Tag Archives: evolution

Mildly altruistic blog post rooted in the brain

Brain science is super interesting and important, of course. In fact, “the brain” is gaining on “the mind” as a topic of our brain-mind’s fixation (Google ngrams):

brainmind

I take a tiny share of responsibility for this trend, as during one of my journalism careers I wrote a 1995 news article about “brain-based learning” for a newsletter sent to more than 100,000 K-12 educators.

On the plus side, in my old article I devoted considerable attention to the issue of brain plasticity, or how brains change in response to time and experience. That plasticity perspective was conspicuously absent from Michelle Trudeau’s NPR story this morning about the brains of extreme altruists. The story was based on a paywalled PNAS article which reported that a nonrandom group of 19 anonymous kidney donors had bigger right amygdalas, and heightened emotional response to pictures of faces, than a nonrandom group of 20 controls. The authors conclude that “these findings suggest extraordinary altruism [is] supported by neural mechanisms that underlie social and emotional responsiveness.”

Or, maybe the cumulative experiences of adults who turn out to be extraordinary altruists change their brains. (Or even, maybe the experience of giving a kidney itself affects people’s brains.) It appears that amygdala size changes within people over time, and that it is correlated with the size of people’s social networks. So, the causal sequencing here is something to consider.

What if, as they imply, something about the way people are born makes them more or less likely to be an extraordinary altruist versus a psychopath (a group this researcher previously studied). How much of the real-life variation in altruism might such a genetic or anatomical influence account for? If that proportion is low, then this is a fascinating evolutionary question with little social implication — worth studying, but not worth writing about with headlines like, “Good Deeds May Be Rooted In The Brain.”

The PNAS authors conclude:

It should be emphasized, however, that the mechanisms we have identified are unlikely to represent a complete explanation for altruistic kidney donation, given the extreme rarity of this phenomenon, and given the overlapping distributions we observed for the variables we measured. Acts of extraordinary altruism are likely to reflect a combination of the neurocognitive characteristics identified here, along with other individual- or community-level variables.

That seems like a safe bet, given this distribution of amygdala size across the two groups:

altruismbrains

In short, we should consider the possibility, however slight, that altruism also has social causes. Disciplinary culture, I suppose, but I’ve never finished an article with a caution to readers that I may not have completely explained the phenomenon under study.

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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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Reviewing Nicholas Wade’s troublesome book

boston-review-frontpage

I have written a review of Nicholas Wade’s book, A Troublesome Inheritance: Genes, Race and Human History, for Boston Review. Because there already are a lot of reviews published, I also included discussion of the response to the book. And because I’m not expert in genetics and evolution, I got to do a pile of reading on those subject as well. I hope you’ll have a look: http://www.bostonreview.net/books-ideas/philip-cohen-nicholas-wade-troublesome-inheritance

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Take it from the Pope

pontificating

For the “World Day of Peace,” which is today, instead of congratulating the newly weds — who are upholding the transformed but still living (for better or worse, in sickness and in health) institution of marriage — Pope Benedict (Ratzinger) issued a statement that included this about homogamous marriage:

There is also a need to acknowledge and promote the natural structure of marriage as the union of a man and a woman in the face of attempts to make it juridically equivalent to radically different types of union; such attempts actually harm and help to destabilize marriage, obscuring its specific nature and its indispensable role in society.

These principles are not truths of faith, nor are they simply a corollary of the right to religious freedom. They are inscribed in human nature itself, accessible to reason and thus common to all humanity. The Church’s efforts to promote them are not therefore confessional in character, but addressed to all people, whatever their religious affiliation. Efforts of this kind are all the more necessary the more these principles are denied or misunderstood, since this constitutes an offence against the truth of the human person, with serious harm to justice and peace.

I’m not enough of a Pope-ologist to know how rare this is, but what struck me was his claim that his opinion is “accessible to reason and thus common to all humanity.”

There is a convention in the U.S. that we can criticize each other’s opinions, but it’s impolite to criticize each other’s beliefs (as long as those beliefs are religious, meaning not too recent in origin). So it’s fine for me to say that you are wrong about secular subjects, like physics and sports, but it’s impolite to say you are wrong if you believe that God speaks directly to you or that cavemen played with dinosaurs. Or, more directly relevant to the Pope, scientists can say that virgin conception is generally unlikely, but it would be impolite to say it never ever happened, not even once.

Anyway, that’s a long way of getting around to the point that I find the Pope’s statement galling. If he wants to express political opinions, fine. I have no objection to that as long as the giant, multibillion-dollar real estate and educational empire he runs isn’t tax exempt.

But if he’s going to make statements with that hat on — that is, subject to a declaration of infallibility* — he should lay off the social-science proclamations. If he wants to argue in the realm of reason, rather than faith, then we may weigh his record of expressed belief in fairy tales against his scientific credibility.

Believe it or not

Learning as I go here: turns out the Pope has a whole scientific academy called the Pontifical Academy of Sciences (where the “peer review” is not done by your peers, if you know what I mean). And naturally they’ve been all over this subject of reason and faith. I read a 2006 talk titled “Secularism, Faith and Freedom,” which was apparently presented to this audience:

secularismontrial

And I thought the American Sociological Association conference was a dynamic scene!

The paper says it’s necessary for religious people to argue their positions freely in a secular state’s public square. These positions include, “Faith is the root of freedom,” and “a proper secularism requires faith.” That is because liberal democracy otherwise is a moral vacuum of pragmatic consumerism with no higher purpose. So I gather that, just as any “gaps” in the fossil record summon Creation as an explanation, so does any lack of morality in the public sphere demand to be filled by faith — specifically, a “Creator who addresses us and engages us before ever we embark on social negotiation.” Absent that presence, “the liberal ideal becomes deeply anti-humanist.”

Although, after reading this whole paper and the Pope’s statement, I confess (my word choice) that I’m not sure “humanist” is really what they’re going for.

Can. 749 §1. By virtue of his office, the Supreme Pontiff possesses infallibility in teaching when as the supreme pastor and teacher of all the Christian faithful, who strengthens his brothers and sisters in the faith, he proclaims by definitive act that a doctrine of faith or morals is to be held.

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Who’s teaching creationism to kids?

…and when did I get so touchy about it?

When someone gave us this chunky dinosaur puzzle, I did a double-take. Yes, that’s a caveman there with the dinosaurs:

The blurb on the company’s website says that, along with the puzzle, ” The accompanying board book teaches young learners about dinosaurs.” Teaches, that is, with lessons like this:

A little harmless fun, or a little creationist indoctrination? (Do sociologists even believe in “harmless fun”?)

According to the Shure company, they deliver these “common threads” in all their products: “Originality and inventiveness; Excellence in design; Attention to detail; Exceptional quality; Educational merit.” So, not just entertainment.

A quick perusal suggests the rest of their products are not creationist — just the usual toy-gendering. They do have a Noah’s Ark puzzle, but it doesn’t claim to be educational. In that Shure is just keeping up Melissa & Doug (whose puzzle is at least Genesis-correct in not naming Noah’s wife):

And anyway, the story of Noah’s Ark is actually not a bad way to talk about reproduction.

But back to dinosaurs and people. Dinosaurs are not really more problematic for creationism than any other creatures that pre-date humans. But maybe because kids love dinosaurs so much, creationists spend inordinate energy trying to place them chronologically with people. Writes one such site:

The idea of millions of years of evolution is just the evolutionists’ story about the past. No scientist was there to see the dinosaurs live through this supposed dinosaur age. In fact, there is no proof whatsoever that the world and its fossil layers are millions of years old. No scientist observed dinosaurs die. Scientists only find the bones in the here and now, and because many of them are evolutionists, they try to fit the story of the dinosaurs into their view.

Up against this kind of propaganda, it is tempting to bring the hammer down on “harmless fun” featuring humans and dinosaurs playing together. That would mean none of these, either:

That is basically the argument of James Wilson, a University of Sussex lecturer, who has a talk on the subject here on Youtube.

For non-biologists, like me, who like evolution and want some ammunition to defend it, I recommend Richard Dawkins’ recent book The Greatest Show on Earth. Some do find it a little dogmatic, and in the grand scheme I prefer Stephen Jay Gould, but it’s good for this purpose. Because rather than block access to dinosaur cartoons, I would rather arm myself – and the surrounding children – with the tools they need to handle them with confidence.


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Color gender by the numbers

Men and women weigh in on their favorite colors.

Update: I’m curious. Will you take a color preference survey here?

More on the many mysteries of pink and blue, this time from college students expressing their own preferences, rather than adults’ choices for children.

This research is from 2001, but I just stumbled on it. In a survey of 5,000 college students from several dozen universities, men and women were asked to express, on an open-ended form, their favorite color.

MEN                                                     WOMEN

Favorite colors for college students, 1990s.

Other responses not shown (4% of men, 5% of women). My chart from data in the article.

These men have a strong blue preference; the women are more diverse in their choices. Proportionally, the biggest differences are on pink (women 10.6-times more likely to choose) and blue (men 1.8-times more likely).

Here is the interpretation of the authors:

Without ruling out any possibility at this point, we are inclined to suspect the involvement of neurohormonal factors. Studies of rats have found average sex differences in the number of neurons comprising various parts of the visual cortex. Also, gender differences have been found in rat preferences for the amount of sweetness in drinking water. One experiment demonstrated that the sex differences in rat preferences for sweetness was eliminated by depriving males of male-typical testosterone levels in utero. Perhaps, prenatal exposure to testosterone and other sex hormones operates in a similar way to “bias” preferences for certain colors in humans.

You really have to love it. Although it’s not as far gone as the speculation that color preferences evolved from the gender division of labor in the hunter-gathering prehistory, it’s not a theory well suited to the rapid historical change we’ve seen in the case of dressing children, at least.

If I were making up an explanation, I’d say maybe these college students were generally pushed toward girl-pink/boy-blue from infancy, and then the girls more actively incorporated color choice into their identities (the idea of having a “favorite color”) — resulting in greater diversity of choices. On the other hand, maybe boys were more likely not to have a color affinity in their identity toolbox and thus are more likely to have a stuck-in-childhood response that matches the preference their parents had for them, or one they consider socially desirable. How’s that?

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Pink/blue, boy/girl?

Update: I’m curious. Will you take a color preference survey here?

Which is the boy and which is the girl here, anyway?

If you said the girl is the one on the right, you are living in the past. Like around 1918, when Ladies Home Journal wrote:

“the generally accepted rule is pink for the boy and blue for the girl. The reason is that pink being a more decided and stronger color is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girl.”

Blue was long associated with the Virgin Mary in Europe and therefore with girls, but to the Nazis pink was the effeminate color — so we might owe their anti-Catholicism some credit for reversing the gender scheme.

Anyway, the amazing thing is this information is from an article (behind a pay wall) in the journal Child’s Nervous System that goes on to speculate on reasons why evolution might have made girls prefer pink and boys prefer blue:

Thus, the pink and blue tradition is recent and relatively exclusive to the Western world, but the girls’ preference for the color pink seems to have deeper roots. … It is therefore plausible that, in specializing for gathering, the female brain honed the trichromatic adaptations … and these underpin the female preference for objects reddish. … Whereas discrimination of red wavelengths appears to facilitate identification of plant food, a preference for red or pink appears to have an advantage for successful female reproduction. This preference for reddish-pink is thought to exist because infant faces compared to adult ones are reddish-pink, and red or pink may signal approach behaviors that enhance infant survival…

It’s amazing, isn’t it, that after all these thousands of years, it was just 60 years ago that we finally figured out to dress girls in pink, which is what they wanted all along! (No reason is given for why boys prefer blue.) That must be why women are so happy now. I love this stuff.

Updated here and here.

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