There is pretty widespread agreement in the popular and academic worlds that women were made to be mothers. Picture Mother Mary, Jesus at her bosom (there were no breasts in the Renaissance images I am seeing), so designed to be a mother that she didn’t even have to participate in the act of conception to achieve her mothering perfection. There is such variation in the ways that women mother, however – from the 50s doting Donna Reed to mothers employing wet nurses and nannies to Andrea Yates, who drowned her 5 children – that one has to wonder: if mothering is so natural, why are some women so shoddy at or disinterested in it? And why do traditional societies, history, and comparative psychology contain so many examples of mothering requiring practice?

Humans possess relatively few, if any, skills that can be performed naturally, without practice. Even walking, once believe to just happen is now known to occur only after the infant has the chance to acquire other skills including balance and the coordination of upper and lower body. But walking is a skill that every normally developing infant eventually acquires, whereas mothering is not a skill that all women are willing or able to acquire – and there is much more variation in the outcome. Even still, a person can hardly think of a woman without picturing her as a mother. In fact, when men or mothers meet a married woman of reproductive age who has chosen not to have children, who among them doesn’t ask “why?” We even have many names for childless women, all pejorative (e.g. spinster, old maid).

Among hunter-gatherer groups, older sisters are often employed throughout the day to assist in childcare of younger siblings (Sear & Mace, 2008). In a Western context, we can see this practicing in the pretend play of (predominantly) girls with their dolls and accessories. Among the upper-class “founding mothers” generation of the U.S. colonies, upper-class teenage girls would often be apprenticed to new mothers to learn how to become mothers when their turns were up (Roberts, 2004). Even in other primate species, adolescent females yearn to get exposure to new infants, though humans alone among the great apes will share their very young infants with group members (Hrdy, 2009). Common chimpanzees will not share the infant until it is around 3.5 months, orangutans around 5 months – whereas in humans, it is mere minutes after birth. Women need training in all elements of parenting – from breastfeeding, which likewise does not just occur “naturally” (Volk, 2009) to dealing with a hormonal teenager. Feel free to leave a comment if you have tips about the latter!

Mothering can at times be overwhelming, especially when a mom finds herself with little to no help during most of the day. For those who have full-time careers, finding time to excel at work and raise a child can be daunting. Likewise, for mothers who stay at home with the children, dedicating yourself to the child at the expense of yourself, trying to complete daily tasks such as cooking and cleaning while tending to and entertaining a child, and trying to maintain a schedule that works for both you and the child (as in 5 am is too early, kids!) can be an exhausting challenge. This truth is inescapable.

Given the overwhelming nature of raising one of the most helpless and needy infants among primates, human mothers need others. In our modern world, we can see examples in Facebook, which has the support group Circle of Moms, where one can tag her friends who are also moms, and there are many mothers’ groups for finding playmates for mom and her child(ren) (such as the national group Las Madres). When new mothers were given support in the form of only 21 visits by RNs over the course of two years, their children benefited in many ways for at least the first 15 years of life, including cognitively (Hrdy, 2009). So, then, it is possible that when ‘others’ are around and help mothers hone their skills, both the mother and the infant benefit. In the Sear and Mace (2008) study cited above, for those infants who had older sisters to help in the childcare, they saw marked decreases in mortality. In other words, moms and infants both need moms who have help and support so that the moms may perfect their skills.

Switching from a natural mothers to practiced mothers perspective can be a real relief for modern moms. Perhaps a not so recent challenge is the feeling of isolation by being literally geographically isolated from friends and family. [I say not so recent because there are many times in history when women have been isolated from childhood friends and family by migrating due to marriage, and perhaps even woman have traditionally been the sex to migrate out of the group. I’ll save that for a future post]. Raising a human is at least the longest commitment among the great apes, if not the most challenging as well – humans are born completely helpless, unable to even cling to the mother; and require care well into adolescence. In fact, recent research suggests they need it much longer – humans don’t begin contributing as many nutritional resources as they consume until into their 30s (Kaplan, 2009). Accepting that mothering is a skill that takes practice can alleviate some of the stress of feeling like a fish out of water.

Similarly, accepting the practiced mothers perspective allows a new mother to accept help more readily. More often than not, mothers, mothers-in-law, and friends are offering help with childcare or advice because they’ve been there before and know how difficult transitioning from carrying a 25-pound bag of baby etc. in your uterus to caring for a 6-pound lump of baby can be. If a mother feels as if she should be a natural, then asking for help can be really intimidating.

So, are women natural born mothers? All signs point to no. Yes, their anatomy allows them to bear children, but that does not mean that they will be great mothers from day one, or ever. If you give a teenager a car, chances are through trial and error they’ll learn how to make it move – but that doesn’t mean that they’ll instantly be good drivers, and some might never even take the time to learn. So too, we need to remember that when it comes to mothering, perfection is not bred but requires a lot of practice.

References

Hrdy, S. B. (2009). Mothers and others: The evolutionary origins of mutual understanding. Cambridge, MA: Harvard University.

Kaplan, H. (2009). Learning, menopause and the 70-year lifespan. Keynote address of the 21^st Annual Human Behavior and Evolution Society Conference, Fullerton, CA.

Sear, R. &  Mace, R. (2008). Who keeps children alive? A review of the effects of kin on child survival. Evolution and Human Behavior, 29(1), 1-18.

Roberts, C. (2004). Founding mothers: The women who raised our nation. New York: William Morrow.

Volk, A. A. (2009). Human breastfeeding is not automatic: Why that is so and what it means for human evolution. Special Issue: Proceedings of the 3rd Annual Meeting of the NorthEastern Evolutionary Psychology Society. Journal of Social, Evolutionary and Cultural Psychology, 3(4), 305-314.

Luke Skywalker, Han Solo, and the Importance of Adaptation Implementation in Evolutionary Psychology

I’m not going to lie. If you follow my work at all, hopefully this isn’t a surprise – I try to stay honest – it’s a way to compensate for my deficits. Lots of folks I know – several of whom I consider good friends – report that they just can’t stand evolutionary psychology. Some seem to think it’s the devil – morally and scientifically irresponsible and reprehensible. I do my best to deal with things, but every now and then, honestly, I just shake my head. And sometimes I just have to write about it.

A few weeks ago, a really interesting discussion about the mating-relevant differences between Luke Skywalker and Han Solo emerged in my graduate course in social psychology. This was one of these moments when a thread of the fabric of American culture and the content of the course interfaced perfectly.

Luke is prototyipically non-masculine – whiny and wimpy throughout three episodes. Han is just macho. He plays it cool, doesn’t need anyone’s help, and has classic masculine good looks.

What’s attractive about Luke? What’s attractive about Han? The conversation touched on several themes relevant to evolutionary psychology – mate choice, optimal features of long-term mates, optimal features of short-term mates, morphological features of sexually attractive males, the handicap principle applied to high levels of testosterone, inbreeding depression, and so forth. It was an exciting class discussion that put a face to many of the concepts from the readings of the week.

About a week later, I had a passing conversation with a long-time academic friend – who’s, notably, not a huge fan of evolutionary psychology. Somehow, I briefly mention this great class discussion – and my friend sort of scoffs – saying something like “can’t it be just that Han Solo would be way better in bed? It’s not like I’d want to have babies with him!”

I’ve learned to not bother arguing about evolutionary psychology in certain circles – but my mind immediately went to a conversation I’d had with David Schmitt when he visited New Paltz last year (to give a talk about mating psychology on Darwin’s 200th birthday). David is, of course, a leading thinker and researcher in the field – and the only thing as substantial as the academic rigor of his work is his reasonable take on things. An expert on the nature of psychological adaptations (see Schmitt & Pilcher, 2004), David introduced me to the distinction between “adaptation implementers” and “fitness optimizers” (a conception that he attributed to his mentor David Buss, a luminary in the field).

If we think of organisms as designed by evolutionary forces to propagate their own genes (Dawkins, 1976), we can have two general ways of understanding organisms. Perhaps (a) organisms are “fitness optimizers,” designed to consciously do whatever it takes to successfully produce viable progeny. On the other hand, perhaps organisms are “adaptation implementers,” designed with a battery of specific adaptations that, on average, had the effect of increasing the reproductive success of the organism’s ancestors compared with conspecifics without said adaptations.

OK – so let’s put a face to all this. Think about pregnancy sickness, famously studied by Margie Profet (1992). If pregnancy sickness is conceptualized from a fitness-optimization perspective, then pregnant women are essentially framed as conscious of the deleterious effects of certain foods on their babies, and they make themselves sick to certain stimuli as a result. If women with pregnancy sickness are, instead, framed as “adaptations implementers,” then the fact that they tend to get sick in certain contexts (e.g., when eating certain foods that are likely to possess toxins) is the result of this psychological and physiological tendency (that we call pregnancy sickness) to have increased the fitness of ancestral women – regardless of conscious thought surrounding the reproductive benefits of pregnancy sickness.

As Dave put it to me, evolutionary psychology sees humans as “adaptation implementers” – not “fitness optimizers.”

This important construct can be applied, really, to any adaptation. Think about fear of heights – one of the most basic and culturally universal fears. On one hand, we can think of this fear in terms of “conscious fitness optimization” – with people thinking “I know that if I fall 100 feet, that’s it for me – and my entire genetic lineage – ouch!” OR we can think of expressed fear of heights as explicating “adaptation implementation.” In this way, we can think of a natural fear of heights as the product nature selecting for ancestors across generations who happened to, by chance – and likely unconsciously – fear heights. In this way, someone expressing a fear of heights is simply implementing an adaptation that, on average, across generations, gave the ancestors of people with a fear of heights a reproductive advantage over others.

This same line of reasoning makes it so that modern-day contraception is not a deal killer for evolutionary psychology. I’ve heard people argue essentially that “well if evolutionary psychology says we do everything to propagate our genes, but we use contraception and many of us CHOOSE to not have kids, doesn’t that just say that evolutionary psychology is all wrong?” No. Actually. It doesn’t. Such an argument does, however, suggest that the conscious fitness-optimization approach to evolutionary psychology is completely misguided. If we were designed to consciously maximize fitness regardless of any other factors, then maybe contraception would not be as prevalent as it is – and maybe more people would choose to have children. But, in fact, people who use contraception (and there are lots of us out there) are still products of evolution whose psychologies are filled with adaptations. Contraception users still fear heights, spiders, and snakes more than other stimuli. Contraception users still show nepotistic tendencies when considering whom to help in emergency situations. They still get angry at being cheated by others in their close social circles. Contraception users experience the basic emotions of joy, sadness, surprise, disgust, and anger – and contraception users can identify these emotional states accurately in humans from across the globe. And they still find spoiled milk totally gross. Contraception users are attracted to the same features in mates that non-contraception users are attracted to – they still prefer that a mate be kind, intelligent, witty, and attractive. And, back on task, female contraception users still find Han Solo more sexually attractive than Luke Skywalker. That is, they implement psychological adaptations – regardless of conscious efforts to reduce the likelihood of reproducing. And this is exactly what we would expect in organisms that are designed to implement a battery of fitness-increasing adaptations – as opposed to organisms with general-purpose mechanisms designed to consciously increase reproductive success regardless of environmental conditions.

Being a person who uses contraception and chooses to not have children does NOT make that individual a person whose behavior and psychology are unrelated to the evolutionary history of homo sapiens

Back to the Order of the Jedi: Think about the sexual attraction that a heterosexual woman may feel toward Han over Luke. I haven’t done a poll, but suppose we find evidence that more heterosexual women find Han sexually attractive than Luke – thus, corresponding to a non-random mate-choice situation. Is it accurate and comprehensive to just say that Han would probably be better in bed? I don’t think so! I think that such a response actually screams for a distinction between fitness optimization and adaptation implementation!

In the domain of short-term mating, there are reasons underlying why women are attracted to masculine-looking men – with muscular bodies, high shoulder-to-hip ratios, deep voices, and symmetrical faces (Shoup & Gallup, 2008). And an evolutionary perspective on why women are attracted to such Han Soloesque features does not need to presume that women want to have Han’s baby! When we think of adaptation implementation, this way of thinking, in fact, can be greatly elucidated. It’s not enough to say that a woman would rather sleep with Han than Luke, and that’s just that. Science is about addressing WHY – why would such a pattern typify short-term desires of most heterosexual women? From the adaptation implementation perspective, the answer is steeped in our past. Women with such desires in short-term mates were more likely to leave viable offspring in the future. Mating with such “cads” likely led ancestral women who utilized short-term mating strategies to bear healthy, fit, and attractive offspring who were effective at fending off parasites (Gangestad & Buss, 1993).

So, in short, my friend who made this comment about being more attracted to Han than to Luke was completely right – it doesn’t have to be about consciously wanting to have Han’s baby over Luke’s. From an adaptation-implementation perspective, the ultimate causes of differential attractiveness toward one potential mate over another need not have any bearing on consciously trying to reproduce whatsoever. Just as fear of heights can exist without one consciously thinking about how falling a long way will lead to sudden death. Even if you don’t think that, being on the edge of a cliff in the mountains is still scary! And that’s because such fears gave our ancestors survival and reproductive benefits over others. Similarly, being sexually attracted to a potential mate may not make one think about the fitness-relevant end-product (e.g., shared offspring) – it may simply put one in a state (a hot state!) that is likely to lead to increased likelihood of mating.

And to top it off, remember, Han might be more masculine, but Luke can use the force!

References

Dawkins, R. (1976). The selfish gene. Oxford: Oxford University Press.

Gangestad, S. W., and Buss, D. M. (1993). Pathogen prevalence and human mate preferences. Ethology and Sociobiology, 14, 89-96.

Profet, Margie (1992). “Pregnancy Sickness as Adaptation: A Deterrent to Maternal Ingestion of Teratogens”. The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Oxford University Press. pp. 327–365.

Schmitt, D. P., & Pilcher, J. J. (2004). Evaluating evidence of psychological adaptation: How do we know one when we see one? Psychological Science, 15, 643-649.

Shoup, M. L. & Gallup, G. G., Jr. (2008). Men’s faces convey information about their bodies and their behavior: What you see is what you get.
Evolutionary Psychology, 6, 469-479.

Women hold up half the sky…but what about the other genders?

On August 19, 2009, South African runner Caster Semenya won the woman’s 800 meters at the World Championships.  She also set the world record.  This in and of itself is not particularly interesting.  The challenge to her victory is.  Caster Semenya’s physical appearance is not stereotypically female.  This has led some to claim that she is really not a female and a formal protest has been filed.  Many South Africans are outraged at this challenge, identifying it as resulting from “white” racism.  After the race it was revealed that the International Association of Athletics Federations (IAAF) had asked her to take a gender test three weeks before the world championships.  These tests include genetic, gynecological, endocrine, and psychological measures.  Typically when we talk about sex we are referring to something that is biological and when we discuss gender we are referring to how individuls perceive themselves and our perceived by society. Thus gender is more socially constructed than biological. This explains why all four of these tests are conducted to determine eligibility for female sports.  Caster Semenya was allowed to compete in the world championships because the IAAF had no evidence that could be used to stop her from competing.  At the time of this writing these results have not been released. 

There are a number of issues that can explain this challenge.  Some of it may be European racism, but the primary problem here is the notion that the human species contains only two genders with distinct body types and behaviors.  This is a mythological view, but one not held by all cultures.  Plato for example thought that there were three genders, male, female, and hermaphrodite.  Hermaphrodites are defined as individuals that have various mixtures of gonadal structures and secondary sexual characteristics.  The word hermaphrodite comes from the Greek gods Hermes (son of Zeus, messenger) and Aphrodite (Goddess of sexual love and beauty.) Even early Biblical scholars thought Adam was originally a hermaphrodite and that he later became male after the fall².  Clearly this notion of humanity did not survive later Biblical interpretations in which there are only supposed to be two sexes/genders and their sexual behavior is rigidly proscribed.  The destruction of Sodom and Gomorrah in Genesis results in part from the sexual wickedness of the inhabitants.  The word sodomy (referring to anal intercourse) derives from reference to Sodom.

Fruitfulness (in more ways than one)

One of the ways that scientific hypotheses are judged is their fruitfulness.  That is how many predictions or avenues of investigation are engendered if the hypothesis or theory is true.  Evolutionary biology is particularly fruitful in explaining sex, gender, and mating/sexual behavior and this is one of the weakest aspects of Biblical literalist special creationist ideology.  For example, evolutionary theory requires that reproduction be at the core of the biology of all organisms.  Natural selection is best defined as “differential reproductive success.”  Humans, as complicated as they may be, are not immune to this dictum. 

For example, Biblical literalist interpretations of the human birth process claim that women are cursed to deliver their young in pain because of Eve’s sin (Genesis 3:16.) The passage actually says that God would greatly increase her pain in childbearing, possibly indicating that even without this event there might have been some pain.  Evolutionary biology provides another explanation.  Human females experience more pain in childbirth compared to other closely related primates (Gorilla, Chimpanzee, and Orangutan) because of the size of their offspring’s head compared to the diameter of their pelvis bone³. The increase in human head size and the relative narrowing of the human pelvis result from the mosaic history of human evolution.  On one hand, increasing head size of offspring (and delayed brain development) and on the other upright posture and running are concomitant with the changed pelvis diameter.  These adaptations did not come without cost however, human childbirth is risky and until the age of modern medicine, childbirth was still one the largest sources of death to young women.  This had impacts on the social structure of our species.  Social networks of women may have been crucial in reducing the risk of death during childbirth⁴.

How Many Genders/Sexes?

During the writing of the Origin of Species, Darwin was particularly impressed by the sexual characteristics/behavior of barnacles.  The more he learned about them, the more he was convinced that his species theory was correct.  He was astounded to find many species in which the males had become completely dependent upon the females (and were only found attached to the female body.)  In these species the entire male anatomy was reduced to simply being a “giant penis⁵.”  If this occurrence was limited to barnacles than this observation is not particularly important; however there are many species in which parasitic males are the norm, such as the adult of the Schistosoma spp.  In this species the adult male worm spends his entire life in the gynocophoric grove of the female.  His sole function is the production of sperm.

Taking this logic further we can ask: why do males exist at all?  After all if we define female as the capacity to reproduce, then all original life was female.  This question has dominated research in evolutionary biology.  The take home lesson of this research program is that: hermaphroditic species are extremely common in nature, separate sexes evolve under specific conditions, and that individuals can change their sex under specific conditions⁶.  Given that humans evolved from animal lineages with these features, why would anyone be surprised that human gender/sex determination is both complex and fluid?

Instead of viewing human sex/gender as a dichotomy (male or female) it is more profitable to think of this as continuum from individuals who look and behave in a stereotypically female to those that behave in stereotypically male ways.  To understand this we must understand that sex/gender is influenced by events that occur at the level of genes, organs (specifically gonads and brains), and organ systems (body.)  The expression of genes is influenced by chance and environmental effects and these can have important impacts on development.  In our species, sex determination occurs via the 23^rd set of chromosomes, designated X and Y.  The Y chromosome has very few genes, but it carries testes determining factor (TDF).  Generally, individuals who are genetically XY develop testes and a penis.  However, all human embryos start out with identical structures (or are female.)  Therefore it is possible for individuals who are genetically XY to complete development in ways that produce external genitalia that are female.  Fausto-Sterling 2000 summarizes the various common ways that embryos can undergo nondimorphic sexual development.

These data suggest that around 2% of live births are intersex individuals. These frequencies can differ by population due to genetic drift and it has been shown that the frequency of hermaphrodites in the indigenous S. African population is higher than the value reported in this table⁷.

When it comes to the sexual behavior aspect of gender, particularly sexual orientation, knowing the frequency of intersex individuals is not particularly informative.  This is because what we think of as gender is influenced by a complicated interaction of genetic, cellular, physiological, and organ interactions.  For example, there are a number of regions in the human brain that influence sexual orientation.  For example three areas around the hypothalamus are sexually dimorphic (SDN-POA, BSTc, and VIP-SCN. ) In non-transgendered heterosexual males, BSTc is 150% the size of (2.5 mm³ versus 1.75 mm³) and has about 33,000 neurons compared to 19,000 neurons in non-transgendered heterosexual females.  VIP-SCN size for homosexual men is bigger (1.7 times and 2.1 times the neurons) than that of heterosexual men or of heterosexual women⁸.  From this we conclude that gay male brains are different from those of straight men, but not equivalent to those of female brains in this region.   At another region surrounding the hypothalamus, INAH3; heterosexual male size = 0.1 mm³; heterosexual women and gay males = 0.05 mm³.  Consider the combination of brains that result from these 4 regions = 2⁴ power = 16; and if we consider brain and body type combinations (male/female organs and brain types) = 2⁵= 32.  Given that intersex individuals exist with ovo-testes than we could increase the number of combinations to 3 x 16 = 48. In this scenario, those we think of as “women” would be holding up less than half the sky, since 47 other genders exist (even if many of the others are less frequent than “male and female”.)

Using positron emission tomography of sexual attraction a study of 25 heterosexuals of each sex and 20 homosexual also of each sex found that cerebral and amygdale asymmetries of the homosexual group reflected those of the opposite sex in heterosexuals⁹.   This again suggests that gays may inherit brain structures that more closely resemble the opposite sex, but how this might lead to attraction towards the same sex or whether it is inevitable ‘from the womb’ or still subject to social selection remains to be established.   Thus it is premature to conclude we are born with a rigid sexual orientation.  For example, identical twins which share the same genes display opposite sexual orientation around 50% of the time when one of the twins is gay.

 Genetic contributions to gay sexual orientation

Hamer and Pattatucci 1993 found that gay men tended to cluster in families¹⁰.  This study recruited homosexual men (and their families) from HIV clinics in Washington, D.C. area.  The brother of a gay man had a 13% chance of being gay, while the brother of a heterosexual man had only about a 2% chance. This result indicates that genes are involved in determining gay sexual orientation.  Subjects rated their sexuality on the Kinsey scale (0 for exclusive heterosexuality to 6 for exclusive homosexuality.)  These ratings were revealing.  For example, only 70% of the individuals who self-described as heterosexual claimed that they never had experienced homosexual activity to orgasm.  Which means that 30% of the self-described heterosexual men admitted to having some homosexual experiences in their past.  Similarly > 40% of the men who described themselves as homosexual admitted to having heterosexual activity to orgasm.  This again underscores the complexity of human gender.

The Hamer study localized the genetic contribution in this population to five genetic loci on the tip of the X chromosome that where statistically significantly higher in gay males.   This raises an interesting evolutionary question.  How could these genes circulate at such high frequency if homosexual males have a lower reproductive output than heterosexual males?  The answer is that no gene could increase in frequency by natural selection if its net impact is to lower the reproductive output of those that carry it.  Two hypotheses have been advanced to explain the existence of genes that increase the likelihood that its carrier will be gay.   Imagine that the role of these specific genetic markers is to signal that the carrier should be attracted to men.

If the five markers are inherited together on the X chromosome, they can be symbolized as one locus = s.  This results in five phenotypes:

•XX =    “normal” woman

•X_sX =    normal woman (possibly more highly attracted to men.)

•X_sX_s= “super” woman (most highly attracted to men.)

•XY =     heterosexual man

•X_sY=     homosexual man

If we assume that only heterosexual men and heterosexual women are having children, then the predisposition to be a gay male can be produced by heterosexual males and their mating with any woman that carries the s allele.  If the women carrying the s alleles are more likely to mate than women without, that would explain the persistence of the “gay gene.”  Obviously this explanation only applies to gay maleness but not any genetic contribution to lesbianism.  There is no reason why a mechanism of this kind couldn’t be in operation.  Such genes are labeled as “sexually antagonistic.”  A second hypothesis that has been applied to how gay behavior may evolve is through the mechanism of kin-selection and multiple gender families.  Roughgarden describes this in a number of non-human species¹¹.  In short, this operates because an individual can contribute to the reproductive success of a relative, even if they do not reproduce themselves.  If multiple gender families are more successful than dual gender families, than genes contributing to this behavior would spread, even if they resulted in homosexual behavior.

Fruitfulness Explained and its consequences

Genesis 1:20 describes how God blessed the animals and exhorted them to be fruitful and multiply after their kind.  Beyond this poetic language it does not describe specific mechanisms and read literally what it claims is wrong.  Reproduction implies evolution.  For this reason, anything in an organism’s reproductive biology is a great interest to evolutionary biologists.   This is just as true in humans as in any other species.  Applying evolutionary theories to sex and gender tells us a great number of things, including how someone could have a male-looking body, female genitalia, and female gender behavior (or any other combination.)  This reality applied to the world of athletic competition means that the present gender categories need revision.  This reality applied to the world of human society as a whole means that it can no longer rationally support anti-gay bigotry.  Case in point, North Carolina has a “crimes against nature” statute.  As written it is applied mainly to oral and anal sexual acts, generally only applied to homosexuals.  This act is discriminatory and its origin is based in the mythology of dichotomous gender and sex.  It and all remaining discrimination against gay and lesbians should be struck down immediately.  It is time for rational understanding of the human condition to determine our laws.

References

1. Is she really a he? Women’s 800 meter runner shrugs off gender storm to take gold. http://www.dailymail.co.uk/news/worldnews/article-1207653/Womens-800m-gold-medal-favourite-Caster-Semenya-takes-gender-test-hours-World-Championship-race.html

2. Fausto-Sterling, A, Sexing the Body: Gender Politics and the Construction of Identity, (New York, NY: Basic Books), 2000.

 3. Shultz, A.H., Sex differences in the pelvis of primates, Am. J. Physical Anthropology 7: 401-424.

4. Trevathan, W., Evolutionary obstetrics, in Evolutionary Medicine, Trevathan, W, Smith, E.O, and McKenna, J.J, Eds, (New York, NY: Oxford University Press), 1999.

 5. Desmond, A. and Moore, J. , Darwin: Life of a Tormented Evolutionist, (New York, NY: Norton), 1994.

 6. An excellent discussion of this topic can be found in Rose, M.R. and Mueller, L.D, Evolution and Ecology of the Organism, (Upper Saddle River, NJ: Prentice Hall), 2006.

 7. Danso A.P, Nkrumah F.K, The challenges of ambiguous genitalia. Cent. Afr. J. Med. 38:367–371, 1992; Blackless, M, Charuvastra, A, Derryck, A, Fausto-Sterling, A, Lauzanne, K, and Lee, E, How Sexually Dimorphic Are We? Review and Synthesis, Am.  J. Human Biology 12:151–166, 2000.

 8.  Roughgarden, J, Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People, (Berkeley , CA: University of California Press), 2004.

 9. Savic, I and Lindstrom, P, PET and MRI show differences in cerebral asymmetry and functional connectivity between homo-and heterosexual subjects, PNAS 10.1073/pnas.0801566105Â, 2008.

10. Hamer et al., A linkage between DNA markers on the X chromosome and male sexual orientation, Science261: 321-327, 1993.

 11.  Roughgarden, J, Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People, (Berkeley , CA: University of California Press), 2004; see specifically chapter 6: Multiple Gender Families.

Recently I heard an episode of This American Life detailing Jerry Springer, who almost resigned his position as a city council member after he was found to have used the services of a prostitute. This of course is not an entirely rare event – I was instantly reminded of Elliot Spitzer, who resigned from his position as Governor of New York after a similar occurrence; and Hollywood heart-throb Hugh Grant busted in a car. All three were at the time involved in committed relationships. Why would these powerful and/or unnaturally attractive men resort to these hook-ups? And why don’t we hear about women involved in similar situations?

We could turn to a socialization approach and say clearly there is a discrepancy in the social allowance of male v. female infidelity, and this may well be. Perhaps women are judged more harshly for stepping out, but that doesn’t mean that they aren’t in fact stepping out. In a 1940s study of sexual habits in the U.S., blood tests revealed that almost 10% of the babies examined were conceived from extramarital affairs (as cited by Diamond, 1992). In other words, the husbands were not the fathers in almost 1 in 10 cases! Since not all sexual encounters result in pregnancy, one could presume the rates of infidelity to be higher among these women. Women are having affairs, even if we are being socialized with a “double standard”.

Maybe we can turn to a dominance-based explanation. These cheating men were in positions of power; perhaps power lends itself to more frequent sexual liaisons. Those who can, will, right? Historically, men have held such positions in Western cultures. However, women today hold positions of power, and even still it is Elliot Spitzer and not Hilary Clinton who got exposed for using the services of a prostitute. Since the establishment of the Women’s Rights movement in the U.S., women have shown that in the proper environments, they can be just as aggressive as men (e.g. female boxers); hold positions of power traditionally held by men (e.g. political office); and be the primary breadwinners in families (creating a small group of stay-at-home dads). If dominance is the explanation, as women continue to attain powerful positions, shouldn’t too we be hearing about increases in their high-profile infidelities?

Turning to some mating strategies research from an evolutionary perspective might lend some insight. Far from the misunderstanding that men are supposed to “sow their oats” while women maintain their virginal status until marriage, Schmitt and colleagues (2003) found that both men and women are designed to adopt short-term mating strategies, even if involved simultaneously in a long-term strategy*. However, what each sex looks for in a short-term mate differs. In line with parental investment theory, men, as the least compulsory investing sex (e.g. they don’t bear or nurse offspring), use short-term mating strategies to get a variety of mates (which doesn’t always mean the most desirable). Women, as the most compulsory investing sex, seek short-terming mating opportunities to find a high quality mate (which doesn’t always mean a good long-term investor).

At the risk of sounding like an NPR nerd, I think a quote from All Things Considered (March 11, 2008) sums up what we know from evolutionary psychology, at least in terms of men’s short-term strategies -  “They are seeking greater variety, something simple, no commitment.” While high profile men who cheat might be seeking out easy-to-acquire extra mates, high profile women who cheat are likely to continue seeking out high quality mates, who judging by media stories seem to be more discrete in their dealings than prostitutes.

*That these approaches have worked in our ancient past doesn’t mean they are either in line with our current morals OR unchangeable in our current environments. Check out the naturalistic fallacy for more.

References:

Diamond, J. (1992). The third chimpanzee: The evolution and future of the human animal. New York: Harper Perennial.

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 and Social Psychology, 85(1), 85-104.

I recently had what I like to call my ‘gay week.’ It started on a Friday when I went to attend Gay Pride at Faneuil Hall in Boston, followed by seeing Kathy Griffin (a comedian loved by gays). The following Wednesday I went to see the Indigo Girls (an indie rock group made up of two lesbians, Emily and Amy), and finished it off with my friend’s gay support meeting on the next Friday. I went to the meeting to report on the results of the data I had collected from the gay men in that group about a year before. Although there are many things different about the gay community, one of the most striking differences I noticed at all these different venues was the openness with which the gay community discusses sex.

As teachers of evolution, one of the most common and most sensitive topics we discuss is sex. After seeing how open the gay community is when talking about sex, I wondered how we could make our students more open to talking and thinking about sex. The following are some suggestions I have come up with, but I would encourage other teachers to post more suggestions as well.

1. Create an open atmosphere.  I think as teachers, we all strive to have a welcome and open atmosphere, where students feel free to discuss their opinions openly.  However, when we begin to discuss more sensitive topics, like sex, I think we realize just how tenuous this open atmosphere is. Some common suggestions include talking with students casually before class begins (this means actually entering the classroom 10 minutes before class), calling students by their first names and allowing students to call you by your first name, and encouraging students when they share their opinions, thoughts, and questions by maintaining eye contact and thanking students for their participation.
2. Don’t create unnecessary tension. Sometimes we forget that students do always like to share about their lives, especially their sex lives, so I think it best to avoid ‘poll’ type questions like “How many of you have been cheated on, or cheated on someone else.” A better way to get this information is to use index cards, where students can answer or ask questions of a sensitive nature anonymously, and it allows you to edit student answers and questions without students knowing by just passing over an index card.
3. Start off slow. I wouldn’t recommend jumping in with the shape of the human penis, or menstrual cycle differences instead start with the innocuous and fun topics of attraction or jealousy, so students have a chance to get comfortable talking about some mild topics before the more personal topics arise.
4. Be professional, but not too professional. Unfortunately, for men this seems to be an important point. I have had many students characterize male professors as ‘dirty old men’ because of the way they joked about sex. I think students like somewhat of a professional tone when talking about sex to help them feel comfortable, but they also enjoy some humor too. For example, when I discuss some of the early theories on kamikaze sperm, I act out the sperms with silly voices. The students love seeing me make a fool of myself.
5. Be honest and open. Students appreciate when you tell them about being uncomfortable. For example, I tell my students about a conference where I saw Becky Burch discuss the shape of a male penis. I have to admit I was mortified at first, seeing the videos of dildos penetrating condoms, but interested as well. I use this as a way to help the students realize that it is okay to be embarrassed and okay to be interested in sex.

I think it is very important for students of psychology, and particularly evolutionary psychology, to be able to talk about and be knowledgeable about sex. As educators, the responsibility for making these students comfortable is on our shoulders.  I would love to hear what other suggestions you have for creating an atmosphere conducive to sensitive discussions, whether related to sex or not.