoddy reasoning and the use of ad hoc hypotheses to save the theory from falsification. I will conclude that the CWT has no scientific value and is nothing more than a just-so story that explains what it purports to explain while not successfully predicting novel evidence.

Cold winter theory – Lynn

One of the earliest instance of CWT can be found in Wallace (1864). In his article, he states things that contemporary hereditarians would then argue. In 1987, Richard Lynn argued that the selective pressures of cold winters explains the high IQs of “Mongoloids” (Asians) (Lynn, 1987). Lynn states that the higher IQs of Asians can be explained by the selective pressures of cold environments. He posits adaptations that evolved in Asians, which cold winter environments then selected-for. In 1991, Richard Lynn argued that surviving in novel environments that our species didn’t evolve in led to selective pressures which increased the IQs of “Caucasoids” and “Mongoloids.” The two groups had to survive in cognitively demanding environments and, due to the cold, needed to create shelters, make clothes and fire along with hunting game. So this explains why the two groups have evolved greater intelligence than Africans. Although Ian Deary is himself an IQ-ist, he rightly states that Lynn’s theory is nothing more than a just-so story:

Another review of the thorny issue which Lynn deals with in the first paper may be judged worthwhile if there is a wealth of convincing new evidence, or a Flynn-like (1987) fine-toothcombing of the past evidence. Neither of these objectives is achieved. Therefore, the Pandora’s box has been opened once more, some may say, to no great purpose. What of Lynn’s evolutionary account of the origins of intelligence test score differences between groups? It puts me in mind of Kipling’s Just So stories. When one is more used to examining factor analyses or anova tables the type of evolutionary evidence that is offered here is difficult to evaluate. One suspects that there is an infinite number of more or less plausible historical accounts of the causes of racial differences in IQ test scores, and that all would leave aside uncomfortable facts (like the intelligence needed to exist in hot arid climates). The issue addressed in Lynn’s first paper is difficult enough, but the evidence is far too sparse to be telling the story of how the eskimo got his/her flat nose. (Deary, 1991: 157)

Thus, if this relationship were to hold, then those who experienced the harshest, coldest conditions should have the highest IQs. However, this is not what we see. Arctic people have IQs around 91, and so, this seems to be a piece of evidence against CWT. Lynn, though, has an ad hoc hypothesis for why they don’t have higher IQs—they had a small population size and so high IQ generic mutations didn’t have a large chance to appear and then become stabilized in the genome like they did for Asians (population size for Arctic people 56,000; for Asians 1.4 billion; Lynn, 2006: 157). So due to geographic isolation along with a small population size, Arctic people did not have the chance to gain higher IQs. This is nothing more than an ad hoc hypothesis—an ad hoc hypothesis is produced “for this”, and a hypothesis is ad hoc if it cannot be independently verified. It’s a case of special pleading, as Scott McGreal’s argues.

The fact of the matter about CWT, is that the conclusion was known first (higher IQs in certain geographic areas), and then a form of reverse reasoning was used in order to attempt to ascertain the causes of the observed differences between groups. This is known as reverse engineering, where reverse engineering is defined as “a process of figuring out the design of a mechanism on the basis of an analysis of the tasks it performs” (Buller, 2005: 92). This is also one of Smith’s (2016: 227-228) just-so story triggers:

1) proposing a theory-driven rather than a problem-driven explanation, 2) presenting an explanation for a change without providing a contrast for that change, 3) overlooking the limitations of evidence for distinguishing between alternative explanations (underdetermination), 4) assuming that current utility is the same as historical role, 5) misusing reverse engineering, 6) repurposing just-so stories as hypotheses rather than explanations, and 7) attempting to explain unique events that lack comparative data.

Lynn (1990) attempted to integrate gonadotropin levels, testosterone and prostate cancer into the theory, stating that by having fewer children and showing mote care to them, non-African populations then shifted to a K strategy, which then led to a concomitant decrease in testosterone and subsequently aggressive tendencies (Rushton, 2000: 263). However, this is based on the false assumption that testosterone is directly responsible for aggression, meaning that as testosterone increases so does aggression. They have the cause and effect backwards, though—aggression leads to an increase in testosterone, so Lynn’s explanation fails.

Rushton then comes along and champions Lynn’s “contributions to science” (Rushton, 2012), while also praising Lynn’s theory as explain why northerly populations evolved higher IQs and larger brains than southerly populations (Rushton, 2005), while making the grandiose claim that “documenting global race differences in intelligence and analysing how these have evolved may be his crowning achievement” (Rushton, 2012: 855). Rushton wrote an Amazon review of Lynn’s book, and then again in the white nationalist magazine VDare. Of course Rushton would go to bat for Lynn, since Lynn’s theory is a cornerstone of Rushton’s r/K selection theory, which is where we will now turn.

Cold winter theory – Rushton

Starting in 1985, Rushton began arguing that there was a suite of dozens of traits that the races differed on (Rushton, 1985). He collated his arguments in his first book, Race, Evolution, and Behavior (Rushton, 1995), and he argued that what explained the differences in these traits between his races were the selective factors that influenced and dictated survival in those environments. Rushton and Jensen (2005: 265-266; cf Andrade and Redondo, 2019) argued that there are genetically-driven differences in IQ scores between races (blacks and whites, in this instance), and one of the largest reasons for these differences was the different types of environments the two races were exposed to:

Evolutionary selection pressures were different in the hot savanna where Africans lived than in the cold northern regions Europeans experienced, or the even colder Arctic regions of East Asians. These ecological differences affected not only morphology but also behavior. It has been proposed that the farther north the populations migrated out of Africa, the more they encountered the cognitively demanding problems of gathering and storing food, gaining shelter, making clothes, and raising children successfully during prolonged winters (Rushton, 2000). As these populations evolved into present-day Europeans and East Asians, the ecological pressures selected for larger brains, slower rates of maturation, and lower levels of testosterone—with concomitant reductions in sexual potency, aggressiveness, and impulsivity; increases in family stability, advanced planning, self-control, rule following, and longevity; and the other characteristics listed in Table 3.

So this is where Rushton’s r/K selection comes in. He proposed that “some groups of people are more K selected than others” (Rushton, 1990: 137). So if some groups are more K selected than others, then some groups would have different trait values when compared to others, and this seems to support Rushton’s theory. However, Rushton’s theory can be explained environmentally, without appealing to genetics (Gorey and Cryns, 1995) and it also has not been independently replicated (Peregrine, Ember and Ember, 2003).

Devestating Objections to CWT

Objection 1: The fact of the matter is, when it comes to CWT, this is a perfect example of ideas and beliefs that shift with the time based on current observations. Aristotle argued that since the ancient Greeks had the middle geographic position between Asia and the rest of Europe, they were spirited and intelligent and therefore continued to be free while those who inhabited cold places like Europe lacked intelligence and skill, they had spirit while those in Asia were intelligent while being skilful in temperament, while also being subject to slavery. It was the Greeks who were right in the middle—they were just right, like Goldilocks—to have both all of the good and none of the bad traits they associated with those in other geographic locales. Meloni (2019: 42) cited one Roman officer who stated that recruitment of individuals from cold climates “as they had too much blood and, hence, inadequate intelligence. Instead, he argued, troops from temperate climates be recruited, as they possess the right amount of blood, ensuring their fitness for camp discipline (Irby, 2016).” This is solid evidence that who is or is not “intelligent” can and has changed with the times, along with other explanations of differences between people. This, then, proves the contingency of the concept of “more intelligent people”, and that people will marshal any kind of evidence for their pet theories at the time they have observed them and work backwards to form an argument, a kind of inference to best explanation. Thus, an evolutionary psychologist or IQ-ist transported back to antiquity would have formulated a different theory of intelligence, which obviously would have been at-odds with what they try to argue for today.

Objection 2: In 2019, I contrasted the CWT with the vitamin D hypothesis. I argued that there was one successful novel prediction made by the VDH—namely the convergent evolution of skin color in hominids that left Africa (Chaplan and Jablonski, 2009: 452), which was successfully predicted by Chaplan and Jablonski (2000). I wrote:

If high ‘intelligence’ is supposedly an adaptation to cold temperatures, then what is the observation that disconfirms a byproduct hypothesis? On the other hand, if ‘intelligence’ is a byproduct, which observation would disconfirm an adaptationist hypothesis? No possible observation can confirm or disconfirm either hypothesis, therefore they are just-so stories. Since a byproduct explanation would explain the same phenomena since byproducts are also inherited, then just saying that ‘intelligence’ is a byproduct of, say, needing larger heads to dissipate heat (Lieberman, 2015). One can make any story they want to fit the data, but if there is no prediction of novel facts then how useful is the hypothesis if it explains the data it purports to explain and only the data it purports to explain?

It is possible to think up any kind of story to explain any observation to give it an air of scientific objectivity. Of course it is possible to argue that other climates can select higher intelligence, as Anderson (1991), Graves (2002), and Flynn (2019) have argued. Sternberg, Grigorenko, and Kidd (2005) have also argued that it is possible to think of any kind of explanation/story for any kind of observed data. Nevertheless, the fact of the matter is this: There is no reason to accept the CWT, since there is no independent evidence for the theory in question.

Objection 3: If the Lynn-Rushton CWT were correct, then we would observe lower variation in IQ scores between whites and Asians, since it is well-accepted that natural selection reduced genetic variation in traits that are important for survival (Howe, 1997: 70; Richardson, 2017: 46). In the hereditarian conception, of course intelligence is important for survival, and so if the hereditarian argument for CWT is true, then we should observe lower variance in IQs in whites and Asians compared to blacks, but we don’t see this. (Also see Bird, 2020 for an argument against the hereditarian hypothesis, showing that there is no natural selection in blacks and whites on cognitive performance.)

Objection 4: Hereditarians have relied on the concept of heritability for decades. If T is highly heritable, then T has a genetic component and what explains the variance in T is genetics, not environment. Many critiques of the heritability concept have been mounted (eg Moore and Shenk, 2016), and they spell trouble for the hereditarian CWT and the hereditarian hypothesis as a whole. But these estimates are derived from highly confounded studies, and so the “laws” derived from them are anything but.

Objection 5: Rushton and Lynn posit that Asians are K- while Africans are r-selected. Rushton rightly stated that Africans endure endemic and infectious disease, which he wrongly stated was an r trait. He also stated that cold winters shaped K traits in Asians and European populations. However, based on the (accepted at the time) tenets of r/K selection, it would actually be Africans that are K and Asians that are r, since groups that move out of environments they evolved in and into new ones are freed from density-dependent control (Anderson, 1991: 59).

Objection 6: The irreducibility of the mental to the physical means that psychology can’t be an object of selection since it is not physical. Intelligence is posited as a psychological trait, so it cannot be selected. This is a devestating objection to not only the CWT but to most hereditarian hypotheses which reduce mental states to brain states or genes. Such irreducibility arguments make hereditarianism untenable.

Arguments against CWT

With all this being said, here are a few arguments derived from the discussions above. It is well-established that the CWT hardly had any evidentiary basis. It’s merely the argument of ideologues.

P1: If CWT were true, then there would be independent evidence for it.
P2: There is no independent evidence for the CWT.
P3: The correlation between race and IQ is better explained by social and environmental factors than by the CWT.
P4: The evidence cited in support of the CWT, including Lynn’s national IQ data, is fraudulent and lacks scientific rigor.
C: Therefore, the CWT is false.

Premise 1: This is a basic tenet of scientific explanation. Independent evidence refers to evidence not used in the construction of the hypothesis. The only evidence for CWT is the observation of differences in IQ between people that inhabit different geographic locations. So if CWT were true, it is entailed that there should be independent, novel evidence to support the hypothesis. It is evidence that isn’t based on the original assumptions or data used to construct the hypothesis. If there is, then that raises the probability that the state of affairs that is proposed is true. Independent, novel evidence is important, since it helps confirm or disconfirm a theory or hypothesis by providing additional support from sources that were not originally taken into account. Evidence is novel when it is not already known or expected based on prior knowledge or previous observations. So novel evidence would, in this instance, refer to evidence that supports the theory and is distinct from the evidence that is used to support it. So in order for CWT to be scientifically valid, there would need to be independent evidence that shows a direct causal link between intelligence and cold winters.

Premise 2: This is a denial of the claim that there is independent evidence that supports CWT, on the accepted definition of “novel, independent evidence.”

Premises 3 and 4: These two premises are linked—access to education along with nutrition better explains the relationship between latitude and IQ. There is also the fact that Lynn’s “national IQs” are fraudulent (Sear, 2022). Thus, there is no evidentiary reason to accept Lynn’s IQs (the only reason is bias and that it “explains” the differing civilizational states of different races). It’s merely working backwards (returning to reverse engineering) since they have their conclusion in mind and then construct an argument to prove their already-held conclusion.

So the Conclusion follows—CWT is false since there is no independent, novel evidence for it. Therefore the only reason to believe it is bias in thinking against groups of people.

P1: The CWT suggests that differences in average IQ scores between racial groups can be largely explained by differences in the coldness of the winter climates that these groups evolved in.
P2: All of the evidence used to support the CWT is based on previously existing data, such as Lynn’s national IQ data or historical temperature records.
P3: There is no new independent evidence that supports the CWT beyond this existing data.
C: Thus, there is no novel, independent evidence for the CWT.


P1: If there is new independent evidence for the CWT, then the CWT can be independently supported.
P2: There is no novel independent evidence for CWT beyond the existing data.
C: So the CWT cannot be supported by new independent evidence.

These arguments are valid and I hold them to be sound, based on the discussion in this article and my previous articles on the matter of CWT and the prediction of novel facts of the matter.


We don’t need evolutionary stories to explain IQ differences between countries (Wicherts, Borsboom, and Dolan, 2010). Lynn’s national IQ data is highly suspect and should not be used (Sears, 2022). High intelligence would be useful in all environments. The Rushton-Lynn CWT states that those who migrated to more northerly, colder biomes needed to plan ahead for the winter, and they would also need to plan and create hunting parties to procure food. This, of course, is ridiculous. Because you need to plan ahead to survive anywhere. Moreover, Will et al (2021) state that their:

analyses detected no such association of temperature with brain size. … These results suggest that brain size within Homo is less influenced by environmental variables than body size during the past 1.0 Ma.

This is of course a huge strike against the Rushton-Lynn CWT. Anthropological evidence also conflicts with the CWT (MacEachern, 2006).

Since I have shown that the evidentiary bases of the CWT doesn’t hold, then it isn’t logical to hold the belief that the CWT is true. Views like this are expressed in Rushton (2000: 228-231)Jensen (1998: 170, 434-436) and Lynn (2006: Chapters 15, 16, and 17). Since the main proponents of the model hold eugenist ideas, then it can be posited that they have underlying alterior motives for pushing this theory. Even a claim that there is “molecular genetic evidence” for CWT fails, due to, again, the irreducibility of the mental.

Nevertheless, there is no novel, independent evidence for the belief that cold winters shaped our minds and racial differences in psychological traits after the exodus out of Africa. There can be no evidence for it since we lack time machines and we can’t deconfound correlated traits. So these considerations point to the conclusion that the CWT is a mere story based on data which was then used to work backwards from an already-held conclusion. Thus, CWT is false.

Rushton, Lynn, Kanazawa (2008, 2012), (Kanazawa assumed a flat earth in his 2008 paper; Wicherts et al, 2012) Hart (2009), and Winegard, Winegard, and Anomaly (2020) therefore, are nothing more than just-so storytellers since they lack novel evidence for their assertions. So the so-called argument for evolutionary differences in intelligence/IQ rests on a house of cards that is simple to push over. The six objections laid out in this article are devestating for the CWT. There never was any evidentiary support for CWT—the kind that scientific hypotheses need in order to be valid, it’s merely an ideological series of statements, not an actual scientific hypothesis.


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