A Scientific Look at Sexually Unfaithful Personalities
Posted Jun 28, 2011
In 2005 and again in 2008, a group of anthropologists trekked into the lowland forests of Bolivia to study the Tsimane, a small-scale society of Amerindian people. As part of their scientific mission, Christopher von Rueden and his colleagues interviewed 88 male villagers, asking them how physically imposing (powerful) and well-respected (prestigious) each of the other men in the villages were. The anthropologists then interviewed the married men's wives. Like most pre-industrial cultures the Tsimane are mildly polygynous, with about 5% of adult men having more than one wife and around 15% having no wives at all. From three well-trusted informants, the anthropologists also took the special step of gathering data on the extra-marital affairs of each married man. What do you think they found?
Historically, many personality psychologists have thought basic biological traits explain our sexual peccadilloes. In his seminal book Sex and Personality, Hans Eysenck (1976) was one of the first to point out the trait of extraversion is highly related to our sex lives. Extraverts are more likely than introverts to be talkative, optimistic, excitement-seeking, and socially assertive. They're also more likely to have a lot of sex, in a lot of different positions, and with lots and lots of partners. In a 2004 study of American political personalities researchers found the most extraverted U.S. Presidents of all time to be...JFK and Bill Clinton. Really, the evidence is overwhelming--studies using national samples, large cross-cultural studies, and even meta-analyses (studies of many past studies) all confirm that extraverts are highly sexual creatures, taking more sexual risks and having more affairs than introverts. Extraverts even tend to possess a type of gene variant that doubles the likelihood of being sexually unfaithful (Garcia et al., 2010).
So, our personality is a big part of whether we are among the 25% or so of Americans who will ever have extra-marital sex. Wide-ranging evidence suggests many other traits--especially Narcissism, psychopathy, impulsivity, attachment insecurity, and sexual excitability--also correlate with engaging in dangerous liaisons. Note I wrote correlate, we can't really say for sure these traits cause affairs. And some of these correlations are really rather modest statistically-speaking. Still, when psychologists have examined many of these traits together (along with other things like religious attendance, one's attitudes toward infidelity, physical attractiveness, and testosterone), it does seem each trait adds a little "personality risk" to having an affair.
Personalities don't exist in social isolation, though. Traits lead us into situations, especially traits like extraversion. Extraversion typically leads us to seek out large social gatherings, to engage in deeply intimate conversations, and to climb social ladders. Bingo! Such situations are a crucial part of turning up the heat on marital affairs, probably more so than biological traits. Some of these social situations can be incredibly potent at stirring up feelings of sexual entitlement...of wanting more.
For instance, if we look at modern Americans with high social status (say, politicians and A-list actors, athletes, and rock stars), it seems like those situated within the highest echelons of power and prestige have much more than their fair share of affairs. Certainly the news headlines over the last few years have barraged us with examples of that. But is there evidence that achieving high status causes us to want more sexual partners, either from affairs or maybe changing to a new spouse, or even having more than one spouse at the same time?
Most research does show that making more money is associated with having more affairs. In a 2001 study using a nationally-representative sample of the USA, David Atkins and his colleagues found people making more than $75,000 were 1½ times more likely to have an affair compared to those making less than $30,000. In that same study, people with graduate degrees were 1¾ times more likely to cheat on their spouses than those who did not graduate high school. A lot of other evidence points to high status people having extra-marital sex, but interpreting this can be tricky. Does achieving high status cause us to desire an affair, or do the same personality traits that cause us to achieve high status also cause us to be more likely to have affairs? It's probably a little bit of both.
When it comes to multiple spouses, most industrialized cultures like the USA don't allow people of high status to have more than one spouse at a time. So perhaps high status extraverts don't end up having more mates than those of us with low status. It turns out, though, that getting divorced and re-married (especially marrying younger and younger spouses, which many high status men do) basically leads to the same thing as having numerous spouses at the same time--it is called de facto polygyny. Combined with more affairs, this leads those with higher status to have many more mates overall, especially for men. How do we know this?
In her 1986 book Despotism and differential reproduction: A Darwinian view of history, Laura Betzig examined historical and cross-cultural records and everywhere she looked strong evidence existed that men's social status has been linked to their sexual success. A 2003 study found about 8% of all men in Central Asia carry the same unusual Y chromosome, probably from Genghis Khan and his male offspring. For decades anthropologists have conducted in-depth investigations into foraging cultures, and they usually find that status gains afford men more wives (and more children). The same is less true for women. In modern cultures like the USA, nationally-representative samples find that men who have 3 or more consecutive marriages have 19% more children than men with only one spouse, whereas there is no effect of multiple re-marriages on women's fertility (Jokela et al., 2010). Modern men with more income and education tend to have more biological children, whereas high status women have fewer children (Hopcroft, 2006). Unlike extraversion and our personalities, perhaps gaining status doesn't lead to more spouses or kids for women.
This doesn't mean high status women don't have more affairs, though. Evolutionary psychologists like Martie Haselton from UCLA have documented that women in some situations (and at certain stages of their ovulatory cycle) are more likely to cheat, seemingly in a manner that leads them to obtain better genes than their husbands can provide (see Pillsworth & Haselton, 2006). In this way, maybe having an affair can lead women to have not more but better kids, at least in the right situation. In a recent internet study of over 1,000 business professionals in the Netherlands, both men and women who had more power and prestige in their jobs were more likely to cheat. The affair-enhancing effects of salary and education noted earlier apply to both men and women in the USA, though in less developed countries it is often lower status women that engage in more affairs. And in a new study by Terri Fisher and her colleagues (in press), young women were found to think about sex nearly as often as young men do in the USA (see http://www.psychologytoday.com/blog/you-it). So in some ways and in some cultures, men and women share the same sexual temptations.
Even if we accept that personality traits and social status can directly affect our sexual desires, this doesn't mean extraverted and high status men (or women) should have more affairs, or spouses, or children. To conclude that would be to commit the Naturalistic Fallacy. Instead, psychological science helps us to understand why humans tend to behave this way. And if we wish to change or control these behaviors, understanding our basic desires is a good first step.
When we (or our partners) are lucky enough to increase our social status, it's good to know that some of our new sexual feelings may be natural, but that we needn't be driven by them. These feelings may have been designed by evolution to get us to reproduce more, something our more reflective selves might not want to do. So, when our extraverted egos start to inflate with sexual hubris, it can be helpful to keep in mind what's really going on. I'm reminded of a related Incubus song lyric, "If I turn into another/Dig me up from under what is covering/The better part of me."
I don't mean to condemn all affairs or suggest we must always overcome our natural desires. Some sex and marital therapists, including influential psychotherapist Carl Rogers, have considered affairs and open marriages appropriate for certain couples. Also, not all affairs have the same duration, intensity, frequency, or fundamental motivations, all of which can profoundly affect the psychological impact of adultery. As I detailed in my inaugural post, if we treat our partners with honesty, equality, and responsibility, "sextraverted" desires and behaviors may be perfectly healthy forms of expression from a sexual science perspective.
And oh yeah, remember those Tsimane villagers? The anthropologists found that men who were more powerful and prestigious had more wives, more children, and...wait for it...more extra-marital affairs. I hope now you have a little better understanding of why. I also hope that you're at least a little bit curious about which Tsimane women were engaging in these affairs, and why. Any guesses?
Atkins, D.C., Baucom, D.H., & Jacobson, N.S. (2001). Understanding infidelity: Correlates in a national sample. Journal of Family Psychology, 15, 735-749.
Betzig, L. (1986). Despotism and differential reproduction: A Darwinian view of history. Hawthorne NY: Aldine Press.
Eysenck, H. (1976). Sex and personality. London, UK: Open Books.
Fisher, T.D., Moore, Z.T., & Pittenger, M. (in press). Sex on the brain? An examination of frequency of sexual cognitions as a function of gender, erotophilia, and social desirability. Journal of Sex Research.
Garcia, J.R. et al. (2010). Associations between dopamine D4 receptor gene variation with both infidelity and sexual promiscuity. PLoS ONE, 5(11): e14162. doi:10.1371/journal.pone.0014162.
Hopcroft, R.L. (2006). Sex, status, and reproductive success in the contemporary United States. Evolution and Human Behavior, 27, 104-120.
Jokela, M. et al. (2010). Serial monogamy increases reproductive success in men but not in women. Behavioral Ecology, 21, 906-912.
Pillsworth, P.G., & Haselton, M.G. (2006). Male sexual attractiveness predicts differential ovulatory shifts in female extra-pair attraction and male mate retention. Evolution and Human Behavior, 27, 247-258.
von Rueden, C., Gurven, M., & Kaplan, H. (2010). Why do men seek status? Fitness payoffs to dominance and prestige. Proceedings of the Royal Society B, Biological Sciences: doi: 10.1098/rspb.2010.2145