Category: human evolution

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

Finally: a sensible discussion of “race”

March 23, 2018 • 11:15 am

And by “sensible,” of course, I mean a discussion that aligns with my own views. I’ve often written that while there are no finite and strongly genetically demarcated human “races”, there are meaningful and statistically diagnostic differences between populations, ethnic groups, or whatever you want to call them. This is in opposition to the common Left-wing view that races are purely “social constructs” having no biological reality.

Well, there aren’t a finite number of groups whose members are 100% genetically differentiated from other groups. But when you take all genes together, there are sufficient average frequency differences that one can discern statistical clusters that, in turn, allow you to use lots of genes to pretty much diagnose where somebody’s from and who their ancestors were. These “statistical clusters” are real, not social constructs, for they fall out regardless of the politics or biases of the investigator.

Recognizing their existence by no means justifies bigotry or stereotyping, but we shouldn’t dismiss the existence of those clusters simply because, in the past, people with an incorrect idea of “race” have used differences to justify segregation and prejudice. Yet all too often, as with genetic differences among ethnic groups, behavioral differences between the sexes, and evolutionary psychology, those on the Left simply dismiss entire fields because of a fear that scientific research will justify discrimination. And in theory it could, as it did in the past, but it’s better to know the facts and at the same time absorb the idea that the moral and legal equality of all humans, and the equality of opportunity they deserve, does not depend on evolutionary or genetic details. For if it did, then scientific findings could be used to justify prejudice—something that all humanists reject. Asserting that entire fields, like genetic analysis of human ethnic groups, are simply parsing “social constructs” is a form of anti-intellectualism that will stifle scientific progress. If some Leftists had their way, for instance, there would be no evolutionary psychology, no attempt to understand the evolutionary roots of modern human behavior. Do we really want to impose a moratorium on such work?

The recognition of genetic clusters as meaningful entities is the point that David Reich makes in the article given below. Reich, as you may know, is an accomplished professor of genetics at Harvard who’s done a lot of work on DNA-based human and primate phylogenies, human disease genes, interbreeding among ancient lineages of hominins (e.g., Denisovans, Neanderthals, etc.), and mapping human ancestry by looking at statistical grouping. (There’s a big NYT article about his work here.)

I highly recommend you read his essay in the New York Times‘s Sunday Review (click on screenshot):

I’ll give just two quotes from Reich: one about the scientific data and the other about its moral implications—or lack thereof. But read the article!

The data:

[After the 1972 paper of my advisor Dick Lewontin], a consensus was established that among human populations there are no differences large enough to support the concept of “biological race.” Instead, it was argued, race is a “social construct,” a way of categorizing people that changes over time and across countries.

It is true that race is a social construct. It is also true, as Dr. Lewontin wrote, that human populations “are remarkably similar to each other” from a genetic point of view.

But over the years this consensus has morphed, seemingly without questioning, into an orthodoxy. The orthodoxy maintains that the average genetic differences among people grouped according to today’s racial terms are so trivial when it comes to any meaningful biological traits that those differences can be ignored.

The orthodoxy goes further, holding that we should be anxious about any research into genetic differences among populations. The concern is that such research, no matter how well-intentioned, is located on a slippery slope that leads to the kinds of pseudoscientific arguments about biological difference that were used in the past to try to justify the slave trade, the eugenics movement and the Nazis’ murder of six million Jews.

I have deep sympathy for the concern that genetic discoveries could be misused to justify racism. But as a geneticist I also know that it is simply no longer possible to ignore average genetic differences among “races.”

Groundbreaking advances in DNA sequencing technology have been made over the last two decades. These advances enable us to measure with exquisite accuracy what fraction of an individual’s genetic ancestry traces back to, say, West Africa 500 years ago — before the mixing in the Americas of the West African and European gene pools that were almost completely isolated for the last 70,000 years. With the help of these tools, we are learning that while race may be a social construct, differences in genetic ancestry that happen to correlate to many of today’s racial constructs are real.

Recent genetic studies have demonstrated differences across populations not just in the genetic determinants of simple traits such as skin color, but also in more complex traits like bodily dimensions and susceptibility to diseases. For example, we now know that genetic factors help explain why northern Europeans are taller on average than southern Europeans, why multiple sclerosis is more common in European-Americans than in African-Americans, and why the reverse is true for end-stage kidney disease.

I am worried that well-meaning people who deny the possibility of substantial biological differences among human populations are digging themselves into an indefensible position, one that will not survive the onslaught of science. I am also worried that whatever discoveries are made — and we truly have no idea yet what they will be — will be cited as “scientific proof” that racist prejudices and agendas have been correct all along, and that those well-meaning people will not understand the science well enough to push back against these claims.

And how we should handle the future discoveries of genetics:

For me, a natural response to the challenge is to learn from the example of the biological differences that exist between males and females. The differences between the sexes are far more profound than those that exist among human populations, reflecting more than 100 million years of evolution and adaptation. Males and females differ by huge tracts of genetic material — a Y chromosome that males have and that females don’t, and a second X chromosome that females have and males don’t. [JAC: I find this statement somewhat misleading, because he’s talking about “biological” differences, not differences in genetic content, and the Y chromosome doesn’t have many genes.]

Most everyone accepts that the biological differences between males and females are profound [JAC: Again, it’s not clear what he means by “profound,” but I’d agree that they are there and that they do explain differences between the sexes in both morphology and behavior.] In addition to anatomical differences, men and women exhibit average differences in size and physical strength. (There are also average differences in temperament and behavior, though there are important unresolved questions about the extent to which these differences are influenced by social expectations and upbringing.)

How do we accommodate the biological differences between men and women? I think the answer is obvious: We should both recognize that genetic differences between males and females exist and we should accord each sex the same freedoms and opportunities regardless of those differences.

It is clear from the inequities that persist between women and men in our society that fulfilling these aspirations in practice is a challenge. Yet conceptually it is straightforward. And if this is the case with men and women, then it is surely the case with whatever differences we may find among human populations, the great majority of which will be far less profound.

An abiding challenge for our civilization is to treat each human being as an individual and to empower all people, regardless of what hand they are dealt from the deck of life. Compared with the enormous differences that exist among individuals, differences among populations are on average many times smaller, so it should be only a modest challenge to accommodate a reality in which the average genetic contributions to human traits differ.

It is important to face whatever science will reveal without prejudging the outcome and with the confidence that we can be mature enough to handle any findings. Arguing that no substantial differences among human populations are possible will only invite the racist misuse of genetics that we wish to avoid.

Between the unwarranted pseudoscientific statements of Nicholas Wade and James Watson on one hand (both criticized in Reich’s article) and the genetic blank-slateism of various ideologically-biased scientists and cultural anthropologists (who don’t act like scientists) on the other, lies the reasonable position—the one limned by Reich.

Greg’s Take on Reich’s Article

by Greg Mayer

I also like Reich’s article, but if he hopes to be able to talk about genetic differentiation, he’s going to have to stop accepting the “race is a social construction” fallacy, because that means everyone who thinks race is a social construction, or been convinced it is because they keep getting told it is, will ignore everything else he says. As he points out, there is measurable genetic variation; that that variation can be important (clinically, cognitively, etc.); and that that variation allows the identification of the geographic origin of individuals– and the latter is what race means. (As always, I use the zoological definition of a geographic race or subspecies. Subspecies may be described when it is the case that if you show me a specimen I can tell you where it is from, and, conversely, if you tell me where it is from I can tell you what it looks like.) The mass of genetic data on humans now allows us to divide indigenous populations  (i.e. pre-Columbian) into so many races that fit the zoological definition of a race that one of the chief arguments against recognizing races is that there are too many recognizable races– 23 and Me is selling microracial identification on television! Very fine scale genetic data make recognition of geographic groupings so easy that the problem with subspecies isn’t that you can’t tell them apart, but rather you can tell everything apart, even local populations.  Nomenclaturally, subspecies are optional, and there could be reasons, both practical and social, not to name them.

Reich cites Dick Lewontin‘s 1972 apportionment of diversity finding (which, of course, is true), but then doesn’t mention (or perhaps even realize) that that finding  says nothing about whether there are recognizable races. What Reich does do, although more indirectly than I would, is to argue that human moral equality must not rest upon an empirical finding of no genetic differences, because then the finding of genetic differences will undermine the argument for moral equality. I 100% endorse him on the principle that human moral equality should NOT depend on an empirical argument about genetic differentiation. The problem with basing human moral and civil equality on empirical claims about human biological similarity is that such claims may prove to be mistaken. Anthony Tony Edwards, in his commentary on Dick’s 1972 paper, says it quite nicely:

“But it is a dangerous mistake to premise the moral equality of human beings on biological similarity because dissimilarity, once revealed, then becomes an argument for moral inequality.”

[Also, Reich seems terribly naive if he thinks “Most everyone accepts that the biological differences between males and females are profound.” I predict he will be assailed from the left on this point. And, Jerry and I wrote our commentaries independently of one another.]

h/t: Rodney, Greg

The first Neanderthal cave art

February 23, 2018 • 10:30 am

There has been some debate about the artistic ability of Neanderthals, and to date no art has been found, though their “spirituality” has been suggested from traces of ochre in burial sites. That suggests either that living bodies were decorated before burial or were adorned after death in some kind of ritual.  People seize on that, eager to detect signs of religiosity. (Ochre is a red “earth” pigment that contains ferric oxide.)

There are of course famous representational cave paintings, like the wonderful beasts of Lascaux, but these were made about 20,000 years ago. That was after Neandertals became extinct and when “modern” H. sapiens had already colonized Europe from Africa around 40,000 years ago. (Note: I’ve always considered Neanderthals a “subspecies” of H. sapiens, H. sapiens neanderthalensis, while “modern” humans are H. sapiens sapiens. Needless to say, some anthropologists disagree, though the interfertility of these forms, as evinced by Neanderthal genes in the modern human genome, makes me deem them members of the same biological species.)

Neanderthals are conventionally thought to have been in Europe from about 250,000 years ago to about 40,000 years ago. Thus the finding of 65,000 year old cave paintings in Spain, as documented in a new paper in Science by D. L. Hoffmann et al. (reference below; free access with Unpaywall, pdf here), not only bespeaks an artistic bent of Neandertals, but is the oldest cave paintings by a hominin. (The previous records are a hand stencil in Indonesia and a red disk  in a Spanish cave: both date to about 40,000 years ago and were therefore almost certainly done by H. sapiens sapiens.)

So what did Hoffmann et al. find? The three Spanish caves they investigated bear red hand stencils, abstract art consisting of geometric figures, as well as figures of animals like deer and birds. Since the caves appear to have been continuously occupied for at least 100,000 years, there’s no way of knowing, without dates, which subspecies produced which art.

The novel thing about this paper, though, is that the authors were able to actually date the art using uranium-thorium dating on the carbonate crusts that form on top of the paintings. These carbonates are what make stalactites and stalagmites, and form when the calcium compounds crystallize out of dripping water. A crust on top of a painting therefore had to form after the painting was created. I didn’t look up how they can date the formation of the crusts using uranium and thorium, but I’m sure a reader will tell us.

At any rate, here’s a geometric ochre panel, with crusts over it (see inset), that was dated at a minimum age of 64,800 years. It’s called a “red scalariform sign” (“resembling a ladder especially in having transverse bars or markings like the rungs of a ladder”), but I sort of see a humanlike figure to the right, though it’s probably my imagination. You can see the crust that was dated atop the red pigments. What a lucky find!

Fig. 1 Red scalariform sign, panel 78 in hall XI of La Pasiega gallery C. This panel features the La Trampa pictorial group (21). (Inset) Crust sampled and analyzed for a minimum age (64.8 ka), which constrains the age of the red line.

Here’s a hand stencil almost completely obscured by calcite, but made visible with software (right). This is between 45,300 and 48,700 years old, but other samples indicated a minimum age of 65,000 years.

Fig. 2. Hand stencil GS3b in Maltravieso cave (minimum age 66.7 ka). (Left) Original photo. The inset shows where the overlying carbonate was sampled for MAL 13. (Right) Same picture after application of the DStretch software (25) (correlation LRE 15%, auto contrast) to enhance color contrast. See (20) for details.

Finally, here are some “speleothem curtains” (calcite sheets) which have some red pigment (surely of human origin) covered with calcite; the ages here are 65,500 years.

Fig. 3 Speleothem curtain 8 in section II-A-3 in Ardales cave with red pigment, painted before at least 65.5 ka ago. (Left) Series of curtains with red paint on top, partially covered with later speleothem growth. The white rectangle outlines the area shown at right. (Right) Detail of curtain 8. The black square indicates where carbonate, overlying the red paint, was sampled for ARD 13. See (20) for details.

Paintings and ochre daubings from all three caves are, as the authors say, consistent, and, at 64.8 kyr (64,800 years), “substantially predate the arrival of modern humans in Europe, which has been variously estimated at between 45 ka and 40 ka ago.” Thus this art predates the arrival of “modern” humans by 20,000 years. (“Modern H. sapiens” remains simply aren’t found Spain at the time of these paintings). Since the only hominins in the area were Neanderthals, it’s presumed these paintings are by that subspecies—unless there’s some still-undiscovered hominin, which seems unlikely.

Neanderthals, then, had art—though it’s not representational—well before the famous cave paintings of France. This shows, as the authors say, that Neanderthals had a light source and premeditation, both of which are necessary to create hand stencils. They add, “it is difficult to see them [the art] as anything but meaningful symbols places in meaningful places.”  Well, we are meaning-seeking creatures, so I wouldn’t go that far. Perhaps they’re the Neanderthal equivalent of graffiti, not having much meaning at all. (“Hey, Zog, look: I made a print of my hand!”)

It’s unlikely that this kind of art was unique to these three caves, and so, as Hoffman et al. propose, it seems likely that eventually we’ll find Neanderthal art in other caves. And it will be interesting to see if that subspecies hit on representational art—showing animals or hominins—before H. sapiens sapiens came to Europe and Neanderthals died out.

_______

Hoffmann, D. L., C. D. Standish, M. García-Diez, P. B. Pettitt, J. A. Milton, J. Zilhão, J. J. Alcolea-González, P. Cantalejo-Duarte, H. Collado, R. de Balbín, M. Lorblanchet, J. Ramos-Muñoz, G.-C. Weniger, and A. W. G. Pike. 2018. U-Th dating of carbonate crusts reveals Neandertal origin of Iberian cave art. Science 359:912-915.

New jaw and teeth puts first exodus of Homo sapiens from Africa about 180,000 years ago

January 26, 2018 • 10:30 am

Note: I’m not an expert on human evolution, so this post is largely derived from some catch-up reading I had to do, and there may be some errors. Feel free to comment or correct me in the comments. I use the subspecies designation H. sapiens sapiens as a synonym for “modern H. sapiens” and to distinguish them from Neanderthals, which on reproductive grounds (see below) I consider a subspecies: H. sapiens neanderthalensis.

__________

Hominins migrated out of Africa several times, including Homo erectus, whose members left Africa about 1.8 million years ago and spread throughout Eurasia, making it as far as to what are now China, Vietnam, and India. But for reasons unknown that species went completely extinct about 140,000 years ago, and contributed nothing to the modern human genome.

The extant species, our own Homo sapiens sapiens, evolved in Africa but also left the continent—several times. The most recent exodus was about 60,000-90,000 years ago, and descendants of those migrants include all living non-African populations of our species (we know this from genetic data). However, most modern humans also carry a bit of genome from earlier migrations: most notably that of the Neanderthals, whose ancestors probably left Africa about 300,000 years ago and went extinct between 40,000 and 25,000 years ago. Before they died out, though, they certainly interbred to some extent with the lineage that produced modern humans, so that many of us carry a handful of Neanderthal genes. (As I said at the top, I consider Neanderthals a subspecies of Homo sapiens—H. sapiens neanderthalensis—because they produced viable and fertile hybrids with “modern” H. sapiens, which I call H. sapiens sapiens to simplify matters. Some anthropologists, however, consider Neanderthals a full species: H. neanderthalensis.)

The characteristics of H. sapiens sapiens, compared to other hominins, include, as a summary in Science describes (“When did modern humans leave Africa?“; reference and link below), “a globular braincase, brow ridges that are divided into central and side portions, a flat and retracted midface, a chin on the lower jaw, and a narrow pelvis.” Hominins with these modern features, probably having split off from the H. erectus lineage, first appear roughly 300,000 years ago in Africa.  There followed several bouts of migration out of Africa, producing groups like the Denisovans and Neanderthals, but until now H. sapiens sapiens fossils found outside Africa date from 120,000-90,000 years ago—in Israel.  These emigrants probably went extinct, too, so though they are considered members of H. sapiens sapiens, they were a group that didn’t survive.

Now a new paper in Science by Israel Hershkovitz et al. (and there are a lot of “al.”s; see reference below with free access and full pdf here) pushes back the date of H. sapiens emigrants a long way—to roughly 180,000 years ago. These emigrants, too, apparently went extinct (we don’t know why—perhaps their population was too small?), and left no genetic contribution to the modern human genome. But the paper suggests that there were excursions of H. sapiens sapiens to lands outside Africa even longer ago than we thought.

The new data come from a single jawbone collected in Misliya cave on Mount Carmel in Israel. Here’s the collecting site from the Science paper (all captions from that paper):

A) The excavation area and the location of the Misliya-1 maxilla (red dot). Squares K9 to K12 are indicated. (B) Map of the Misliya Cave Upper Terrace excavations (1 m2 grid) with denoted excavated squares and showing the location of the human maxilla (Misliya-1). (C) Stratigraphic section of the Upper Terrace, squares K9 to K12. Apart from Unit 2, a Terra Rosa soil intrusion, all units contain EMP finds or assemblages. The present-day dripline roughly separates between highly cemented (Units 1,3,5) and more loosely cemented (Units 4 and 6) sediments. Misliya-1 was retrieved from the upper part of Unit 6.

What the authors found was the left side of the left upper jaw, including all eight teeth, some of the cheekbone and the roof of the mouth, and a bit of the nasal cavity (left in photo below). The specimen was dated in several ways, including uranium/thorium dating of the dentine and sediments adhering to the jawbone, uranium and combined uranium/electron-spin data on the enamel, and thermoluminescence on burnt stone tools associated with the fossils. The dating ranges are shown to the right:

 

(A) Lateral, occlusal, and oblique views of the hemimaxilla from Misliya Cave. Left: The virtual reconstruction; all adhering matrix was removed using virtual techniques. The enamel caps of the teeth were removed to show the dentine surfaces (which were analyzed through landmark-based methods); right: the original specimen. (B) Overview of the dating results obtained at Misliya Cave. All ages are given at a 2σ confidence level. Key: (*) The U-series age on dentine and calcitic crust on the maxilla should be considered as a minimum age estimate for Misliya-1; (**) the combined US-ESR age should be regarded as a maximum age estimate for Misliya-1; (***) average TL date based on nine samples of burnt flint obtained from nearby squares (N12, L10; see Fig. 1). Dark gray: Age range for Misliya-1, based on dates obtained from the fossil (U-Th provides the minimum age and combined US-ESR the maximum age), is between 177 ky (=185 – 8 ky) to 194 ky (=174 + 20 ky). Light gray: Age range for the EMP period in the Levant (250 to 140 ky) based on the combination of TL dates obtained for Tabun Cave, Hayonim Cave, and Misliya Cave.

The dates are pretty concordant except for the U-series on the dentine, which gives an age of about 70,000 years, not different from the most recent migration out of Africa that led to all modern extra-African H. sapiens sapiens populations. That outlier bothers me, but the authors, combining the data, come up with an age of the specimen between 177,000 and 194,000 years (dark band in the figure to the right above). This being above my pay grade, I’ll take their word that the youngest date of 70,000 years is wrong.

How do we know this is “modern” H. sapiens? The authors did morphological analysis of the teeth and show that they fall well within the boundaries of the teeth of that group. Here’s a principal component analysis of the crown shape of one molar from the specimen. (This analysis combines several features of morphology into two main axes that capture most of the variation among specimens.) In the figure below, the new molar is “Misliya1” on the left, grouping nicely with the gray diamonds of modern H. sapiens and shaped differently from the teeth of Neanderthals (black diamonds), early modern humans (presumably from Africa; greenish-yellow x’s), early and middle Pleistocene humans from Europe, which aren’t H. sapiens but in the genus Homo (purple squares), and specimens from Africa of that same age (burgundy + sign), and Middle Pleistocene Asian Homo (probably H. erectus; blue triangles).  If you want the exact locations, check the paper’s supplementary data.

First two principal components (PCs) of the crown shape of Misliya-1 M1. Misliya-1 is distinct from Neandertals and other Middle Pleistocene hominins and clearly grouped with modern humans. Red star, Misliya-1; gray circles, recent modern humans (without labels), Upper Paleolithic and Epipaleolithic modern Homo (with labels); black diamonds, Neandertals; yellow X, early modern humans; violet square, European Early and Middle Pleistocene Homo; burgundy plus sign, African Early and Middle Pleistocene Homo; blue triangle, Middle Pleistocene Asian specimens; for the specimen labels, refer to table S7.

Granted, it’s only one molar, but the age is pretty compelling, and it does fall out with modern H. sapiens. Other data I haven’t shown, on the maxilla (jawbone) shape as well as features of other teeth, show that these, too, group with recent modern humans and not with earlier non-sapiens Homo. 

Further, the tools found in the same stratum and dated with thermal methods show what is called “Levallois technology,” which is explained and animated by Wikipedia:

 A striking platform is formed at one end and then the core’s edges are trimmed by flaking off pieces around the outline of the intended lithic flake. This creates a domed shape on the side of the core, known as a tortoise core, as the various scars and rounded form are reminiscent of a tortoise’s shell. When the striking platform is finally hit, a lithic flake separates from the lithic core with a distinctive plano-convex profile and with all of its edges sharpened by the earlier trimming work.

This way of making cutting tools is also seen in African specimens of H. sapiens sapiens dated about the same time, further supporting the notion that the Israel specimen came from modern H. sapiens and does go back about 200,000 years.

THE UPSHOT:  This finding does not “revolutionize the story of human evolution”: after all, if these specimens are about 180,000 years old, they’re from a population of our species that went extinct without leaving descendants. But what it does show is that modern H. sapiens sapiens—members of our own subspecies—left Africa considerably earlier than we thought. And it shows that there were several migrations of H. sapiens sapiens out of Africa at different times. All modern “out of Africa” populations, however, do descend from the most recent exodus, roughly 60,000-90,000 years ago.  The story is complex, and also involves mating of “modern” H. sapiens with the H. sapiens neanderthalensis lineage—both in and out of Africa.

More surprises surely await, as hominin fossils are rare, and each one can potentially tell us something amazing. As Steve Gould once said, every time he taught human evolution he threw away all of his previous notes and completely rewrote the course.

Here’s a figure from the Stringer and Galway-Witham “news and views” piece showing the different migrations of modern humans, with an even older one within Africa:

 

________________

Hershkovitz, I., G. W. Weber, R. Quam, M. Duval, R. Grün, L. Kinsley, A. Ayalon, M. Bar-Matthews, H. Valladas, N. Mercier, J. L. Arsuaga, M. Martinón-Torres, J. M. Bermúdez de Castro, C. Fornai, L. Martín-Francés, R. Sarig, H. May, V. A. Krenn, V. Slon, L. Rodríguez, R. García, C. Lorenzo, J. M. Carretero, A. Frumkin, R. Shahack-Gross, D. E. Bar-Yosef Mayer, Y. Cui, X. Wu, N. Peled, I. Groman-Yaroslavski, L. Weissbrod, R. Yeshurun, A. Tsatskin, Y. Zaidner, and M. Weinstein-Evron. 2018. The earliest modern humans outside Africa. Science 359:456-459.

Stringer, C. and J. Galway-Witham. When did modern humans leave Africa? Science 359:389-390.

A new hypothesis about consciousness

January 15, 2018 • 11:00 am

In my view, there are two big problems of consciousness. The first is mechanical: how does it work? (This is called “The Hard Problem of Consciousness”.) What configurations of neurons create “qualia”, the sensation of conscious experience that includes pain, pleasure, self-awareness, and so on? Many theologians and obtuse academics maintain that we’ll never be able to understand how materialism can explain this, and thus use it to either attack materialism and “scientism”, or to plump for God, the Thing That Can Explain Stuff That Science Hasn’t Yet. I’m pretty confident that we’ll one day understand this, but surely not in my lifetime.

That’s the proximal or mechanical problem. The other is evolutionary: what selective pressures, if any, gave rise to consciousness? It surely evolved one way or another, because I doubt that microbes are conscious, but somewhere on the line between us and our microbial ancestors, animals became conscious. (I’m pretty sure that humans aren’t the only conscious animals!)

Now it’s not clear that there was natural selection for consciousness itself, for it may simply be a spandrel—a byproduct of other aspects of brain evolution and activity.

That is in fact the idea of David Oakley and Peter Halligan, professors of psychology and neuropsychology respectively, as outlined in their essay at The Conversation, “What if consciousness is not what drives the human mind?” Here’s a precis of their view; it’s based on a paper that I haven’t yet read (see link at bottom).

Most experts think that consciousness can be divided into two parts: the experience of consciousness (or personal awareness), and the contents of consciousness, which include things such as thoughts, beliefs, sensations, perceptions, intentions, memories and emotions.

It’s easy to assume that these contents of consciousness are somehow chosen, caused or controlled by our personal awareness – after all, thoughts don’t exist until until we think them. But in a new research paper in Frontiers of Psychology, we argue that this is a mistake.

We suggest that our personal awareness does not create, cause or choose our beliefs, feelings or perceptions. Instead, the contents of consciousness are generated “behind the scenes” by fast, efficient, non-conscious systems in our brains. All this happens without any interference from our personal awareness, which sits passively in the passenger seat while these processes occur.

Put simply, we don’t consciously choose our thoughts or our feelings – we become aware of them.

As I interpret their essay (see below), our adapted brain is constantly taking in information in a “stream of unconsciousness”, and processes this information in a way to further our reproduction, of which survival and an ability to get along with our fellow humans are components. Some of this leaks into our awareness as “consciousness”, but we neither choose what leaks out nor use it to adjust our behavior:

. . . this may leave one wondering where our thoughts, emotions and perceptions actually come from. We argue that the contents of consciousness are a subset of the experiences, emotions, thoughts and beliefs that are generated by non-conscious processes within our brains.

This subset takes the form of a personal narrative, which is constantly being updated. The personal narrative exists in parallel with our personal awareness, but the latter has no influence over the former.

The personal narrative is important because it provides information to be stored in your autobiographical memory (the story you tell yourself, about yourself), and gives human beings a way of communicating the things we have perceived and experienced to others.

This, in turn, allows us to generate survival strategies; for example, by learning to predict other people’s behaviour. Interpersonal skills like this underpin the development of social and cultural structures, which have promoted the survival of human kind for millennia.

Thus the reception, processing, and acting upon information are the results of natural selection, but consciousness itself is not. As the authors argue, it “does not confer any particular advantage.” At the end they get into issues of free will and responsibility, arguing that these are social constructions (yet also “embedded in the workings of our nonconscious brain”!) that have “a powerful purpose in society” and a “deep impact on the way we understand ourselves.” I’d argue that this is confusing (perhaps it’s explained more clearly in their paper), and even though these concepts may affect how “we understand ourselves”, they are illusions: in the authors’ view, they are not what we think they are.

So much for that. What intrigues me more is their idea that our consciousness is a spandrel, with the real adaptive work going on independent of our awareness. (We know this is true for some things, like our ability to drive from one place to another on cerebral autopilot.) If that’s the case, why the leakage? Is it really a byproduct of deep and unconscious stirrings in our brain—something that’s simply unavoidable given our wiring? Why aren’t we just zombies, with our brain doing everything without the need for consciousness? I doubt that, given our ignorance of how the brain works, Oakley and Halligan have an explanation for this, but their hypothesis is surely intriguing to ponder. It’s sort of the biological equivalent of quantum mechanics: something that’s deeply weird. 

I’ve put their paper and the link below; by all means weigh in below if you’ve read it.

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Oakley, D. A. and P. W. Halligan. 2017. Chasing the rainbow: the non-conscious nature of being. Front. Psychol., volume 814 November 2017 | https://doi.org/10.3389/fpsyg.2017.01924

A new study on how humans are evolving

January 8, 2018 • 10:15 am

I’ve often said that the most frequent question I’m asked in public lectures about evolution is this: “In what direction are humans evolving?” I’ve addressed it in several posts, including here, here, and here. The answers aren’t exciting, and are usually limited to just one population, since such studies involve following a cohort of humans for a long time so one can see what traits are correlated with higher (or lower, or intermediate) reproductive success.  Here’s a summary of the changes we think are occurring by natural selection:

Humans in Massachusetts:

  • Total cholesterol: going down.  Projected to drop 3.6% in ten generations
  • Weight:  going up a tad, projected to increase 1.4% in ten generations
  • Height:  we’re getting shorter projecting a drop of 1.3% (2.1 cm) in ten generations.
  • Systolic blood pressure:  Going down, as predicted. Projected to drop 1.9% in ten generations
  • Age at menopause:  Going up; projected to rise 1.6% (0.8 years) in ten generations.
  • Age at first reproduction: Going down. Projected to drop 1.7% (from 26.18 to 25.74 years).

Humans in several countries (see below), but no worldwide study:

  • Both women and men are under selection for earlier age at first birth in all populations.  The authors see this as a result of lowered juvenile mortality resulting from improvements in medical care, nutrition, and sanitation.  If it costs you to reproduce early, but the benefits are increased because your kids no longer die so often, then selection will favor your reproducing at an earlier age.
  • “Women are under selection for later age at last birth in a pre-industrial population [Finland, 17th-19th century] and later age at menopause in two post-industrial populations [USA and Australia, 20th century]. The authors don’t explain the basis of this finding, but I suppose it’s because women now live longer, giving a selective advantage to females who can produce more offspring at ages that they wouldn’t have attained earlier.  Combined, these first two observations show the “temporal window of reproductive opportunity” is broadening in humans:  we reproduce both earlier and later than populations a few centuries ago.
  • “Women are under selection for increased height in one pre-industrial population [Gambia, 20th century] and for decreased height in three post-industrial populations [Great Britain and USA, 20th century].” The authors suggest that, for the same reasons that it’s adaptive to reproduce earlier in industrial populations, it’s also adaptive to mature at a smaller size and divert your effort to reproduction.  To explain the Gambian data, they suggest that this trade-off doesn’t exist in populations where infant mortality of shorter and younger mothers is higher.  This is, of course, special pleading, but that’s just speculation. The data are what is important here.

Divergent selection: local adaptations in some human populations but not others. Traits involved, which are largely those over historical time rather than the traits above—thought to evolve in “real time” (i.e. now)—are:

  • Adaptation to marine diet
  • Lactose tolerance
  • Malaria resistance
  • Cholera resistance
  • Cold climate
  • Adaptation to arsenic-rich environment
  • Adaptation to high altitude
  • Light pigmentation
  • Short stature

A new paper in Proc. Nat. Acad. Sci. by Jaleal Sanjak and colleagues (reference below; only the abstract is free, though judicious inquiry might yield the paper) adds further data from a longitudinal dataset from the UK. The data come from the UK Biobank, which has 500,000 individuals not only measured for various traits and the individuals’ “long term reproductive success” relative to other people (LTRS; an index of “fitness” based on number of kids relative to the average), but who were also genotyped for various bits of DNA that allow the genetic correlations between traits to be analyzed. What that means is that apparent selection on one trait, say height, might not reflect a reproductive advantage of being shorter or taller, but only the fact that the trait’s expression involves some of the same genes also involved in the real trait under selection, say body mass.  To gauge this effect, the researchers examined examined the genetic data from 157,807 females and 115,902 males in the sample to look at the genetic correlation between traits, assuming that that would involve the presence of the same genetic variants associated with correlated traits.

Further, what you want to look for, if a trait is experiencing selection, is that the same genetic variants associated with the trait are also associated with LTRS. If they’re not, then we can’t say that variation in the trait has some connection with variation in “fitness”.

This is an improvement over previous studies in which traits are, by and large, studied individually, with genetic correlations not taken into account.

There were lots of correlations, but many were ruled out by showing that “selection” on a trait might really have been selection on a genetically correlated trait. So here’s a short list of the traits that, in this UK study, were being independently selected:

  • Age of first birth (or first reproduction) in females. It’s getting younger. This isn’t a new result, but is from UK data, and it seems that this may be a ubiquitous phenomenon.
  • Selection favors shorter females. (It appeared to favor taller males, too, but male height wasn’t genetically correlated with LTRS).
  • Selection favors higher body mass index (BMI) in males. (The results showed an insignificant trend in females in the same direction). BMI is the mass of the body (usually expressed in kilograms) divided by the square of the height (usually expressed in meters). It’s often used to judge whether people are skinny, “normal” or overweight.

Those are the major results, and most of them, save selection for higher BMI in males (and perhaps a weaker effect in females), are consonant with previous results. As to why selection is doing this, we can only speculate. Clearly, those women who reproduce earlier will have higher fitness, so that’s not problematic. But why shorter women or chunkier males leave more offspring is something I can’t comment on.

There were also some contradictions with previous results: this study, for instance, found no correlation between LTRS and age of menopause, while earlier studies showed that selection was favoring later menopause. This is one of the issues with extrapolating results from one population or study to others.

Finally, it’s worth looking at the authors’ list of potential problems with their results, which is pretty clear to the non-specialist:

There are a few other important caveats and limitations to our present analyses. All of our results are conditional on the suite of phenotypes that we have measured; there is a real possibility that there are unmeasured phenotypes that drive or confound some of our results. This issue is related to the phenomenon of apparent selection and should always be kept in mind when studying phenotypic selection. In addition, the genetic correlations are estimated using common SNP [single nucleotide polymorphism] markers (minor allele frequency > 0.01), which may be a source of bias because the genetic variants with deleterious effects on fitness are likely to be rare and thus absent from our analyses. However, this should simply reduce the power of our analyses. Further, there is evidence that the population of the UKB may not be perfectly representative of the whole population of the United Kingdom.  The potential ascertainment bias (heathy participant bias) in the UKB is important to consider and may have a quantitative effect on our estimates, but the bias is not likely to be large enough to disrupt the conclusions of our work in a qualitative way.

The upshot? Not anything astounding, but a thorough analysis that confirms to some extent previous findings and gives us more confidence in these authors’ results than do earlier studies. If there’s one finding that I have faith in, it’s that in nearly all studies done, selection is on women to reproduce earlier. (That’s a shorthand way of saying that “women who reproduce earlier leave more offspring.”) Given that early reproduction doesn’t have some other effect that in net reduces LTRS, it’s pretty clear why selection would do that. There may of course be a limit (young girls aren’t equipped to give birth), but it appears that in the future the average age of first reproduction will be lower than it is now.

But that isn’t exciting to most people who, when they ask me THE QUESTION, want to know if we’re getting smarter or handsomer or stronger. Well, we just don’t have the evidence.

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Sanjak, J. S. et al. 2017. 2017. Evidence of directional and stabilizing selection in contemporary humans. Proc. Nat. Acad. Sci. USA 115:151-156. published ahead of print December 18, 2017,

In an article on race and medicine, New York Times does its best to ignore and denigrate race

December 11, 2017 • 10:15 am

Furthering my claim that the New York Times is becoming more regressive in its Leftism, we have a long article in the science section on race and medicine. The thing is, the author of the piece does his very best to pretend that there’s no such thing as “race”, even while investigating—and buttressing, to some extent—the connection between race (or ethnicity, if you will) and illness.  But the ideological petticoat of author Moses Velasquez-Manoff shows throughout, particularly at the end. Valasquez-Manoff, a science writer, lacks science degrees, which may explain his cluelessness about how scientists conceive of “race,” but, given that I tried to explain it to him in a long phone interview, I doubt it.

I’ve explained my take on “race” many times before, and you can search for it on this site. (If you want just one article, go here, which summarizes and glosses a like-minded piece from Quillette by Bo Winegard, Ben Winegard, and Brian Boutwell). Like virtually all geneticists, I don’t see a finite and absolutely discrete number of easily identifiable “races”—that’s a strawman that people like Velasquez-Manoff attack. Maybe the general public thinks this, but Velasquez-Manoff is talking to scientists and about accepted science here.  “Race” (or “ethnicity”, if you like that word better) is simply a term for human “ecotypes”: groups of different evolutionary ancestry that have evolved different traits.

Like many animal species, humans, especially during our evolution after we left Africa, were divided into relatively discrete groups that were geographically isolated from other groups. In the absence of frequent migration between areas (such as we have now), these groups differentiated genetically, and generally along lines of geography. (Barriers like oceans and mountains are formidable obstacles to inter-group mating!) That differentiation was due to either divergent forms of natural or sexual selection, or to random genetic drift.

You can see these differences using either DNA sequencing or morphology (physical traits). Although, as is well known, there is more genetic differentiation among individuals among one ethnic group or population than among different groups, you can nevertheless pick out these groups by using combinations of genes, for differences at one gene tend to be correlated with differences in other genes. So, for example, we can see clustering of genes among people from the Americas, Oceania, native Australians, Europe/Middle East, and East Asia, and this clustering enables their recognition as groups that evolved semi-independently.

The Winegard et al. paper gives several examples of how “ethnicity” is correlated with genetic clustering; here’s one quote:

Empirical studies bear this logic out. The geneticist Hua Tang and her colleagues, for instance, found that self-reported ethnicity corresponded almost perfectly with genetic clusters from 326 microsatellite markers  (a microsatellite marker is a piece of repetitive DNA in which a series of DNA base pairs are repeated). Other studies have demonstrated even more power to identify people’s ancestry accurately. These studies illustrate that, whatever the meaning of the claim that there is much more variation within than among races, researchers can, if they use the appropriate procedures, distinguish human ancestral groups from each other with remarkable accuracy. The significance of these genetic differences among groups is entirely an empirical question.

And my own words, which quote the Tang et al. paper:

Here’s a quote from the abstract of the Tang et al. paper, published in The American Journal of Human Genetics, an excellent journal. The article is free online:

Of 3,636 subjects of varying race/ethnicity, only 5 (0.14%) showed genetic cluster membership different from their self-identified race/ethnicity. On the other hand, we detected only modest genetic differentiation between different current geographic locales within each race/ethnicity group. Thus, ancient geographic ancestry, which is highly correlated with self-identified race/ethnicity—as opposed to current residence—is the major determinant of genetic structure in the U.S. population.

Despite the clear evidence that human populations are genetically different and differentiable—although the presence of clusters within clusters precludes us from picking out discrete “races” having sharp boundaries—ideologues pretend that these differences don’t exist or aren’t meaningful. That’s because they fear that recognizing different groups will lead to discrimination against those groups, for the very same reason that biological ideologues won’t consider the possibility that there are genetically based differences between the behavior and neurology of men and women. Recognizing differences, they fear, will lead to institutionalizing bigotry based on those differences: to racism and sexism. The article by Winegard et al. dismantles this idea handily. The truth is the truth, regardless of whether it fits your ideological biases. And we can and should promote equality on moral rather than biological grounds.

But Velasquez-Manoff doesn’t like the idea of race, and so when he’s trying to discuss whether we should base some medical decisions or treatment on ancestry or ethnic background, he gets all antsy. You can read the article for yourself:

Here are a few quotes from the piece that shows the author’s lack of understanding of a more sophisticated concept of “race”, and his attempt to dismiss the importance of geographic differences between human populations:

Professor Yudell belongs to a growing chorus of scholars and researchers who argue that in science at least, we need to push past the race concept and, where possible, scrap it entirely. Professor Yudell and others contend that instead of talking about race, we should talk about ancestry (which, unlike “race,” refers to one’s genetic heritage, not innate qualities); or the specific gene variants that, like the sickle cell trait, affect disease risk; or environmental factors like poverty or diet that affect some groups more than others.

Ummm. . . race and ancestry are pretty much the same thing, and if genetic differences aren’t innate qualities, I don’t know what they are. What Velasquez-Manoff means by “innate qualities” is probably stuff like IQ or behavior, controversial topics about which we have little firm knowledge with respect to ancestry. What we’re talking about here are genetic differences that may have an effect on the incidence of diseases like sickle-cell anemia and Tay-Sachs, (Valasquez-Manoff’s tortuous attempt to avoid concluding that sickle-cell anemia is more frequent in populations descended from West Africa then from other populations is amusing.)

Here’s more:

What’s new today is that modern genetic science has revealed just how arbitrary the old race categories — Negroid, Caucasoid, Mongoloid and so on — really are. Yes, there is variation in the human family, but there are few sharp divides where one set of traits ends and another begins. Rather, traits exist in gradients, reaching high frequency in some populations and lower frequency in others. As the geneticist Sarah Tishkoff of the University of Pennsylvania reminded me, human beings are too young as a species, too promiscuous and full of wanderlust, always moving and mixing, for the kind of separation and differentiation that would cause true speciation to have occurred.

Well, these categories are not completely arbitrary: they just don’t pick out the totality of genetically recognizable groups. And yes, there aren’t sharp divides between groups and traits (or genes), for we see groupings within groupings—exactly what you’d expect if humans formed populations that were semi-isolated after they left Africa.  And who on earth even claims that there are “true species” in humans? No scientist I know! We’re not reproductively incompatible or isolated, which is the criterion for true species. We simply differ in our traits and genes, which is what we call “subspecies” or “ecotypes.” Remember, genetic differences among ethnic groups are correlated, for groups became genetically differentiated as semi-isolated populations.

Velasquez-Manoff prefers medical diagnostics based on genes rather than ancestry, apparently not realizing that these are correlated. Yes, we’d like to know everyone’s full DNA sequence for the best medical treatment, but sometimes an ancestry-based approach is better, simply because some diseases are clearly correlated with ancestry (and I recognize that there’s a conflating issue of culture, which isn’t genetic), and because in most cases we don’t know which genes are involved in disease and which variants are associated with which conditions. So these paragraphs, for instance, are confused:

The takeaway from studies like this is that rather than relying on race, doctors should focus on the genes important to whatever puzzle they face — an approach often called “precision” or “personalized” medicine. The idea is that tailoring treatment to the patient’s genotype, not to skin color or hair texture, would improve outcomes.

Consider the case of kidney disease. Scientists have found that African-Americans fare worse than whites when it comes to this illness. The assumption had long been that some environmental factor explained the difference. But in recent years, scientists have linked certain variants of a gene called APOL1 to worse kidney-related outcomes. Those variants are enriched in people of African ancestry. Girish N. Nadkarni, a kidney specialist at Icahn School of Medicine at Mount Sinai in New York City, explained to me that scientists think this may be because those variants protect against the sleeping sickness endemic to some parts of Africa.

Yes, it would be good to have the APOL1 genotype of all patients, but look: here the author admits that there are genetic differences between groups that correlate with their ancestry. They just don’t show a perfect correlation. Further, there may be other genetic differences between groups beyond APOL1 that affect kidney disease, but we don’t yet know about them, and so might be able to use self-identified ancestry as a correlate of those unknown differences. This is why my own doctor, Alex Lickerman, uses “race” as a guide to diagnosing prostate cancer. He’s quoted in the article:

Alex Lickerman, founder of ImagineMD, a medical concierge service in Chicago, cites the example of prostate cancer. For unclear reasons, African-Americans have a higher risk than whites. One test for the cancer, which looks at prostate-specific antigen, is controversial because it can yield false positives. Some recommend against using it at all.

But Dr. Lickerman says that merely being aware that African-Americans have a higher disease risk impels him to order the test more often for African-American patients. To his mind, the elevated risk of cancer outweighs the risk of a false positive. “Race is a crude marker, but it’s a usable marker,” he said. In that respect, it is no different from other factors doctors consider, most of which are based on imperfect studies of limited size and scope, and need to be weighed carefully.

Note that Lickerman recognizes race as a sign of ancestry that is correlated with genetic differences—and the genes for prostate cancer probably haven’t all been identified. It’s better in this case to partly base tests on race than to do nothing in the absence of genotypic data. What Lickerman is doing here, which seems sensible, involves recognizing the reality of “race”.

When discussing the higher incidence of hypertension in African-Americans than in white Americans, Velasquez implicates racism. He doesn’t seem to recognize two things: that hypertension in American blacks might be due to other cultural differences, like diet, or that it might be due to an interaction between evolved black/white genetic differences with factors like diet. The author simply wants to flaunt his virtue by singling out racism as the likely cause:

African-Americans, who on average have about 20 percent European ancestry, suffer from high blood pressure more often than whites do. Some studies indicate that among African-Americans, the darker one’s skin, the greater the risk of high blood pressure. The pattern could indicate that African ancestry is responsible.

Yet Africans in Africa don’t generally have high blood pressure. So some argue that the experience of having dark skin in the United States — of experiencing racism — is what’s raising blood pressure. In this case, Dr. Burchard says, even though race is a social construct, the best way to talk about the associated disease risk may be to use the labels, since the societal baggage that comes with them may be causing the problem.

Note that Velasquez-Manoff fails to present alternative but even more credible hypotheses (I don’t think that experiencing racism is a more likely explanation for hypertension than is diet, for instance). At any rate, he fails to lay out both genetic and interactive explanations. And the notion that “race is a social construct” is simply ridiculous. If it were, Lickerman’s ministrations would be futile. If race were purely a social construct, ancestry and ethnicity wouldn’t be correlated with any biological factors.

Of course we’d like to have the DNA profile of all patients, but we’d also like more research on exactly which genes are associated with disease. Such genes, though, may be hard to identify because they have tiny effects. In the meantime, there are occasions, as with sickle-cell anemia and prostate cancer, that ethnicity, or “race”, or “self-identified race”, can be used meaningfully in a medical way. And that, of course, means that ethnicity is not a “social construct”, for it has biological meaning. That’s the point that the Winegard et al. article tries to make.

Velasquez-Manoff’s virtue signaling and distaste for any concept of race is most evident in his last paragraph:

Science seeks to categorize nature, to sort it into discrete groupings to better understand it. That is one way to comprehend the race concept: as an honest scientific attempt at understanding human variation. The problem is, the concept is imprecise. It has repeatedly slid toward pseudoscience and has become a major divider of humanity. Now, at a time when we desperately need ways to come together, there are scientists — intellectual descendants of the very people who helped give us the race concept—who want to retire it.

It’s pretty clear that he doesn’t like race because it “divides humanity.”  Well, it partitions humanity on the basis of genetic difference, but that’s not what he means. He means that genetic differences cause friction between people. The solution to that is not to pretend that the genetic differences don’t exist, but to stop them from creating bigotry and hatred.

And if you want, discard the word “race”—but let’s keep “ancestry,” shall we?. No biggie, since “ancestry” is a term that enlightened biologists see as closely associated with “race”. Should we retire the concept of “ancestry”, too? If so, then why does Velasquez-Manoff mention it repeatedly?

I have to say that when I talked to Velasquez-Manoff and tried to tell him about the more modern concept of “fuzzy” race that encompasses a variety of nested populations that differ genetically, I could sense that he didn’t like what I was saying. And at the time I got a bad feeling about what he was going to write, as I could sense him ignoring what I was trying to tell him. In fact, I’ll go so far as to say that he was determined at the outset to downplay the significance of genetic differences between ethnic groups. And that is surely reflected in his piece, which I found notably unenlightening and genetically ignorant, even if it was politically correct.