Cold winters theory

Cold winters theory is a proposed evolutionary model for what some believe to be heritable genetic differences in intelligence between human groups or races.^[1]^[2]^[3]^[4]

Mechanism

According to the model, when some human populations left Africa, they encountered new climates and adapted to them. Colder, more northern climates are thought to be more difficult to survive in and would therefore, according to the model, increase or create additional selection pressure for the evolution of higher intelligence.^[2]^[3]

In support of the model, several studies have correlated latitude, mean annual temperature and similar metrics with national IQs estimated from IQ data and scholastic tests such as PISA, and observed very strong correlations. For instance, a 2006 study correlated mean temperature, national IQ, skin color and per capita income in a sample of 129 countries.^[4] They reported a correlation of -.66 between mean winter temperature and national IQ.

Criticism

A 2014 study reported a correlation of -.66 between estimates IQs of US states and mean temperature.^[1] This relationship was also present when they controlled for percent Blacks, r = -.53. The authors interpreted this as being evidence against the cold winters theory because it shows that such correlations can arise in a situation where we know that the differences are not due to evolution. In a 2016 study other researchers analyzed relationships between IQ and latitude within race/ethnicity groups, thus controlling for racial composition by design.^[5] When this was done, the correlations between latitude and IQ were weaker, -.29, -.16 and .01 for Whites, Blacks and Hispanics, respectively. The authors argued that the stronger result from the 2014 paper were due to inadequate controls for racial composition.

References

^ ^a ^b Pesta, Bryan J.; Poznanski, Peter J. (2014-09-01). "Only in America: Cold Winters Theory, race, IQ and well-being". Intelligence. 46: 271–274. doi:10.1016/j.intell.2014.07.009.
^ ^a ^b Lynn, Richard. "The evolution of race differences in intelligence". Mankind Quarterly. 32.
^ ^a ^b Kanazawa, Satoshi (2012-07-01). "The evolution of general intelligence". Personality and Individual Differences. Evolution of race and sex differences in intelligence and personality: Tribute to Richard Lynn at eighty. 53 (2): 90–93. doi:10.1016/j.paid.2011.05.015.
^ ^a ^b Templer, Donald I.; Arikawa, Hiroko (2006-03-01). "Temperature, skin color, per capita income, and IQ: An international perspective". Intelligence. 34 (2): 121–139. doi:10.1016/j.intell.2005.04.002.
^ Kirkegaard, Emil O. W.; Fuerst, John (2016). "Inequality in the United States: Ethnicity, Racial Admixture and Environmental Causes". Mankind Quarterly. 56 (4).

[:0-1] Pesta, Bryan J.; Poznanski, Peter J. (2014-09-01). "Only in America: Cold Winters Theory, race, IQ and well-being". Intelligence. 46: 271–274. doi:10.1016/j.intell.2014.07.009.

[:1-2] Lynn, Richard. "The evolution of race differences in intelligence". Mankind Quarterly. 32.

[:2-3] Kanazawa, Satoshi (2012-07-01). "The evolution of general intelligence". Personality and Individual Differences. Evolution of race and sex differences in intelligence and personality: Tribute to Richard Lynn at eighty. 53 (2): 90–93. doi:10.1016/j.paid.2011.05.015.

[:3-4] Templer, Donald I.; Arikawa, Hiroko (2006-03-01). "Temperature, skin color, per capita income, and IQ: An international perspective". Intelligence. 34 (2): 121–139. doi:10.1016/j.intell.2005.04.002.

[5] Kirkegaard, Emil O. W.; Fuerst, John (2016). "Inequality in the United States: Ethnicity, Racial Admixture and Environmental Causes". Mankind Quarterly. 56 (4).

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