Tag Archives: evolutionary psychology

Evolved: Nicholas Wade critique trilogy complete

Photo by Philip Cohen from Flickr Creative Commons.

Photo by Philip Cohen from Flickr Creative Commons.

After writing a book review, and further critique of Nicholas Wade’s book, A Troublesome Inheritance: Genes, Race and Human History, I have completed the trilogy with a piece forthcoming in the Annals of the American Academy of Political and Social Science.

The final article includes much of what was in the earlier pieces but edited, with more sources, and with additional material on the social science context. I have posted a pre-publication version here as, “Troubling race in the social sciences.”

Here is the conclusion:

It may be the case, as Freese (2008:S1) claims, that “the vast majority of individual-level outcomes of abiding sociological interest are genetically influenced to a substantial degree.” And it may be true that the historical migration and dispersion of people around the planet has resulted in genetically identifiable clusters that sometimes follow the contours of commonly understood races. But it does not follow that genetics explains the relative status and wellbeing of today’s racially-identified groups or their societies. In fact, these two lines of inquiry – the genetics of behavior and the geographic variation in human genetics – do not depend upon each other; the strong case linking them is the contemporary expression of scientific racism. The publication of Wade’s Troublesome Inheritance serves as a potent warning of the continued resonance of racially deterministic narratives of social inequality.

I’ve learned a lot from working on this. I hope you find it helpful.

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Nicholas Wade followup, deeper dive edition

I’m very happy with the editing and fact-checking they did at Boston Review for my review of Nicholas Wade’s book, A Troublesome Inheritance: Genes, Race and Human History, and I don’t want to undermine their work (thanks to managing editor Simon Waxman and associate web editor Nausicaa Renner). If you only have time to read 4,000 words on it, their version is what you should read. It’s up here for free.

But in the thousands of words that ended up on the cutting room floor, there were a few ideas I’d like to post here, for the very interested reader.

Photo from Flickr Creative Commons by epSos.de

Photo from Flickr Creative Commons by epSos.de

Human bones

A number of critics have said that Wade’s early chapters are good, and the book only gets crazy-racist in the second half when he starts attributing social behavior to races and tracing global economic disparities to evolution by natural selection. But I did want to stress that he’s got plenty wrong in the early part of the book as well. In particular, I highlighted the question, why did human bones get thinner in the millennia before they settled down? This isn’t something we worry over much, but I think it’s an important clue to his biases and assumptions. From the published review:

To establish that genes determine social behavior, Wade looks to ancient history, when humans first settled in agricultural communities. “Most likely a shift in social behavior was required,” he writes, “a genetic change that reduced the level of aggressivity common in hunter-gatherer groups.” Of course, many elements were involved—climate change and geography, population pressure, the presence of various plants and animals, advances in tools and weapons, and human biological evolution—but there is no evidence that a behavioral genetic change was required.

I actually spent a fascinating few hours reading the scientific literature on evolution and bone structure, and saw no mention of the reduction in human aggressive behavior as a cause of human bones becoming weaker. To elaborate, Wade thinks natural selection gave people genes for thinner bones because strong bones became less necessary for survival as people fought each other less. He thinks genetic change in behavior led to genetic change in bones. Please correct me if I’m wrong, but I don’t see any literature at all to back this up (Wade doesn’t cite any).

In fact, if I read it right, we might have thinner bones today than people did 50,000 years ago even though our bone genetics haven’t changed much, as a result of diet and lifestyle changes alone. How is that possible? When the bones of young people bear less weight they don’t grow as thick when they’re adults. This is the issue of tool use and the declining “habitual loads” on human limbs. It might also extend to our skulls because we’re not grinding pre-agricultural superfoods with our teeth all day long. Biological anthropologist Christopher Ruff writes: “In a few years, the strength of a person’s bone structure can change as much as the total average change over the past 2 million years of human evolution.” He cites classic research showing the bones of tennis players’ arms are thicker on the side they hold the racket. There is an alternative view that genetic adaptation did drive changes in bone size, having to do with climate change (here is some of that debate). But nothing about aggression I could find.

This point about the bones not-so-subtly underlies his later argument about Africa’s poverty, which he attributes in part to the genetic propensity toward violence among its people. Rather than aggression being an asset as society evolved, Wade speculates that, in the centuries leading up to the first settlements, “the most bellicose members of the society were perhaps killed or ostracized” (again, no evidence). Cue footage of UN peacekeepers landing in Africa.

Anyway, it’s potentially an important lesson in the malleability of human bodies through life experience rather than (only) through genetic change. The implication is that each generation may still be genetically ready to have thick bones again, but we just keep lucking out and being born into societies with tools and soft foods, so we don’t need to grow them. I find that amazing. I don’t want to push it too far, but I imagine that a lot of behavioral things are like that, too. Evolution has brought us to the point where we have vast potential to grow in different ways, and huge differences between people can emerge as a result our life experiences.

More on the “warrior gene”

In the review I included some discussion of the MAO-A studies:

Wade devotes considerable attention to MAO-A, the gene that encodes the enzyme monoamine oxidase A, which is related to aggression. He singles out studies showing that a rare version of the gene is associated with violence in U.S. male adolescents. Out of 1,200 young men surveyed in the National Longitudinal Study of Adolescent Health, eleven particularly violent young men carried the 2R version of MAO-A, subsequently known as the “warrior gene.” Nine of those eleven were African American, comprising 5 percent of the black male adolescents in the study.

Sometimes in genetics there is some gene or coding that produces some measureable effect, and that’s how most people seem to think about genetics most of the time – there is “a gene for” something. In the days before today’s genome-wide association (GWA) studies, before scientists had the means to investigate hundreds of thousands of genetic markers at a time, they often looked for effects of such “candidate” genes. This approach was valuable, especially when the role of specific genes was known (as in the case of the BRCA1 gene, associated with higher risk of breast cancer). However, with most diseases, and even more so with behavior, which is presumed to be more complicated than single-gene mechanisms, candidate gene studies were (are) often fishing expeditions, with a high risk of false-positive results, amplified by selective publication of positive findings. It is quite possible that’s at least part of what happened with MAO-A and aggression.

Most studies about MAOA have been gene-environment interaction studies, where some version of MAOA has a statistical association with a behavior only in the presence of a particular social factor, such as a history of child abuse (e.g., this one). This kind of study is tricky and offers a lot of opportunity to fish around for significant effects (which I’m specifically not accusing any particular person of doing). The MAO-A 2R studies he cites weren’t interaction studies. But a couple of cautions are important. First, that 2R version of MAO-A is very rare, and the two studies Wade cites about it (here and here) both used the same sample from Add Health – 11 boys with the variant. Two studies doesn’t mean two independent results. You could never get a drug approved based on that (I hope). Second, as far as I can tell there was no strong reason a priori to suspect that this 2R variant would be especially associated with violence. So that’s a caution. I have to say, as I did in the review, that it may be correct. But the evidence is not there (and you shouldn’t say “not there yet,” either). Those two studies are the entire evidentiary basis for Wade saying that genes that shape social behavior vary by race (“one behavioral gene … known to vary between races”.) I didn’t find any other studies that show MAO-A 2R varies by race (though maybe there are some).

 

Yao Ming and Ye Li

Yao Ming and Ye Li

Modern evolution

Does natural selection still apply to humans? Of course. But I can’t see how it works very efficiently in modern societies, because our demography seems like a poor launching pad for genetic revolutions. Most threats to our survival now occur after we’ve had the opportunity to have children. And it’s getting worse (which means better). The decline in child mortality and the extension of life expectancy beyond the childbearing years means that relatively few people are left of out of the breeding community. That’s how I was raised to understand natural selection: individuals with stronger, better traits breed more than those with weaker, worse traits. In the U.S. today, 97.8% of females born live to age 40, and 85% of those have a birth, so 83% of females born become biological mothers. And a good part of modern childlessness is voluntary, rather than the consequence of a genetic weakness. Even as recently as 1900, in contrast, Census data and mortality statistics show that only 53% of females born lived to be age 40 and had a surviving child. So I don’t know how evolution is working today, but except for really bad health conditions I’m skeptical.

Of course, we have selective breeding producing subpopulations that have concentrations of genetic traits. Yao Ming’s parents were both basketball players, and his wife is 6′ 3″. So they’re on their way to producing a subpopulation of really tall Chinese people. But most social divides we have are not like that — they aren’t based on genetic traits. So I don’t see that being very effective either. To take Wade’s example of Jews and math ability (a chapter I didn’t write about because I was already 3,000 words long), you would need to have Jews not only have good math genes, and only reproduce with each other, but they’d also have to cast out those kids who were relatively bad and math and put the boys and girls who were relatively good at math together. That could happen, but it would be inefficient and very slow, and next thing you know some historical event or trend would come along and mess it all up.

Even the much-discussed increasing tendency of college graduates to marry each other — which gives us about three-quarters of couples today being on the same side of the college/non-college divide — is just sloppy and slow by selective-breeding standards. Maybe it could produce a race of people who like baby joggers and The Economist, but given the low levels of isolation between groups and the length of human generations I just think any progress in that direction would be so slow as to be swamped by other processes pushing in all different directions.

Australia

Wade used Australia to argue against Jared Diamond, whose account of world history, Guns, Germs and Steel, dismisses genetic evolution as an explanation, making him the villain in Wade’s story. How is it, Wade wonders, that Paleolithic Age native Australians were unable to build a modern economy, but Europeans could waltz onto the continent and be successful so easily? He writes:

If in the same environment … one population can operate a highly productive economy and another cannot, surely it cannot be the environment that is decisive … but rather some critical difference in the nature of the two people and their societies.

That’s one of the worst head-scratchers in the book. Does Wade really think that Europeans just dropped in to Australia on an equal footing with the local population, and had to figure out how to thrive there on their raw genetic merits, proving their superiority by their relative success? It can’t be that “the nature of the two people and their societies” means the boats, weapons, technology and modern state social organization the Europeans possessed, because then he has made Diamond’s point. So the “nature” he’s referring to must be genetics. To the reader who has a passing familiarity with modern social science, this is just jarring.

Does cancer genetics help?

To help show the dead-end of Wade’s very mechanical view of genetic influence, I drew out an example from cancer genetics (with a little help from my brother-in-law, Peter Kraft, who is not responsible for this interpretation).

What if we found that genetic factors contributed to social behavior in any of the ways Wade imagines? Speculative as that is at present, it is of course a possibility. Most people are concerned about the implications for genocide and eugenics, for good reason. But even if our scientific motives were pure, the functional utility of such information would be questionable.

Consider a comparison to the much better understood genetics of disease. Take prostate cancer, which is known to have a family history component. Genome wide association studies have identified some genetic markers that are significantly associated with the risk of developing prostate cancer, such that a genetic test can identify which men are at highest risk. However, a review of the statistical evidence in the journal Nature Reviews Genetics pointed out that, even among the high-risk group only about 1.1% of men would come down with prostate cancer in a five-year period. That’s much higher than the 0.7% expected in the general population, but what do you do with that information? Invasive procedures, medications, or preventative surgery on millions of men would not be worth it in order to prevent a small number of cases of prostate cancer – the side effects alone would swamp the benefits. On the other hand, we don’t need any genetic tests to tell smokers to quit, or urge people to eat better and exercise.

This is just one example. Risk factors for this and other diseases are the subject of intense research, and there are actionable results out there, too. But I suspect that genetic influences on social behavior, if discovered, would present an extreme version of this problem: slight genetic tendencies implying tiny increases in absolute risks – and interventions with huge costs and side effects – all while more effective solutions stare us in the collective face.

To complete the analogy: In other words, if – big if – we could identify them, should we incarcerate, surveil, or segregate a subpopulation with a small increased odds of committing crime – thereby preventing a tiny number of crimes while harming a large group of innocent people? And should we isolate and elevate the children of some other subpopulation because of their slightly higher odds of success in some endeavor? Or should we instead devote our resources to improving education, nutrition, employment and health care for the much larger population, based on the well-established benefits of those interventions? We know lots of effective ways to affect social behavior, including against “natural” inclinations.

I’m really not against scientific exploration of behavioral genetics. But the risk of exaggerated results and inflated importance seems so high that I doubt the research will be useful any time soon.

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What was I supposed to do, not report the results?

In case you haven’t been following the research on this, my understanding is that there is some evidence that women in several cultures are more likely to wear red-related colors when they are trying to look sexually attractive. We know that from the article “Women Use Red in Order to Attract Mates” in the journal Ethos. That’s all well and good, but to make it really interesting, we’d like to know that women are especially likely to do that when they are in the most fertile time in their menstrual cycle. Because, you know:

Photo by D. Gordon E. Robertson from Wikimedia Commons

Photo by D. Gordon E. Robertson from Wikimedia Commons

Unfortunately, that paper from Ethos did not find that red-wearing was associated with menstrual cycles. But, Beall and Tracy were able to find that link. Their conclusion:

Our results thus suggest that red and pink adornment in women is reliably associated with fertility and that female ovulation, long assumed to be hidden, is associated with a salient visual cue.

As Kim Weeden pointed out when I mentioned this on Twitter, Andrew Gelman used that paper as an example of how researchers have many opportunities to slice findings before settling on those that support their hypotheses.

Fortunately, Beall and Tracy set out to replicate their finding. Unfortunately, when they attempted to replicate the results, they were not successful. Fortunately, they realized it was because they were being confounded by the weather. As they have now reported, this is important because in warm weather female humans don’t need to resort to red because they can manage their attractiveness by reducing the amount of clothing they wear (and then, who cares what color it is?). Thus:

If the red-dress effect is driven by a desire to increase one’s sexual appeal, then it should emerge most reliably when peak-fertility women have few alternative options for accomplishing this goal (e.g., wearing minimal clothing). Results from re-analyses of our previously collected data and a new experiment support this account, by demonstrating that the link between fertility and red/pink dress emerges robustly in cold, but not warm, weather.

And here it is. Happy, Gelman?

journal.pone.0088852.g001

Confirmatory classroom exercise

Since I am teaching love and romance in my family course this week, I thought we should add something to the conversation. I only did one exercise, and I am reporting the full results here. Nothing hidden, no tricky recodes, no other questions on the survey, no priming of the respondents (it was at the start of the lecture).

I have 80 students in the class, which means 53 were there in time for the exercise, 29 men and 24 women. I gave them this two-part question:

shirt-question

Because red and pink are both associated with fertility (see the baboon), I combined them in the analysis (but it works if you just use red, too). And these were the results:

redpink-shirts-results

The statistical test for the difference between date and family event for women is significant at the level of p<.035. This is not research, it’s just a classroom exercise (which means no IRB, no real publication). But if it were research, it would be consistent with the women-wear-reddish-to-attract-mates theory (although without the menstrual cycle question, its contribution would be limited).

Most sociologists might not go for this kind of stuff. Maybe it’s a slippery slope that leads to unattractive conclusions about gender inequality in the “natural” order. My perspective is that I don’t care. Of course this is not really evidence that evolution determines what American (or, in the case of the Ethos paper, Slovak) students wear on dates. But it doesn’t refute the theory, either.

More importantly, I am confident that we could, if desired, through concentrated social engineering, eliminate the practice of women wearing reddish on dates if we thought it was harmful — just as we have (almost) engineered away a lot of harmful behaviors that emerged from the primordial past, such as random murder, cannibalism, and hotmail. After all, they did it in China:

chinese-red-women

Sorry, wrong picture:

chinese-women-mao-suits

For previous posts in the series, follow the color tag.

 

 

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Fatherhood’s transformations: What if someone checked the facts?

For Father’s Day, W. Bradford Wilcox wrote a piece for Slate, “Daddy’s Home: Fatherhood transforms men. But only if they live with their kids.” Raising the question: what if Slate checked the facts they published? Oh, right.

im-home

Anyway, people who publish what Wilcox writes by now have been duly notified of his dishonesty, data manipulation, and incompetence in the service of ideological (and financial) ends. But I do this as an exercise in critical thinking and research, and to help people who want to be informed understand these shenanigans.

So here we go, on the specific claims only. Bogus claim-inflating spin between claims ignored. For each claim, the source, interpretation, and Veracity Score™ from 0 to 10.

fatherhoodjoy

The claim: “For many men, the transformative physical power of fatherhood first manifests itself when the pounds start piling up. One recent survey found that the average father puts on more than 10 pounds while waiting for baby to arrive.”

  • The source: A Motherlode post that links to a BBC news story that reproduces a press release from a marketing firm. No information on the research methods. The marketing firm, Onepoll, has no information about the poll on its website. Does this supposed weight gain of fathers-to-be reflect the evolutionary draw of wedded fatherhood? Said a spokesperson for Onepoll (who we are listening to why?): “So if the kitchen cupboards are suddenly brimming with snacks and food, it’s no wonder blokes are tempted to tuck in as well.”
  • Veracity Score: 2 (Maybe fathers gain weight during their partners’ pregnancies. This is “transformative physical power”?)

The claim: “Studies suggest that after the arrival of a baby men’s testosterone falls…”

  • The source: This paper measuring testosterone level in a sample of Filipino men at two points four years apart. Those who were married with children four years later had larger drops and lower levels. This seems like a legitimate finding. Why wouldn’t men’s hormone levels change in response to such changes in their environment and behavior? It seems a little dicey that the men took their own saliva samples, since other research (from the same study) shows levels change dramatically in the first half hour after people wake up. Although they supposedly took the samples right when they woke up, and recorded the time, it seems possible sleep is the issue here (although they controlled for a simple indicator of “sleep quality.”)
  • Veracity Score: 6

The claim: “Studies suggest that after the arrival of a baby men’s… prolactin levels rise.”

  • The source: Unsourced claim from a parenting advice book.
  • Veracity Score: 0 (Maybe true, who knows? No evidence here.)

The claim: “But these hormonal changes don’t just happen for any father; they appear to be most likely for men who are living in a long-term relationship with the mother of their children.”

  • Source: The link is to the same Philippines study. There, the authors write: “Because this sample is drawn from a cultural setting in which it is rare for men to become new fathers outside of stable romantic partnerships or to file for divorce, there were few single new fathers (n = 12) or divorced men (n = 9), who therefore were excluded from longitudinal analyses.”
  • Veracity Score: 0 (the study specifically said not that)

The claim: “Moreover, research by anthropologist Peter Gray indicates that drops in testosterone are most pronounced among men engaged in ‘affiliative pair bonding and paternal care.'”

  • Source: This paper that measured testosterone levels at one point in time among 126 men in Beijing, 30 of whom were fathers (all conveniently having exactly one child). The fathers had lower testosterone levels. The paper doesn’t have a longitudinal design, however, so it can’t make causal claims – and does not mention drops in testosterone. Also, among the fathers there was no difference between those with younger children and those with older children, which is not good for the hands-on-nurturing effect theory.
  • Veracity Score: 2 (some association, no causal connection, bogus description of “drops” by Wilcox)

The claim: “Fathers who live with their children are significantly less likely to be depressed, and more likely to report they are satisfied with their lives, compared to childless men.”

  • The source: This paper using the National Survey of Families and Households. The paper did not use longitudinal data, and the authors wrote, “Before we can be confident that fatherhood is causally associated with the outcomes we observed, we must address this possibility [of selection effects], probably with longitudinal data.” Is it just possible that happier men are more likely live with their children, rather than the other way around? I’d consider it. Further, they entered some statistical controls for marital status, income, and race/ethnicity. They wrote:
    • Once a number of controls were entered, however, especially marital status, these effects of fatherhood largely disappeared. The two exceptions were that men with children living elsewhere remain somewhat more likely to have depressive symptoms than men who were currently living with their children, and men with older children were slightly more satisfied. For the most part, however, fatherhood does not appear to be independently associated with psychological and physical health.
  • To clarify: (a) those living with children over age 19 were slightly more likely than those with younger children to be satisfied with their lives! (b) those living apart from their children were slightly more likely to be depressed than those living with their children. This does not require evolutionary rocket-science to predict.
  • Veracity Score: 0 (would be 1 for the partial effect, but he loses a point for gross exaggeration and misstatement of the findings.)

The claim: “After the arrival of a baby, new fathers tend to work more hours and pull down more money.”

  • The source: The link is to a 1998 book by the late Steven Nock. I don’t have the book, but more recent research by Rebecca Glauber (using the same data) confirms this. Glauber suggests the effects could be the result of the gender division of labor within marriage or employers’ preferential treatment (or other unobserved factors).
  • Veracity Score: 8 (true statement, but doesn’t address whether “fatherhood is socially transformative for men.”)

The claim: “By contrast, men who have children outside of wedlock, Nock found, are less likely to be employed, earn less, and have higher rates of poverty compared to their peers who did not father children outside of wedlock.”

  • The source: This paper by Nock. When you are talking about a group of men who are poor on average to begin with, it’s hard to know if unmarried fatherhood made them poorer. The paper reports that these negative outcomes are associated with men who father children outside of marriage. However, the paper also reports (grudgingly) that the effects are no longer significant when prior conditions are controlled or when brothers are compared with each other. Thus, there is no causal effect found for men having children outside of marriage.
  • Veracity Score: 1 (“less likely” is true, but the non-causal nature means it offers no support for the claim that “fatherhood is socially transformative for men.”)

The claim: “men who live apart from their children attend church infrequently and drink more frequently, much like their peers without children.”

  • The source: This paper again. Quick check of the tables shows that alcohol and drug abuse is no different between men who live with children versus without once a few basic demographic variables are controlled, so that’s wrong. As for church, the paper shows the association in the cross section but makes no causal claim.
  • Veracity Score: 1 (association for 1/2 the claim, no causal effect.)

You will note some of these claims have Veracity Scores > 0. I didn’t ignore those claims because that would have been misleading (however, if I’m wrong and the testosterone stuff is wronger than I thought, please let me know).

To some blog editors, claims come and go. You might balance them out by posting something from someone who disagrees. Hanna Rosin, a founder of Slate’s XX, dismissively calls this “data wars.” More clicks for them. One alternative would be to not publish the bogus stuff in the first place.

h/t Neal Caren for suggesting this.

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I hope Charles Murray’s gay friends also have some better friends

Charles Murray still thinks legalizing homogamy is a “dangerous thing in a philosophical sense,” although he acknowledges that the political train has “left the station” and urges Republicans to stop fighting it for practical reasons.

charles-murray

Speaking at the Conservative Political Action Conference, he described his “number of gay and lesbian friends” and how they surprised the social scientist in him by being not just responsible parents, but “excruciatingly responsible parents” (See, “some of my best friends are…” and “aren’t gays hilariously fastidious?”)

But Murray’s gay friends should beware, because when he is acting as an (alleged) social scientist, he’s not so kind. In a section of his book Coming Apart that has received disappointingly little attention, he wrote:

I am predicting that over the next few decades advances in evolutionary psychology are going to be conjoined with advances in genetic understanding, leading to a scientific consensus that goes something like this: There are genetic reasons, rooted in the mechanisms of human evolution, why little boys who grow up in neighborhoods without married fathers tend to reach adolescence not socialized to the norms of behavior that they will need to stay out of prison and to hold jobs. The same reasons explain why child abuse is, and always will be, concentrated among family structures in which the live-in male is not the married biological father. The same reasons explain why society’s attempts to compensate for the lack of married biological fathers don’t work and will never work.

There is no reason to be frightened of such knowledge. We will still be able to acknowledge that many single women do a wonderful job of raising their children. Social democrats may be able to design some outside interventions that do some good. But they will have to stop claiming that the traditional family is just one of many equally valid alternatives. They will have to acknowledge that the traditional family plays a special, indispensable role in human flourishing and that social policy must be based on truth.

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