A visit with Dick Lewontin

July 19, 2019 • 2:00 pm

by Greg Mayer

While on the East Coast to attend the Evolution 2019 meetings in Providence, Rhode Island, I also stopped for a few days at the Museum of Comparative Zoology (Jerry’s and my alma mater), and got a chance to visit with Dick Lewontin, Jerry’s Ph.D. advisor, and my de jure Ph.D. advisor (my actual advisor, E. E. Williams, was retired, and so could not officially be my advisor). WEIT readers may recall that Jerry posted greetings for Dick’s 90th birthday earlier this year. I went to see Dick with Steve Orzack, another one of Dick’s Ph.D. students, who took the two pictures below.

Visiting with Dick Lewontin, Cambridge, Mass., 21 June 2019. Picture by Steve Orzack.

We chatted for an hour or two about various things. Steve and I both had some things we wanted to ask Dick about, one of mine being whether Dick’s advisor, Theodosius Dobzhansky, was Russian or Ukrainian. (Wikipedia claims he’s Ukrainian, and I once had a Ukrainian complain to me about an exhibit about Dobzhansky that I curated that referred to him as Russian.) Dick was adamant that Dobzhansky was Russian, noting that he spoke Russian at home with his wife, thought of himself as Russian, and had Russians as his lab assistants and technicians. Historians, friends, and colleagues of “Dodik/Doby” have always called him Russian, so I was not surprised by Dick’s response.

Dick hams it up for the camera. Picture by Steve Orzack.

Dick also regaled us with stories of when he worked with Buckminster Fuller on geodesic domes back in the ’50s, when Dick was at North Carolina State. Bucky, he assured us, did not understand the geometry of solids! Dick mentioned that he considered leaving academia to work full time with Fuller, but was now glad he hadn’t, as Fuller’s company went under a few years later. Steve replied that if Dick had joined the company full time, Dick could have saved the company!

Dick has given up essentially all his space at the Museum, and most of his papers (correspondence, etc.) have been taken by the American Philosophical Society, (which also has a considerable trove of Dobzhansky material), and Dick has given his books to the Ernst Mayr Library– the library of the Museum of Comparative Zoology. This is appropriate, as Ernst Mayr, while Director of the MCZ from 1961-1970, engaged in correspondence with Dick on “genetical problems” (Haffer , 2007:265), and pushed for the building of the Museum of Comparative Zoology Laboratories, the MCZ’s lab wing, completed in 1973 (Mayr, 1973), of which Dick’s fly lab was one of the first inhabitants, arriving at Harvard in that opening year. (Dick mentioned that the proximity of the MCZ to his summer place in Vermont, which he’d had to travel to by train from Chicago, was a consideration in moving from the University of Chicago to Harvard.)

Dick’s books are being sorted, and I looked though several of them, finding a number of interesting inscriptions. First, a set of inscriptions from Mayr himself. These show that Mayr was presenting Dick with his books as early as March 1969, prior to Dick’s arrival at Harvard. I’m not sure if discussions involving Dick’s movement to the MCZ had begun this early.

To Dick Lewontin, | evolutionary geneticist, |who appreciates the importance of systematics, | in friendship | Ernst | March 1969

The ISBN stamp on the following cover page (and some further below) are from a cataloging effort in Dick’s personal library, not from the MCZ Library.

To Dick Lewontin | fellow worker in the evol. vineyard, | in the hope that he will crack | some of the nuts that were too hard for me! | With best wishes | Ernst | Christmas 1976

 

To Dick Lewontin | to whom I owe so much intellectual | stimulation | in friendship and admiration | Ernst

 

For Dick Lewontin | whose deep understanding of genetics | I admire beyond words (and song!) | in friendship | Ernst Mayr

[I am unsure of my transcription of the final word of the third line, “song”.]

 

For Dick Lewontin | in friendship and admiration | from the non-Marxist dialectic materialist | Ernst Mayr

The following is Dick’s MCZ bookstamp, which appears in many, though not all, of his books from his MCZ years.

The following is of interest, coming from Tom Schopf, one of the “young Turks” of paleontology in the early 1970’s, whom I mentioned in my tribute to David Raup.


To Dick Lewontin | I hope you will enjoy this effort to make invertebrate paleontology a “creative, chancy young man’s game” | As you will see from citations to your | work, you have had a large influence. | And I look forward to your continuing | analysis of problems critical to paleontologists. | Tom | December 2, 1972

The following is an inscription to Dick from a younger colleague, Jonathan Losos, on his book Lizards in an Evolutionary Tree. Note that Dick had been Jonathan’s intro bio professor!

Dick, | With great appreciation for the influence you have had on my | career through your writings, your teaching | of my introductory biology class) of which | I have vivid recollections) and your | helpful conversations with specific | reference to points herein. | Jonathan

And finally, some inscriptions from Dick’s Ph.D. advisor, Theodosius Dobzhansky. These I got from Dick several years ago, when I visited him while preparing my exhibit on Dobzhansky. I used all three inscriptions in the exhibit. The first is on a copy of the third edition of Dobzhansky’s classic Genetics and the Origin of Species. It was published in 1951, which is about the time Dick went to Columbia to work with Dodik. (Dick was in the Harvard class of 1950, but since he had been “rusticated” for a year, he actually graduated in 1951.) The inscription isn’t dated, but it seems to be earlier than the other two, referring to Dick’s “scientific youth”, and his “coming” eminence. According to Dick, Dodik referred to finishing graduate students as “soon to be professor” (as did Dick himself), so this inscription is probably early in Dick’s grad school days.

To Dick Lewontin, the coming | eminent geneticist, in his scientific | youth, with best wishes of continued | success | Th Dobzhansky

The next inscription is on a bound set of numbers I to XX of Dobzhansky’s monumental series of paper on “The Genetics of Natural Populations”. These 20 papers were published from 1938 through 1952. It is interesting that Dodik refers to the greater success of succeeding generations; the inscription was made only 5 years before Dick published his groundbreaking papers with Jack Hubby on allozyme polymorphism, confirming Dodik’s long-argued view that genetic variation was abundant and “normal” in natural populations.

Progress of science means that | succeeding generations do better than | preceding generations— and this | is what is to happen when the | genetics of natural populations | is investigated by my old | friend and spiritual son, | Prof. R. Lewontin! | Th Dobzhansky | New York, February 4, 1961

The final inscription is on a bound set of numbers XXI-XL of “The Genetics of Natural Populations”, published from 1953 through 1968. This inscription is undated but necessarily postdates initial Dick’s work on allozymes. There were three more papers in the series to come, published from 1969 through 1976; for the last, Dobzhansky was a posthumous coauthor, having died in December,1975. (The notation “GNP | XXI-XL” was made by me on the copy I made, and is not on the original.)

These lucubrations of the | old age of Th. Dobzhansky | dedicated to the super-star | R.C. Lewontin

You can see in these inscriptions the development of Dobzhansky’s appreciation of Dick as a scientist, from promising “youth”, to “old friend and spiritual son” (Dobzahnsky had one child, a daughter), and finally to “super-star”. You can also see Dodik’s colloquial phrasing and sense of humor, also evident in his  aphorism, “Heaven is where, when the experiment is over, you don’t need statistics to figure out what happened.” (Which Dick reconfirmed, on my latest visit, was indeed Dodik’s.)


Haffer, J. 2007. Ornithology, Evolution, and Philosophy: The Life and Science of Ernst Mayr 1904-2005. Springer, Berlin

Hubby, J. L., and R. C. Lewontin. 1966. A molecular approach to the study of genic heterozygosity in natural populations. I. The number of alleles at different loci in Drosophila pseudoobscura. Genetics 54:577-594.

Lewontin, R. C., and J. L. Hubby. 1966. A molecular approach to the study of genic heterozygosity in natural populations. II. Amount of variation and degree of heterozygosity in natural populations of Drosophila pseudoobscura. Genetics 54:595-609.

Losos, J.B. 2009. Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles. University of California Press, Berkeley.

Mayr, E. 1969. Principles of Systematic Zoology. McGraw-Hill, New York.

Mayr, E. 1973. Museums and biological laboratories. Breviora 416, 7pp. BHL

Mayr, E. 1976. Evolution and the Diversity of Life. Harvard University Press, Cambridge, Mass.

Mayr, E. 1988. Toward a New Philosophy of Biology. Harvard University Press, Cambridge, Mass.

Mayr, E. 1991. One Long Argument. Harvard University Press, Cambridge, Mass.

Mayr, E. 1997. This is Biology: the Science of the Living World. Harvard University Press, Cambridge, Mass.

Schopf, T.J.M., ed. 1972. Models in Paleobiology. Freeman Cooper, San Francisco.

Teaching Evolution: Richard C. Lewontin: The genetic basis of evolutionary change

May 10, 2018 • 11:00 am

by Greg Mayer

Our seventh installment of Teaching Evolution is an extract from The Genetic Basis of Evolutionary Change by Richard C. Lewontin. As regular WEIT readers will know, Dick was Jerry’s Ph.D. dissertation advisor (and mine too in the de jure sense, since my de facto advisor, Ernest E. Williams was retired). In this book, Dick summarized and critiqued the initial results of the “find ’em and grind ’em” school of population genetics, which studied electrophoretically detectable allelic variation in soluble proteins. In the extract chosen, he lays out the basic questions of population genetics, and how, historically, they have been addressed. It turns out that protein electrophoretic data were inadequate to our needs, leading to a further “struggle to measure variation”, leading eventually to nucleotide sequencing.  The last of Dick’s books mentioned below is a collection of reviews from the New York Review of Books; it contains “Sex, Lies, and Social Science” (and the subsequent exchange), which along with Peter Medawar’s takedown of Teilhard de Chardin, and E.E. Williams’ takedown of Soren Lovtrup, is among the best book reviews ever.

Richard C. Lewontin (b. 1929) is Alexander Agassiz Professor of Zoology Emeritus in the Museum of Comparative Zoology at Harvard University. One of the most influential population geneticists of the 20th century, he studied under Th. Dobzhansky at Columbia. His work has centered around what he has called “the struggle to measure variation”, and the interpretation of that variation in terms of the evolutionary forces acting on populations. In 1966, he and Jack Hubby at the University of Chicago, and, independently Harry Harris in England, introduced the technique of protein gel electrophoresis to the study of genetic variation in natural populations and showed that there is abundant variation in nature. His student Marty Kreitman was the first to use DNA sequencing to study variation, which, like electrophoresis before it, has revolutionized empirical population genetics. Lewontin’s books include The Genetic Basis of Evolutionary Change (1974), Human Diversity (1982), The Triple Helix (2000), and It Ain’t Necessarily So: the Dream of the Human Genome and Other Illusions (2000).

Reading:
Lewontin, R. C. 1974. The Genetic Basis of Evolutionary Change. Columbia University Press, New York. Extracts from Chap. 1, “The Structure of Evolutionary Genetics” (pp. 3-6), and Chap. 2, “The Struggle to Measure Variation” (pp. 19-38 and pp. 86-94). (access to entire book)

Study Questions:
1. What does Lewontin see as the most essential part of Darwin’s contribution? Why does this contribution make the study of genetic variation crucial for the study of evolution?

2. What are the “classical” and “balance” schools of population genetics? What are the views of these schools on the nature and amount of variation in natural populations, the modes of natural selection acting in natural populations, and the genetics of speciation?

3. What degree of variability in populations is inferred from the study of visible mutations, and from the study of the results of artificial selection? How do these estimates compare to one another?

4. How would DNA sequences, as opposed to mere identification of protein alleles (as is done in electrophoresis), provide richer information for addressing the questions posed by Lewontin? In particular, how would they provide better data on the nature of selection? (The answer to this is not in the reading.)

More on biology and race

August 29, 2017 • 9:15 am

by Greg Mayer

Jerry posted yesterday on an article at Quillette by Bo Winegard, Ben Winegard and Brian Boutwell on biology and race, commending it for its sensibleness. I thought I’d chime in with my own thoughts. Jerry’s a population geneticist and I’m a herpetologist, but our views turn out to be quite similar.

So, here, in a nutshell, is what biology has to say about race. To begin with, race is not a technical term in biology—it is used loosely for any differentiated subdivision of a species. For example, there is a fruit fly in Wisconsin that feeds on hawthorn and apple, and the flies that feed on the different trees are somewhat different, and so people refer to the “hawthorn race” and the “apple race”. Often, as in fact is true in this case, the term “race” is used because people aren’t quite sure exactly how different the forms are from one another.

In zoology, the term “geographic race” does have a well-defined meaning. It means that if you look at an individual of a species, you can tell where it is from, or conversely, that if you tell me where the individual is from, I can tell you what it looks like. For example, there’s a species of lizard in Jamaica that if you brought one back and showed it to me, I could tell you whether it’s from the vicinity of Kingston, or Montego Bay, or Negril, etc. Lizards from these various places are members of the same species because they interbreed with one another where they are in geographic proximity; they are geographic races because I can tell where they are from by looking at them. Geographic races, if they are given taxonomic names, are called subspecies.

With regard to humans, most of the genetic variability is within populations, not between local populations or races. This was pointed out by Dick Lewontin in 1972 (Dick, of course, was Jerry’s dissertation adviser, and my de jure adviser). However, just because most of the variation is within populations doesn’t mean you can’t tell where someone is from by looking at him. The geneticist A.W.F. Tony Edwards later called the mistaken notion that a majority of variation being within populations precludes identification of population membership “Lewontin’s Fallacy”. [I’ve no idea where I got the idea he was called “Tony”. I’ve never met him, and people who do know him have assured me he’s called “Anthony”.]

As a former student of Lewontin’s, I’m not especially fond of Edwards’ choice of term, but nonetheless Edwards is entirely correct. It is of crucial importance to note that the scientific questions asked by Lewontin and Edwards were different. Lewontin asked “What proportion of genetic variation (in the analysis of variance sense) in humans is within and among populations?” The answer is that roughly 85% is within populations, the rest among local populations and races. That is the answer Lewontin gave in 1972, and it is entirely correct, confirmed by much more molecular data since that time. Edwards asked “Can individual humans be assigned to races from genetic data?”, or, alternatively, “Can human races be diagnosed (in the taxonomic sense of subspecies)?” The answer is yes, they can. Edwards shows that his answer to his question is entirely compatible with Lewontin’s answer to Lewontin’s question. A paper by Rosenberg et al. (2002) clearly illustrates for a large data set the truth of both Lewontin and Edwards’ answers to their respective questions. Lewontin goes on from his finding (with which Edwards entirely agrees), to argue further that this level of difference between races is not worthy of taxonomic recognition. Edwards doesn’t actually express an opinion about whether human races should be recognized taxonomically, but does show that the 85/15 division of within/among population variation is no bar to doing so.

One thing a bit off in the Quillette piece is their claim that Lewontin’s conclusion “was based on a peculiar way of measuring genetic variation.” It was not; it was based on a perfectly natural and obvious way of measuring genetic variation, and, indeed, Dick was right, as Edwards acknowledged. The distinction between single and multi-locus genotypes mentioned by Winegard et al. does not at all nullify Lewontin’s conclusion as to the apportionment of variation. What Edwards showed very clearly is that multi-locus genotypes allow individuals to be reliably assigned to populations, even when most of the variation is within populations. In understanding patterns of genetic variation in humans, it is very important to see that Lewontin and Edwards asked different questions, and that they are both right in their answers to their respective questions.

Lewontin and Edwards agree on the moral equality of human beings; Edwards just doesn’t want that moral equality to depend on any contingent facts of genetic similarity. Lewontin wouldn’t want it to, either, but sees the high genetic similarity among human races (genetic similarity is much lower among races in some other species) as empirical reinforcement for his moral conclusion. 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. Because it does not depend on some empirical finding which new data may put into question, I think Edwards has the more robust basis for his moral conclusion.

As Edwards sums up:

“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.”


Edwards, A.W.F. 2003. Human genetic diversity: Lewontin’s fallacy. BioEssays 25:798–801. pdf

Lewontin, R.C. 1972. The apportionment of human diversity. Evolutionary Biology 6:381-398. pdf

Rosenberg, N.A., J.K. Pritchard, J.L. Weber, H.M. Cann, K.K. Kidd, L.A. Zhivotovsky, and M.W. Feldman. 2002. Genetic structure of human populations. Science 298:2381-2385. pdf

Dick Lewontin and Tomoko Ohta nab the Crafoord Prize

January 15, 2015 • 11:27 am

I’m so pleased: my Ph.D advisor, evolutionary geneticist Dick Lewontin, has received the prestigious Crafoord Prize in Biosciences this year, along with Japanese theoretician Tomoko Ohta. The press release announcing it (and describing their contributions) is here, and there’s also a video that you can see by clicking on the screenshot at the bottom.

Lewontin made major contributions in both experimental and theoretical population genetics, with his most famous finding being the revelation of substantial genetically-based polymorphism (variation among individuals) in the sequences of proteins, a finding confirmed by subsequent DNA sequencing. Ohta, a theoretician, made fundamental contributions in explaining why that variation is there, especially variation that is “neutral” and doesn’t affect the fitness of an individual. They are deserving recipients.

The prize is 6 million Swedish kroner, which works out to be about $737,000 US.

Screen Shot 2015-01-15 at 11.17.16 AM

The human genome ten years on (part 2) – it ain’t necessarily so

June 14, 2010 • 11:14 am

by Greg Mayer

In a post a couple of months ago, Matthew took note of the tenth anniversary of the completion of the draft human genome, noting that Nature had published a retrospective.  Matthew rightfully took issue with the dreadful “blueprint” metaphor for the genome, but also concisely noted the meager medical results:

…despite all the hype, the contribution of the genome to human health has been pretty negligible. In other words, from a purely medical point of view, there isn’t much to celebrate.

In yesterday’s New York Times, Nicholas Wade provides a journalistic analysis, and confirms that the results so far are disappointing. Money quote:

…the primary goal of the $3 billion Human Genome Project — to ferret out the genetic roots of common diseases like cancer and Alzheimer’s and then generate treatments — remains largely elusive. Indeed, after 10 years of effort, geneticists are almost back to square one in knowing where to look for the roots of common disease.

This does not come as much of a surprise when you realize that most diseases are not genetically caused (in any straightforward reading of the word caused); that even when there is a genetic basis, the genetics are apt to be complex; and that even when simple, identification of a gene does not lead readily to a cure. These issues were raised most presciently by Dick Lewontin, especially in an essay-review (subscription required) he wrote for The New York Review of Books in 1992. Dick decried scientists’ selling the genome project to governments on the basis of its health benefits, while in fact the project would primarily advance disciplinary (and, in some cases, financial) interests. Endorsing Dick’s genetic arguments, I wrote the following in 2000, at the time of the announcement by Bill Clinton and Tony Blair:

Few diseases are caused by a “gene.” Most diseases, in fact, are caused by the invasion of the body by another organism (bacteria, viruses, protozoa). Our susceptibility and resistance to disease may often have a genetic basis, but these too are usually the result of multiple genes in interaction with the environment. Even when a disease does have a singular genetic cause, finding the gene does not necessarily lead easily to treatment or prevention (e.g. cystic fibrosis).

Last year, over at Mermaid’s Tale (in a post I noted here at WEIT), Ken Weiss put it succinctly (he also discusses Wade’s new NYT article here):

…most common diseases have little to do with genetic variation in any sensible way.

The genome project has provided much useful scientific information. As Wade notes, “For biologists, the genome has yielded one insightful surprise after another.” But that’s not why the project was done. Bill Clinton said it would lead to treatments for “most, if not all, human diseases”; Francis Collins said we’d have genetic diagnosis of diseases within ten years. The genome project’s architects oversold it’s medical (not to mention philosophical) benefits, and now scientists (or at least genome scientists) will lose credibility because of it. Harold Varmus is quoted by Wade as saying “Genomics is a way to do science, not medicine.” If only that had been said louder, and earlier, and by more people.

[PZ and some others are taking Wade to task for saying “humans… [are] higher on the evolutionary scale”. While this is an inopportune use of the scala naturae, it’s part of one paragraph (which does make the interesting point that genome size, as measured by number of protein coding genes, does not vary very widely among metazoans), and does not detract at all from the main thrust of the article.]

More on Dick Lewontin and WEIT: what’s the deal with natural selection?

May 12, 2009 • 6:58 am

Several days ago I called attention to Richard Lewontin’s review of WEIT and several other books in The New York Review of Books.  In it, Dick (excuse the informality, but he was my Ph.D advisor) praises the book but takes me to task for implying that the evidence for natural selection is as strong as the evidence for evolutionary change per se:

Where he is less successful, as all other commentators have been, is in his insistence that the evidence for natural selection as the driving force of evolution is of the same inferential strength as the evidence that evolution has occurred. So, for example, he gives the game away by writing that when we examine a sequence of changes in the fossil record, we can

“determine whether the sequences of changes at least conform to a step-by-step adaptive process. And in every case, we can find at least a feasible Darwinian explanation.”

But to say that some example is not falsification of a theory because we can always “find” (invent) a feasible explanation says more about the flexibility of the theory and the ingenuity of its supporters than it says about physical nature. Indeed in his later discussion of theories of behavioral evolution he becomes appropriately skeptical when he writes that

“imaginative reconstructions of how things might have evolved are not science; they are stories.”

While this is a perfectly good argument against those who claim that there are things that are so complex that evolutionary biology cannot explain them, it allows evolutionary “theory” to fall back into the category of being reasonable but not an incontrovertible material fact.

There is, of course, nothing that Coyne can do about the situation. There are different modes of “knowing,” and we “know” that evolution has, in fact, occurred in a stronger sense than we “know” that some sequence of evolutionary change has been the result of natural selection. Despite these misgivings, it is the case that Coyne’s book is the best general explication of evolution that I know of and deserves its success as a best seller.

This “critique” has been picked up by several bloggers (see below), and I want to respond in a bit more detail.

First of all, yes, it’s true that the evidence for natural selection as the cause of most evolutionary change in the past is not as strong as the evidence that evolutionary change occurred.  It cannot be otherwise.  We can see evolution happening in the fossil record, but it is infinitely harder to parse out the causes of that change.   We weren’t around when it occurred, so we must rely on inference.  This difficulty is one reason why it took biologists much longer to accept natural selection than to accept evolution.   But to say that the evidence for selection is weaker than for evolution does not mean that the evidence for natural selection is weak, a conclusion I fear that creationists will extract from Lewontin’s comment.

Here is why selection still seems the best hypothesis for the origin of adaptive features of organisms.

1.  It is the only scientific theory, among all of those that have been adumbrated, that currently makes sense.  Failed explanations include teleology, intelligent design, and Lamarckism.  Some of these were once valid scientific alternatives to natural selection, but have failed either because they are untestable or because they were testable and shown to be wrong. If Lewontin and others want to say that some process other than selection is responsible for the limbs of tetrapods, the fins of whales, and the white color of polar bears, they must say what they envision.  Yes, Lewontin and Gould showed that many things for which we can concoct adaptive stories may be “spandrels” — nonadaptive traits hitchhiking on other adaptations — but this does not mean, as Lewontin seems to imply, that selection may not play a major role in creating adaptations.

2.  In cases where we can actually investigate whether selection is responsible for an adaptive change in a species, it is.  I give several examples in WEIT, including coat colors in mice and the famous work of Rosemary and Peter Grant on Darwin’s finches. And of course there are those dozens of cases of antibiotic resistance in bacteria, insecticide resistance in arthropods, and herbicide resistance in weeds.  In bacteria, for instance, we can show that the genetic variation for resistance preexisted in the population and not invoked by the selective agent, precisely as the theory of natural selection posits.

3.   In tests where we envision that selection was responsible for an adaptation, we can do laboratory tests to see if the adaptation at least gives a fitness advantage to those individuals possessing it.  One example of this is the Browers’ work on Batesian mimicry in the viceroy butterfly.  It was shown that exposure to a toxic monarch made naive bluejays sick, and that later these bluejays avoided the nontoxic viceroys, giving a survial advantage to mimics.  This is precisely what has to happen for that mimicry to evolve by natural selection.  Likewise with color in guppies:  brightly colored guppies get eaten more often in Trinidadian streams than do their duller confreres.  This explains why guppies are less colorful in predator-filled streams.

4.  The prerequisites for selection — the heritability of traits, the fact that there is competition between individuals, and that there are fitness differences between individuals with different traits — have all been demonstrated in living organisms in nature.  If few traits showed any heritable genetic variation, we’d be justified in rejecting selection as a major cause of evolution. Guppy coloration is heritable.

5.   Even in ancient species we can test the likelihood that selection caused evolutionary change.  Horses lost their toes right about the time when the forests were disappearing on the Great Plains.  We know that hooves are more effective adaptations for running in open grassland than are multi-toed feet. Likewise, horse teeth become higher and more robust precisely when silicon-rich grasses were replacing the leafy forests.  We know that herbivores need higher and more robust teeth to deal with grass. It is a good inference that the appearance of grassland was the selective factor promoting the loss of horse toes and the change in horse teeth.

6.  As discussed in previous posts, selection as we envision it has certainly been adequate to explain the evolution of complex adaptations like the eye, and in geologically reasonable periods of time.  Therefore it remains a viable hypothesis for adaptive change. This didn’t have to be the way it turned out.

What about my supposed double standard about accepting natural selection for many traits but being skeptical when it comes to evolutionary psychology?  This is a reasonable tactic for one important reason: we have many more alternative theories for the appearance of human behavioral traits than we do for morphological adaptations in other species.  How many alternative theories do we have for the appearance of flippers in proto-whales, or for the movement of their nasal passages to the top of their heads?  In contrast, there are many alternative theories for the appearance of traits like human rape, depression, music, art, religion, etc.  Blowholes aren’t likely to be spandrels; the appearance of music and poetry might well be.  Humans have culture and rationality to a degree possessed by no other animal, and can learn many things not permitted in species having smaller (or no) brains.   That’s why we need to be more cautious about imputing selection to human behaviors than to blowholes.

Now I think Dick did have a point: I should have pointed out (though I might have; I can’t remember!) that it is a lot easier to come up with evidence for evolution than for selection.  But I think Lewontin’s own anti-selectionist biases are intruding here. As I mentioned in an earlier post on ideological grounds neither he nor Gould were ever very strong promoters of selection. I’m not sure what the connection is between selection and politics (it may be the misuse of selectionism that Gould and Lewontin saw among sociobiologists), but neither of these chaps were avid promoters of selection.  They preferred to emphasize other processes, including pleiotropy, spandrels, genetic drift and the like. I think this was a deliberate strategy.

Over on EvolutionBlog, Jason Rosenhouse analyzes Dick’s review and has some good comments:

I don’t understand what it means to say that “natural selection is the driving force of evolution.” Given Lewontin’s past writing (most notably his spandrels paper with Stephen Jay Gould) I would guess that his point is that some biologists are too quick to attribute some anatomical feature of some organism to the prolonged working of natural selection.

That may be true, but when we are talking about adaptations the evidence for natural selection seems to me to be very strong. For one thing, it is the only natural mechanism known that can account for complex structures (like bird wings or vertebrate blood clotting systems). For another, every complex structure studied to date shows clear evidence of being a cobbled together Rube Goldberg machine, which is exactly what we would expect if they were crafted by natural selection.

On top of this, biologists routinely use adaptive reasoning to generate testable hypotheses about the creatures they are studying. Lewontin would know better than I whether biologists engaging in flights of fancy is a genuine problem in the field, but it is undeniable that “the adaptationist program” has yielded great dividends over the years . . .

. . In fairness, I think Stephen Jay Gould was pretty clear on this point [the ubiquity and importance of selection] in several of his essays. I compiled some of his statements on the matter in this essay. But I share Coyne’s frustration. I’ve never really understood what it is exactly that anti-selectionists are complaining about. If they agree that complex adapations arise as the result of gradual accretion mediated by natural selection, then I fail to see how they are really so different from people like Richard Dawkins or Daniel Dennett (two people often described as being beknighted uber-selectionists). If they do not agree then I would like to hear their proposed alternative mechanism.

Now I have great affection for Lewontin (as all of his students say, “I love that man”), but I would like to see him make an explicit statement about what aspects of nature he imputes to natural selection.  We’re not just talking about rape, male domination, and music here, but coat colors, physiology, feathers, gills, flowers, toxins, and the like.  Like Jason, I think the anti-selectionists have gone way, way overboard, and have thrown out the baby with the bathwater.  (These people also include the “structuralists,” and those who attribute adaptations to the self-organizing properties of biological matter.)

Dick Lewontin reviews Brown, Gibson, Darwin, and Coyne in the NYRB

May 8, 2009 • 11:00 am

Richard Lewontin (who, I confess, was my Ph.D. advisor at Harvard) reviewed WEIT and three other books in the latest New York Review of Books (Janet Browne’s Darwin’s Origin of Species: A Biography, James Costa’s The Annotated Origin,  Greg Gibson’s  It Takes a Genome: How a Clash between Our Genes and Modern Life is Making Us Sick.)

As usual, Dick’s intellectual energy (and immense knowledge) takes him far beyond the bounds of the books under review. He traces Darwin and Wallace’s theory back to the socioeconomic climate of Victorian England, explores the hagiography of Darwin, and takes on the hegeomony of selection (this harkens back to his and Steve Gould’s famous –and explicitly antiselectionist — paper, The Spandrels of San Marco).  He does disagree somewhat with how I dealt with selection in WEIT:

The scientific community has the definite sense of being embattled and one of its responses is to use the two hundredth anniversary of the birth of its apostle of truth about the material basis of evolution and the 150th anniversary of the appearance of his gospel to carry on the struggle against obscurantism. Jerry Coyne’s Why Evolution Is True is intended as a weapon in that struggle.

Coyne is an evolutionary biologist who, like his former student H. Allen Orr, has been a leader in our understanding of the genetic changes that occur when species are formed. His primary object in writing this book is to present the incontrovertible evidence that evolution is a physical fact of the history of life on earth. In referring to the theory of evolution he makes it clear that we do not mean the weak sense of “theory,” an ingenious tentative mental construct that might or might not be objectively true, but the strong sense of a coherent set of true assertions about physical reality. In this he is entirely successful.

Where he is less successful, as all other commentators have been, is in his insistence that the evidence for natural selection as the driving force of evolution is of the same inferential strength as the evidence that evolution has occurred. So, for example, he gives the game away by writing that when we examine a sequence of changes in the fossil record, we can “determine whether the sequences of changes at least conform to a step-by-step adaptive process. And in every case, we can find at least a feasible Darwinian explanation.”But to say that some example is not falsification of a theory because we can always “find” (invent) a feasible explanation says more about the flexibility of the theory and the ingenuity of its supporters than it says about physical nature. Indeed in his later discussion of theories of behavioral evolution he becomes appropriately skeptical when he writes that “imaginative reconstructions of how things might have evolved are not science; they are stories.”  While this is a perfectly good argument against those who claim that there are things that are so complex that evolutionary biology cannot explain them, it allows evolutionary “theory” to fall back into the category of being reasonable but not an incontrovertible material fact.

There is, of course, nothing that Coyne can do about the situation. There are different modes of “knowing,” and we “know” that evolution has, in fact, occurred in a stronger sense than we “know” that some sequence of evolutionary change has been the result of natural selection. Despite these misgivings, it is the case that Coyne’s book is the best general explication of evolution that I know of and deserves its success as a best seller.

I have to say that Dick has indeed hit on a tricky issue in compiling the evidence for evolution.  While natural selection is the only reasonable explanation for the evolution of adaptations, we cannot in most cases do more than adduce its plausibility.  Direct demonstrations are rare (note to creationists: this is only because they’re HARD TO DO, so don’t take this out of context), and demonstrations in the past nearly impossible.  And I should have talked more about this in WEIT (although we have discussed it on this website).  But I can’t help but sense Dick’s own anti-selectionist views here:  views that may stem from seeing others support preconceived biases by invoking soft adaptationism , and views that were of course instrumental in Lewontin and Gould’s battle against sociobiology in the 1970s.   When I was at Harvard with Dick and Steve, it was almost as though selection was a forbidden topic — just once I would have liked either of them to have admitted openly, “Yes, of course selection is the only plausible explanation for adaptations.”  In their fight against unthinking adaptationism, they nearly threw the baby out with the bathwater.

Nevertheless, Dick has a point.  But I’m glad he that he seems to have liked the book.  As one friend wrote me today:

An interesting piece.  Lewontin certainly can’t be accused of lobbing his old student a batting-practice pitch!  Even so, I see that he was careful to supply a line that would serve perfectly in an ad: “Coyne’s book is the best general explication of evolution that I know of and deserves its success as a best seller.”

Oh, and for those who didn’t see this before, Dick turned 80 this year.

Dick Lewontin is 80 today

March 29, 2009 • 5:15 am

My Ph.D. advisor, mentor, and friend Richard C. “Dick” Lewontin turns 80 today.  Still active at Harvard’s Museum of Comparative Zoology, churning out pieces for The New York Review of Books (here’s a good exemplar), and chopping wood on his Vermont farm, let no one say that Dick has reached his dotage.  Distressing to the rest of us who are ageing fast, Dick has only a few gray hairs and wrinkles, and looks pretty much as he did when I came to his lab in 1973.   On his 70th birthday, several hundred of his former students, postdocs, and collaborators assembled at Harvard for “Dickfest”, and there will be a “Dickfest II” this summer.   This is not the place for me to wax effusive about Dick’s many talents as researcher, writer, and teacher; just let me say that I dedicated WEIT to him.  Hoist one for the “old” guy today.

richard_lewontin

If you’d like to see him in action, eloquent as always, below is an hour-long interview (“Conversation with History”) he did with Harry Kreisler at Berkeley:

Coat color in wolves

March 6, 2009 • 11:08 am

by Greg Mayer

An alert reader has directed my attention to an interesting paper on coat color in wolves (abstract only without subscription) in today’s issue of Science by Tovi Anderson of Stanford and 14 colleagues from the US, Canada, Italy, and Sweden. Coat color in wolves is a polygenic trait affected by age, but Anderson and her colleagues show that black color in young wolves is associated with a 3 base-pair deletion in a gene called CBD103, and that there is a habitat correlation with the frequency of this color: black wolves live in the forests, gray (or white) wolves on the tundra.  This would be very interesting on its own, but Anderson et al. go further.  By careful phylogenetic analyses, they show that the gene for black color has entered North American wolves, and coyotes and Italian wolves as well, by hybridization with domestic dogs; and that the gene has been subject to recent positive natural selection (shown by low variability in the part of the chromosome immediately surrounding the gene, indicating what is known as a “selective sweep”).  Thus, a correlation between habitat and coat color that is suggestive of adaptation, is shown to be based on heritable variation undergoing natural selection.

The sort of combined field and lab study done by Anderson et al., using classical genetics (they have pedigrees of the wild wolves!), ecology, and now molecular genetics, is among the kind of work that first attracted me to evolutionary biology, and is known as ecological genetics. This field of study, pioneered by the great British geneticist E.B. Ford, was once characterized by the great American geneticist Dick Lewontin as carrying on the British “genteel upper-middle-class tradition of fascination with snails and butterflies”; I’m glad the fascination has moved to some of the colonies and beyond, and been extended to wolves, coyotes, and dogs.