Category: evolution

Lactase persistence in populations that drink milk: a classic story of human evolution re-evaluated

July 29, 2022 • 9:15 am

The classic tale of “gene-culture coevolution” in humans—the notion that cultural changes in behavior changed the selection pressures that impinged on us—is the evolution of “lactase persistence” (LP) over the past four thousand years.  LP is a trait that allows you to consume, as an adult, lots of milk or dairy products without suffering the side effects of indigestion, flatulence, or diarrhea.

Young children are able to tolerate milk while nursing, of course, but after weaning many of them no longer tolerate milk—they are lactose intolerant (LI). The ability to digest lactose goes away after weaning because the gene producing the necessary enzyme gets turned off.

The gain of LP, which enables you to drink milk and eat dairy products into adulthood without ill effect, rests on single mutations in the control region of the gene producing lactase, an enzyme that breaks down the milk sugar lactose.  These mutations have arisen independently several times, but only after humans began “pastoral” activities: drinking milk from domesticated sheep, goats, and cows. And the mutations act to keep lactase turned on even after weaning. (Why humans turn off the gene after weaning isn’t known, but presumably involved the metabolic cost of producing an enzyme that wasn’t used in our ancestors, who didn’t drink milk after weaning until about about 10,000 years ago—when farming and animal domestication began.)

Based on analysis of fossil DNA, the LP mutations began spreading through Europe (starting from what is now Turkey) about 4000 years ago. And so the classic story—one that I taught my evolution classes—is that humans began drinking milk from captive herds, and that gave an advantage to retaining the ability to digest milk even after weaning. Ergo, natural selection for the nutritional benefits of milk led to the spread of LP mutations, as their carriers may have had better health (ergo more offspring) than individuals who turn off the enzyme at weaning).

This leads to the “coevolution” that is the classic evolutionary tale: a change in human behavior (raising animals for milk) led to selection for the persistence of the milk-digesting enzyme, and thus to genetic evolution. The “coevolution” part is the speculation that being able to digest milk without side effects would cause humans to raise even more dairy animals and drink even more milk, intensifying the selection for LP, and so the gene for LP would keep increasing in frequency.

A new paper in Nature, which is being touted all over social media, argues against this classic story, suggesting that it’s more complex than previously envisioned.  Although the new results are touted as overturning the earlier story, they really don’t. There is still human genetic evolution promoted by a change in culture, and there’s still a reproductive advantage in drinking milk.

The new part of the story is simply that that reproductive advantage comes not constantly (as previously envisioned), but only during times of famine and disease, when those who couldn’t digest lactose were at a severe disadvantage because the diarrhea caused by lactose intolerance would contribute to the death of diseased or malnourished individuals. This is a twist on the main story, but doesn’t overturn it completely. There’s still the connection between culture and human evolution, and there’s still a reproductive advantage to LP that leads to natural selection and genetic evolution of our species.  What’s different is how and when the selection acts (see “the upshot” at the bottom).

Click the title screenshot below to read, or you can download the pdf here. The full reference is at the bottom, and Nature deemed this worthy of two News and Views pieces in the same issue: (here and here).

First, the authors show the spread of dairy use in the figure below (the redder the color, the more milk usage over time in Eurasia. This was estimated from looking at the frequency of pot shards that had milk residue (click to enlarge). By 1500 BC, milk use was widespread.

Caption (from Nature): Interpolated time slices of the frequency of dairy fat residues in potsherds (colour hue) and confidence in the estimate (colour saturation) using two-dimensional kernel density estimation. Bandwidth and saturation parameters were optimized using cross-validation. Circles indicate the observed frequencies at site-phase locations. The broad southeast to northeast cline of colour saturation at the beginning of the Neolithic period illustrates a sampling bias towards earliest evidence of milk use. Substantial heterogeneity in milk exploitation is evident across mainland Europe. By contrast, the British Isles and western France maintain a gradual decline across 7,000 years after first evidence of milk about 5500 BC. Note that interpolation can colour some areas (particularly islands) for which no data are present.

One reason the authors doubt the classical story is that while dairying and milk-drinking by adults began about 10,000 years ago, the gene for LP (determined from sequencing “fossil DNA”) didn’t spread widely until about 4,000 years ago.  Why is that? The mutation for LP is dominant, which means it could have spread widely very quickly, as even carriers of one copy would have a reproductive advantage. This temporal disparity is what led the authors to propose their alternative hypotheses for the spread of the LP alleles (there are several).

Further, when the authors tried to correlate the frequencies of the LP allele with the frequency of milk use (the classical explanation), they found no correlation—that pattern was indistinguishable from a general rise in frequency over Europe regardless of milk use.

One other set of data led to the new hypothesis. That is the observation that LI people in both Britain and China can still drink lots of milk without suffering any measurable health or reproductive effects (milk drinking has recently proliferated in China).  Of course, things are different now from 4000 years ago, but one of the differences led to the authors’ two hypotheses: the spread of the LP allele was promoted especially strongly in prehistoric times by the prevalence of famine and of disease—with the latter coming often from animals, either domesticated or those that hang around settlements. (As the authors note: “about 61% of known and about 75% of emerging human infectious disease today come from animals”).

So the authors erected two hypotheses, the crisis mechanism and the chronic mechanism. I’ll let them describe the hypotheses that they tested (my emphases)

Given the widespread prehistoric exploitation of milk shown here and its relatively benign effects in healthy LNP individuals today, we propose two related mechanisms for the evolution of LP. First, as postulated in ref. 24, the detrimental health consequences of high-lactose food consumption by LNP individuals would be acutely manifested during famines, leading to high but episodic selection favouring LP. This is because lactose-induced diarrhoea can shift from an inconvenient to a fatal condition in severely malnourished individuals and high-lactose (unfermented) milk products are more likely to be consumed when other food sources have been exhausted. This we name the ‘crisis mechanism’, which predicts that LP selection pressures would have been greater during times of subsistence instability. A second mechanism relates to the increased pathogen loads—especially zoonoses—associated with farming and increased population density and mobility. Mortality and morbidity due to pathogen exposure would have been amplified by the otherwise minor health effects of LNP in individuals consuming milk—particularly diarrhoea—due to fluid loss and other gut disturbances, leading to enhanced selection for LP We name this the ‘chronic mechanism’, which predicts that LP selection pressures would have increased with greater pathogen exposure.

In other words, the reproductive advantage of having the LP allele came from the reproductive disadvantage (through death) of lactose-intolerant people during times of famine and disease.

They tested the two hypotheses by correlating indices of famine and of disease deduced from archeological and paleontological evidence:

Crisis mechanism: “Subsistence instability”, or famine, was assessed by prehistoric fluctuations in population size, which, the authors say, is correlated with the likelihood of famine (they provide no evidence for the latter supposition). But the correlation gives a significantly better fit to the pattern of LP allele frequency than just assuming uniform selection over time and space.

Chronic mechanism:  The authors hypothesized that the frequency of disease would correlate with the likelihood of “zoonoses” (diseases caught from animals), which itself would correlate with temporal variation in settlement densities.  These data, which to me would be correlated with “prehistoric fluctuations in population size” above, also explained LP allele frequencies better than an assumption of uniform selection.

Of course, there’s no reason (and the authors say this) that both mechanisms couldn’t operate together. Curiously, though, indices of the density of domestic animals did not support the “chronic mechanism” though measurements of the proportion of wild animals around humans did.  This implies that, if the “chronic mechanism” is correct, people were getting sick not from their horses, dogs, cattle, or sheep, but from wild animals (perhaps from eating them).

Other hypotheses that the authors mention but didn’t test include “drinking milk as a relatively pathogen-free fluid”, allowing “earlier weaning and thus increased fertility.” I would add that if diseases are causal here, they could come not from being around animals, but having drunk contaminated water, giving an advantage to those who prefer milk. But there’s no way of assessing that from the archaeological record.

The upshot: On the last page of the paper the authors say that they’ve debunked the prevailing narrative:

The prevailing narrative for the coevolution of dairying and LP has been a virtuous circle mechanism in which LP frequency increased through the nutritional benefits and avoidance of negative health costs of milk consumption, facilitating an increasing reliance on milk that further drove LP selection. Our findings suggest a different picture. Milk consumption did not gradually grow throughout the European Neolithic period from initially low levels but rather was widespread at the outset in an almost entirely LNP population. We show that the scale of prehistoric milk use does not help to explain European LP allele frequency trajectories and thus it also cannot account for selection intensities. Furthermore, we show that LP status has little impact on modern milk consumption, mortality or fecundity and milk consumption has little or no detrimental health impact on contemporary healthy LNP individuals.

Instead, they say that they find support for the increase of LP alleles through both famine or pathogen exposure.

Well, the data are the data, and their indices comport better with those data than does the classical hypothesis—the “prevailing narrative.” I’m still not convinced that their proxies for famine or disease are actually correlated with famine and disease themselves, but other researchers will undoubtedly dig into that.

What I want to emphasize is that if the work of Evershed et al. is accurate, it still does not overturn the story of gene-culture “coevolution”.  The “coevolution” is still there, the fact that a change in human culture influenced our evolution is still there, and the fact that drinking milk conferred higher reproductive fitness is still there. What has changed is only the nature of selection. Granted, that’s a significant expansion in understanding the story, but to listen to the media—social or otherwise—you’d think that the “classical narrative” is completely wrong. It isn’t. It’s still correct in the main, but the way selection acted may be different from what we used to think. The media love “evolution scenarios are wrong” tales, and that seems to be the cast of at least some stuff I’ve seen in the news and on social media.

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Reference: Evershed, R.P., Davey Smith, G., Roffet-Salque, M. et al. 2022. Dairying, diseases and the evolution of lactase persistence in Europe. Nature. https://doi.org/10.1038/s41586-022-05010-7

First fossil evidence for brood care in insects, and a remarkable case of directional asymmetry

July 26, 2022 • 9:45 am

I’ll make this short and sweet.  A team of biologists from China have found, examining a fine-grained layer of fossils dated about 164 million years ago, a species of water boatman (“true bugs” in the order Hemiptera) that provide the oldest evidence for parental care in insects. The care is given by females, who attach their eggs to their second pair of legs. The curious thing is that in all the specimens examined, females attach the eggs to only their left middle leg: a rare example of “directional asymmetry”.

You can read about it by clicking below or downloading the pdf here.  The reference is at the bottom of the post.

 

Parental care is not that rare in today’s insects and other arthropods; you can see some examples in modern insects here. It’s also been seen in fossil insects, with the earliest cases described in the paper:

Among Mesozoic insects, the only two direct fossil evidence cases of brooding ethology are provided by the Early Cretaceous cockroach Piniblattella yixianensis with its oothecae enclosing eggs for protection and brood care; and the mid-Cretaceous scale insect Wathondara kotejai, which preserves eggs within a wax ovisac attached to the body of an adult female.

An ootheca is an egg mass, usually enclosed in a hardened shell, as in this modern cockroach (photo below). I assume the mother in the fossil species would stay with the mass, otherwise I can’t see this as an example of “brood care”:

Here’s a picture from Wikipedia labeled “cockroach (Periplaneta americana) with ootheca”:

An “ovisac” is similar: a capsule containing eggs. In the case of the scale insect above, that’s clearly brood care because the ovisac was attached to the body. The Cretaceous period lasted from 145 to 66 million years ago; and oldest of these two insects having brood care dates to about 126 million years ago.

Now, from the Haiffanggou Formation at the Xiayingzi quarry, a formation in NE China with lots of ancient mammals, dinosaurs, and insects, they’ve discovered the water boatman Krataviella popovi. Fu et al examined 157 specimens, 30 of which were females carrying eggs on the middle segment of their LEFT foreleg. Note the directionality of this asymmetry. If it were random, the chance that 30 specimens would all have eggs on the left side would be 9.3 X 10-10.

The age of this formation is 163.5 million years, so the brood care in these boatmen precedes the previous ‘record’ by about 38 million years. It’s not a unique phenomenon in insects, but it’s the earliest example of that phenomenon.

Here are two photos of females carrying eggs (red arrows), both from the paper and both on their left side. The preservation is remarkable, with some of the specimens prepared using only a sharp knife:

Figure 2 [excerpt]. Brooding in Karataviella popovi. (a) General habitus of egg-carrying specimen (NIGP177390). (b) Details of egg (NIGP177447). (c) General habitus of egg-carrying specimen (NIGP177445). Scale bars: 2 mm in (a,c,d); 1 mm in (f–h), 500 µm in (b,e)
Females and males can be identified independently of egg-carrying, so this is clearly a female trait.  Modern water boatmen often attach their eggs directly to the substrate with a kind of biological glue, and then leave, so there is no brood care. The authors hypothesize that the females in these fossil specimens were still using some kind of adhesive, but that it was used this way:

Since water boatmen eggs cannot adhere to new surfaces after being detached from their original place of deposition, this suggests that the females first secreted mucous substance and then laid eggs onto their own left mesotibia by specific bending movements of the abdomen, and then carried the brood until hatching. The unoccupied right mesotibia might have been used to maintain balance when swimming and feeding.

What seems unusual to me is the directionality of the trait: it’s only found on the left middle leg, never the right one.  This is called “directional asymmetry”. (If eggs were laid randomly on the left or right legs, it would be called “fluctuating asymmetry”.)

Directional asymmetry has fascinated me because, if it’s an evolved trait, it means that genes producing the directional trait “know” which side of the body they’re on. How can that be? If an ancestor already had biological or genetic gradients from top to bottom and front to back, it still means that a point on the right and left side with equal positions on these other two gradients would experience the same environment. So how do genes determine which side their cells are on so those genes can be activated differentially?  I’ve talked about this before, and you can read about it here, here, and here.  It’s a fascinating issue that’s not fully resolved. (Of course, once a genetic directional asymmetry is in place, it can be used as a developmental key for the evolution of further asymmetries. We ourselves have a fair number of such asymmetries.)

One solution, which just pushes the question back a bit, is to posit that the females have directionally asymmetrical ovipositors, and it’s simply easier to lay eggs on your left leg than on your right. But if the ovipositors and genitals are symmetrical (the authors don’t say), then it would probably be a directional behavioral asymmetry, with females behaviorally evolved to lay eggs on only one side. I don’t see the advantage of that, but of course behaviors can be directionally asymmetrical and conditioned by genes, like handedness in humans.  It’s still interesting to me that one of the earliest cases of directional asymmetry known isn’t discussed by the authors except to mention it. Their own big message is that this is the earliest case of brood care seen in insects, not that it’s directional.

Finally, what is the advantage of evolving this kind of brood care? I’m sure you can think of answers: having your eggs with you protects them from predators, and also aerates the eggs as the beetle moves through the water.  Or, as the authors note:

Karataviella adopted a strikingly similar brooding (egg-carrying) strategy to most marine and freshwater shrimps, lobsters and kin (Pleocyemata), where the females attach eggs to their pleopods using a sticky substance, allowing them to actively and intermittently adjust the position of the eggs in water or air, together with the movement during swimming that generates currents, to ensure ventilation and moistening of the eggs. Moreover, in K. popovi and some pleocyematans, a firm but elastic egg stalk is present and may contribute to the aeration of the eggs by facilitating regular shaking motion. Therefore, we speculate that the particular brooding behaviour of K. popovi effectively addresses the problems that large eggs experience relating to hypoxia, drowning and desiccation, resulting in enhanced offspring survival.

To close, here’s a drawing from the paper labeled “Ecological reconstruction of Karataviella popovi and anostracans in the Middle–Late Jurassic Daohugou biota.” What’s weird here is that all the egg masses are shown on the RIGHT mesotibia, and water boatmen do not swim upside down.  Go figure.

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Fu. Y. , P. Chen, and D. Huang. 2022.  The earliest known brood care in insects. Proc. R. Soc. B.2892022044720220447 http://doi.org/10.1098/rspb.2022.0447

More ideological distortions of biology described by Dawkins and an article on pervasive ideological censorship of Wikipedia articles

July 25, 2022 • 9:45 am

Two days ago, for a small project, I compiled a list of ten ways that biology (and evolutionary biology in particular) has been distorted by ideology. These distortions usually come from the “progressive” (really “regressive”) Left, but the Right contributes, too. What’s important is that biological facts are being hidden or distorted in the service of people’s personal ideologies and politics. Ideologues find some lines of biological research, or conclusions from that research, uncomfortable—even deeming it dangerous—and think they’re doing a service by this kind of distortion and censorship. They aren’t.

Besides a few additional suggestions from readers in the comments, we have two new forms of distortion suggested by Richard Dawkins in a tweet:

I appreciate the call out! The “revival of Lamarckism”, I think, is the current view that epigenetic modifications of the genome, induced by the environment, can be inherited, and can constitute adaptations. There are no good examples: most of the alterations aren’t adaptive, and none of them last beyond a few generations. The ideology motivating this view is presumably a “Darwin-was-wrong” view, and perhaps the political notion that organisms are malleable by environmental change—though this form of change gets inscribed in the genes. (Another method is the “plasticity” hypothesis of Mary Jane West-Eberhard. but even my smartest colleagues can’t figure out how to interpret that theory.)

Group selection, of which we have no good examples in humans and only a few in other species (see the last chapter of my book Speciation with Allen Orr), may reflect another form of ideological “anti-Darwinism”, or perhaps a drive to explain how humans can become altruistic and kind via “selfish genes”. (But as Dawkins has explained repeatedly, apparent altruism, and certainly cooperation, can evolve via individual selection, and Steve Pinker has explained why group selection for human traits is cumbersome and unlikely.)

However, the promotion of group selection by Ed Wilson, the latest big revival of the idea, wasn’t so much in the service of an ideology but of ambition—Wilson wanted to be remembered for having his own Big Theory of human behavior, and group selection was it. His last books and talks pushed the idea that, in fact, almost every aspect of human behavior had evolved via group selection. (This isn’t just my interpretation, but one made by several of Wilson’s colleagues and friends.)

Now, this new article in Quillette, by a person using a pseudonym (no, I don’t know who it is), represents another substantial attempt to distort biology in the interest of ideology.  The author documents at length how a whole group of Wikipedia articles, involving human behavior, intelligence, race, and other traits have been edited or even removed because the claims adduced weren’t comforting to the “progressive” Left. (And yes, the editing is all in the direction of expunging things that contradict wokeness). I haven’t checked the claims, which involves going through the editing history of many Wikipedia articles (the discussion is all on public view), but I direct you to the article to show you how censorious the woke editors have been.

Click to read:

The claims, if true, contradict Wikipedia‘s avowed aim of presenting the latest well-supported ideas from reputable sources; instead, they’ve cut out new and reputable sources in favor of older sources that buttress the ideologues’s claims, and have often replaced the claims of scholars with those of journalists. The aim is to effect “social justice”, not to give information.

“Tezuka” gives five examples of Wikipedia-tampering that he’s followed in depth; these are the areas covered:

1.) Recent evolution in our own species.

2.) Differences in average IQs among countries

3.) The “Flynn effect”: the observation that over the last century, IQs have risen gradually: about three points per decade

4.) The intelligence of Ashkenazi Jews, well known for being academic overachievers.

5.) Race and intelligence: the controversy about the terms “no evidence” versus “no direct evidence”

I recommend you read the article, as here I will focus on only one area: “Ashkenazigate”. This kerfuffle resulted in the removal of the entire Wikipedia article on Ashkenazi Jews and intelligence and the mention of that association on the entire site. I was especially curious about this one, as 23 and Me tells me this is my own genetic constitution:

So what happened? The author first explains why the topic deserves an article:

Although they comprise only about 0.2 percent of the world’s population, the Jewish people account for a large portion of its top achievers in domains of intellectual success. For example, they have won between a fifth and a quarter of the world’s Nobel prizes, and comprise over half of its chess champions. Ashkenazi Jews are particularly noted for their high achievement, including their high average performance on IQ tests. In his textbook IQ and Human Intelligence (Oxford University Press, 2011), Nicholas Mackintosh gives the following summary:

[I]t has long been known that Ashkenazi Jews have an unusually high average IQ (see Chapter 1); some of them also have the misfortune to suffer from a number of diseases, such as Tay Sachs disease, caused by the possession of two copies of particular recessive genes. One suggestion is that the two are linked: while homozygotes with two copies of the genes develop the disease, heterozygotes with only one copy develop higher than usual intelligence (Cochran et al., 2006). (Mackintosh 2011, p. 285)

Aside from its scientific importance, this topic of research is also an important part of the rebuttal to antisemitic explanations for Jewish achievements. In 2006, Steven Pinker wrote in the New Republic that “Jewish achievement is obvious; only the explanation is unclear. The idea of innate Jewish intelligence is certainly an improvement over the infamous alternative generalization, a worldwide Jewish conspiracy.”

Now I’m not touting myself here as being super-smart; I just haven’t followed this very closely, though I’ve heard the claim that there is “overdominance” for a disease gene, like Tay-Sachs, so that although having two copies of the gene form (“allele”) gives you a fatal disease, having one copy gives you higher intelligence than usual. (Presumably having two copies of the “normal” allele gives you lower intelligence than having one copy, though I don’t know why that would be true.)

A similar kind of “overdominance” obtains for sickle-cell anemia. In Africa, having one copy of the disease allele (a mutant of the beta chain of hemoglobin) makes you more resistant to malaria, while two copies gives you the disease, usually fatal at a young age. Having two copies of the normal hemoglobin allele makes you susceptible to malaria. In such a situation, where the heterozygote has higher fitness than either homozygote, the gene will be maintained in the population by selection—called “balancing selection”. This is why the allele for sickle-cell anemia is so common in West Africa, as well as in U.S. blacks whose ancestors came from West Africa. (The frequency is declining in the U.S. because we don’t have malaria and also because there’s been substantial intermarriage between whites, who don’t carry the allele, and blacks.)

By the way, I used this example in my evolution course to show that evolution doesn’t create the best possible situation: the price of heterozygote advantage is having a number of people die from the disease and a number of people with two “normal” alleles die from malaria. If there was a beneficent creator, he would have endowed us with a hemoglobin allele that protects us against malaria when present in two copies but doesn’t cause sickle-cell anemia. Then everyone in Africa would be protected from malaria and not susceptible to the disease. But that hasn’t happened. This is another bit of evidence against a loving creator, for if our genes do reflect a creator’s will, he/she/it has allowed many people to die of malaria and sickle-cell anemia. (I didn’t talk about the god stuff in class.)

Anyway, I don’t know the evidence for this hypothesis for the Ashkenazi, and in truth am doubtful about it. Besides not knowing the single-gene evidence for intelligence, there has to be a correlation of intelligence with number of offspring for selection to work. Further, we need data showing that two copies of the “normal” allele give you lower IQs than the heterzygotes. I’d like to read about this issue in a brief piece, but the original article from Wikipedia has been EXPUNGED.

For reasons I don’t know—perhaps connected with antisemitism or just a general denigration of genes affecting IQ—the article, which was documented with sources, was proposed seven times for deletion from Wikipedia. Then the manipulators made it vanish:

In October 2020, Wikipedia’s “Ashkenazi Jewish intelligence” article was nominated for deletion the seventh time. The argument presented for its deletion was more or less the same one that had been made in every previous deletion proposal:

[O]ur article is some sort of pseudo-academic jaunt through fringe literature as promulgated by the IDW-sorts and the evo-psychs. Meanwhile, nary a hint is here that the true context of this is antisemitism. The article is here to wave a flag: such discussions of race and intelligence cannot possibly be race realist in the WP:NONAZI sense because look at who benefits at this article? *wink*, *wink*

This seventh attempt employed a tactic that had not been used in the other six. Rather than directly arguing for Wikipedia to cease covering the article’s topic, this deletion proposal suggested that the most effective way to address the nominator’s complaint would be to delete the article and then recreate it in an improved state. This argument succeeded where every previous deletion attempt had failed, and Wikipedia’s article about Ashkenazi Jewish intelligence was deleted on October 19th, 2020.

After the article’s deletion, this stated plan to recreate it turned out to be a false promise. Instead, references to high average IQ among Ashkenazi Jews were subsequently removed from every other Wikipedia article in which this topic had been discussed, including the “List of Jewish Nobel laureates” article and the general “Ashkenazi Jews” article, with edit summaries stating that the various papers, articles, and books discussing this topic were no longer reliable sources. Among the many sources rejected with this justification were papers and articles published in the Journal of Biosocial Science, Mens Sana Monographs, Commentary, and the New York Times, and the book Abraham’s Children by Jon Entine (Grand Central Publishing, 2007). Following the final removal of this material in March 2021, Wikipedia no longer covers the topic of Ashkenazi intelligence.

So it’s gone, and the ideologues have managed to suppress both data and discussion. Note as well that a change like this in one part of Wikipedia ramifies through the site, so that there appears to be no discussion of an interesting phenomenon—Ashkenazi overachievement—anywhere on Wikipedia.

As I said, I don’t know a lot about the topics covered, and nothing about Wikipedia editing, but this article does scare me about the power of ideologues to affect what has in effect become the world’s go-to source of information. (It shouldn’t be for scholars, but erroneous material on Wikipedia has made it into scientific publications.)

The author ends his/her/their article with a warning about this kind of censorship affecting the credibility of Wikipedia. (That will bring joy to the heart of Greg Mayer, who has been promising us an article on “What’s the matter with Wikipedia?” for many years. It’s even partly written.)

The ending:

The original purpose of Wikipedia was to reflect the current understanding of the topics that it covers, not to exert an influence over fields to enact social change. The fact that it performed the first function so well for most of its existence, and came to be regarded as a trustworthy source, is what has made it such an effective tool for those who wish to use it for the latter purpose. While Wikipedia may ultimately prove successful at undermining research about topics related to human intelligence, it also may undermine its own reputation in the process. Formerly trusted institutions have begun to lose society’s trust as these institutions have surrendered to “woke” ideologies, as Quillette has previously described in the case of the New York Times, and Wikipedia will not necessarily be immune to this effect.

It’s clear why the author used a pseudonym.

The New Yorker writes about the hoatzin, implies that Darwin’s idea of evolutionary trees may be a phantom

July 17, 2022 • 1:00 pm

I have one hour to analyze in detail a new article about a bird. Can I do it? The answer, yes I did!

When the New Yorker publishes a piece about pure science, as it does in this article about a South American bird, I always suspect there’s a hidden agenda. That’s because the magazine isn’t really pro-science. As I quoted a respected colleague in an earlier post:

The New Yorker is fine with science that either serves a literary purpose (doctors’ portraits of interesting patients) or a political purpose (environmental writing with its implicit critique of modern technology and capitalism). But the subtext of most of its coverage (there are exceptions) is that scientists are just a self-interested tribe with their own narrative and no claim to finding the truth, and that science must concede the supremacy of literary culture when it comes to anything human, and never try to submit human affairs to quantification or consilience with biology. Because the magazine is undoubtedly sophisticated in its writing and editing they don’t flaunt their postmodernism or their literary-intellectual proprietariness, but once you notice it you can make sense of a lot of their material.

. . . Obviously there are exceptions – Atul Gawande is consistently superb – but as soon as you notice it, their guild war on behalf of cultural critics and literary intellectuals against scientists, technologists, and analytic scholars becomes apparent.

I think a lot of that is true, so what’s the reason we get a rather confusing article about the evolutionary history of a South American bird? Well, I don’t know the author’s brief or motivation (Ben Crair is a freelance writer), but judging from the title and the content, this is an article in the “Darwin-was-wrong” genre—in this case mentioning Darwin and the tree of life as being somehow overturned by the ancestry of the hoatzin bird. It isn’t, of course, but in trying to make his case the author produces a farrago of confusion that will not only befuddle the layperson, but also confused both Matthew and me. Click to read (it’s free):

Let’s meet the subject, first. The hoatzin (Opisthocomus hoazin) is one of the world’s weirdest birds in appearance and habits. Here’s its South American range:

Below: a video of what it looks like and the very weird climbing behavior of the chicks, who have retained ancestral claws on its wings (they lose them as adults). When predators attack, the clawed chicks, whose nests are built over water, simply drop into the drink, swim to shore, and use their claws to climb back to the nest.

Here’s a video that makes the climbing behavior more obvious:

The front claws, which made people think the bird is primitive, is not the only weird thing about it (and no, it’s not the only species with claws, just one that uses them for such a bizarre reason). This excerpt is from an article by Elizabeth Deatrick on Sketch, a feature of the Audubon Society.

Hoatzins are the only birds in the world that eat nothing but leaves, which, compared to seeds and fruit, aren’t very nutritious, and are hard to digest. So to accommodate this diet, the Hoatzin has evolved a multi-chambered digestive tract with lots of little “stomachs,” where the leaves can sit for a while and be digested by friendly bacteria. During the digestion process, the bacteria release methane that the bird then belches out, producing an olfactory aura that’s landed the Hoatzin a less-than-flattering nicknamed: the stinkbird. So much for fitting in.

It’s also called the “skunkbird.”

So we have some interesting facts. But what intrigues Crair is that when you try to place the hoatzin on the family tree of birds, it’s very hard. Its structure and morphology aren’t useful, because it diverged from other birds so long ago (it may occupy a long, old branch of its own). So people turn to DNA, which, if you use enough of it, should, via inspecting similarities and differences, tell you what species the hoatzin is most closely related to.  But because it’s so long diverged, that’s been problematic too. Various analyses, depending on which parts of the DNA you look at, have suggested that it’s most closely related to turacos, or maybe to cuckoos, or maybe to rails, or maybe, as this article suggests, to the ancestor of cranes and shorebirds. The problem is that the DNA is so long diverged from that of other bird species that, depending on what part of the DNA you look at and which bird species you use for comparison, you get different answers.

But this is not your typical bird, and we can usually place a bird near its closest relatives if we use a lot of DNA. That kind of analysis sometimes yields surprising results: one I like to mention is that peregrine falcons are more closely related to parrots than to other birds of prey (“raptors”) like hawks, ospreys, and eagles. That’s based on a lot of DNA, and that is the correct placement of falcons on the bird evolutionary tree.

Of course the hoatzkin kind of difficulty does not invalidate the idea of a “branching tree of life”, for we are using a phylogeny of genes (one branching scheme) to determine the phylogeny of species (or populations), which can be a different branching scheme. And if you look at some animals and some genes, you’ll find that the family tree of genes, whose own evolutionary history branches when they mutate, does not match the phylogeny of the species themselves: the evolutionary history of the organisms that contain the genes.

These discrepancies between the “tree” of some genes and of the organisms that contain them have several causes.

The first is what we call “incomplete lineage sorting”. Let me explain. Suppose that an ancestral species has two mutant forms of a gene or DNA segment. Let us call them A, and B. Let us then suppose that the ancestor branches in such a way that it produces species X, Y and Z, and the branch that eventually splits to produce Y and Z comes off separately from the branch that leads to X. Now assume that each of these ancestors has all the A and B mutants, but then species Z loses the A form via genetic drift, while species X and Y lose the B form.  This happens, for genes can change their frequencies by random processes not involving natural selection (“genetic drift”).

The history of the species themselves shows that Y and Z are more closely related to each other than either is to X, since they share a more recent common ancestor. But if you look at the one gene that had the two forms A and B, you’ll see that species X and Y are more closely related than either is to Z in terms of that gene, for they both have form A, while Z has form B. In other words, a tree for this gene shows an evolutionary history different from that of the tree for the species themselves. And if you look at another gene, which drifts independently, you may find that species X and Z are more closely related to each other than either is to species Y.

Since there are a gazillion genes to look at, it’s not unlikely that you would find such discrepancies. The genes can show three different evolutionary histories while there is only one for the species themselves, based on which populations evolved into new species. Gene trees and species trees can be discordant.

The way to solve this, of course, is to use lots and lots of genes, for together they should show a preponderance of phylogenies that match the tree of species themselves, since genes (with two exceptions mentioned below) stay within the borders of species. (The definition of “biological species” involves barriers to gene exchange.)

And, in general, that’s what we find. When we sequence whole genomes of species, like humans, chimps, and gorillas, we find what we knew from other data: humans and chimps (I lump bonobos with chimps) are more closely related to each other than either is to the gorilla, which is the more distant ancestor or “outgroup”. And all four of these species are yet more distantly related to the orangutan.  The more genes we use, the closer we get to reconstructing the true evolutionary history of the species themselves.  

Since the hoatzin is so long removed from other species of birds, it’s evolved nearly independently for nearly sixty million years, and so, depending on which species and which genes you look at, you could find that the hoatzin has genetic similarities that are discrepant if you use different comparison groups. There is no species closely enough related to the hoatzin to allow us to show a general similarity between its genes and that “sister” species. Ergo we don’t know the closest relative of the hoatzin. And we may never know.

I haven’t done a great job explaining this, but perhaps you’ll understand. Still, author Crair doesn’t try to explain this at all, referring in one sentence to incomplete lineage sorting as a “kind of genetic scrambling.” The key, though, is to understand that the evolutionary history of individual genes or segments of the genome is not the same thing as the evolutionary history of the populations of organisms that contained those genes—the species themselves.

The other factors that causes discrepancies between gene trees and species trees are hybridization, which can transfer genes between species that aren’t all that closely related, or horizontal gene transfer (“HGT”) via vectors like viruses. Both of these transfer bits of DNA into species that don’t reflect their evolutionary history, and trying to suss out species’ history from such wide gene exchange is confusing. That, too, could have been a problem with placing the hoatzin, but I doubt it.

Here’s one example from humans. Because of ancient hybridization between Homo sapiens and Neanderthals—I won’t get into the issue of whether they’re different species, though I don’t think they are—if you looked at the right gene in me, Jerry, and compared just that one gene to other gene forms in my species and to the Neanderthal genome, you might find that “for gene X Jerry is more closely related to Neanderthals than to his fellow H. sapiens.” And that would be true. Most of us probably carry a different set of gene bits from Neanderthals, and if you wanted to make a tree using just those bit, you’d find out that every one of us is more Neanderthal than sapiens. But of course this is only for the bits of genome that we’ve inherited after ancient hybridization between Neanderthals and our own ancestors. If you look at whole genome analysis, you’ll see that this small discrepancy washes out and you get the correct answer: all of us are more closely related to each other than to Neanderthals.

It is these issues that allow the author to conclude that the idea of Darwin’s branching evolutionary tree may be way overrated. Here’s how he states it:

The tree is so ingrained in evolutionary biology that scientists encourage “tree thinking.” By learning to think in terms of trees, students can avoid the common fallacy of reading evolution as a ladder in which simpler organisms become more complex, as in the famous image “The Ascent of Man,” which shows a knuckle-walking ape evolving into an upright human. For all its pedagogical value, however, the tree also embeds subtle assumptions about evolution. The tree tends to downplay the genetic variation within species, which can obscure the fact that common ancestors are actually diverse populations that can pass on different versions of a gene to different descendants. It tells a story of endless partition and diversification, with branches that diverge and never reticulate.

Now doesn’t that imply that the idea of evolutionary trees is dubious? In fact, the idea of trees for species, which is the way Darwin meant it to be construed, is doing fine; it just doesn’t always comport with trees for some genes within a species. Tree thinking is well and good and isn’t likely to go away.

And yet. . . and yet Crair admits this in one place:

The outlines of animal evolution still look a lot like a tree in many places, which is why scientists continue to spend so much time developing and debating different branches. But, if tree thinking taught biologists that everything is connected, genes are suggesting that the connections can run even deeper than a tree can capture. To gain a more complete picture—and to answer questions like how such an unusual mix of traits came together in the hoatzin—scientists may need to think outside the tree.

If Crair was careful to distinguish between species trees on the one hand and gene trees on the other, he wouldn’t have to create these apparent “discrepancies”. We’ve known about this issue for years; in fact, I wrote about it in my book Speciation with Allen Orr, and that came out in 2004. (See the Appendix.)

I don’t know if sloppy editing exacerbated the confusions in this article, or whether the author didn’t clarify them (I think he understood them). In the end, we’re simply left with these facts:

a. The hoatzin is a damn weird bird.
b. We haven’t been able to deduce its closest bird relatives.
c. There are evolutionary/genetic reasons for this difficulty.

But that wouldn’t make as click-worthy an article as the one that the New Yorker published—to wit:

a. The hoatzin is a damn weird bird.
b. We haven’t been able to deduce its closest bird relatives.
c. Therefore there must be something wrong with Darwin’s idea of a “tree of life”.

“a” and “b” are what you should remember, and also remember about why the hoatzin smells bad and the weird claws its chicks use to climb up trees.

Now it’s time to feed the ducks!

The Freethinker interviews Richard Dawkins

July 16, 2022 • 1:00 pm

I’m not sure about the nature of this website, The Freethinker, but it appears to be a rationalist and humanistic venue. But I haven’t investigated it in any detail as I really don’t care about its politics given that the article at hand is an interview with Richard Dawkins. Nor is the interviewer named; it’s just “Freethinker.”

Much of the interview you may already know about, as a lot of people here follow Richard, but I’ll highlight just a few intriguing questions and answers. The Q&As in the piece are indented, and click on the following to read:

The introduction includes this:

On his sitting room wall, I spotted two paintings that seemed somehow familiar. They turned out to be by Desmond Morris, the zoologist and surrealist painter; the larger one was The Expectant Valley, which served as the cover for the first edition of The Selfish Gene (1976). Dawkins later acquired them from the artist.

You’ll recognize the painting to the right:

(from the article): RICHARD DAWKINS IN HIS HOME IN OXFORD, WITH WEAVER BIRD NEST, TORTOISE SKULL, AND DESMOND MORRIS’ THE EXPECTANT VALLEY. PHOTO: E. PARK

‘Please focus on the science in your write-up rather than the politics,’ he said as I was leaving, ‘it’s more interesting.’ But that is the risk of being a public intellectual with a Twitter account: humans are an odd species, and with all the scientific insight in the world, it is hard to predict which ideas will do best in the meme pool. We leave readers to judge for themselves.

Well, the job of the interviewer isn’t to call attention to Twitter scandals, but to illuminate a person. The interview does a creditable job, but concentrates too much on social media and on memes—an idea I still consider clever but unfruitful, as it hasn’t explained much. More later  Here are a few parts of the interview that struck me.

First, and I love this, Dawkins explains what The Selfish Gene is about. It’s a masterpiece of concise summary:

Freethinker: In a nutshell, how would you sum up the book’s thesis?

Dawkins: Natural selection is the differential survival of genes in gene pools. Individual organisms can be seen as survival machines for the genes that ride inside them. When an individual dies, its genes die with it. If it dies before it reproduces, they really do die. Individuals are descended from an unbroken line of successful ancestors, where ‘successful’ means that they reproduced and their descendants therefore inherit the genes that made them successful. That is what makes living creatures such good survival machines for the genes inside them.

So when you look at an animal and ask why it does what it does, the answer is, for the good of its genes. Genes are ‘selfish’ in the sense that they look after their own self-preservation. Individuals do not – they are not selfish, or not necessarily. They may be driven to be selfish by the selfish genes, but the selfish genes may equally well drive them to be altruistic. The ways in which individuals work for the survival of their genes is dependent upon their ecology, and they may do it up trees or underground, or in water or in deserts. They may be predators or prey, parasites or hosts. But it is all fundamentally about the same thing, which is preserving the genes into the distant future.

“Freethinker” asks a lot of questions about memes (it’s the subject of more questions than any other), referring to a word coined by Richard as a “unit of culture” analogous to a gene. Like genes, memes can spread or not spread via selection, in this case cultural or psychological selection. As examples of memes, Dawkins has often used catchy “earworms”: music or phrases that you can’t get out of your head.  And Dawkins notes, as he has before, that religion is a particularly insidious and invidious meme, since it spreads both horizontally (via proselytizing) and vertically (through indoctrination of children). He mentions that religion is, perhaps, a highly successful meme because children are identified by their religion: we speak of a “Jewish child” or a “Hindu child” while we wouldn’t speak of a “Republican child” (poor kid!).

I don’t want to dwell on why I think memes, though a good idea, hasn’t proven especially fruitful. Richard himself—while he thinks the idea has been fruitful—mentions some of the difficulty of analogizing memes and genes. My own view and critique is best summarized in my review of Susan Blackmore’s enthusiastic book on memes, The Meme Machine; that review was in Nature in 1999 and you can read it here.

Another exchange below: “I don’t do movements?”

Freethinker: Looking back on the New Atheist movement in the 2000s, what was the high point of that for you?

Dawkins: I don’t do movements. I suppose when four books came out within a couple of years of each other: The God Delusion, Sam Harris’ End of Faith, Dan Dennett’s Breaking the Spell and Christopher Hitchens’s God is Not Great. By coincidence – there was not a conspiracy or anything. That might have been a high point.

The question below I consider confrontational, which after all is part of an interviewer’s job, but it’s naive and, indeed, trivial. It’s a “gotcha” question. (The whole interview is peppered with stuff like this.) Richard’s writing may sometimes be polemical, but I see it as “passionate”. Indeed, I give the first part of Dawkins’s response:

Freethinker: As a writer who has done a lot to popularise many areas of science, your style has been compelling and vivid, but often polemical. Why did you choose to write in this way?

Dawkins: I am not sure I see it as polemical. It is certainly read as polemical by religious readers. . , ,

But of course all critiques of religion are seen as polemical, just as all critiques of wokeness are seen as polemical. The best way to shut down discussion is to call a critic “polemical” or “strident”. But If you want to see real polemics, read Mencken!

On accommodationism and humanism, Dawkins gives good answers, though “logically speaking” is ambiguous pharasing by the interviewer.

Freethinker: People can be inconsistent, and believe incompatible things at the same time. But logically speaking, is it possible to be scientific and religious?

Dawkins: Many people are, but I am not sure whether that falls under the heading of logic. I suppose I have to say it is possible, yes. You could say the universe is such a mysterious place that it would be foolish to be over-confident one way or the other about whether some monster intelligence lies behind it. That would be, for me, bending over backwards an awful long way. It is very hard to be a logical theist.

Freethinker: Would you describe yourself as a humanist?

Dawkins: My only hesitation in describing myself as a humanist would be that it implies giving too much of a privilege to the human species as opposed to other species. I would like to call myself a ‘sentientist’ or something like that – with a moral regard for sentient awareness. A large part of that would be human, but no doubt there are other animals that are capable of feeling pain and suffering something like the way we are. With that reservation, I would call myself a humanist.

The interviewer asks Richard about the American Humanist Association revoking his Humanist of the Year Award (a rather boorish thing to bring up), and asks “Speaking as a scientist, what are your views about the transgender debate?” Did he expect Dawkins to come of as a transphobe, which he isn’t? You can read Richard’s answer for yourself.

Two more bits:

Freethinker: Over the course of your long career, what is the achievement of which you are proudest?

Dawkins: My second book, The Extended Phenotype (1982), about the visible manifestations of genes, because it has the most of me in it, and the most original thought. It is aimed at professionals rather than lay people, although lay people can enjoy it.

Richard has given this answer many times, and means it. I’ve read the book, and yes, of all his books, this has the most “meat”, and is the hardest to read and the most original. But the meat is savory, and if you’re feeling ambitious, you must read it.  I can understand why he is proudest of this, because I feel the same way about Speciation (written with Allen Orr). I’ve had two fairly successful trade books, but of everything I’ve written, I’m proudest of Speciation, also written for professionals. When I dip into that book from time to time, I think, “Damn! I could really think then!” I don’t think I could write it now, but I was at the right age to do so and my mental faculties hadn’t yet begun their inexorable decline.

However, if you consider everything that Richard has written, and combine literary quality with scientific explanation, I put The Blind Watchmaker at the top. Some of the prose is so lovely that it almost brings one—or at least a scientist—to tears. Those who claim, as E. O. Wilson did, that Richard is just a “journalist”, or that he’s not a scientist but a popularizer, should read The Extended Phenotype. 

Finally, the discussion turns to Dawkins’s next book:

Freethinker: What projects are you working on at the moment?

Dawkins: I am working on a new book called The Genetic Book of the Dead, which is aimed at the same kind of audience as The Selfish Gene. Its thesis is that an animal is a description of ancient worlds, of an ancestral world in which its genes are naturally selected. A sufficiently knowledgeable zoologist of the future should be able to pick up an unknown animal and read it as a description of a palimpsest of ancestral worlds in which its ancestors were naturally selected.

Now that is also an original idea of Richard’s, and in principle a good one. But as a biologist, I would have drilled deeper into this answer (there are no followup questions). How can you be so sure that you can read environments of the ancient past from a DNA sequence?  After all, that sequence is a palimpsest which has been overwritten continuously for three billion years. And don’t you have to know tons of information about developmental genetics to even start such an endeavor? We know that all very young vertebrates develop gill slits, and that’s a clue that we’re all descended from fish and that our ancestors lived in water. But how do you know which bits of the DNA produce the gill slits, allowing us to infer an aquatic ancestor? And how do you know whether the ancestor lived in fresh or salt water? We carry genes from extinct and unknown ancestors that lived in unknown environments; what way can we reconstruct those ancestors and their environments from just a DNA sequence? I’d ask for an example.

In fact, the fossil record combined with a good phylogeny can answer such questions, but I am doubtful about sequencing DNA as a way to infer the environmental forces that impinged on an organism’s ancestors. Dawkins describes DNA as a palimpsest, as it is, but when a document is overwritten millions of times, you lose a lot of the past information.

These are some of the things that I would have preferred to ask Richard about instead of his supposed “transphobia” and “polemic style.” In fact, I’d love to have this as part of a public conversation onstage, which I’ve had the honor of having with Dawkins several times. But I’ll wait until the book comes out, as I anticipate it with keen interest. And my construal of its contents above is purely speculative, as I know nothing about this upcoming book.

h/t: Daniel

Was Ernst Mayr a eugenicist?

July 13, 2022 • 1:30 pm

A while back the Society of Systematic Biologists (SSB) had second thoughts about the name of its Ernst Mayr Award, a prize given to the best student paper presented at the SSB’s annual meeting. (Mayr, one of my scientific heroes, also endowed that award and left a sum in his will to keep funding it.) If you look at the rationale for the proposed de-naming of the award, given at the link above, you’ll find there were two reasons proposed by the SSB Council for this:

Many current members do not see themselves reflected in awards that bear the names of these early scientists and can feel excluded as potential recipients as a result. In a field whose composition still does not reflect global human diversity, having an award named after a particular individual reinforces that members with other identities are outsiders.

In other words, Mayr was an old white man and its name could make people feel unsafe. I have strong doubts about whether this is true, although perhaps a tiny handful of individuals could object on those grounds, but they would surely be outweighed by the proud recipients of the “Ernst Mayr Award”, who could put it on their c.v.s. Many of these would be people of color.. The other reason was this:

This proposal is not intended to cast judgement on the legacy of Ernst Mayr, who was a prolific and profound scholar of evolutionary biology and a dedicated champion of students, nor are we intending to defend the contents of his writings which some find problematic.

Yes, Mayr was one of the greats, a man who in fact helped found and fund the SSB. And the proposal doesn’t even mention which writings people found “problematic”. I wasn’t aware of any, and I read a lot of Mayr, but of course I didn’t know about his correspondence or other personal issues. I know that he wrote a lot of antiracist stuff, some of which you’ll see here and some of which you can see at this link.

At any rate, thanks to the intercession of Ceiling Cat, the SSB membership narrowly voted down the deplatforming of Mayr.  It was a squeaker, though, as most of the SSB voted to remove the name. Fortunately, it takes a 2/3 vote to do so. From the SSB’s announcement:

After much deliberation, the Council approved sending the constitutional amendment to the membership for their vote. Under our constitution, all amendments require approval by two-thirds of the voting members. While 63.4% of the voting members favored the change, this is short of the 66.7% required for the amendment to be adopted. Thus, the award will continue to be called the “Ernst Mayr Award in Systematic Biology”.

That was a victory for rationality, especially because the reasons for the renaming were either unclear or unspecified, and I suspect that most of the “rename” votes were by people who didn’t know much about Mayr.

Since I wrote my posts on this, one reader informed me that a letter existed from Mayr to his friend Francis Crick, a letter in which Mayr apparently espoused some pro-eugenic views. This letter, written in 1971, can be found in the NIH collection here, and a better version, a pdf, is here.

And indeed, Mayr does show himself in favor of what he calls “positive eugenics”, but eugenics based not on race but on rewarded breeding for “positive traits”, or, alternatively, as one correspondent interpreted it, on eliminating genetic defects that could be somehow rectified. But it is absolutely clear in Mayr’s views, and in this paper he wrote, is that his views had absolutely nothing to do with race (Mayr was an anti-racist), and that he thought in terms of incentives for individuals possessing more “desired” traits to have more children. He absolutely abjured the racist views of Shockley and others. Here’s are excerpts from his 1971 letter to Crick, but I urge you to read it for yourself

I have been favoring positive eugenics as far back as I can remember. As I get older, I find the objective as important as ever, but I appreciate also increasingly how difficult it is to achieve this goal, particularly in a democratic western society. Even if we could solve all the biological problems, and they are formidable, there still remains the problem of coping☂with the demand for “freedom of reproduction,” a freedom which fortunately will have to be abolished anyhow if we are not drown in human bodies. The time will come, and perhaps sooner than we think, when parents will have to take out a license to produce a child. No one seems to question that it requires a license for such a harmless activity as driving a car, and yet such an important activity as influencing the gene pool of the next generation can be carried out unlicensed. A biologist will understand the logic of this argument, but how many non-biologists would? Obviously, then, we need massive education. Such education is going to be – paralyzed at the very start if it gets mixed up with racist and anti-racist arguments. This is why the Academy has to disassociate itself from Shockley’s arguments. JI have heard him argue by the hour, and it is very obvious that he treats human beings like so many sodium atoms or pi mesons. Population differences for him are real, the differences between individuals, however, are errors of sampling that can be ignored by focusing on mean values. I will not claim that Shockley does not somewhere know that his approach is wrong, because he must realize that even differences between individuals have a significant genetic basis. What is crucial, however, is that he seems to ignore these individual differences in his conclusions and generalizations.

Now as to positive action! The most important thing at this time/to stop talking about “The White” and “The Black.” As long as we use this language, we will produce only heat but no light. We must think in terms of adopting a strategy that will permit meaningful research without offending people’s sensitivities and without coming too aggressively in conflict with popular prejudices. Please do not forget that thinking in anthropology in this country was shaped by Boas (and his various disciples) and in psychology by the behaviorist school. Both schools magnify the importance of the environment and hardly mention or even deny the role of inheritance. The American school of psychoanalysis, likewise, denied any importance of inheritance, even in such clearly genetic conditions as schizophrenia. This must be kept in mind when one is thinking about strategies to be adopted for the initiation of meaningful eugenic research. A bull-in-the-china-shop attitude, like that of Shockley, will result only in the erection of impassable roadblocks. What is equally deplorable is the action of certain geneticists who imply, by overemphasizing the environmental uncertainties, that the genetic factors can be ignored as far as human abilities are concerned. But this is not the place to discuss this any further.

The question, then, is what Mayr meant by “positive eugenics”.  Did he want to encourage breeding of individuals to, say, raise the IQ of human populations, or was he trying to encourage people to breed who were free of genetic defects like schizophrenia? (We do some of the latter already, by either choosing embryos free from specific genetic diseases or telling parents early in pregnancy and allowing them to abort the fetus.)

I’ve had answers from colleagues on both sides. For example, one colleague interpreted Mayr as holding the former view: breeding of the best classes. I quote:

Yes this is par for the course for mid-century intellectuals. Very tiresome. Crick’s eugenics was undigested Galton.: very English and Edwardian, and based on class. Crick, for instance, supported Shockley’s right to spout his garbage along with many others. From the 1970s onwards, Crick learned to keep his opinions to himself. And don’t forget that Linus Pauling himself wanted people to be tattooed with their genetic defects so people would avoid having sex with them!
The key point is that [Mayr’s thinking] reveals how bad these people were about thinking through things they had learned as kids. Both just repeated garbage from the 1920s, which was very disappointing.
Another colleague plumped for the second alternative:

One problem is that the words “positive eugenics” have changed in meaning over time. People now associate those words with encouraging “genetically advantaged” people to have children. What Mayr meant by “positive eugenics” would now be called “gene therapy”: using molecular techniques to cure genetic diseases. He also considered other future technologies (in his time)  like in vitro fertilization to be a type of “positive eugenics”. Those are the two examples that he gave in discussing the future and potential uses and dangers of “positive eugenics.”

Even in this letter, Mayr is very careful to note the dangers associated with racism, and is very clearly an anti-racist.
It is not fair to damn Mayr for using a word in a reasonable, but different, way than people now use it. Now no one would use the word “eugenics” to talk about the things that Mayr was discussing, like gene therapy and in vitro fertilization. In vitro fertilization is now widely used and accepted. Gene therapy is more controversial and still in development, but there are lots of people who would happily use it to cure their genetic disease if they could.
The question, then, is whether Mayr really is using the words “positive eugenics” to mean “gene therapy” rather than “selective breeding of the best and the brightest.” If you read this paper from 1967, you see the antiracism, but also a sense that Mayr thinks that the human species could be improved by specified differential reproduction. But he’s also very pessimistic, saying that we know very little about the genetics of human traits and that nothing could be done for many generations.

Well, now that we have whole-genome sequencing and the construction of Genome Wide Association Studies (GWAS), we could indeed begin to do incentivized selection by rewarding people with traits that society wants to change: we just give bonuses to people with, say, high career achievement if they have more children. That would work given the estimates of heritability for such traits given by people like Kathryn Harden.

Would it work? Almost certainly, for most human traits have substantial heritability with a measured populations (Harden’s statistics come from whites), and if there is heritability, then there will nearly always be a response to selection.

Should we do this? HELL NO!  Getting the government or biologists involved in trying to make humanity move in a certain direction by choosing which traits are “best”, and then rewarding people that have those traits for producing more kids seems deeply unethical.  Who decides? Wouldn’t people object? And of course it would have to be implemented on a worldwide scale if you wanted to change our species. Besides, we are doing fine as we are and, I think, are not being dragged down by “bad genes”. Cultural changes are far better and faster at improving humanity, and far less invidious, than effecting genetic change. Plus this kind of incentivized breeding is extra odious because it would increase inequality among people.

But relevant to this topic, did Mayr espouse the “selective breeding” form of eugenics? I think you can say that he did in places, though you cannot say that he supported a bigoted form of eugenics that labeled ethnic groups as inferior, or wanted to impede people’s reproduction. And at any rate he never did anything about it.  To say that “eugenics” = “Nazi” is simply a boorish, tendentious, and unnuanced way to address a historical controversy, one that continues today with discussions about gene therapy and selective abortion.

So yes, you can find at least this letter as “slightly problematic”. Is that enough to remove Mayr’s name from an award? Not in my view, not unless you want to remove Crick’s and Pauling’s names from awards, and basically deplatform every biologist who was working before, say, 1950. Is anyone’s closet free from skeletons?

Indeed, it’s hard to think of any biologist of earlier generations who didn’t have views that many of us, including me, reject in our day. But given Mayr’s immense positive contributions, both to biology and to antiracism, I don’t see one letter, or even several and a paper, as sufficient to efface his name from an award. I’ve always thought that a name should be kept if it’s there to honor the positive achievements of a person, and also if that person’s existence was a plus for humanity. Surely Mayr qualifies on both counts.

Here’s Ernst in New Guinea as a young white biologist, before he became an old white biologist:

How Darwin caused global warming with his theory of sexual selection

July 9, 2022 • 12:00 pm

Yet another letter has appeared in the Guardian about Stephen Buranyi’s misleading “long read” on the site, “Do we need a new theory of evolution?” (Buranyi says “yes”). I’ve mentioned the problems with Buranyi’s article before, and three of us even wrote a letter about the article’s flaws that the Guardian published.

Apparently, though, the fracas hasn’t died down, because another one just appeared, this time on sexual selection. The letter is by anthropologist Heather Remoff, who wrote a book on sexual selection mentioned at the bottom of her letter.

Here’s the letter (click to go to the Guardian site), and my take on it is below:

There’s a lot to “unpack” here, and I’ll try to be brief.

First, the letter doesn’t address Burayni’s claims, which was that the modern theory of evolution was incomplete and perhaps obsolete. He was not referring to Darwin’s theory of evolution but to Darwin’s theory as it has been updated and expanded in light of modern research. Darwin’s failure to understand everything does not mean that the modern theory of evolution is woefully lacking, for we’ve had more than a century and a half of work on evolution since The Origin.

Ergo, showing that Darwin’s theory of sexual selection was incomplete—and yes, it was his theory, rejected even by A. R. Wallace (except in humans!)—does not support Buranyi’s thesis. That theory was published in 1871, and now it’s 150 years on. Modern evolutionary biology has added tons of knowledge and theory about sexual selection. There are entire books on the topic (here’s one) that go far beyond Darwin’s ideas. But showing that “Darwin’s theory was incomplete” doesn’t say anything about the modern theory of evolution, which is what this whole controversy is about.

Darwin actually had two theories of sexual selection, one involving male-male combat for females, and the other involving female preference for “beauty”. The former theory, which Darwin called the “law of combat”, explains the evolution of weapons like antlers in male deer—weapons far less developed in females because they’re not used.  Darwin’s second theory is that females have an aesthetic sense that males appeal to with ornaments, striking colors, extreme behaviors, or lovely calls. This causes female-imposed natural selection on males, which, thought Darwin, explains sexual dimorphism in appearance, behavior, calls, and so on.

Note first that, contra Remoff, female preference was already a crucial part of Darwin’s theory, for without that preference we wouldn’t have the striking sexual dimorphism we see in many animals. Even though male-male competition remains an important explanation for male-limited weapons or competitive behaviors, Darwin had already diagnosed a large portion of the sexually dimorphic world using the lens of female preference.

But Darwin’s theory was incomplete in a way Remoff fails to mention. Exactly why do males compete for females? Darwin had no answer, and you don’t find an answer simply by viewing the issue through the female lens. In general, biologists agree that sexual selection results from this:  female investment in offspring is often much larger than that of males. When females have to do the hard work of gestation and rearing of offspring, as well as contributing metabolically expensive large gametes (eggs), while male investment is often limited only to a small amount of tiny sperm, an asymmetry in the interests of the sexes arises. Evolutionarily, males can leave more of their genes by copulating with any female they can, while it pays for females to be choosy about her mates, since once she mates, she’s made a huge investment that has to be tended. A good choice by a female often means her offspring have a better change of surviving, ergo it pays to be picky.  A male fly can mate with 20 females in a few days and have 20 batches of offspring, but a female fly who mates with 20 males within a few days doesn’t have many more offspring than if she copulated only once. It thus pays the males to be profligate and the females to be choosy.

I often use this example in evolution class to show the asymmetry (see this page for the records). This is what your body is capable of producing if you’re a woman or a man:

Record number of children produced by one mother: 69 (many twins and triplets birthed by a Russian woman)

Record number of children produced by one father: 1000-2000 by Genghis Khan (estimated) or, in more modern times, over 868 fathered by Moulay Ismail Ibn Sharif, a Sultan of Morocco, in the 18th century.

A male can have more than ten times as many offspring over his life than can a woman! Of course the average number of offspring has to be the same for men and women (after all, each child has one mother and one father), but the variation is such that while women produce relatively comparable numbers of offspring, a lot of males produce just a few and a few males produce many. That is, males have a much higher variance in offspring number. And that is the basis for sexual selection. (This difference in variance is seen in humans as well as in many other species.)

The asymmetry between the sexes, then, rests on the best way to choose. For males it’s not evolutionarily “wise” to be choosy (I am generalizing here, for of course there are cases in which males should also be choosy), while for female it pays to make sure you choose well, as you don’t have as many shots as being a parent. As I said, this is a short explanation for sexual selection that has exceptions, but it’s the going explanation for why, when the sexes differ in ornamentation, behavior, or calls, it is males who show elaborated traits.

This asymmetry is critical in understanding the whole process of sexual selection, and it rests not on seeing it through a female lens, but seeing it through a lens that looks at what both sexes have to gain from behaving in various ways. In the end, it’s largely based on gamete size. That was what Darwin missed, but we understand it now and can test it.

Further, since Darwin’s time we have new theories of sexual selection that have been mathematically elaborated: the runaway model (Richard Prum has used this to update Darwin’s “beauty” hypothesis), the “honest signalling” model, the “sexy son” hypothesis, and so on. Some of these models overlap.  All of them consider female preference.

Now I’ve said in the past that, in my view, one of the contributions of the “female view” of biology has been an increased emphasis on female choice in sexual selection, for the process involves an interaction between males and females. Some women (but not solely women) helped direct research by emphasizing female preference. And that’s understandable; you don’t want your sex and its importance in evolution to be overlooked.

That said, though, both men and women have made important contributions to the modern theory of sexual selection; it was not incomplete because the “female lens” was totally overlooked by patriarchal male biologists. And, as I said, female behavior—aesthetic preference—was absolutely critical for the “beauty” aspect of Darwin’s original theory.

As for the “genetic breakthoughs” that have led to a new understanding of sexual selection, particularly when viewed through that female lens, I am stymied. I don’t know what breakthroughs Remoff is talking about. Perhaps she’s referring to this:

The evolutionary moonshot that enabled Homo sapiens to go where other species have failed to follow has its roots in a reproductive mutation – concealed ovulation and continuous sexual receptivity – that dramatically increased the strategic agency employed by females.

Concealed ovulation and continuous sexual receptivity (the latter is possessed by many animals) are not “mutations”; they are traits, likely ones that arose via many mutations of small effect. And yes, these traits have obviously changed the playing field for sexual selection. But whether they have been  “moonshot” that has enabled us to go where other species have not, well, other species have had their own “moonshots”, like hypodermic insemination in some invertebrates, the “pseudopenis” of the female hyena,”and the male pouches of pipefish and seahorses.

The last trait gives male seahorses most of the investment in offspring (males, in effect, get “pregnant”, and females, who can produce lots of eggs, must compete for limited male pouch space). The result that in this group it’s most often females rather than males who are ornamented. This reversal of investment, coupled with a reversal of the sexual dimorphism, is striking support for the “differential investment” theory of sexual selection.

Sexual selection operates in different ways in different species, and, truth be told, we don’t understand the details that have led to the evolution of most sexually dimorphic traits. not involved in male-male competition. We know the basis for the evolutionary process—differential investment in offspring—but we don’t know why particular traits are chosen and whether they are indicators of fitness or of something else. If you ask me why the peacock has a long tail instead of a big head crest, and what information that elaborate tail conveys to females, I wouldn’t be able to tell you. We do know that the more spots a male peacock has on his tail, the more likely he is to be chosen as a mate, but we don’t know the advantage accruing to females that have such a preference.

And no, sexual selection does not “establish the origins of everything that defines human exceptionalism”. Semantic language? Bipedality and manual dexterity? Our remarkably complex brain? Did all those traits rest on sexual selection? I think not.

Remoff ends with a paragraph that is pure hyperbole:

Why does all this matter? Because humans are facing an environmental disaster of our own making. Only by developing an accurate understanding of the factors that shaped human species-specific behaviour will we be able to avert the rapidly approaching climate apocalypse. Sexual selection may have shaped us, but our failure to take an unbiased look at ourselves could be handing natural selection the power to eliminate us.

Will understanding sexual selection, or human evolution in general, help us stave off climate change? Again I think not. Only by limiting carbon emissions will we be able to avert climate change. And that does not depend on understanding human evolution, much less sexual selection.

In the end, Remoff is tilting at two windmills that have already fallen. Her attack on Darwin is wrongheaded since Darwin’s correctness is not the issue in Buranyi’s piece and because female preference was already a crucial part of Darwin’s theory. And her claim that it was only the “female lens”, used recently, that helped us understand sexual selection, is also misleading. Female preference has been considered by evolutionists since 1871.