Category: human biology

Angela Saini misrepresents Galton kerfuffle at University College London; fails to see the beam in her own eye

March 15, 2020 • 10:30 am

Angela Saini is a British science writer who has two degrees: in Engineering from the University of Oxford and in Science and Security from King’s College London. She’s written three books:

Although I haven’t read any of these in full, I’ve read several of her essays and watched several of her videos, as well as having read criticism of her latest book, which is largely an indictment of science for trafficking in racism, some of it unrecognized. More about that in a minute.

Last week Saini wrote a one-page “World view” piece in Nature that I want to discuss and criticize. Click on screenshot below; or get a pdf here

Most of the article deals with a recent controversy in which a committee of employees, students, and staff from University of College London (UCL) investigated whether the name of Francis Galton, a famous statistician, biologist, and polymath, should be removed from UCL buildings and endowments. Why? Because Galton was an advocate of eugenics, and helped set up commissions, journals, and organizations to study it.

Although none of Galton’s work ever resulted in any eugenic activities involving breeding or prevention of breeding, or the creation of British laws or government policies, his advocacy of eugenics is  deemed sufficiently repugnant to warrant the creation of a UCL commission of inquiry whose task was to deal with how to erase Galton’s history. Most of the people on the commission weren’t scientists (there were a few), and there were a lot of people from diversity offices and the social sciences. Given that, the outcome was preordained.

I have a copy of the long report (ask and ye shall receive), which basically recommends that everything with the name of “Galton” on it be renamed. Further, there are recommendations that the University apologize (though it’s not clear to whom), and that everybody in UCL be given mandatory instruction about this shameful episode in the University’s history.

Saini makes two claims in her Nature piece.  First, that the reexamination of Galton’s history was prompted by “humanities scholars” rather than by the university’s biologists.  As we’ll see in a subsequent post, this claim is flatly wrong: UCL’s biologists have been teaching about Galton’s eugenic views for decades. Yes, humanities scholars were on the committee that decided to censor everything Galton did out of UCL history, but Saini’s claim below (in bold) is incorrect and disingenuous:

When a survey conducted as part of the UCL inquiry asked staff and students whether “we should separate science and politics”, it found agreement among higher percentages of those in the sciences and engineering than in the social sciences and history. In my coverage of the inquiry, I’ve seen that it was not the university’s biologists, but its humanities scholars — including curator Subhadra Das and historian Joe Cain — who forced their workplace to confront a sordid history that some geneticists had been willing to overlook.

There will be more on this as many UCL geneticists, including ones we’d consider liberal or woke, are taking violent exceptions to Saini’s claim above, as well as to the “erasure” of Galton that the committee recommended. When they speak out publicly, I’ll then write another piece.

As far as the “separation of science and politics” are concerned, that leads us to the second issue: Saini’s arrogant claim that we should all admit that we are not objective, even when we deal with science. All, that is, EXCEPT FOR SAINI, who apparently does not include herself in the list of “non-objective people.” Have a gander:

Scientists who imagine that bias lies in others, not themselves, fail to recognize that to live in the world today is to be drip-fed assumptions and prejudices that guide our thoughts and actions. If it were any other way, the demographics of academia would be more equitable, and the current strain of genetic determinism in governments wouldn’t be possible.

. . . Scientists rarely interrogate the histories even of their own disciplines. When I studied engineering at university, I was expected to write just one essay on ethics in four years. No wonder that new technologies perpetuate racial and gender stereotypes, or that automated facial recognition struggles to identify people with darker skin.

The best research is done not when we pretend that we are perfectly objective, but when we acknowledge that we are not. The UCL inquiry report recommends that students and staff be exposed to the history of eugenics, and that students be encouraged to value the history of their own fields. I would go further. Scientists need both history and the social sciences to develop the intellectual tools to think critically about their research and

What’s most curious about Saini’s self-exemption from The Biased is that she’s clearly biased: she’s uses Critical Race Theory in her analyses, is pretty much of a blank slater, and, from what I read in reviews (including direct quotes), and from what I’ve seen in her YouTube talks and interviews (e.g., here), she denies any usefulness of the term “race” (I avoid the term, too, but human populations are structured in biologically meaningful ways), and, most important, appears to have distorted and cherry-picked the biological literature on human differentiation to make the ideological point that differentiation isn’t particularly meaningful.  Further, she appears to have the attitude that finding any difference between races, whether physiological or, especially, psychological, would somehow buttress racism.

I’ve argued against that latter view repeatedly, saying that regardless what science shows—and I can’t deny that many scientists were biased and propped up racism with specious arguments—our moral view on the equality of people should not be based on biological facts. If that were the case, and you make Saini’s argument that we really are biologically equal in the most important ways, and that such a finding dispels racism, then you become liable to future studies that might show biological inequalities between groups. And that would then prop up racism. Moral equality should be a philosophical, not a biological argument, but Saini appears to believe (or at least behave) otherwise.

I’ve read several reviews of Saini’s latest book, and found the one below the most cogent and reasonable. Yes, it’s in Quillette, and I do take issue with a few of its clams, but it seems quite even-tempered and rational on how we should regard genetic differentiation in humans.  (I note that both authors were dismissed from their jobs for their work on race, yet I can’t see any grounds for dismissal from this review, at least.)

The long piece below pretty much damns Saini’s book, using direct quotes. Click on the screenshot to read it:

As I said, I take issue with a few of the authors’ claims. I haven’t read The Bell Curve, so I can’t speak to their argument that many scholars signed a petition defending the book. And I was pretty critical of Nicholas Wade’s book on race, “A Troublesome Inheritance,” which Winegard and Carl think was “unfairly condemned” (see my posts here and here.) But other claims, like Saini’s misunderstanding the “Lewontin Fallacy” committed by my Ph.D. advisor in defense of the genetic equality of races, are accurate, and make one realize how tendentious Saini’s claims really are. (Lewontin, god bless him, was also tendentious and wrong on several issues.)

It’s a long review and I’ll give only one quote.  This is about using science to prop up morality.

Finally, by far the most prominent fallacy in Superior, one which lies at the very heart of Saini’s book, is the fallacy of equating any claim that genes might contribute to population differences on non-“superficial” traits with racism. (For the sake of brevity, we shall refer to this as ‘the fallacy of equating hereditarian claims with racism.’) Indeed, this fallacy encompasses the third and fourth of the theses that we laid out in the introduction.

By way of illustration, Saini employs the terms “scientific racism” or “scientific racist” 17 times in the book, and she employs the terms “intellectual racism” or “intellectual racist” an additional 11 times. In Chapter 1 she describes the supposition that population groups “may have evolved into modern human beings in different ways” as “unconscionable.” And in Chapter 6, when discussing the work of famed geneticist Luigi Cavalli-Sforza, she writes, “as he saw it, racism was just a scientific idea that turned out to be incorrect.”

Before proceeding, we should be clear about what we are not saying. First, we are not denying that research into the genetics of human differences has been misused for appalling purposes at various points over the last two centuries. Second, we are not denying that some of the scientists who have undertaken such research were motivated by racial animus or by a desire to subjugate other people. Hence we understand the temptation to assume the worst about anyone who might be willing to entertain what we have called ‘hereditarian claims.’ Nonetheless, equating hereditarian claims with racism is a fallacy, and one that we believe is likely to end up doing more harm than good.

As Steven Pinker argued at length in his book The Blank Slate, those who equate testable scientific claims with various ‘isms’ (sexism, racism, fascism, etc.) are effectively holding our morals hostage to the facts. By using the word ‘racist’ to describe a claim such as ‘genes may contribute to psychological differences between human populations,’ they are implying that:

  • The claim must be false; but also that
  • If the claim were ever shown to be true, then racism would be “scientifically correct.”

Yet as Pinker notes, this is a complete non-sequitur:

I hope that once this line of reasoning is laid out, it will immediately set off alarm bells. We should not concede that any foreseeable discovery about humans could have such horrible implications. The problem is not with the possibility that people might differ from one another, which is a factual question that could turn out one way or the other. The problem is with the line of reasoning that says that if people do turn out to be different, then discrimination, oppression, or genocide would be OK after all.

The argument that we should not hold our morals hostage to the facts has been made over and over again by scholars interested in the genetics of human differences. As far back as the 1960s, one of the 20th century’s leading biologists, Ernst Mayr, said the following:

Equality in spite of evident non-identity is a somewhat sophisticated concept and requires a moral stature of which many individuals seem to be incapable. They rather deny human variability and equate equality with identity […] An ideology based on such obviously wrong premises can only lead to disaster. Its championship of human equality is based on a claim of identity. As soon as it is proved that the latter does not exist, the support of equality is likewise lost.

The market for woke books is huge, and you won’t get anywhere claiming that scientists should be studying genetic differentiation between sexes and races because it’s interesting (one must of course always be sensitive to how people feel about this). Ergo you can get away, as Saini has, with being deeply tendentious. A parallel is Cordelia Fine, whose books on gender always are supercritical of studies showing differences between males and females, but go easy on studies that claim the opposite (see my posts on her work here and here).

In view of Saini’s own ideological biases and tendentious treatment of the literature, it’s ironic that she chastises scientists for not recognizing their biases, while completely failing to recognize—or at least mention—her own. Or is she the only writer completely free of bias?. I have ordered her book and will read it, but I already discern from her essays and interviews, as well as excerpts from Inferior, that she is no less ideological than the so-called “nonobjective” scientists she criticizes.  The parable about motes and beams in one’s eye applies.

h/t: William L.

Vestigial limb muscles in human embryos show common ancestry—for the gazillionth time

October 6, 2019 • 9:00 am

There are three kinds of vestiges that constitute evidence for evolution, or rather its sub-claim that modern species share common ancestors. I discuss all three in Why Evolution is True:

1.) Vestigial traits that persist in modern species but either have no adaptive function in a species or a function different from the one served in that species’ ancestors. The vestigial ear muscles of humans are one, the flippers of penguins (functional, but not for flying in the air) is another, and the coccyx in humans (sometimes with attached “tail muscles” that can’t move it) is a third.

2.) Vestigial genes that are functional in our relatives (and presumably in our ancestors) that have been inactivated in some modern species. There is no explanation for these “dead genes” save that they were useful in ancestors but aren’t useful any longer. Examples are “dead” genes that code for egg yolk proteins in humans (but don’t produce them); a dead gene for vitamin C synthesis in humans (we don’t make the vitamin because that gene is inactivated, but rather get it from our diet; and the many dead “olfactory receptor” genes in cetaceans (whales, dolphins, etc.)—genes that were active in their terrestrial ancestors but became inactivated because “smelling” underwater uses different genes and traits.

3.) Features in development that are transitory, and whose appearance makes sense only under the supposition that those features were present in common ancestors and persist in some descendants but not others. The lanugo (a transitory coat of hair in human embryos) is one.

Today’s paper, which just appeared in the journal Development, shows several other “transitory” evolution-attesting features. Diogo et al. show that human embryos develop muscles that disappear as development proceeds, but those muscles don’t disappear in some of our relatives, including closely related ones like other primates as well as distant relatives like reptiles.

Moreover, these muscles, which disappear in most human embryos, sometimes don’t disappear, persisting in adults as rare and nonfunctional variants. Or they appear in malformed individuals, with both phenomena often seen in “vestigial traits”. For example, some people are born without wisdom teeth, considered a vestigial holdover from our ancestors; and the functionality of human vestigial ear muscles that move the ears in our relatives, like cats and dogs, is variable: some people like me are able to move those muscles and wiggle their ears, while others can’t.

Click on the screenshot below to access the paper, and the pdf is here (reference at the bottom of this post).

The authors visualized the muscles in the embryonic arm and leg by doing immunostaining—using antibodies that would affix to proteins in the muscles and also carried ancillary molecules that would make those muscles more easily visualized under the microscope in a three-dimensional way. The authors used 70 antibodies, but the main ones bound to muscle-specific proteins like myosin and myogenin.

They stained the mounted limb sections of 13 embryos (presumably from abortions) ranging from nine to thirteen weeks after gestation (quantified as “gestational weeks”, or GWs), and with the standard measurement “crown-rump length” (CR) ranging from 2.5 cm to 8.0 cm (about 1 to 3 inches). These were thus very small embryos, but the sophistication of the technique, and the efficacy of the stain, combined with our knowledge of embryonic development and tetrapod muscle anatomy, enabled the authors to produce pictures like these: the muscles in the hands of a 10 and 11-GW fetus:

 

What they found is that human embryos show a number of muscles present in the adults of some other tetrapods (including our closest relatives, the chimps), but that disappear during human development, with a few of these “atavistic muscles” fusing with other muscles in human fetuses although remaining distinct in our tetrapod relatives.

Here’s how the authors describe the main results, listing some of the atavistic muscles in the embryos (I’ve put them in bold):

As summarized in Tables 2-5 and also noted above, various atavistic muscles that were present in the normal phenotype of our ancestors are present as the normal phenotype during early human ontogenetic stages and then disappear or become reduced and completely fused with other muscles, thus not being present/distinguishable in human adults. These include the upper limb muscles epitrochleoanconeus (Fig. 3), dorsoepitrochlearis, contrahentes 3-5 (Fig. 4) and dorsometacarpales 1-4 (Figs 3-5), and the lower limb muscles contrahentes 3-5, dorsometatarsales 1-4 (Fig. 6) and opponens digiti minimi (Fig. 6). These muscles are present in some other tetrapods, as shown in Tables 6 and 7, which summarize the comparisons with other limbed vertebrates. Of all these muscles, only the dorsometacarpales often remain in adults, fused with other muscles: all the others are normally completely absent in human adults. Fascinatingly, all these atavistic muscles are found both as rare variations of the normal adult population and as anomalies in individuals with congenital malformations such as those associated with trisomies 13, 18 and 21, reinforcing the idea that such variations and anomalies can be related to delayed or arrested development.

Here are two of the fetal atavistic muscles. First, the dorsometacarpales in the hand, which are present in modern adult amphibians and reptiles but absent in adult mammals. The transitory presence of these muscles in human embryos is an evolutionary remnant of the time we diverged from our common ancestor with the reptiles: about 300 million years ago. Clearly, the genetic information for making this muscle is still in the human genome, but since the muscle is not needed in adult humans (when it appears, as I note below, it seems to have no function), its development was suppressed:

 

Here’s a cool one, the jawbreaking “epitrochleoanconeus” muscle, which is present in chimpanzees but not in adult humans. It appears transitorily in our fetuses. Here’s a 2.5 cm (9 GW) embryo’s hand and forearm; the muscle is labeled “epi” in the diagram and I’ve circled it:

This muscle must have become nonfunctional, and reduced in development, over the last six million years or so, when the common ancestor of humans and chimps gave rise to our separate lineages.

An interesting sidelight of this study is that some of these vestigial muscles occur as rare variants in adult humans, either via developmental “accidents” or as part of congenital malformations. Presumably these screwups in development block the genetic changes that normally lead to the suppression and disappearance of muscles in embryos. Variable expression of vestigial traits is common in organisms where the traits haven’t evolved into something else that’s useful. (For more on human vestigial traits, see the Wikipedia article on “human vestigiality”). The authors note that when the muscles do appear in adults, they are “functionally neutral, not providing any type of major functional advantage or disadvantage.”

The presence of these vestigial muscles is pretty irrefutable evidence of evolution and common ancestry, for there’s no reason why either God or an Intelligent Designer (a pseudonym for “God” to ID advocates) would put a transitory muscle in a human fetus that’s of no use whatsoever, but just happens to resemble the fetal muscles that goes on to develop into adult muscles in our relatives.  I wonder how creationists, including IDers, will explain this as the work of a designer. Will they say the muscles are really functional in a fetus? If so, why do they disappear? And doesn’t the fact that they go on to develop into functional muscles in our relatives like chimps and reptiles say something about common ancestry?

Two more points:

1.) The order of appearance of these muscles in development doesn’t completely comport with their order of evolution. This shows that the “recapitulation theory”—that the order of development mimics the order of evolution—isn’t completely obeyed. But we’ve known that for a long time. The time of appearance of a trait in development can be changed by other factors, like its usefulness in “priming” the development of other features. But this doesn’t overturn the very strong conclusion that the presence of transitory muscles in the human fetus that remain in adults of our relatives is evidence for evolution.

2.) Finally, muscles in the arms and legs that appear “homologous” (i.e., have the same evolutionary origin) may have had independent evolutionary origins, and may involve different genes, so they’re not really “homologous” in the way evolutionists use that term. As the authors note,

These differences support the emerging idea that the topological similarities between the hand and foot of tetrapods, such as humans, are mainly secondary (see recent reviews by Diogo et al., 2013, 2018; Diogo and Molnar, 2014; Sears et al., 2015; Miyashita and Diogo, 2016). This idea is further supported by the fact that the order of developmental appearance of the hand muscles is markedly different from that of the corresponding foot muscles (Tables 6, 7). As an illustrative example, whereas the lumbricales are the first muscles to differentiate in the hand, together with the contrahentes (Table 6), in the foot the lumbricales differentiate only after most other foot muscles are already differentiated (Table 7). Thus, these developmental data and evidence from comparative anatomy and from the evolutionary history of human limb muscles (see Tables 6, 7) indicate that several of the muscles that seem to be topologically similar in the human upper and lower limbs actually appeared at different evolutionary times; appear in a markedly different ontogenetic order; derive from different primordia; and/or are formed by the fusion of different developmental units in each limb.

Now the authors didn’t do this study to demonstrate evolution; like most rational people, they accepted it long ago. Rather, their stated aim was to “build an atlas of human development comprising 3D images. . . that can be used by developmental biologists and comparative anatomists, as well as by professors, students, physicians/pathologists and the broader public.” But one of the bonuses, especially for the broader public, is the very clear demonstration of the common-ancestry tenet of modern evolutionary theory.

h/t: Liz

______________

Diogo, R., N. Siomava, and Y. Gitton. 2019. Development of human limb muscles based on whole-mount immunostaining and the links between ontogeny and evolution. Development 146: doi: 10.1242/dev.180349. Published 1 October 2019

“Modern” Homo sapiens may have been in Eurasia as long as 210,000 years ago

July 11, 2019 • 9:00 am

The conventional wisdom about the migration of Homo out of Africa, where the genus originated, involves the spread of Homo erectus about 2 million years ago across Eurasia, with that species appearing to have gone extinct without issue.

After that, the Neanderthals, which split from the lineage producing “modern” (i.e., living) H. sapiens about 800,000 years ago, moved to Europe some time between then and 600,000 years ago. (For convenience, I’ll call Neanderthals “Neanderthals” and “modern H. sapiens” as sapiens, though I think they’re both subspecies of H. sapiens.)

Then, it was thought, sapiens moved into Europe and then Asia beginning about 60,000 years ago, with Neanderthals becoming extinct around 40,000 years ago, though having left a genetic legacy within sapiens. (That ability to produce fertile hybrids between H. sapiens sapiens and H. sapiens neanderthalensis is why I consider both lineages to be subspecies of the same biological species).

There was, however, tantalizing evidence—as summarized in a Nature News & Views article (free with UnPaywall) about the paper discussed today—that two skulls found in Israel, dated between 500,000 and 200,000 years ago, might also been close to the “modern H. sapiens” lineage, but the evidence is fragmentary and these could actually be Neanderthals.

The figure below, from the News & Views piece, summarizes fossil finds of Homo from the Eastern hemisphere (see key at bottom of figure for species designation, and note the Neanderthals and Denisovans):

Figure 1 | Some key early fossils of Homo sapiens and related species in Africa and Eurasia. Harvati et al.5 present their analyses of two fossil skulls from Apidima Cave in Greece. They report that the fossil Apidima 1 is an H. sapiens specimen that is at least 210,000 years old, from a time when Neanderthals occupied many European sites. It is the earliest known example of H. sapiens in Europe, and is at least 160,000 years older than the next oldest H. sapiens fossils found in Europe (not shown). Harvati and colleagues confirm that, as previously reported, Apidima 2 is a Neanderthal specimen, and they estimate that it is at least 170,000 years old. The authors’ findings, along with other discoveries of which a selection is shown here, shed light on the timing and locations of early successful and failed dispersals out of Africa of hominins (modern humans and other human relatives, such as Neanderthals and Denisovans). kyr, thousand years old.

The Israeli fossil provided weak evidence that sapiens may have left Europe well before the conventional date of about 60,000 years, though these forays into Eurasia, at least judging from genetic evidence, didn’t give rise to humans living today.

Now a new article in Nature by Katerina Harvati et al. (click on screenshot below for free UnPaywall access, with pdf here and reference at bottom), suggests much more strongly that sapiens did indeed leave Africa for Eurasia much earlier than we thought: in fact, way earlier—about 210,000 years ago. That more than triples the time length of time since the first sapiens left Africa. Note, though, that the new find, even if it is sapiens (and there are doubts), is not ancestral to living modern humans; the population seems to have vanished without issue.

The paper is based on two skulls originally found in 1978 in a cave in Apidima in southern Greece, but were only now dated and thoroughly analyzed morphologically.

There were two skulls in the same place and piece of sedimentary rock, one dated at about 170,000 years ago (“Apidma 2”) and the other a bit older at 210,000 years (“Apidima 1”). Apidima 2 is represented by a pretty complete cranium, minus the jaw, while Apidima 1 is only the rear of the skull. The fossils are shown below, with Apidima 2 at top. Both are pretty badly banged up.

(All figure captions are from the Nature paper).

a–c, Apidima 2. a, Frontal view. b, Right lateral view. c, Left lateral view. d–f, Apidima 1. d, Posterior view. e, Lateral view. f, Superior view. Scale bar, 5 cm.

Because the skulls were so incomplete, their shapes had to be determined through reconstruction by computed tomography; and for Apidima 1, which has no face at all, the rear of the skull was reconstructed by making a mirror image of the better-preserved half. This fragmentary nature of Apidima 1 has to be kept in mind when assessing what it was.

The take-home lesson from the paper is that the dating and structural studies (done through uranium series analysis) shows that Apidima 2 falls well within Neanderthal types, but Apidima 1 shows features that lead the authors to conclude that it is indeed sapiens.  These sapiens features include a more rounded rear of the cranium as well as the lack of a characteristic Neanderthal trait, a bulge at the back of the skull like a bony hair bun. As the authors say, using morphological argot that you can skip (I’ve eliminated references in the paragraph below):

By contrast, Apidima 1 does not have Neanderthal features; its linear measurements fall mainly in the region of overlap between taxa. It lacks a Neanderthal-like rounded en bombe profile in posterior view. The widest part of the cranium is relatively low on the parietal; the parietal walls are nearly parallel and converge only slightly upwards, a plesiomorphic morphology that is common in Middle Pleistocene Homo. It does not show the occipital plane convexity and lambdoid flattening associated with Neanderthal occipital ‘chignons’. Rather, its midsagittal outline is rounded in lateral view, a feature that is considered derived for modern humans . The superior nuchal lines are weak with no external occipital protuberance. In contrast to some Middle Pleistocene specimens, the occipital bone is not steeply angled and lacks a thick occipital torus. A small, very faint, depression is found above the inion  Although suprainiac fossae are considered derived for Neanderthals, similar depressions occur among modern humans and in some African early H. sapiens. The Apidima 1 depression does not present the typical Neanderthal combination of features. It is far smaller and less marked even than the ‘incipient’ suprainiac fossae of MPE specimens from Swanscombe and Sima de los Huesos, and is closest in size to the small supranuchal depression of the Eliye Springs cranium, a Middle Pleistocene African (MPA). Apidima 1 therefore lacks derived Neanderthal morphology, and instead shows a combination of ancestral and derived modern human features.

The placement of Apidima 1 with sapiens and Apidima 2 with Neanderthals is shown in the following two graphs, where known fossils are grouped and identified with dots of various shapes. In the following, “modern” sapiens are blue triangles, Neanderthals are red stars, Middle Pleistocene Eurasians are yellow squares, and Middle Pleistocene Africans (presumably sapiens) are purple squares. The two axes represent various “principal components” that capture combinations of shapes and measurements that help distinguish specimens.

“Rec 1-4” are the reconstructions of Apidima 2. As you see, they fit pretty nicely within Neanderthals, or are closer to them than they are to sapiens (blue polygons). This is why Apidima 2 is considered a Neanderthal skull.

a, Analysis 1. PCA of Procrustes-superimposed facial landmarks, PC1 compared to PC2. H. sapiens, blue triangles (n = 19); Neanderthals, red stars (n = 6); MPE, yellow squares (n = 3); MPA, purple squares (n = 3). b, Analysis 2. PCA of Procrustes-superimposed neurocranial landmarks and semilandmarks, PC1 compared to PC2. H. sapiens (n = 25), Neanderthals (n = 8), MPE (n = 3), MPA (n = 5); Apidima reconstructions, black polygons, Apidima reconstruction mean configuration, black star. Wireframes below the plots illustrate facial and neurocranial shape changes along the PC1 of each analysis, respectively. Specimen abbreviations can be found in Supplementary Table 9. See Methods for detailed descriptions of analyses 1 and 2.

Here is Apidima 1, which is labeled as a diamond symbol in both left and right. As you see, it falls within the sapiens parameters and isn’t near the shape of Neanderthal skulls (red stars).

a, Analysis 3. PCA of Procrustes-superimposed neurocranial landmarks and semilandmarks, PC1 compared to PC2. H. sapiens (n = 23), Neanderthals (n = 6), MPE (n = 4), MPA (n = 5). b, Analysis 4. PCA of Procrustes-superimposed midsagittal landmarks and semilandmarks, PC1 compared to PC2. H. sapiens (n = 27), Neanderthals (n = 10), MPE (n = 5), MPA (n = 6).Wireframes below and next to the plots illustrate neurocranial and midsagittal shape changes along PC1 (analyses 3 and 4), and PC2 (analysis 4). c, Neurocranial shape index (analysis 3). Violins show the minimum–maximum range, boxes show the 25–75% quartiles and lines indicate the median. Modern Africans, green dots (n = 15); all other samples and symbols as in a and Fig. 2. See Methods for detailed descriptions of analyses 3 and 4.

Finally, here’s a different analysis that places both Apidima 1 (black triangle) and reconstructions of Apidima 2 (“Rec 1-4”) on one plot. Apidima 1 is close to “modern sapiens” (blue polygon(, but falls between it and early H. sapiens from Africa (purple polygon), demonstrating that, while sapiens-like, it wasn’t fully “modern” in its morphology.

Apidima 2 falls squarely within the ambit of Neanderthal skulls (red stars).

Analysis 5. PCA of Procrustes-superimposed neurocranial landmarks and semilandmarks shared between Apidima 1 and Apidima 2, PC1 compared to PC2. H. sapiens (n = 23), Neanderthals (n = 6), MPE (n = 4), MPA (n = 5). Wireframes below and next to the plot illustrate shape changes along PC1 and PC2. Symbols as in Fig. 2.

So there you have it: decent but not wholly convincing evidence that sapiens had already left Africa 210,000 years ago, and lived in the same period and place as Neanderthals. That’s a long time before we thought, and constitutes a dramatic revision of how we thought humans moved about in the last few thousand years.

A couple of questions remain:

How reliable is this conclusion? Well, I’m not a paleontologist, so I won’t put a definitive imprimatur on this diagnosis. In his News & Views piece, Eric Delsen notes that “Given that the Apidima 1 fossil and those from Misliya and Zuttiyeh (latter from Israel) are only partial skulls, some might argue that the specimens are too incomplete for their status as H. sapiens [JAC: they mean “modern H. sapiens”] to be certain. Delsen suggests that “paoleoproteomics”—sequence analysis of ancient proteins from the skulls—might help resolve this issue, even if DNA isn’t available.

Chris Stringer, one of the paper’s authors, issued a tweet that Matthew retweeted, praising it for its rigor and scrupulous honesty (Stringer says the reaction should be “a healthy skepticism”):

Did these early-emerging sapiens have contact with Neanderthals? Perhaps, though the dates of the two skulls are 40,000 years apart. But there is evidence for a long persistence of Neanderthals in Greece, so it’s likely that the two subspecies did coexist in the same general area. But if they mated with each other, there are no traces of that Neanderthal DNA in modern humans, which helps answer the next question:

If this fossil is indeed sapiens, what happened to the population? The authors suggest that the sapiens population simply died out without issue, and that’s supported by genetic data suggesting that all modern humans descend from an egress from Africa about 60,000 years ago. The Greek population may have simply gone extinct by attrition, or may have been wiped out by Neanderthals. Who knows? But if they died out without issue, as is likely, they are not our direct ancestors.

As Steve Gould used to say, when he taught human evolution every year he simply dumped his previous year’s teaching notes in the trash and wrote an entirely new lecture. That may have been an exaggeration, but shows how rapid the pace of understanding human evolution was. And still is! Given the paucity of finds in the genus Homo, there are many surprises to come.

_____________

Harvati, K., C. Röding, A. M. Bosman, F. A. Karakostis, R. Grün, C. Stringer, P. Karkanas, N. C. Thompson, V. Koutoulidis, L. A. Moulopoulos, V. G. Gorgoulis, and M. Kouloukoussa. 2019. Apidima Cave fossils provide earliest evidence of Homo sapiens in Eurasia. Nature, online.

You have mites on your face

May 22, 2019 • 11:30 am

As you sit there reading this, thousands of mites are living on your face, burrowed into the follicles of your facial hair and the pores around your eyes, nose, and mouth. As the NPR article below shows (click on second screenshot), every human is colonized by “eyelash mites”, members of the subphylum Chelicerata—yes, relatives of spiders and scorpions—in the species Demodex folliculorum. Here’s what they look like:

Source

Read more about them here, watch the video below, or do both (they give different information):

They pretty much rest head down within the pores from which hairs arise (several mites per pore), coming out at night to mate and eat the grease that your face exudes. Gross, eh?

But you don’t notice them, as they’re innocuous and rarely cause problems. Occasionally they will get out of control, usually when your immune system is suppressed for some reason. This causes a white sheen called “Demodex frost”, which looks like this (it’s a particularly bad case). But it can be treated.

Source

I find it interesting that this species, which is limited to Homo sapiens, is with us all of our lives, and does us no harm. I bet more than 95% of people don’t even know they have them. You’re not born with them; you acquire them from contact with others (most likely the mother) after you’ve exited the womb. And the good news is that they have no anus, so they don’t defecate on you. (They store their wastes for the duration of their short lives.)

Here’s a cool NPR video giving you more information about them. As expected, their low mobility means that they’ve become genetically differentiated among human populations, so you can tell where a mite came from by sequencing its DNA. It would be interesting to compare a phylogeny of human groups with that of their eyelash mites. If there is any “cross-group” movement, the phylogenies wouldn’t coincide.

Watch this, because these are on YOU!

How do we know that Neanderthals were nearly all right-handed?

October 25, 2018 • 12:00 pm

A while back I wrote about my visit to the Croatia Natural History Museum, where curator Dr. Davorka Radovčić kindly gave three of us a several-hour look at Neanderthal bones from the nearby location of Krapina, one of the most fruitful Neanderthal sites known. At the time I mentioned there was evidence that most Neanderthals were right-handed, but I didn’t really explain why. Now Davorka has sent me two papers (references and links below) that show how we know this. I’m going to write mostly about the Lozano et al. paper (free with the legal UnPaywall app), which tells the tale up to the present. If you can’t get either or both of these papers, email me and I’ll send them.

It is in fact true that about 90% of Neanderthals were right-handed, and that’s the same as present-day H. sapiens sapiens, even though Neanderthals aren’t really the ancestors of modern humans (we do, however, carry some of their genes). That probably means that the common ancestors of our two subspecies—I consider Neanderthals as H. sapiens neanderthalensis, a subspecies of H. sapiens—were also right handed. And indeed, chimpanzees (though not bonobos) are 49% right-handed and 29% left-handed, with 22% of individuals “ambiguous”.

But new data also shows that our ancient ancestors—before the split between modern H. sapiens and Neanderthals, were also right-handed. How did they do this?

It doesn’t come from looking at arm robustness in fossils, for that doesn’t work, nor does it come from looking at brains (as seen in crania), as that doesn’t work, either. It comes from looking at incision marks on the teeth made when a hominin is holding something in its mouth and cutting it—cutting it with the dominant hand. It looks like this (figures from the Lozano et al. paper:

 

Figure 1 [All captions from figures] Demonstration of how marks were likely made on the incisors and canines. A right‐hander pulls down with a stone tool, cutting through the object held between the anterior teeth. Occasionally, when the tool accidentally strikes the tooth’s surface, it leaves a permanent striation on the labial tooth face. Repetitive marking of the labial face allows for the assessment of which hand was used in this bimanual task
Sometimes you’ll hit your teeth with the cutting tool, and the striations (scratches) that this leaves on your teeth—in particular the incisors and canines, but especially the upper incisors—tell you what hand is doing the cutting. Try it!  Imagine you’re holding a piece of meat, or a skin, in your teeth and cutting it with your right hand (if you’re right handed, that’s what you’ll be doing). If you hit your teeth with the cutter (a sharpened stone), it will make a scratch from lower right to upper left, because the tool  will be oriented that way (hold a piece of paper in your mouth and pretend you’re cutting it). If you’re using your left hand, the cuts will be from lower left to upper right. And since you know where in the jaw the teeth are, you can determine handedness if there’s a consistent direction to the scratch marks.

Sometimes the marks will be horizontal or vertical, and sometimes they’ll be made not by humans but by taphonomic (preservation) forces, like sand scratches. You can deal with the latter by using marks only on the front edge, comparing them to those on the rear of the tooth, which should be subject to the same taphonomic modification. Also, you want not he percentage of teeth that show handedness, you want the percentage of individuals that show handedness. To deal with the first and last problem, the authors used these methods:

Thus, striations were separated into four orientation categories: horizontal (H: 0°–22.5°, 157.5°–180°), vertical (V: 67.5°–112.5°), right oblique (RO: >22.5°–<67.5°), and left oblique (LO: >112.5°–<157.5°). This underestimates the number of right or left handers; for example, an oblique mark of 21° would be classified as horizontal, so if the intervals were expanded the tooth being examined would have come from a right‐hander. However, since most studies have not published the raw data and have used the Bermúdez de Castro et al. intervals, we also used them.

Many of the teeth are isolated, especially in the Krapina sample. For this site we used Wolpoff’s reassembled tooth sets, each of which he labeled as a Krapina Dental Person (KDP). His tooth associations were based on similar morphology, occlusal wear, and interlocking interproximal facets, not on the presence of labial scratches. It is unlikely that any of the KDPs in our sample can be grouped together into a smaller number of individuals.

They also tested the “direction” hypothesis by making mouth guards that could be scratched, but also by looking at mouth guards with embedded teeth, as well looking at present day hunter-gatherers and Inuits. These showed directional striations consistent with observed handedness.

Finally, the authors analyzed several samples of hominin teeth: the total sample included five different types of humans (Homo habilis [OH 65, 1.8 million years old], Homo antecessor [from Gran Dolina, 860‐936 kya] the Sima de los Huesos fossils [430,000 years old probably ancestors of Neanderthals], European Neandertals, and modern Homo sapiens).

Here’s the earliest one, the OH-65 Homo habilis, 1.8 million years old. The graph below gives the directions of the scratches, and the predominance of the red bar (right oblique) over the blue bar (left oblique) shows that this individual was probably right handed:

OH‐65 shows a concentration of striations on the labial faces of the anterior teeth. These are visible to the naked eye. Microscopically, they conform to the striations found in much later hominids. The striations are mainly confined to the left and right I1s, the right I2, and right C1. Right oblique scratches predominate, leading to the identification of OH‐65 as a right‐hander. (n = number of striations per category) [Color figure can be viewed at wileyonlinelibrary.com]
The Gran Dolina H. antecessor individual didn’t have enough scratches to be identified but here’s the tooth of a right-hander from about 400,000 years ago (the Sima de los Huesos site):

Here are three Neanderthal teeth with the striations emphasized: the first is a left-hander and the other two right-handers based on the numerical predominance of directionally oblique scratches:

Here’s the final table that tabulates handedness. The earliest hominin was right handed, as were all 15 of the Sima de los Huesos individuals, suggested that by at least half a million years ago, right-handedness predominanted in hominins. The Neanderthals are the ones from Krapina down, and they show a 90% frequency of right-handedness, similar to humans today.

I should add that they also found directional scratches over old directional scratches (the enamel partly heals itself), so the directionality continued throughout the life of an individual, and they find directionality in teeth estimated to be from 10-year-old children as well. Since they didn’t have knives, I suspect much of this involved cutting meat, but also animal skins.

It looks as if since the hominin lineage branched from the lineage leading to chimps and bonobos, we’ve been largely right-handed: about 90%. It would be nice to have earlier fossil data, but this is pretty damn good.  I think the methodology, with its controls and observations of modern humans, is sound. The authors conclude:

We contend that the handedness data reviewed here shows that right‐handedness extends deep into the past of our species. The modern right‐handedness frequencies in earlier European human fossils from Sima de les Huesos and new specimens from the Early Pleistocene of China and Africa suggest that handedness stretches back well before the appearance of Homo sapiens. European Neandertals represent the biggest samples and continue this pattern, showing a right‐to‐left hand ratio identical to that among living Homo sapiens. In our view, the unique 9:1 ratio of right to left handers appears well before the emergence of modern Homo sapiens and is typical of our genus wherever and whenever it is found.

One question remains:

Why does there have to be a dominant hand? Why can’t humans (or those animals that show handedness) be equally dextrous with both hands?

This may be a byproduct of our brain structure (the authors posit that it’s a result of brain lateralization for language or other reasons), or there may be some other reason we don’t understand why one hand must predominate (and it can’t be random because most of us are righties, and there’s a genetic component to that). Who knows? But we do know that most of our ancestors were right-handed—at least according to these data and the data from the Fiore et al. paper.

____________

Lozano, M. et al. 2017. Right-handed fossil humans. Evol. Anthropol. 26: 313-324.

Fiore, I., L. Bondoli, J. Radovčić, and D. W. Frayer. 2015. Handedness in the Krapina Neandertals: A Re-Evaluation. PaleoAnthropology 2015:19-36.

Neanderthal bones in Croatia

October 18, 2018 • 9:30 am

Note: This has been slightly updated after I ran it by Davorka, who caught a few errors.

Over the years we’ve had a number of posts about Neanderthals and their genetic legacy in “modern humans” (see here for a collection), many of them written by Matthew Cobb. Croatia—in particular a hill near the small town of Krapina—is famous for its large collection of Neanderthal skeletons and relics, first discovered during quarrying in 1899. Because there were so many bones, this site afforded a unique look into a population of Neanderthals that lived about 130,000 years ago.

I reported a few days ago on my visit to the Neanderthal Museum in Krapina, which has nice dioramas of Neanderthal life, a cool movie (which, I’m told, was as accurate as possible given what we know about the subspecies), and casts of the bones.

But the bones themselves, and the Neanderthal relics, are carefully sequestered at the Croatia Natural History Museum, where they’re curated by Dr. Davorka Radovčić. My hosts here arranged for me and two of them to visit the Museum. There Dr. Radovčić spent several hours showing us the bones and artifacts, and explaining what they meant and what mysteries still remain (there are many). This required special permission from the Museum, and the visit was one of the high spots of my trip to Croatia. How often do you get to be a few inches away from Neanderthal skulls and teeth, and to hold a spearpoint chipped by one of them so long ago?

You can read more about the Krapina website here. As that article says (I’ve tweaked the English a bit):

. . . a total of 876 single fossil Neanderthal fossil remains were found, placing Krapina in the world”s scientific heritage as the world”s richest Neanderthal finding site.

The Krapina proto-human, scientifically known as Homo sapiens neanderthalensis was discovered in 1899, at the time of geological and panteological explorations at the Hušnjak hill in Krapina started. The excavations lasted for six years, supervised by Professor Dragutin Gorjanović-Kramberger, a famous Croatian geologist, paleonthologist and paleoanthropologost. His works contributed significantly to the European and world science about the fossil man. The half-cave in Krapina was soon listed among the world”s science localities as a rich fossil finding site, where the largest and richest collection of the Neanderthal man had ever been found.

In the sandy deposits of the cave about nine hundred remains of fossilised human bones were found – the fossil remains belonged to several dozen different individuals, of different sex, from 2 to 40 years of age. Numerous fossil remnants of the cave bear, wolf, moose, large deer, warm climate rhinoceros, wild cattle and many other animals were also found. Over a thousand pieces of various stone tools and weapons from the Paleolithic era were found, all witnessing to the material culture of the Krapina proto-human. This rich locality is approximately 130.000 years old.

And the site is here (the dots are other Neanderthal sites):

I’m going to show some of the bones and stones we saw, and explain as best I can remember what they mean.

The collection is stored in several locked metal cabinets, each containing wooden drawers with foam inserts holding the relics. Each drawer is labeled with its contents: “teeth”, “mandibles”, “patellas” (kneecaps), and so on. Here’s Davorka removing a drawer:

The first thing we saw were the crania (skulls), some of which were very well preserved. Notice the labeling of the drawer in the second photo:

This is a particularly interesting skull for a reason I’ll explain in a minute. It’s very well preserved but also has a feature unique among Neanderthal skulls known to science:

Davorka explains some of the features of the skull that set it apart from modern H. sapiens sapiens, and also identify it as a female skull:

You can see the prominent brow ridges and the upper part of the skull, which bears the cool feature:

This skull, of a young adult female (probably in her 20s or early 30s; you can tell the sex from the way the skull is shaped), has a series of 40 horizontal incisions made in the forehead at or soon after death (they aren’t healed). Their purpose isn’t known, but it seems likely it was involved with some kind of postmortem ritual, perhaps indicating a respect for the dead or even something associated with an idea of the afterlife. We simply don’t know, as Davorka emphasized. Below are two photos of the incisions and a brief video of Davorka explaining them:

 

Davorka explains the cuts in this video: they weren’t made to butcher or scalp the woman:

Neanderthal DNA is extracted from the middle ear capsule, as it is tough and well insulated from the environment. I erred in an earlier post in saying that DNA has been extracted from Krapina Neanderthals; Davorka tells me that Svante Pääbo and his colleagues extracted it from another Croatian Neanderthal site called Vindija.

We now know that Neanderthals interbred with “modern” humans (H. sapiens sapiens), and that the average non-African human carries about 3% of their genome from Neanderthals, including genes now used in the immune response. Although the offspring in at least one direction of the cross must have been fertile—for that’s the only way Neanderthal DNA could get into H. sapiens sapiens—we don’t know if offspring from both directions of the cross were fertile. For example, we haven’t found mitochondrial DNA from Neanderthals in modern humans. That could reflect either accidental loss of mitochondria, selection against mitochondrial DNA that did infiltrate modern human populations, or the sterility of offspring between Neanderthals mothers and H. sapiens sapiens fathers.

The middle ear capsule is at the upper left here, just above the red lettering that reads “88.11”. That’s the precious bit for paleogeneticists:

Mandibles! The teeth are relatively larger than ours, and the jaw has more space to accommodate all the molars, so the “wisdom teeth” are not crowded as they are in modern humans.

Two lower jaws (mandibles); note the rotation of one tooth in the left row of teeth:

The “rotated” tooth between the two white-ish ones. I can’t remember what the significance of this was, but I wrote to Davorka who said that some feel it’s due to genetic relationship and possibly inbreeding:

The scientists who worked on this concluded that they rotate due to “biological origin, an inherited condition common in the Krapina people. . . The sample is too small to for the observation to have significance, but we believe a hypothesis of biological relationship among the individuals found in Krapina levels 3 and 5 can be proposed to explain our results. Such a hypothesis is supported by the unusual superior deflection of the internasal suture in the only three Krapina specimens to preserve the suture” (Rougier et al. 2006; you can see the whole article in the book New insights on the Krapina Neandertals, pp. 43).

The jaw of a young (probably 6-7 year-old) Neanderthal, showing the deciduous teeth (“milk teeth”) and the three adult teeth that haven’t yet erupted. Neanderthals didn’t live very long: a 40-year-old individual was old:

Unfortunately, some of the mandibles were cleaned, removing the precious calculus (hardened plaque that the dentist scrapes off of your teeth at cleaning time). Davorka explains in the video how that cleaning caused the loss of precious biological information. Note the “retromolar space” giving ample room for all the molars.

Teeth, including a “shovel shaped” incisor, different from the shovel-shaped incisors found in Asian specimens of modern H. sapiens.

A well preserved molar:

A shovel-shaped incisor.

The wear patterns of these front teeth indicate that the Neanderthals held items in their teeth while processing them, like holding a skin in your mouth while scraping it with your hand. The position of the wear marks also shows that about 80% of Neanderthals were right-handed, scraping with their right arms while holding the item in the left side of their mouth. Isn’t that cool? In fact, this is about the same proportion of right-handers in Croatia today:

Arm bones. A drawer full of humerus (upper arm) bones:

This is an ulna (one of the two lower arm bones) that has been chopped off and then healed, indicating that the individual lost part of his or her arm. Then it healed after the injury, so the individual survived missing a hand:

A drawer full of kneecaps. They are lighter than kneecaps that are “fossilized”, as the sandstone has probably leached out many of the bone constituents:

A smashed leg bone (tibia), either trod on soon after death or smashed during death, perhaps during hunting or warfare. (Neanderthal bones show much less frequency of “warfare” damage than do the bones of earlier hominins like australopithecines. They seem to have been a peaceful subspecies.)

This Neanderthal shows a healed bash in the head (the dent in the center, which didn’t penetrate the skull), along with lines surrounding the wound. Life was tough for these hominins!

Here Davorka explains that we’re not sure what the lines are: they could have been deliberately incised (trephination) to relieve pressure on the wound coming from pus, or perhaps the lines  could be just a taphonomic (preservation) artifact.

Neanderthals were largely carnivores, though we know they also used medicinal plants. They ate bears, beavers, and even rhinos. Here’s an adult rhino that I believe was killed by the Krapina Neanderthals. They would of course have had to hunt in groups, and it must have been very dangerous to spear a bear or a rhino to death.

They apparently killed birds, too, as bits of bird skeletons, with some of the parts modified, are found in association with the Neanderthal bones. Here are some talons and foot bones from the white-tailed eagle, Haliaeetus albicilla, a species that is still around.

There are cut marks in the talons and foot bones to which they were attached, suggesting that Neanderthals were using the talons and bones as jewelry. This is supported by recent findings of gut “fiber” tied around part of a talon. Here are a foot bone and a talon that have been modified by having grooves cut in them.

This is a toe bone to which the talon was attached. See the cut groove at the lower end?

Modified eagle talons:

Davorka is pointing to the human-cut groove:

Here’s a paper (click on screenshot to read) in which Davorka and her co-authors suggest the use of talons as jewelry:

A bowl full of Neanderthal tools:

I got to hold a beautiful 130,000 year old Neanderthal spear point, chipped out of flint:

I previously described the tool below as a “scraper”, but I remembered wrong. As Davorka tells me, it’s not a tool, but something even more interesting. It’s a piece of “mudstone” that was probably picked up and brought to the Krapina site because it is a curiosity: it has “ichnofossils” in it (traces of living organisms, like worms, that have modified the sediments). Of course the Neanderthals didn’t know what these were, but might have been so impressed by the unusual patterns of this rock that they decided to keep it.

And Davorka and I after our visit. It truly was one of the great experiences of my life, and I’m immensely grateful to Davorka for her instruction and kindness, and to my hosts, Igor, Damjan, Darko, and Pavel, for arranging this visit. (We all went to lunch after this, but more on that in another post.)

 

 

Geneticist David Reich responds to critics of his views on race

April 1, 2018 • 10:45 am

On March 23, I called your attention to paleoanthropologist David Reich’s op-ed in the New York Times, “How genetics is changing our understanding of ‘race’.” I thought the article was quite good, one of the few articles that takes a pretty objective and open-minded stand on “race”. It noted that conventionally named races are social constructs (that is, there is no homogenous “black” or “caucasian” race that is diagnostically different from other races), but that even the social constructs reflect elements of history (different groups evolved in geographic isolation, and their genetic constitutions, which still reflect that isolation, can be used to reconstruct evolutionary history and give some help with medical diagnoses).

Reich notes that there has been ample time for different populations to have evolved genetic differences and that, although most variation in humans is found within groups rather than between them, we still do not expect all groups to be exactly equal in any trait that is genetically variable—an expectation that goes for both morphology and behavior. Finally, Reich makes the point—one that I’ve always emphasized—that even if there are group differences, that says nothing about how we should treat individuals, and we need to make it a moral principle that all individuals, regardless of gender, ethnicity, or other biological status, should be afforded equal opportunities, as well as personal treatment based on individual qualities rather than group membership. It is always unwise to predicate moral views on biological realities, for that makes your morality vulnerable to future empirical findings in ways we don’t want. (Of course some aspects of morality, like views on abortion, can vary depending on what science finds out. But I don’t see race this way, as I can’t imagine any genetic discovery that would alter the kind of equality I want in our species.)

This is a reasoned approach to the data, but there are many scholars who reject it, for they are aware of the history of eugenics in which “racial” differences were used to discriminate among (and even kill) people. That happened, and we must be aware of it. But the solution is not to simply deny science or reject whatever science finds about ethnic groups. Rather, we must ground our morality on a fundamental equality of humans based on their individuality.

We should never use ideology as a basis to accept or reject science. That way lies both madness and dissolution, as evidenced by the Lysenko affair in Soviet Russia, in which “Western genetics” was rejected in favor of a bogus form of heredity more congenial to the socialist view of human malleability. The result: millions starved to death. For both gender and ethnicity, much of the Left has an a priori assumption that all groups are equal—something Pinker questioned in his book The Blank Slate.  The denial of science, or suppression of research, comes from the fear that any differences could be used to justify sexism, racism, bias, prejudice, and lack of opportunity. But Reich and I are concerned to show that we can have our genetic cake and eat it too: we can create a society of equal opportunity while still studying group and gender differences in our species.

If Reich’s essay had any weakness, it was the conflation of “race” with “population”, though he was concerned with that. As for me, I’m happy to abandon any traditional racial classification of humans, or even the word “race” itself, so long as we replace it with terms like “population” or “ethnic groups” that can help guide genetic and evolutionary research. These other terms have a biological reality not contained in the conventional (i.e., erroneous) use of “race”. Futher, recognizing populations and ethnic groups, fuzzy as they are, is essential in understanding the evolutionary history of humans—and has medical implications as well. What we always need to remember is that human evolution involved the differentiation of geographically isolated groups who evolved some differences, but now, with human movement, those differences are blurring, so that we have a fuzzy and overlapping set of populations. And yet those populations still show statistical differences that are useful. If they didn’t, you couldn’t spit in a test tube and have places like 23andMe give you a pretty accurate take on where your ancestors came from. Nor could we use genetic patterns in modern humans to reconstruct our migration throughout the world. The patterns remain, and have afforded immense understanding of our evolutionary history.

Reich’s article was excerpted from his new book, which just came out and will surely be worth reading (click on screenshot to order):

Reich’s piece, temperate as it was, was widely criticized by readers, who wrote letters to the New York Times. That paper then gave Reich the unprecedented opportunity to respond in a longish piece that was published two days ago. You can read it by clicking on the screenshot below.

Readers were still concerned that science could be used to justify prejudice and inequality, and Reich once again says that we don’t have to let that happen.  Some readers repeated the conclusion (first suggested by my advisor Dick Lewontin) that the notion of group differences is meaningless since most variation in our species is within rather than between populations. That’s true, but people don’t understand that this doesn’t bar us from using constellations of genes to discern (not define!) groups and learn something about population structure and human evolution. Finally, in his response Reich lays out six principles which seem eminently reasonable. Number 6 is especially worth your attention.

From my point of view, it should be possible for everyone to hold in their heads the following six truths:

1. “Race” is fundamentally a social category — not a biological one — as anthropologists have shown.

2. There are clear genetic contributors to many traits, including behavior.

3. Present-day human populations, which often but not always are correlated to today’s “race” categories, have in a number of instances been largely isolated from one another for tens of thousands of years. These long separations have provided adequate opportunity for the frequencies of genetic variations to change.

4. Genetic variations are likely to affect behavior and cognition just as they affect other traits, even though we know that the average genetic influences on behavior and cognition are strongly affected by upbringing and are likely to be more modest than genetic influences on bodily traits or disease.

5. The genetic variations that influence behavior in one population will almost certainly have an effect on behavior in others populations, even if the ways those genetic variations manifest in each population may be very different. Given that all genetically determined traits differ somewhat among populations, we should expect that there will be differences in the average effects, including in traits like behavior.

6. To insist that no meaningful average differences among human populations are possible is harmful. It is perceived as misleading, even patronizing, by the general public. And it encourages people not to trust the honesty of scholars and instead to embrace theories that are not scientifically grounded and often racist.

In short, I think everyone can understand that very modest differences across human population in the genetic influences on behavior and cognition are to be expected. And I think everyone can understand that even if we do not yet have any idea about what the difference are, we do not need to be worried about what we will find because we can already be sure that any differences will be small (far smaller than those among individuals).

Reich’s original piece (and response) was not sufficient for 68 scholars, who wrote a joint piece, “How not to talk about race and genetics” (clearly named after Reich’s piece above), taking Reich to task for his “misunderstandings.” This piece was apparently submitted to the NYT but was rejected, so it was published in BuzzFeed.

The thing is, most of the things these scholars criticize were already taken into account by Reich, including the notion that conventional races are social constructs. But the 68 also object to the notion of “populations”, an objection that is unwise given that they admit later in the piece that there are differences between populations—they just don’t fall into the conventional categories of “race”—something that Reich already admitted.

Their main beef seems to be that those like Reich who unravel the genetic patterns of our species need to constantly consult with people like cultural anthropologists and social scientists. I’m not sure this is good advice, since those people have, by and large, tried to foist ideological views onto research on human groups. The bit below, for example, smacks of an unwarranted hubris:

Precisely because the problems of race are complex, scientists need to engage these issues with greater care and sophistication. Geneticists should work in collaboration with their social science and humanities colleagues to make certain that their biomedical discoveries make a positive difference in health care, including the care of those studied.

Of course discoveries should be used constructively, but is that the responsibility of people like Reich, who simply look at the frequencies of disease genes in different groups and the pattern of genetic differentiation across the globe? I don’t think so. How to use the findings of geneticists in medicine is the purview of bioethicists and physicians, not paleoanthropologists.

And have a look at this:

Even “male” and “female,” which Reich invokes as obviously biologically meaningful, has important limitations. While these categories help us to know and care for many human beings, they hinder our capacity to know and care for the millions of human beings born into this world not clearly “sexed.’ Further, overemphasizing the importance of the X and Y chromosomes in determining sex prevent us from seeing the other parts of the genome involved in sex.

Well, yes, there are people not clearly “sexed”, but the categories of “male and female” fit the overwhelming majority of humans, and have and can lead to useful research: both biological and medical. What we see here is more Pecksniffery that invokes rare exceptions to criticize a binary classification that, in the main, is correct and useful.

As for the signatories, there are some geneticists and biologists among them, but they’re outnumbered by anthropologists (I suspect mostly cultural anthropologists), sociologists, physicians, gender and ethnic studies professors, biomedical ethicists, historians, and professors of law. In short, just the mix of people you’d expect to object to Reich’s reasonable take. But you can read and judge for yourself.

h/t: Andrew