Race, Sexual Permissiveness, and Questionable Science

Why Differential-K Theory gets Racial Differences in Sexuality Wrong

Posted Mar 06, 2016

In two previous posts, I discussed a study (Dutton, van der Linden, & Lynn, 2016) that aimed to test predictions from the highly controversial differential-K theory. Among other things, this theory proposes that there are racial differences in sexual attitudes and behavior, so that people of sub-Saharan African descent are supposed to be the most sexually permissive, while people of East Asian descent are supposed to be the most sexually restrained, and Caucasian descended people are said to be in-between. The authors used data from a sex survey by Durex, the condom manufacturer, to provide evidence of racial differences in sexual behavior that they claimed supported their theory. This method has a number of problems because the survey lacked data from African nations, and the survey methodology was not up to rigorous scientific standards. Fortunately, more rigorous scientific research is available using data from 48 countries, including several African ones, that can shed some light on this subject. As will become clear, the evidence from this research contradicts the predictions of differential-K theory in a number of major respects. Furthermore, cross-cultural differences in sexual attitudes and behavior are related to a variety of environmental, social and cultural factors that need to be taken into account before making sweeping generalisations about race.

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Discussion of racial differences can become heated, but hopefully cooler heads will prevail. 
Source: Wikimedia Commons

I have discussed differential-K theory before in some detail, so I will recap it only briefly here. According to this theory, over thousands of years, various racial groups have developed different reproductive strategies in order to adapt to differences in their local environments. Sub-Saharan African people developed a fast life history strategy entailing sexual permissiveness and high fertility. Caucasian and to an even greater extent Asian peoples have developed slower life history strategies, which entail more sexual restraint, and more intensive parental investment in a smaller number of children. Dutton et al. (2016) proposed that these racial characteristics are related to differences in levels of androgens (male hormones including testosterone), with higher androgen levels being related to faster life history strategies. The evidence they presented did not wholly support this theory, as they actually found that African peoples were more similar to Asian ones in some respects.

Dutton et al. argued that since sexual behavior is influenced by androgen levels, racial differences should be evident in this respect. Using data from the Durex sex survey, they found that survey respondents from Caucasian nations reported a higher annual frequency of sex and more lifetime sex partners than respondents from Asian nations. Unfortunately, the only African nation sampled in the survey was South Africa, so it was not possible to compare Africans with the other two groups. Nevertheless, Dutton et al. concluded that the results were broadly in line with the prediction of differential-K theory that Asians would be more sexually restrained than Caucasians.

Apart from the lack of African data, the survey has problems with lack of scientific rigour. It was conducted mainly as a promotional activity for Durex and it is not clear how representative the respondents are of the general population from which they were drawn. (This article explores these concerns in more detail.) Furthermore, the survey makes no attempt to take into account important differences between the nations sampled that could influence sexual behavior, such as social and economic conditions. Hence, the survey provides a crude comparison between nations and it is unclear how much the results are due to biological factors related to the respondents’ race as Dutton et al. propose or to other salient factors.

One prediction of differential-K theory is that populations with a predominantly fast life history strategy should have more interest in short-term mating, whereas those with a predominantly slow life history strategy should be more focused on long-term mating. One way to assess interest in short-term versus long-term mating is to look at attitudes towards sex without commitment to a long-term relationship, which is known as sociosexuality. People high in sociosexuality feel comfortable with uncommitted sex and are interested in having many sexual partners. Conversely, people low in sociosexuality are generally unwilling to have sex without being in a committed relationship and consequently desire fewer partners. If differential-K theory is correct, African nations should have the highest rates of sociosexuality, Asian ones should have the least, while Caucasian ones should be intermediate. There has been a study on national levels of sociosexuality (Schmitt, 2005) which includes enough nations from each of these three groups to allows the necessary comparisons. This study found that both African and Asian nations on the whole had significantly lower levels of sociosexuality compared to Caucasian nations from Europe, North America and Australia. This result contradicts differential-K theory and is also consistent with Dutton et al.’s other findings that people from African nations were more similar to those from Asian nations in some respects than they were to Caucasians.

Looking more closely into Schmitt’s results reveals more findings that are inconsistent with differential-K theory. National sociosexuality was positively correlated with the level of human development, including life expectancy, and negatively correlated with infant mortality, teen pregnancy rate, prevalence of child malnutrition, prevalence of low birth weight, and fertility. According to life history theory, environments in which life expectancy is short and infant mortality is high should foster a fast life history strategy, involving early marriage and high levels of fertility. Differential-K theory predicts that fast life history strategies should be associated with sexual permissiveness, yet in countries with shorter life expectancy, high infant mortality and high fertility people actually tend to be more sexually restrained compared to people in more developed countries with better life expectancy and so on. Schmitt’s results are more consistent with an alternative theory, known as strategic pluralism, that low sociosexuality and a preference for monogamy are more adaptive in harsh, difficult environments because infants then have a better chance of survival when bi-parental care is more prevalent. Conversely, in resource-rich environments, such as in developed nations, single-parenting becomes more viable and higher sociosexuality becomes more common.

Another environmental factor associated with sociosexuality is imbalanced sex-ratio (Barber, 2008). For example, in societies where there are more men than women available for marriage, levels of sociosexuality tend to be lower. In this situation, marriageable women are highly in demand, and women can demand a higher level of relationship exclusivity from prospective partners, and they are more likely to delay intercourse until after marriage. Conversely, when there are fewer men than women available for marriage, levels of sociosexuality tend to be higher. In this situation, women must compete more intensively for mates and sex outside of marriage and more permissive sexual attitudes are more common. Imbalanced sex ratios featuring more men than women occur today in a number of East Asian countries and this might help explain why these countries tend to be more sexually conservative (Schmitt & Project members, 2003). Additionally, societies where it is common for women to delay marriage in order to pursue a career also tend to be more sexually permissive. This might help explain why higher levels of economic development in a country are associated with higher levels of sociosexuality (Barber, 2008).

International differences in sociosexuality might also be related to changes in societal values as countries become more developed. Improvements in economic development are not only marked by increased life expectancy and reduced infant mortality, but by changes in societal values. Poorer countries tend to be marked by survival values, which emphasise tradition and obedience to authority. Economically developed societies tend to shift away from survival values towards self-expression values emphasising individual freedom. (I have discussed national values in more detail in a previous post.) An emphasis on personal freedom may also bring about greater sexual permissiveness.

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Truth will come out in the end. 

Source: Wikimedia Commons


Differential-K theory makes predictions about racial differences in sexual attitudes that are contradicted by research evidence. Differential-K theory assumes that a fast life history strategy should be associated with greater sexual permissiveness, but this may be incorrect. Harsh environments that foster a fast life history strategy due to shorter life expectancy and higher infant mortality are more likely to be associated with sexual restraint and monogamy. Conversely, sexual permissiveness may become less risky in resource-rich environments conducive to a slow life history strategy. Furthermore, differential-K theory is based on the premise that cultural differences in sexual attitudes and behavior are based on inherent differences between racial groups. Specifically, Dutton et al. propose that racial differences in androgen levels are responsible for these variations. However, there is considerable evidence that sexual attitudes and behavior may be linked to social and environmental factors that may be distinct from race as such.

© Scott McGreal. Please do not reproduce without permission. Brief excerpts may be quoted as long as a link to the original article is provided.

Image Credits

The Intervention of the Sabine Women, by Jacques-Louis David, 1799. 

Truth rising out of her well to shame mankind, by Jean-Léon Gérôme, 1896. 

Related posts

Personality, Intelligence and "Race Realism" - critiques J.P. Rushton's theory

The Pseudoscience of Race Differences in Penis Size - critiques Lynn's paper on the subject


Barber, N. (2008). Cross-National Variation in the Motivation for Uncommitted Sex: The Role of Disease and Social Risks. Evolutionary Psychology, 6(2).

Dutton, E., van der Linden, D., & Lynn, R. (2016). Population differences in androgen levels: A test of the Differential K theory. Personality and Individual Differences, 90, 289-295. doi:

Schmitt, D. P. (2005). Sociosexuality from Argentina to Zimbabwe: a 48-nation study of sex, culture, and strategies of human mating. Behavioral and Brain Sciences, 28, 247-311.

Schmitt, D. P., & 118 Members of the International Sexuality Description Project. (2003). Universal Sex Differences in the Desire for Sexual Variety: Tests From 52 Nations, 6 Continents, and 13 Islands. Journal of Personality & Social Psychology, 85(1), 85-104.