Differential K theory
The "differential K theory" regarding differences between human races was originally an adaption of "r-K selection theory" (or "r/K selection theory") which was originally a theory regarding differences between species. "Life history theory" is a more general theory which also includes aspects such as related differences between individuals.
Race, Evolution, and Behavior
|Average racial differences from Race, Evolution, and Behavior|
|Cranial capacity (cubic centimeters)||1,267||1,347||1,364|
|Cortical neurons (millions)||13,185||13,665||13,767|
|IQ test scores||85||100||106|
|2-egg twinning (per 1000 births)||16||8||4|
|Sexually transmitted diseases||Higher||Intermediate||Lower|
|Age of first intercourse||Earlier||Intermediate||Later|
|Age of first pregnancy||Earlier||Intermediate||Later|
|Source: Unabridged edition, Race, Evolution, and Behavior (p. 5).|
r-K selection theory is a theory which argues that species face a trade-off between a high rate of reproduction (r-strategy) or extensive care for their offspring (K-strategy). Humans may be the most K species of all.
The theory grew out of Rushton's 1989 paper, "Evolutionary Biology and Heritable Traits (With Reference to Oriental-White-Black Difference)".
Rushton's book Race, Evolution and Behavior (1995, third edition 2000) compiled a very large of number of earlier studies on racial differences. Average results from these were calculated. The summarized racial differences were argued to support the theory.
Rushton argued that East Asians, Europeans, and Africans fall consistently into the same pattern when compared on a list of 60 different psychological and physical traits. The book argued that East Asians, on average, are at one end of a continuum, that Africans, on average, are at the opposite end of that continuum, and that Caucasoids rank in between East Asians and Africans, but closer to East Asians.
Differences in testosterone levels or sensitivity to testosterone was proposed as a factor that may have caused many of these differences. See also Other race differences: Femininity vs. masculinity.
He further argued that Europeans and East Asians evolved more toward a K-strategy than Africans because of a colder and more predictable climate and environment. Rushton argued that the survival challenges of making warm clothes, building durable shelter, preserving food, and strategically hunting large animals all selected genes for greater intelligence and social organization among the populations that migrated to cold climates.
Rushton argued that alternative purely environmental theories fail to elegantly explain what he sees as such a consistent pattern of both behavioral and physiological differences, but instead just provide a long list of ad hoc explanations. Rushton argues that science strives to organize and simplify data, and seeks the simplest explanation possible which he argued his theory is (see Occam's razor).
Later supportive studies
Rushton argued that the theory was supported by relationships between brain weight and several other variables among 234 mammalian species: longevity (r = .70), gestation time (.72), birth weight (.44), litter size (-.43), age at first mating (.63), duration of lactation (.62), body weight (.44), and body length (.54). The relationship remained after controlling for body weight and body length. Looking at 21 primate species, brain size correlated even stronger at .80 to .90 with life span, length of gestation, age of weaning, age of eruption of first molar, age at complete dentition, age at sexual maturity, inter-birth interval, and body weight.
Templar in a 2008 study argued that Rushton's r/K factor explained 75% of the variance for national differences in IQ, birth rate, infant mortality, HIV/AIDS, life expectancy, skin color, and GDP. "Moreover, the correlations were significantly higher with skin color, a biological variable, than they were with gross domestic product (GDP), a culturally influenced variable."
Rushton and Templar in a 2009 study argued that violent crime (murder, rape, and serious assault) was lower in countries with higher IQs, higher life expectancies, lighter skin color, and lower rates of HIV/AIDS. A factor was found to explain 52% of the variance. Higher national incomes or higher rates of infant mortality did not affect the results.
Suicide may have evolutionary roots as a mechanism which in the ancestral past removed unproductive individuals, such as the elderly, from being a burden to their relatives. This would fit with a K-strategy. Voracek in a study of 75 countries found that "higher suicide rates of the total male, and female population corresponded to higher levels on the superordinate K factor from differential K theory, thought to reflect a set of mutually interrelated life history and reproductive strategy traits. Countries ranking high on suicide rates concurrently ranked high on national intelligence estimates, longevity, and affluence, whilst low on rates of births, infant mortality, HIV/AIDS, and crimes (rape, serious assault, and homicide). These findings integrate previously reported positive population-level associations between suicide rates and cognitive ability variables into the conceptual space of differential K theory."
A 2015 study stated that "Differential-K theory proposes that levels of androgen, i.e. male hormone, differ across three large racial groups with Sub-Saharan Africans having the highest levels, East Asians the lowest, and Caucasians (Europeans, North Africans and South Asians) being intermediate. In this study, we found that most of the national-level indicators of androgen – CAG repeats on the AR gene, androgenic hair, prostate cancer incidence, sex frequency and number of sex partners – are positively correlated at the population (country) level. East Asians showed signs of the lowest androgen level for most indicators and were lower than Caucasians on all of them. Sub-Saharan Africans showed inconsistent results. The results provide a partial validation of Differential-K theory."
A 2015 study stated that "The existence of a genetic factor behind group-level differences in life history strategy (LHS) has long been disputed. A number of recent studies suggest that some polymorphisms in the androgen receptor gene AR, the dopamine receptor gene DRD4, and the 5-HTTLPR VNTR of the serotonin transporter gene are associated with risk acceptance versus prudence and a short-term versus long-term time orientation, which are important aspects of LHS. We integrated studies from diverse nations reporting the prevalence of these three polymorphisms for many countries. We collected national indices for each of the three polymorphisms and found that they define a strong, single factor, yielding a single LHS-related, national genetic index. As expected, this index is strongly associated with reported national measures of LHS and time orientation, even after controlling for socioeconomic variables. The genetic effect seems especially strong across societies with high socioeconomic inequality."
Differential K and welfare
High K races in favor of a high degree of care may support extensive welfare systems in countries where they are predominant. However, this risks being taken advantage of by immigrants from low K races who may have many children (either within their own group or due to race mixing) who are supported by the welfare systems.
A relatively low K subgroup within a high K race may also take advantage of such welfare systems.
Differences between individuals
An extension of the theory is that individuals may differ regarding r-K-strategy or "life history strategy". This could include individuals of the same race. This would be similar to the situation for IQ where the racial averages are different but individual scores may differ. Thus, both individuals and groups are argued to differ regarding "speed" of life history strategy with "slower" speed corresponding to a higher K strategy.
The "general factor of personality" has been argued to be the most important personality variable. It has been named after the general intelligence factor (g factor). A large number of studies have found support for this factor. Studies have also argued that this factor is partially heritable and related to life history theory.
Strategic differentiation-integration effort theory
The "strategic differentiation-integration effort" theory states that correlations among life history traits are stronger among individuals (and groups) exhibiting faster life histories than among those with slower ones. Thus, there is argued to be larger differences between slow life history individuals (and groups) which is argued to be explained by slow life history being associated with factors such as high environmental predictability which encourages specialization into different niches. In contrast, fast life history is associated with a more unpredictably environment, therefore less specialization, and more similarity regarding various traits. Many empirical results are argued to support the theory.
A 2016 study found that sexual strategies are more diverse for individuals with slower life history traits as predicted by the theory.
The Flynn effect
The life history speed of individuals and groups may to some degree be relatively quickly influenced by non-genetic factors (enabling relatively quick changes to a more appropriate life history strategy if the environment quickly changes). An explanation for the Flynn effect is a slowing of life history speed for many groups.
- Regarding race and intelligence differences, race and crime differences, and race realism, see the linked articles.
One difficulty for theory is that it is Europeans and not East Asians who have achieved most discoveries in science and technology and who achieved the scientific and industrial revolutions. This could be interpreted in various way. One is that the theory is missing important traits such as creativity where Europeans may excel. Another is that an extreme K-strategy may have disadvantages. A third is that the East Asians were handicapped by environmental factors. Yet another is that there may be errors regarding the argued racial differences or the r–K theory argued to explain them.
In Race, Evolution and Behavior, Rushton used a methodology in which he averaged hundreds of studies, modern and historical, with equal weight regardless of the quality of the data. He argued that by averaging many studies the results one gets will be accurate. The expectation being that the law of large numbers will make individual flawed results cancel one another out. This has been criticized as producing incorrect results if there is an overall bias in the data. Good data should therefore be separated from bad. However, this criticism do not apply to the later peer-reviewed studies although these do not study all of the traits studied in the book.
There have also been criticisms of the argued differences in genital size. See Race and morphology/physiology: Penis size.
A study used data from the "186-society Standard Cross-Cultural Sample" and found no statistical support for the predicted associations between "race" and behavior. However, this study attempted classify all cultures into three groups corresponding to the three races used by Rushton. For example, the Australoid cultures in Australia were classified as East Asian ("Mongoloid") cultures which is highly questionable.
The theory has been criticized this for ignoring demographic changes such as that in much of the twentieth century, fertility and infant mortality rates have been much higher in China than in European countries. However, the theory applies to different evolutionary adaptations different historical environments, and not necessarily to all behaviors found in the very recent environment which may be very much different from the historical environment. Even a very high K group with a tendency to lower fertility will likely respond to high infant mortality with increased fertility in order to survive.
The General Factor of Personality have been criticized.
r–K theory as an explanation for the differences
Another criticism is that the original r–K theory regarding differences between species has by biologists been replaced by more complex life history theories such as theories on different strategies used during different life stages. However, such theories still incorporate many of the themes important to the r–K paradigm.
Rushton argued that European and East Asian peoples adapted to survival in cognitively demanding but predictable cold environments requiring increased brain size and parenting behavior. A criticism is that many animal species do not follow the predictions of r/K theory. Furthermore, tropical rain-forest conditions, being more constant, would favor K-selection, while seasonal Arctic environments would be less predictable and associated with r- selection. Rushton has responded that it is the unpredictable East African savanna where humans originated that should be compared to cold climates which do have seasons but these being predictable. A response was that assuming that this correct, this would mean that Rushton selectively chose only a few of the wide variety of habitats humans have lived in for a long time, but then makes general clams for much larger areas with many different habitats such as all of sub-Saharan Africa and all sub-Saharan Africans. Another criticism is that northern mice, foxes, and deer are not better endowed intellectually than their tropical relatives, and the same applies to almost all other animals with arctic and tropical representatives. This can be explained by the fact that humans are much more dependent on intellectual faculties for survival, especially with reference to tool use. Therefore, "expensive" K-selected phenotypes in humans tend to increase brain power, while in other organisms physical abilities may be favored.
Alternative explanations for the racial differences
Generally, the politically correct explanation is that any important racial differences can be due to environmental factors such as undernutrition causing differences in birth weight. As noted earlier, Ruston's argues that his theory provides a simpler explanation than numerous ad hoc environmental explanations.
Another criticism is that whether humans choose an r-strategy or K-strategy, or similar behaviors, may depend on environmental factors without being genetically fixed. This would explain the demographic transition which refer to the observation that the number of children per person decreases as a society becomes wealthier and have less unpredictable mortality. A 2004 study examined different rK strategies among different tribes of Gypsi in Serbia and argued that the different strategies observed depended on which one was most favorable in a given environment. The strategies ranged from an extreme r strategy, for humans, to more typical K strategy. However, even if the strategy is not absolutely fixed regarding all behaviors and may be changeable to some degree depending on the environment, there may still be differences between groups regarding preferred strategy and behaviors and some variables may not be possible to change.
There are also alternative genetic explanations. A 1994 study by Edward M. Miller argued that "Paternal investment theory suggests that in cold climates males were selected for provisioning, rather than for mating success. In warm climates, where female gathering made male provisioning unessential, selection was for mating success. Male hunted meat was essential for female winter survival. Genes that encouraged mating success were selected for in warm (was cold) climates. Negroids (blacks) evolved in warm cold climates, while Caucasians (whites) and Mongoloids (Asians) evolved in colder climates. Mating is assisted by a strong sex drive, aggression, dominance, sociability, extroversion, impulsiveness, sensation seeking, and high testosterone. Provisioning is assisted by anxiety, altruism, empathy, behavioral restraint, gratification delay, and a long life span. Explanations are offered for racial differences in many personality characteristics, hormone levels, monamine oxidase levels, testosterone levels, lactase dehydrogenase metabolic paths, life spans, prostate cancer rates, hypertension, genital (penis and testes) size, vocal frequencies, liver size, muscle structure, mesomorphy, bone density, sports performance, crime rates, rape, child abuse, earnings, age at first sexual activity, AIDs, illegitimacy, divorce, marriage, and polygyny rates. Eye color correlations are discussed. Negro family structure in the Caribbean and the U.S. may reflect selection in Africa during hunter-gather times".
Race, Evolution, and Behavior
- Race, Evolution, and Behavior: A Life History Perspective; 2nd Special Abridged Edition - Also including a FAQ
- A New Theory of Racial Differences
- What is Intelligence and Who has it?, The New York Times’ review of Race, Evolution, and Behavior, The Decline of Intelligence in America, and The Bell Curve.
- The Return of Racial Science, by Glayde Whitney, published in Contemporary Psychology, December 1996, pp. 1189–1191.
- Review of Race, Evolution and Behavior, by Henry Harpending, published in Evolutionary Anthropology, 1995.
- Review of Race, Evolution and Behavior, by Irving Louis Horowitz in Society, Jan-Feb 1995 v32 n2.
- Placing intelligence into an evolutionary framework or how g fits into the r–K matrix of life-history traits including longevity
- ↑ Presented at the Symposium on Evolutionary Theory, Economics and Political Science, AAAS Annual Meeting (San Francisco, CA, January 19, 1989)
- ↑ Rushton, J (2004). "Placing intelligence into an evolutionary framework or how fits into the ? Matrix of life- history traits including longevity". Intelligence 32 (4): 321–328. http://dx.doi.org/10.1016/j.intell.2004.06.003. edit
- ↑ Lynn, R. (2000). Population and Environment 22: 73–81. http://dx.doi.org/10.1023/A:1006633632359
- ↑ Richard Lynn, Racial and ethnic differences in psychopathic personality, Personality and Individual Differences, Volume 32, Issue 2, 19 January 2002, Pages 273-316, ISSN 0191-8869, http://dx.doi.org/10.1016/S0191-8869(01)00029-0.
- ↑ Richard Lynn, Race differences in psychopathic personality: a reply to Skeem and Zuckerman, Personality and Individual Differences, Volume 35, Issue 6, October 2003, Pages 1471-1477, ISSN 0191-8869, http://www.sciencedirect.com/science/article/pii/S019188690200363X
- ↑ Templer, Donald I. (2008). "Correlational and factor analytic support for Rushton’s differential K life history theory". Personality and Individual Differences 45 (6): 440–444. http://dx.doi.org/10.1016/j.paid.2008.05.010.
- ↑ Rushton, J. Philippe; Templer, Donald I. (2009). "National differences in intelligence, crime, income, and skin color". Intelligence 37 (4): 341–346. http://dx.doi.org/10.1016/j.intell.2009.04.003. http://www.charlesdarwinresearch.org/2009%20INTELL%20(Crime).pdf
- ↑ Brian B. Boutwella Travis W. Franklin, J.C. Barnes, Kevin M. Beaver, Raelynn Deaton, Richard H. Lewis, Amanda K. Tamplina, Melissa A. Petkovsek. (2013). County-level IQ and fertility rates: A partial test of Differential-K theory. Personality and Individual Differences, Volume 55, Issue 5, September 2013, Pages 547–552 https://www.sciencedirect.com/science/article/pii/S019188691300189X
- ↑ Meisenberg, G., & Woodley, M. A. (2013). Global behavioral variation: A test of differential- K. Personality and individual differences, 55(3), 273-278. https://www.sciencedirect.com/science/article/pii/S019188691200181X
- ↑ Dunkel, C. S., Stolarski, M., Linden, D. van der & Fernandes, H. B. F. (2014). A reanalysis of national intelligence and personality: The role of the general factor of personality. Intelligence, 47, 188-193. https://www.sciencedirect.com/science/article/pii/S0160289614001408
- ↑ Michael Minkov, The K factor, societal hypometropia, and national values: A study of 71 nations, Personality and Individual Differences, Volume 66, August 2014, Pages 153-159, ISSN 0191-8869, http://dx.doi.org/10.1016/j.paid.2014.03.021
- ↑ Minkov, M., & Beaver, K. (2016). A test of life history strategy theory as a predictor of criminal violence across 51 nations. Personality and Individual Differences, 97, 186-192. http://www.sciencedirect.com/science/article/pii/S0191886916302161
- ↑ Kenya Kura, Japanese north–south gradient in IQ predicts differences in stature, skin color, income, and homicide rate, Intelligence, Volume 41, Issue 5, September–October 2013, Pages 512-516, ISSN 0160-2896, http://dx.doi.org/10.1016/j.intell.2013.07.001 http://www.sciencedirect.com/science/article/pii/S0160289613000949
- ↑ Richard Lynn, In Italy, north–south differences in IQ predict differences in income, education, infant mortality, stature, and literacy, Intelligence, Volume 38, Issue 1, January–February 2010, Pages 93-100, ISSN 0160-2896, http://dx.doi.org/10.1016/j.intell.2009.07.004 http://www.sciencedirect.com/science/article/pii/S0160289609000956
- ↑ R. Lynn. North–south differences in Spain in IQ, educational attainment, per capita income, literacy, life expectancy and employment. Mankind Quarterly, 52 (2012), pp. 265–291. http://www.mankindquarterly.org/spring_summer2012_lynn.html
- ↑ Elijah L. Armstrong, Heitor B.F. Fernandes, Michael A. Woodley, SD–IE and other differentiation effects in Italy and Spain, Personality and Individual Differences, Volume 68, October 2014, Pages 189-194, ISSN 0191-8869, http://dx.doi.org/10.1016/j.paid.2014.03.043 http://www.sciencedirect.com/science/article/pii/S019188691400213X
- ↑ Voracek, M. (2009). "Suicide rates, national intelligence estimates, and differential K theory". Perceptual and motor skills 109 (3): 733–736. http://www.ncbi.nlm.nih.gov/pubmed/20178273
- ↑ Edward Dutton, Dimitri van der Linden, Richard Lynn. (2015). Population differences in androgen levels: A test of the Differential K theory. Personality and Individual Differences, Volume 90, February 2016, Pages 289–295. https://www.sciencedirect.com/science/article/pii/S0191886915300519
- ↑ Minkov, M., & Bond, M. H. (2015). Genetic polymorphisms predict national differences in life history strategy and time orientation. Personality and Individual Differences, 76, 204-215. https://www.sciencedirect.com/science/article/pii/S0191886914007223
- ↑ Caroline Just, A review of literature on the general factor of personality, Personality and Individual Differences, Volume 50, Issue 6, April 2011, Pages 765- 771, ISSN 0191-8869, http://dx.doi.org/10.1016/j.paid.2011.01.008.
- ↑ Woodley of Menie, M. A., Figueredo, A. J., Cabeza de Baca, T., Fernandes, H. B. F., Madison, G., Wolf, P. S. A., & Black, C. J. (2015). Strategic differentiation and integration of genomic-level heritabilities facilitate individual differences in preparedness and plasticity of human life history. Frontiers in Psychology, 6, 422. http://doi.org/10.3389/fpsyg.2015.00422 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4405998
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- ↑ Michael A. Woodley, Heitor B.F. Fernandes, Strategic and cognitive differentiation–integration effort in a study of 76 countries, Personality and Individual Differences, Volume 57, January 2014, Pages 3-7, ISSN 0191-8869, http://dx.doi.org/10.1016/j.paid.2013.09.010. http://www.sciencedirect.com/science/article/pii/S019188691301266X
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- ↑ Pietschnig J, Voracek M. (2015). One Century of Global IQ Gains: A Formal Meta-Analysis of the Flynn Effect (1909-2013). Perspect Psychol Sci 10 (3):282-306. DOI:10.1177/1745691615577701 http://pubmed.gov/25987509
- ↑ Book Review of Race, Evolution and Behavior
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- ↑ On the similarities of American blacks and whites: A reply to J.P. Rushton. Zack Cernovsky. Vol. 25, Journal of Black Studies, 07-01 -1995, pp 672.
- ↑ Peregrine, Peter N.; Ember, Carol R.; Ember, Melvin (September 2003). "Cross-cultural evaluation of predicted associations between race and behavior". Evolution and Human Behavior 24 (5): 357–364. http://dx.doi.org/10.1016/S1090-5138(03)00040-0. http://www.lawrence.edu/fast/peregrip/Publications/RushtonEHB2003.pdf
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- ↑ Sexual and Reproductive Strategies Among Serbian Gypsies, Jelena Črovović, POPULATION & ENVIRONMENT Volume 25, Number 3, 217-242, DOI 10.1007/s11111-004-4485-y http://link.springer.com/article/10.1007%2Fs11111-004-4485-y
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