Sunday, October 11, 2009

Effects of Toxoplasma gondii   posted by Razib @ 10/11/2009 11:40:00 PM

An older article on the effects of Toxoplasma gondii in Schizophrenia Bulletin:
Consistent and significant differences in Cattell's personality factors were found between Toxoplasma-infected and -uninfected subjects in 9 of 11 studies, and these differences were not the same for men and women. After using the Bonferroni correction for multiple tests, the personality of infected men showed lower superego strength (rule consciousness) and higher vigilance (factors G and L on Cattell's 16PF). Thus, the men were more likely to disregard rules and were more expedient, suspicious, jealous, and dogmatic. The personality of infected women, by contrast, showed higher warmth and higher superego strength (factors A and G on Cattell's 16PF), suggesting that they were more warm hearted, outgoing, conscientious, persistent, and moralistic. Both men and women had significantly higher apprehension (factor O) compared with the uninfected controls.

I was thinking about this because I was trying to convince a friend who hadn't had cats that he should really think about getting some. It reminded me a bit of the old Garfield episode, "King Cat," where the Egyptians worshiped and pampered their cats. The feline dominated society was overthrown thanks to the influence of dogs upon human beings. There has been plenty of stuff on the differences of Toxoplasma gondii between nations, but I wonder about the effect over time. I haven't been able to find the data, but I recall that widespread pet ownership was a practice which emerged with the rise of the middle class.

Labels: ,

Tuesday, March 31, 2009

Virginity & heritability   posted by Razib @ 3/31/2009 11:43:00 PM

Genes may time loss of virginity:
As genetic determinism goes, the new findings are modest. Segal's team found that genes explain a third of the differences in participants' age at first intercourse - which was, on average, a little over 19 years old. By comparison, roughly 80% of variations in height across a population can be explained by genes alone.
On the other hand, conservative social mores might delay a teen's first sexual experience, causing scientists to low-ball the effect of genes. Indeed, Segal's team noticed a less pronounced genetic effect among twins born before 1948, compared with those who came of age in the 1960s or later.
As for the specific genes involved, another team previously found that a version of a gene encoding a receptor for the neurotransmitter dopamine is associated with age at first intercourse. Others have linked the same version of the gene - called DRD4 - to impulsive, risk-taking behaviour.

The paper is Age at first intercourse in twins reared apart: Genetic influence and life history events.

FuturePundit notes:
The team found a weaker effect from genes with people born before 1948. This supports an argument I've made here previously: the breakdown of old cultural constraints on behavior frees up people to follow genetically driven desires and impulses. We become more genetically driven as external constraints weaken.

When you remove the strength of environmental parameters from the equation it naturally results in a greater salience of heritable ones. Ergo, the logic whereby you can make the case that in a perfect meritocracy there will be much stronger genetic sorting by class (via assortative mating, etc.).

Related: DRD4 and virginity.

Labels: ,

Thursday, March 26, 2009

Finnish Type A personalities have more offspring   posted by Razib @ 3/26/2009 03:45:00 PM

Adolescent Leadership and Adulthood Fertility: Revisiting the "Central Theoretical Problem of Human Sociobiology":
Human motivation for social status may reflect an evolved psychological adaptation that increased individual reproductive success in the evolutionary past. However, the association between status striving and reproduction in contemporary humans is unclear. It may be hypothesized that personality traits related to status achievement increase fertility even if modern indicators of socioeconomic status do not. We examined whether four subcomponents of type-A personality-leadership, hard-driving, eagerness, and aggressiveness—assessed at the age of 12 to 21 years predicted the likelihood of having children by the age of 39 in a population-based sample of Finnish women and men (N=1,313). Survival analyses indicated that high adolescent leadership increased adulthood fertility in men and women, independently of education level and urbanicity of residence. The findings suggest that personality determinants of status achievement may predict increased reproductive success in contemporary humans.

In Finland a "Type-A Personality" presumably refers to someone willing to make eye contact with family members. In any case I think this table is probably the most informative:

The main caveat which is stated in the paper is that we're talking about Finland today. How generalizable is this? If leadership was a primary factor behind reproductive success over long periods of time how come we're not all Type A personalities? I think it seems likely that the fitness of these individuals and their morph exhibits frequency dependence. Additionally the longer term volatility of this strategy probably differs from more retiring personal profiles. The Type A strategy seems more likely to be subject to winner-take-all dynamics; there were many prominent leaders on the Mongolian plain of 1250. Very few of them have descendants due to the fact that one Type A eliminated all the rest. In Farewell to Alms Greg Clark reports data which illustrate that before the 19th century the blooded military nobility might have had below average replacement because of morality during war. In contrast, the gentry were fertile. Not to nerd out, but this shows that the Hobbit strategy can beat the Numenorean over the long term. Modern post-industrial societies have a particular social ecology, and are subject to a dynamic contingent upon that ecology. Let's not overgeneralize.

Labels: , ,

Monday, November 10, 2008

Generation Me?   posted by ben g @ 11/10/2008 07:23:00 PM

In a recent post, Agnostic dismissed Jean Twenge's thesis that narcissism has increased over the last couple of decades. Twenge has been on my reading list for a while, so this intrigued me. Not feeling knowledgeable enough to play devil's advocate against agnostic, I sent Professor Twenge an email inviting her to join the thread. She does a pretty good job of defending her thesis against agnostic's criticisms, in my opinion. I invite anyone who's interested to check out the thread, read the studies, and share their own two cents.


Sunday, September 14, 2008

Personality variation by region (USA)   posted by Razib @ 9/14/2008 06:32:00 AM

Update: Another post where I've transcribed the highest correlations for each trait.

Jason pointed me to this Guardian piece, US personalities vary by region, say researchers. It's pretty thin on the details, but luckily the original paper can be found online in full, A Theory of the Emergence, Persistence, and Expression of Geographic Variation in Psychological Characteristics. I haven't read the whole thing, nor do I know much about personality, so I have put the maps which illustrate regional variation in traits below the fold. But I do want to note the correlations between Openness and the following metrics on the state level:

% Arts and entertainment = 0.23
% Computer and mathematical = 0.24
Patent production per capita = 0.28

* Controlling for income, race, sex, college degree, and proportion of state population living in city with one million or more residents. p < 0.05.





Labels: ,

Friday, July 18, 2008

sextroverts   posted by ben g @ 7/18/2008 01:20:00 PM

Truism of the day: Introverted nerds don't get laid much. Or, in more scientific terms, extroversion in men is linked to a higher number of sex partners.[1] Men and women have similar levels of extroversion, though-- in fact, women have slightly higher levels of it.[2] This begs for explanation; after all, extroversion is significantly heritable (~50%)[3], so why shouldn't it have been positively selected for in males?

It turns out that, while men aren't more extroverted than women, they are more extroverted in the areas where it "counts.""The table below[2] of extroversion and its sub-traits sheds some light:

TraitMean Difference (Female - Male)High (%F)Very Low (%F)
Sensation seeking-1.54270
Positive emotions1.37836

(mean difference is the mean difference between men and women on the trait. high %F and low %F are the percent of women who are at the very high and very low tail-ends of the distribution.)

With the exception of 'ideas' (F-M=-1.6), a sub-trait of Openness to Experience, none of the 30 Big-Five sub-traits show more skew towards men than do assertiveness and excitement-seeking. While these -.9 and -1.5 mean differences may seem minor on their face, it is worth considering how they affect the tails of the distributions. In the case of sensation-seeking, 70% of people who are significantly low on excitement-seeking are female. A great deal of meaningful sexual dimorphism here, so let's look into it...


Browsing through the sensation-seeking literature I came across this very interesting study; sensation-seeking was one of many variables examined in a study of college mens' number of sexual partners.[4] The other variables looked at (and all measured through questionnaires unless otherwise indicated) were: age, attractiveness (measured by self-rating, and female, male interviewer ratings), social intimacy, sexual affect, dominance, hypermasculinity, Eysenck's psychoticism trait measure, and testosterone levels (measured chemically through saliva samples).

Sensation seeking correlated more so than any other variable with both lifetime number of sexual partners (.38) and with maximum partners in one month (.37). Trailing way behind it was hypermasculinity (.29, .29), followed by attractiveness (.20, .28).[4,5]

I'm not going to attempt to unwind the complex causal chains which correlate sensation-seeking to short term mating success. It should suffice to say that there is significant evidence that these traits are both intrinsically attractive to women, and that they serve as an impetus to sexual pursuit of women by men in the first place.[7] Sensation- seeking has the highest narrow-sense heritability of any (Big-5) sub-trait-- .36, and a relatively high broad-sense heritability of .52, by the way.[3]

A Pet Hypothesis

It seems plausible that sensation-seeking garnered a greater number of female mates in the Pleistocene , just as it does now, and that there was therefore positive selection for it in men. I would posit that if this positive selection existed, it was limited in effect by the negative aspects of extroversion, visible in our day in age-- extroverts are more at risk for STD's, being jailed, getting in fights, and generally doing stupid risky things.

The fact that Extraversion has a higher degree of heritability in men than in women (.57 versus .38)[3] might be considered as evidence. I am not knowledgeable enough of the behavior genetics involved to say whether this is meaningful evidence.

The most specific, and testable part of my hypothesis is this: that ADHD (note that I'm not saying ADD) is to some extent the result of "overclocking" for male sensation-seeking. Consider this-- estimates of the male:female ratio for ADHD range from 4:1 to 9:1.[8] People with ADHD are more extroverted than other people, yes, but they are especially more sensation-seeking than other people. Unsurprisingly, people with ADHD have a higher number of sexual partners than people without.[9] The discrepancy between males without ADHD and those with it is probably underestimated because of the widespread use of drugs like Ritalin.


1. (Nettle 2004).
2. (Corbitt & Widiger 1995). See the table in their article for all of mean differences and percentile differences at the tails of the bell curves between men and women.
3. (Loehlin & Bouchard, 2001)
4. (Bogaert et. al 1995)
5. Sensation seeking correlated trivially with age, .14 with Attractiveness, .26 with dominance, .41 with hypermasculinity, and .45 with psychoticism. Statistically eliminating virgins from the sample had no major effects on these correlations. For you data crunchers out there I suggest you read the study yourself if you want to analyze their factor and regression analyses.
6. (McCoul & Haslam 2001).
7. There's a good summary of some of the studies on why sensation-seeking might cause more mates in (McCoul & Haslam 2001).
8. (Gutman 2002)
9. (White 1998)

  • Nettle, D. (2004). An evolutionary approach to the extraversion continuum. Evolution and Human Behavior
  • Corbitt, E.M. and W.A. (1995). Sex Differences Among the Personality Disorders: An Exploration of the Data. Clinical Psychology: Science and Practice.
  • Loehlin, J.C., & Bouchard, T.J. (2001). Genes, Evolution, and Personality. Behavior Genetics.
  • Bogaert, A.F. and Fisher, W.A. (1995). Predictors of University Men's Number of Sexual Partners. The Journal of Sex Research
  • Maryann D. McCoul and Nick Haslam (2001). Predicting high risk sexual behaviour in heterosexual and homosexual men: the roles of impulsivity and sensation seeking. Personality and Individual Differences
  • Gutman, A. (2002). ADHD -- Perspectives From Child to Adult. Retrieved July 18, 2008, from the MedScape Web site
  • White, J.D. (1998). Personality, temperament and ADHD: a review of the literature. Personality and Individual Differences.
  • Kate et al (2006). Childhood ADHD Predicts Risky Sexual Behavior in Young Adulthood. Journal of Clinical Child and Adolescent Psychology

Labels: , ,

Monday, June 02, 2008

Selection speculation: CLOCK and reward-dependence in Africans   posted by agnostic @ 6/02/2008 02:39:00 AM

Since so many comments lead off with some variant of "I would guess," why not try to corrall them all into one post where they could serve a purpose? Each week I'll find some area of the human genome that shows signs of recent selection, see what phenotypes the gene affects, and although I'll likely provide the most convincing story, readers can conjecture to their heart's content about what might have driven selection. It may, for once, improve the discussion to comment while still deranged from last night's drink.

Let's start with the data: using Haplotter, we see that for the gene CLOCK, there is a signal of recent selection in Africans but not in Europeans or Asians. The CLOCK gene is involved in maintaining our circadian rhythm, and I started this search looking for between-group differences in being "day people" vs. "night people." However, other genes related to circadian rhythm -- PER1, PER2, PER3, Tim, CSNK1E, Cry1, and Cry2 -- show no signals of recent selection anywhere. So perhaps there is something else that CLOCK does that these others do not.

It turns out that CLOCK is also involved in the dopaminergic system, which regulates mood and behavior. None of the OMIM entries for the other circadian rhythm genes mentions dopamine, mood, the reward system, etc. So it is more likely that CLOCK has undergone selection for its effects on mood and on the brain's reward system, rather than on circadian rhythm per se. In mice, and so potentially in humans as well, mutations in CLOCK make individuals lower in anxiety and higher in risk-taking (Roybal et al. 2007; free full text).

Turning to data from Lynn & Martin (1995), which I turned into a convenient graph here, we see that Nigerians -- the African group that HapMap data come from -- are indeed the lowest in the world in the personality trait Neuroticism (the Israeli data-point must be a mis-coding by Lynn, who is known for doing so). They are also the highest in the world in Extraversion. Neuroticism measures a tendency toward anxiety and related states, while Extraversion measures, among other things, pace of living (manics living a faster-paced life) and excitement-seeking. So Nigerians show a psychological and behavioral phenotype that's fairly comparable to the mice with mutations in CLOCK, strengthening the hypothesis that selection at CLOCK has acted on personality rather than circadian rhythm per se.

Now comes the fun part -- telling a story about why this phenotype was more advantageous in Western Africa than in Central Europe or Northeast Asia over the past 10,000 or so years. The low-anxiety and high-excitement-seeking phenotype is suspiciously like that associated with derived alleles at the DRD4 locus, and the novelty-seeking 7R allele at that locus does show up at intermediate frequencies in Africans (Chen et al. 1999; see a map here). I concur with Harpending & Cochran (2002) (free full text), who argued in the DRD4 case that the phenotype is more advantageous in "cad societies" than in "dad societies."

More concretely, I suggest, based on the teachings of the pickup artist community, that low anxiety aids in approaching more females in a shorter time -- you are less paralyzed during the approach, and you get over rejection more easily -- and that higher risk-taking motivates you to approach more females. Contingent upon having other traits that are appealing to females (a muscular body, artistic skill, dancing or singing ability, a knack for flirting, and so on), the phenotype here would have increased male success in courtship of (multiple) females, a stronger determinant of reproductive success in a "cad society" than in a "dad society."

Lastly, here are two testable predictions: 1) lowland South American and highland New Guinean tribes should also show signs of selection at the CLOCK locus, since they are even more prototypically "cad societies," and they have the highest frequencies of the 7R allele at DRD4. And 2) African Bushmen should show no signs of selection at CLOCK since they are more "dad societies" and have lower frequencies of the 7R allele at DRD4. (ALFRED does not have data on CLOCK.)

The fact that Northeast Asians do not show signs of selection at CLOCK already supports the hypothesis, since they are more "dad societies" and have a very low frequency of 7R at DRD4 (and even the 2R allele, which shows up somewhat there, has a much more muted effect than does 7R). The lack of selection at CLOCK in Central Europeans is neither here nor there: they are more "dad societies" than Western Africa but not so much as East Asia; Europeans also have intermediate frequencies of 7R and DRD4. So we could have an example of "Rushton's Rule," where East Asians show no selection for low-anxiety / high-novelty-seeking alleles at either DRD4 or CLOCK, Europeans show selection at just one locus, and West Africans show selection at both.

To the best of my knowledge, as they say, this is the first argument for why Africans show a signal of selection at CLOCK. Consider it part of the graduate student with a PC trend in studying human evolution. You heard it here first.


Chen, C., M. Burton, E. Greenberger, & J. Dmitrieva (1999). Population migration and the variation of Dopamine D4 receptor (DRD4) allele frequencies around the globe. Evolution and Human Behavior, 20(5): 309-324.

Harpending, H. & G. Cochran (2002). In our genes. PNAS, 99(1): 10-12.

Lynn, R., & T. Martin (1995). National differences for thirty-seven nations in extraversion, neuroticism, psychoticism and economic, demographic and other correlates. Personality and Individual Differences, 19(3): 403-406.

Roybal, K., D. Theobold, A. Graham, J.A. DiNieri, S.J. Russo, V. Krishnan, S. Chakravarty, J. Peevey, N. Oehrlein, S. Birnbaum, M.H. Vitaterna, P. Orsulak, J.S. Takahashi, E.J. Nestler, W.A. Carlezon, Jr., & C.A. McClung (2007). Mania-like behavior induced by disruption of CLOCK. PNAS, 104(15): 6406-11.

Labels: , , , , , ,

Monday, March 17, 2008

Traits of men who prefer breasts, booty, or legs   posted by agnostic @ 3/17/2008 08:11:00 PM

Pursuing a hunch inspired by a post on breast size and getting married by Irina, I managed to hunt down a study that shows the characteristics of the Boobman, Assman, and Legman. First though, I could not find any studies that investigated what non-obvious correlates there may be of breast size, rump size, or leg length. So I can't back up Irina's observation that larger breasts, as opposed to say a rounder butt, make a woman more likely to get married.

The idea is not ridiculous: females vary in their reproductive strategies, some specializing in shorter-term and some in longer-term relationships, for example. And like many strategic choices, there is likely a trade-off: to wit, between investing a finite amount of body fat more in the upper or more in the lower region. Larger breasts could reflect pleiotropic effects of genes that also contribute to being more focused on stability and the long-term in mate choice. Or perhaps men who are more of the "good dad" type have a bias toward larger breasts, so that these are a response to the preferences of guys who will stick around.

Moving on to what I do have data for, let's see what Wiggins et al. (1968) have to say about what men with different physical tastes are like. They asked 95 male college students which silhouette drawings they preferred, and these independently varied the size of the breasts, butt, and legs: each appeared in a "normal" size, somewhat large, large, somewhat small, and small. They completed personality questionnaires and provided demographic background info.

Men who preferred the "large" figure -- large breasts, large butt, and large legs -- were characterized by "a need for achievement." Those who preferred the "standard" figure -- normal size for all parts -- were characterized by "a tendency to be disorganized in personal habits." And as for the small figure -- small size for all parts --

Those who preferred the small figure tend to persevere in their work. They are not cynical about authority and reported coming from an upper-class background. Although the small figure was generally disliked by the present group of subjects (Table 1), it very well may be a preferred type among members of the upper class (Moore, Stunkard, & Srole, 1962) as suggested by the present data.

I don't think there's any deep evolutionary strategy going on with upper-class people preferring petite females. It could just be a fashion statement.

Men who like large breasts:

Also characterizing large-breast preference was a tendency to date frequently, to have masculine interests, and to read sports magazines. Further, large-breast preference was related to a need for heterosexual contact and for exhibitionism (saying witty things and being the center of attention). In social relations, men who preferred the large breasts tend to be non-nurturant and independent. This latter result gives support to Scodel's (1957) finding of a lack of fantasy dependence among college men who preferred large-breasted figures. In the present study, preference for large breasts was positively correlated with smoking and negatively correlated with endurance (perseverance in work habits).

Sounds like the Boobman is a gregarious "guy's guy."

Men who prefer boobs that are friendly and unpretentious:

Those who preferred small breasts tend to hold fundamentalist religious beliefs and to be mildly depressed. In contrast to those who preferred large breasts, those who preferred small breasts are nurturant in their relations with others. They are not cynical about authority and come from large, nonworking-class families. They are lacking in achievement motivation and are indefinite about career plans. As a group, they tend to be engineering rather than business majors.

Men who prefer large buttocks (that is, men who are not homosexuals):

Preference for the very large buttocks was characterized by a need for order (neatness, organization, orderliness). . . Those who preferred the largest buttocks figure tend to be business majors (accounting?) and tend not to be psychologically minded [* see note, agnostic]. In social situations, they are dependent and given to self-abasement (guilty, self-blaming). Their value orientation tends not to be stoic in nature.

Sounds like the Type A businessman or political leader. (I would say "alpha-male," but that wouldn't be very self-abasing, would it?) Quoth bodybuilder, badass actor, and governator of California Arnold Schwarzenegger (watch from 1:35 - 2:25 in this clip):

"I can absolutely understand why Brazil is devoted to my favorite body part - the ass."

Men who like small buttocks:

Unlike those who preferred large buttocks, those who preferred small buttocks tend not to be self-abasing. They tend to persevere in the completion of their work and do not feel the need to be the center of attention. As a group they tend not to be education majors and their reading interests do not include sports magazines.

Men who like large legs:

The most substantial correlate of large-leg preference is an abstinence from alcoholic beverages as indicated by the negative correlation with both drinking and amount of drinking. Those who preferred large legs are nonaggressive and self-abasing (guilty, self-blaming). They tend to be psychologically minded (intraceptive) and are characterized by a slow personal tempo. . . Subjects who preferred large legs indicated that they are not business majors and that they would choose their mother over their father if they had to make a choice. The personality pattern suggested by these correlates is one of inhibition and restraint in social situations.

Men who like small legs:

[P]reference for small legs is characterized by a strong need for social participation. Those who preferred small legs are characterized by needs for nurturance, affiliation, and exhibitionism. That is, they are helpful to others, feel a need for social participation, and like to be the center of attention in social situations. They are also socially dependent and tend not to stick at a task until completed.

So, men who like the "large" figure (the one who's tall and has t&a) are the more ambitious ones, the Boobman sounds like a social guy's guy, and the Assman sounds like a Type A businessman. It's possible to interpret this pattern as showing that the Boobman is more likely to settle down with one woman, while the Assman would be the polygynous executive type. Admittedly, the data aren't very clear; they certainly don't contain any direct information about willingness to marry, thoughts on monogamy, and so on.

It has been 40 years since this study was done, but in my search I could not find any follow-up studies -- you have to admit that it's not exactly a major research concern. If any readers know of similar studies, or especially of studies on the non-obvious correlates of female breast, butt, and leg size, please say so in the comments.

* I believe "not psychologically minded" in this case means they tend to think of people in simple stereotypes rather than using complex and varied concepts. Terms like "psychologically minded" and "intraceptive" are fossilized jargon from 40 years ago, and it's not totally clear what is meant.


Wiggins, J.S., J. Wiggins, & J.C. Conger (1968). Correlates of heterosexual somatic preference. J Pers Soc Psych, 10(1): 82-90.

Labels: ,

Wednesday, February 27, 2008

More pathogens means more collectivism?   posted by Razib @ 2/27/2008 07:07:00 PM

Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism (Open Access):
...We suggest that specific behavioural manifestations of collectivism (e.g. ethnocentrism, conformity) can inhibit the transmission of pathogens; and so we hypothesize that collectivism (compared with individualism) will more often characterize cultures in regions that have historically had higher prevalence of pathogens. Drawing on epidemiological data and the findings of worldwide cross-national surveys of individualism/collectivism, our results support this hypothesis: the regional prevalence of pathogens has a strong positive correlation with cultural indicators of collectivism and a strong negative correlation with individualism. The correlations remain significant even when controlling for potential confounding variables. These results help to explain the origin of a paradigmatic cross-cultural difference, and reveal previously undocumented consequences of pathogenic diseases on the variable nature of human societies.

The, r = -0.69 at p-value 0.001 and n = 68. You can find the raw data here. It would be cool to see trends within nations/societies. For example, variation in altitude.

Related: Toxoplasma gondii & human culture.

Labels: , ,

Sunday, February 24, 2008

Emotional fragility as a sexually selected trait   posted by agnostic @ 2/24/2008 03:02:00 PM

Roissy recently drew up a list of female skills for attracting males, and although it is clearly weighted toward succeeding in short-term relationships, the rank order seems about right for getting married too. One quick way to see what has mattered to men is to look for sexually dimorphic traits. As Darwin noted, such traits can have the flavor of "armaments," used to shove same-sex rivals out of the mating competition (such as deer antlers), or "ornaments" which attract mates (such as the peacock's tail), or both. I'll review some evidence that emotional vulnerability has been sexually selected in human females due to its attractiveness to males, rather than its use in female vs. female competition.

First, let's use YouTube to convince ourselves that emotional fragility makes a female more attractive, regardless of her physical appearance. Consider Emmylou Harris, Karen O, Elizabeth Fraser, or Hope Sandoval -- each is more desirable as a mate than if she were more tough-minded. In males, the attractiveness of fragility is conditional. If he can honestly signal manliness in dominating other males (however he does that), then emotional fragility around women may convince them that he's the best of both worlds. But if he lacks drive or ambition, then fragility will only make him appear needy and pathetic. Males who succeed here include Johnny Cash, Mike Ness, LL Cool J, and Joey Ramone.

Next, let me clarify the term "emotional fragility." It's a tendency to cry easily about something that would upset a caring person, a trait that will move men to protect and comfort her. More concretely, I'll treat it as a combination of the Big Five personality traits Neuroticism and Agreeableness, with more weight given to the former. A graph will help to illustrate [1]:

As for sex differences in these traits, see this previous post for a review of a meta-analysis by Costa et al. (2001). In brief, across all cultures of the world, females score higher than males on average for both Neuroticism and Agreeablness, though the magnitude depends on the physical and social environment that the population is adapted to: Europeans show huge sex differences, while Africans and East Asians show less pronounced differences. Among Europeans, the female mean is between 0.5 and 0.6 SD above the male mean for both Agreeableness and Neuroticism. A new cross-cultural survey by Schmitt et al. (2008) confirms this, although they find a slightly lower difference between means in Agreeableness. Both of these articles also provide good overviews of previous research.

While other personality traits show sex differences, Neuroticism and Agreeableness are by far the most dimorphic. Interestingly, in the first large-scale study designed to test changes in personality during adolescence, using a personality measure very comparable to an adult measure, McCrae et al. (2002) found a significant Time x Gender interaction effect for Neuroticism. During adolescence, females were much more likely to increase in Neuroticism than were males, in both the US and Belgium. Neuroticism declines for both sexes in the mid-20s, and drops even further by age 40. So, we observe a pattern of dimorphism that emerges just after puberty and gradually switches off beginning at the age when females would have had their first child. It is similar to physical attractiveness in females or muscularity in males, suggesting it has been sexually selected.

It is clear that fragility is unlikely to count as an "armament" used for same-sex competition, since it makes one more vulnerable to intimidation, teasing, and other forms of pushing one's same-sex rivals out of the mating market. We would expect it to be more of an "ornmament" that attracts mates, then. It may not make a female appear sexier, but when a girl starts to cry because she feels that she's become a burden to her friends and family, it may be nonsense, but a guy can't help but want to comfort her and protect her. Once she inevitably feels a little better, the guy will feel like he's performed his service as a man. And, modern malarkey aside, guys feel good when they do chivalrous and manly deeds, so that they would seek out women who offered the greatest opportunity to do so, and girls feel good when these acts are done for them. [2]

Moreover, comforting a female in need often involves close physical contact, such as holding her hand, holding her close and rubbing the upper part of her back, brushing the hair off of her face, or wiping the tears from her eyes. Physical bonding like this strengthens the relationship two people have, and also signals to her that the guy is a "protector of loved ones" (to borrow a phrase from the Mystery Method) -- a quality she is interested in during the years leading up to motherhood. It also tells her that he would take care of her if she became sick. So, it serves the dual purpose of attracting mates and detecting who among them is worth hanging onto.

[1] The fact that the Big Five uses the axes of low Neuroticism - high Neuroticism and low Agreeableness - high Agreeableness doesn't mean anything deep about how the traits are realized physiologically, or about how genes influence personality. We could rotate the old axes by, say, 45 degrees and come up a new set of two axes: a Tough-minded - Fragile dimension and a Cordial - Irascible dimension. The old traits of high A, low A, high N, and low N would lie in the quadrants of the new graph. In short, like a physicist, I'm perfectly free to chose my coordinate system to make life easy; I'm not claiming that things are different from how they're typically described.

[2] Of course, there is variation too -- some women succeed in the tough-minded niche and feel belittled when men try to do romantic things for them, and thus around whom men feel little motivation to behave in a chivalrous way. Roissy's many remarks about female lawyers serve as a good example of this.

Labels: ,

Monday, August 13, 2007

Religiosity and personality: How are they correlated?   posted by agnostic @ 8/13/2007 01:01:00 AM

Bad news for atheists: individuals low in religiosity are more likely to have a "slacker" personality. And worse news: this is true even among intellectually gifted people. First, a disclaimer that I consider myself an atheist, though I would never use that term.* So no guff about having an agenda. Also, though obvious, it needs to be said that correlations don't tell you about particular individuals -- if you're a nose-to-the-grindstone atheist, then great. My purpose here is to describe correlations of interest to students of psychology or religion, as well as to deflate some of the smug -- and in this case false -- stereotypes that some atheists have about religious people.

In the interest of time (that is, to save me time), I'll be quoting most of the results since the authors provide enough exposition already. Throughout, the quoted article is McCullough et al. (2003).

Beginning with a review of the Eysenckian work done:**

Cross-sectional studies using Eysenck's P-E-N model (e.g., Eysenck, 1991) indicate that religiousness, as measured by a variety of indicators including frequency of attendance at worship services, frequency of private prayer, and positive attitudes toward religion, is inversely related to Eysenckian Psychoticism (e.g., Francis, 1997; Francis & Bolger, 1997; Francis, Lewis, Brown, Philipchalk, & Lester, 1995; Lewis & Maltby, 1995, 1996; Maltby, 1997, 1999; Maltby, Talley, Cooper, & Leslie, 1995; Robinson, 1990; Smith, 1996; Svensen, White, & Caird, 1992; Wilde & Joseph, 1997) but essentially uncorrelated with Extraversion or Neuroticism. Indeed, the basic finding that religiousness is negatively related to Eysenckian Psychoticism (i.e., sex-adjusted correlations in the neighborhood of -.30) (e.g., Francis et al., 1995) and essentially uncorrelated with Eysenckian Neuroticism and Extraversion has been replicated with children, adolescents, adults, and older adults from around the world.

And then a review of the Big Five work done:

Several recent studies have employed measures of the constructs in the Big Five, or five-factor personality taxonomy (e.g., John & Srivastava, 1999; McCrae & Costa, 1999), to examine the association of religiousness and personality. Kosek (1999), MacDonald (2000), and Taylor and MacDonald (1999) found that measures of Agreeableness and Conscientiousness were positively associated with measures of religious involvement and intrinsic religious orientation. These results are not surprising in light of the robust link between Eysenckian Psychoticism and religiousness because Eysenckian Psychoticism appears to be a conflation of Big Five Conscientiousness and Agreeableness (Costa & McCrae, 1995).

The authors' original contribution used data from the Terman Longitudinal Study to examine the relationship between religiosity in early adulthood and personality traits in adolescence. The latter were judged by teachers and parents, not self-reported. It's also worth noting that the students in this study were selected to have an IQ of at least 135, a point to which we return. Of the 1528 students in the TLS, the authors looked at 492 of them (280 male) for whom the relevant data was obtainable. Their findings:

Conscientiousness (beta = .14) was also a significant predictor of [early adulthood] religiousness, suggesting that for each standard unit increase in adolescents' Conscientiousness, their religiousness in [early adulthood] increased by .14 standard units.

And although other personality traits did correlate with religiosity:

Table 1 shows that children who were rated as Open to Experience (r = .11), Conscientious (r = .20), and Agreeable (r = .15) in adolescence went on to be slightly more religious 19 years later, p less than .05. In addition, adolescents who became highly religious reported having had relatively strong religious upbringings, r = .43, p less than .001.

These did not remain after their correlation with Conscientiousness was accounted for:

In part, the Openness-religiousness association may simply reflect the variance that Openness shares with the rest of the Big Five -- and Conscientiousness in particular -- in this sample. Measures of Openness and Conscientiousness were related at r = .43, which is not surprising because participants' traits were being evaluated within an achievement setting (i.e., they were rated by their teachers as well as parents), which might cause children who are more conscientious about their studies and assignments also to appear more open to experience (i.e., higher in intellect). Indeed, when we controlled for the intercorrelations among the Big Five through multiple regression, Openness and Agreeableness did not retain significant unique associations with religiousness, but Conscientiousness did.

So that's the reality. Atheists like the author of the following comment will no longer be able to assume they are more conscientious (original emphasis):

Personally, I trust atheists the most. I think they're more likely to keep their word than some Christians who think they're automatically going to Heaven solely because they accept Jesus as their Lord and Savior. I think atheists, in general, are more conscientious about their actions because they don't want to face negative consequences in the here-and-now.

As anyone knows, that attitude is not exceptional among those who wear the atheist label. Nor can they move the goalposts and suggest that, yes, this may hold in general, but since atheists are smart, we don't need religion to make ourselves more conscientious -- "Only retards need a written rule system for how to behave," as brainiacs can rely on their superior common sense to behave diligently. But the TLS data contradict this self-satisfied pap as well: even among MENSA-level people, religiosity correlates positively with Conscientiousness. To be blunt, it's time for atheists to stop patting themselves on the back about how conscientious they are, since as a group they score lower than more religious people.

On a related note, I'm getting pretty sick of atheists congratulating themselves for having low divorce rates or infidelity rates. Steve Sailer has suggested that one reason why Massachussetts citizens have lower divorce rates is that they marry much later in life, so that would-be homewreckers take one look at their wrinkled, sagging skin and say, "Yeah, no thanks." Inductivist showed from GSS data that atheists commit less adultery, but I posited the same reason that Steve would have: for a variety of reasons, they're just not attractive enough to would-be homewreckers, sheer age being the most obvious one (just look at the putz in the article linked to in the beginning of this paragraph). And because infidelity correlates with Psychoticism or low Agreeableness and low Conscientiousness, we expect atheists to cheat more -- ceteris paribus, but in real life things aren't equal and thus most atheists are not put to the same tests of temptation.

In closing, although I'd like for religiosity to hold no relation to Conscientiousness, the real world does not care what I'd like. (On a side note, it's odd how frequently atheists fall victim to the moralistic fallacy in this way, given how many of them profess a belief in a universe indifferent to their desires.) Religious nutballs who paint atheists as deformed scoundrels are wrong, but merely not being a wretch hardly merits all the more-ethical-than-thou braggadocio coming from the other side. The data are in, and it's high time that some atheists lose the vainglory.

* "Atheist" understandably makes a person think of a permanent student activist who works in a used bookstore and argues with his co-workers over which progressive rock album is the best.

** If you want the full references to what McCullough et al. (2003) quote, it shouldn't be difficult to look it up on Google -- how many articles on religion and personality could the given authors publish in a given year? If that doesn't work, then email me. I just don't want to waste space listing out all their references.


McCullough, M., J. Tsang, & S. Brion (2003). Personality traits in adolescence as predictors of religiousness in early adulthood: Findings from the Terman Longitudinal Study. Pers Soc Psychol Bull, 29, 980-91.

Labels: , ,