One of the most widely cited and discussed articles in evolutionary biology is “The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme”, which was written by Harvard biologists Stephen Jay Gould and Richard C. Lewontin and published in the Proceedings of the Royal Society of London in 1979. Their critique of their own field of evolutionary biology spilled out of the Ivory Tower onto the pages of general intellectual forums such as the New York Review of Books.
Gould died in 2002 but his coauthor is still active. Richard C. Lewontin is a population geneticist by training and pioneered the method of gel electrophoresis among many other accomplishments. His academic books include The Genetic Basis of Evolutionary Change (1974), which I eagerly read as a graduate student. His biological books for the general public include The Triple Helix: Gene, Organism, and Environment (2002) and Human Diversity (part of the Scientific American Library Series; 1982). In his role as social critic and theorist, his books include Biology Under the Influence: Dialectical Essays on Ecology, Agriculture, and Health (with Richard Levins; 2007), It Ain’t Necessarily So: The Dream of the Human Genome and Other Illusions (2001), Biology as Ideology: The Doctrine of DNA (1993), and Not in Our Genes: Biology Ideology, and Human Nature (with Leon J. Kamin and Steven Rose; 1984). Finally, Lewontin has served as a mentor for many PhD and postdoctoral students, in philosophy in addition to biology, including my longstanding philosophical collaborator Elliott Sober.
I talked by phone with Lewontin on March 2 2015. In his mid-eighties, he is still scientifically active and could recall his collaboration with Gould in detail. Our conversation is highly relevant to the “Just so story” critique that is frequently leveled against Evolutionary Psychology.
DSW: I’m so happy to be talking with you and thanks for making the time.
RL: I don’t know if anything I can say to you at this stage has any usefulness.
DSW: I think that is overly humble on your part.
RL: You can’t be overly humble.
DSW: That’s true. Humility is a religious virtue but it is also a secular virtue and a scientific virtue. I couldn’t agree more. I am interested among other things in social history. To get started, you are one of the preeminent evolutionary biologists of our time—many achievements. In 1979 you felt the need to write this article with Stephen Jay Gould that became a classic.
RL: Sorry—which article is that?
DSW (laughs): The Spandrels of San Marco.
RL: I thought it was but I didn’t remember the exact date.
DSW: I wonder if you could tell me—what were the circumstances that moved you and Steve Gould to write this article?
RL: Sure, I can give it to you in detail. I was invited by, I think it was the Royal Society, to come and give a lecture. For one reason or another that I can’t remember, I couldn’t go. So I asked if it would be alright if I asked Steve Gould if he would go in my place–Steve and I were teaching evolution together—and they said sure. So Steve went and he gave a talk from the standpoint of what interested him at the time, which was the notion that some traits arise simply as a structural byproduct of selection on other traits, and he chose to call them spandrels. I did make a contribution to the written version of that article, but most of it was Steve’s.
RL: Now I should warn you about my prejudices. Steve and I taught evolution together for years and in a sense we struggled in class constantly because Steve, in my view, was preoccupied with the desire to be considered a very original and great evolutionary theorist. So he would exaggerate and even caricature certain features, which are true but not the way you want to present them. For example, punctuated equilibrium, one of his favorites. He would go to the blackboard and show a trait rising gradually and then becoming completely flat for a while with no change at all, and then rising quickly and then completely flat, etc. which is a kind of caricature of the fact that there is variability in the evolution of traits, sometimes faster and sometimes slower, but which he made into punctuated equilibrium literally. Then I would have to get up in class and say “Don’t take this caricature too seriously. It really looks like this…” and I would make some more gradual variable rates. Steve and I had that kind of struggle constantly. He would fasten on a particular interesting aspect of the evolutionary process and then make it into a kind of rigid, almost vacuous rule, because—now I have to say that this is my view—I have no demonstration of it—that Steve was really preoccupied by becoming a famous evolutionist.
DSW: So he was trying to grab center stage at every opportunity.
RL: Yeah, I think so.
DSW: Is the Spandrels paper like that?
RL: Well, I made a lesser contribution than he did. Most of the Spandrels paper was written by Steve. There is a section in there, which one can easily pick out, where I discuss the various factors and forces of evolution…
DSW: Yes, I can see that division.
RL: That paper never would have been written by us as a joint paper if I hadn’t asked Steve to go to the Royal Society and give a talk in my place.
DSW: Fascinating! To what extent was this paper motivated, either for you or Steve, by Sociobiology?
RL: Well, I don’t know to what extent it was motivated. Sociobiology was certainly contextually relevant. I think we would have written exactly the same paper if Sociobiology had never come into existence. Looking back, that’s hard to say, but I think the idea was to avoid selective caricatures, the making up of selective stories just because you felt you had to. That is, as you are aware, a very common phenomenon in writing about and teaching evolution. For example, why is blood red? The fact that hemoglobin happens to have that absorption spectrum in the visible is not sufficient for some people, who have to show that it’s a good thing that blood is red because it scares off predators who come and scratch you and stuff like that. So we had a lot of that sort of thing to deal with—what we called “Just so stories”.
DSW: So forget about Sociobiology—basically, you saw naïve adaptationism being a problem in general in the field of evolutionary biology?
RL: Exactly. It was really not Sociobiology itself, but a tendency to try to find, in every instance, some selective advantage for things. We were teaching the students—and Steve was not as keen on that as I was—that there are a whole variety of forces that give rise to observed traits and they are not all directly selected for.
DSW: This interests me very much. I’m interested to know that was the primary motivation for the article, not Sociobiology.
DSW: What’s the right way to do it? When I talk about the adaptationist program, I say that an adaptationist hypothesis is often the best way to start because it doesn’t require much information to know what an organism should be like to be well adapted to its environment. So it’s a good starting point, although certainly not the end point. Then the inquiry can go in a direction where you decide—as with the color of blood, by the way, an example that I use myself—that this is probably not an adaptation. You can arrive at the truth of the matter. But thinking in adaptationist terms is part of the process. So what’s the way to do it right and what’s the role of adaptationist thinking in an appropriate procedure?
RL: Well (laughs), you’re asking me what the right way to do it is. I think the right way is to start with the sentence: “We do not have any hard evidence of the forces leading to the following evolutionary change.” There has to be a prelude to the discussion of evolutionary change to make it clear that although the theory of natural selection is very important and happens lots, there are other forces, or other mechanisms, that lead to change and we are not obliged by being Darwinians and being evolutionists to invent adaptive explanations for all changes. I think that’s where you have to start. Then, as either a philosopher or biologist, ask in a particular case what is the direct evidence, besides the desire that we want to find something, that a particular story is true or not true. Most of the time we’re going to have to say that this happened in the Eocene or the Paleocene and we haven’t the foggiest notion of why it happened. I think the admission of necessary ignorance of historically remote things is the first rule of intellectual honesty in evolution.
DSW: Good. Thank you for saying that so clearly. At the same time, sometimes the past can be inferred with amazing certainty. All the historical sciences are like that, right?
RL: Right. And so, I think that the right general strategy for explanation, writing, and teaching is to begin with some really clear cut cases where we have in our very hands the evidence for a particular causal pathway–a greater reproduction and survivorship of one form versus another–and then move from that to living cases where we’re not quite so sure because we can’t actually count the number of offspring of each type, and so on, to somewhat hazier cases, and then go back to extinct organisms and evolutionary past and say, we could make up a good story, but we don’t know how to show that it’s really true.
DSW: Right. There is the humility again that began our conversation. Although I have to say that it was the lack of humility, in part, that caused the Spandrels article to become so widely read. Steve Gould the showman put that on center stage and it became a three ring circus for a long time, as you know. The adaptation wars and all that. I don’t know whether that is good or bad.
RL: All we can say is that sometimes the stories are right and sometimes they’re wrong. One way to deal with this is to take a case where we can in fact—because it’s present and we have the organisms, and we really test what’s going on. Take such a case and put it aside and don’t even mention the result of our determined discovery about it, and make up three stories, all of which sound perfectly biologically realistic and reasonable, and then give the right answer and say now, aside from the necessary observations and experiments—forget the real answer, why should we choose one of these versus another?
DSW: Uh Huh. Interesting.
RL: What we have to decide is whether we’re going to put behind us certain motivations, one of which is the general motivation to struggle against religious anti-evolutionary views, and at the other extreme to be as individuals successful as evolutionary biologists by giving an explanation of something interesting even when we don’t have the observations. I was raised not as an evolutionist but as a population geneticist.
RL: That’s a big difference.
DSW: Why is that a big difference? Let’s clarify that for me. I tend to see it as a small difference. What’s the difference between being a population geneticist and an evolutionist?
RL: A population geneticist by theoretical training has certain parameters of population change. That’s become broadened by the realization that there are between population changes and so on, but within a population we’re talking about changes in gene frequency and we have a catalog of the causes: selection, inbreeding, chance, mutation, and so on. Our job as population geneticists is to do the necessary observations of the various things that give us estimates of the strength of those different forces. Now, historically one of the most interesting—now I want to talk a little about the sociology of our science—Theodosius Dobzhansky, my professor and then greatest living evolutionary biologist…
DSW: Mr. “Nothing in biology makes sense except in the light of evolution…”
RL: Yeah, right. He was a very bad field observer. Theodosius Dobzhansky never, in his entire life, nor any of his students, me included—I would go out in the field with him, actually–ever saw a Drosophila pseudoobscura in its natural habitat.
DSW (laughs): Yeah, OK!
RL: We didn’t know where they laid their eggs. We couldn’t have counted the number of eggs of different genotypes. How did we study Drosophila in the wild? We went out into the desert, into Death Valley, we moved into a little oasis, we went first to the grocery store, and bought rotten bananas. We mushed up the bananas with yeast till they fermented a bit, we dumped that into the paper containers, put it out in the field and the flies came to us.
DSW: Right! No naturalistic context whatsoever.
RL: None…at…all. And to this day we do not know anything about the actual habitat of Drosophila pseudoobscura, although by the way, interestingly enough, in more recent years, Tim Prout actually succeeded in trapping pseudoobscura in orange groves, so we don’t even know how much they hang out with cultivated fruit.
RL: Now let me go one step further because we cannot understand the development of evolutionary biology if we don’t understand questions of the sociology of academic life. If I wanted to study evolutionary forces acting on some genetic polymorphism in Drosophila, I would go and look for some species of Drosophila where I could actually look at, perturb, and work with the actual breeding sites and egg laying sites and pick up larvae in nature and so on. And in fact there is such a group of Drosophila. They the cactophilic ones. There is a group [of scientists] from Texas and other places that studies the cactophilic Drosophila in an ecologically sensible way of going to the rot pockets and perturbing them, getting larvae out of them and so on. That group never acquired the prestige associated with the Dobzhansky school because—I don’t know why. They were doing what one has to do. That’s why, for example, I try to convince students who are entering evolutionary biology not to study animals at all but to study plants. Plants stay in one place. You can manipulate them. You can move them. Plants are much better than animals for studying things in nature. Yet, plant evolutionary biology is not, for sociological reasons that I don’t understand—I could make up stories—has never had the prestige that animal work has had when it comes to population genetics.
DSW: Right. I think that [there was an] all consuming interest in physical mechanisms as opposed to a more fully rounded approach. I place a lot of emphasis on the classic paper by Niko Tinbergen, “The Methods and Aims of Ethology”, in which he says that you have to ask four questions: Function, History, Mechanism, Development. Are you familiar with that paper?
RL: No, I’m not. Send me a reference to it.
DSW: It’s such a succinct summary of what a fully rounded approach needs to be. Dick, I’d like to spend a little bit of time on Sociobiology and also Evolutionary Psychology, because even though that didn’t motivate the Spandrels paper, it still motivated you to be a critic and Steve too. I wonder if you could bring us back to that point and what you saw as problematic about Sociobiology and then Evolutionary Psychology.
RL: This is what I have been talking about for the last five minutes. This is a branch of academic life that consists entirely, as far as I can see, of making up what would seem to be plausible stories. I would say that’s not what we are in business to do. I don’t know what else to say. Look, when I look at Sociobiology, the book or some of the other books he [E.O. Wilson] has written, it drives me mad. For example, if you read—I’ll take an extremely nasty example because it’s so clear—it is written that aggression is a part of human nature. It says that in the book. It lists features of human nature and aggression is one of them. So then I have said to Ed and others of his school, what do you do about people who have spent almost their entire lives in jail because they refuse to be conscripted into the army? What do you think the answer is? That is their form of aggression.
DSW: Well, OK, that’s facile.
RL: I don’t know what you can do about it. If everything can be said to be a form of aggression, even the refusal to be physically aggressive, what kind of science is that?
DSW: Would it be more acceptable to say that aggression is part of the repertoire of human behavior? That leaves it open to be part of the repertoire that we don’t always use.
RL: Before I will allow you to make even that statement, I will insist that you write down how I know whether any particular phenotypic manifestation is or is not included in your definition of aggression.
DSW: That’s fair.
RL: I don’t know what those people would say. But if you are willing to make a clear enough—and most important, and this is perhaps the fundamental contradiction, potentially there has to exist a group of cases of non-aggression. Because if everything by definition can be shown to be aggression then it ceases to be a useful concept in our scientific discussions.
DSW: The problem of explaining everything, and therefore nothing, recurs again and again. What were some of the political implications of Sociobiology that worried you? Misuses of biology, or misuses of evolutionary reasoning–back then and are they still with us today?
RL: My main complaint is not the list of specific manifestations but the underlying claim that there exists a human nature, which then the claimant must give examples of, and so each claimant gives examples that are convenient for his or her pet theory. I think the worst thing we can do in science is to create concepts where what is included or not included within the concept is not delimited to begin with. It allows us to claim anything. That’s my problem with Sociobiology. It’s too loose.
DSW: That brings us to the topic of cultural evolution, which is something that I study a lot and I think that you have thought of a lot. One of the exciting things that I think has taken place is the idea that the study of evolution became too gene-centric over the course of the 20th century. Evolution requires heredity, not genes, and there are other mechanisms of heredity. Culture really is an evolutionary process. That is in part why we are so open-ended, why there’s not a human nature in terms of a fixed human nature because we’re so adaptable. I wonder how much you have thought about cultural evolution in that way and if you have any comment to make upon what studying culture as a genuine evolutionary process with its own inheritance mechanism, including symbolic thought—the evolution of meaning systems—what that does to change the picture of evolution.
RL: I think that the evolution of this thing that’s in our cranium, however it happened, has changed all the rules for the history of the species, for its biology, for everything about it. I mean, rational thought and the kind of communication we have with human language, as opposed to the stereotypical communication of other animals, has really made a fantastic change in the conditions of life and the rates of reproduction of individual types and so on. I would say human evolution is in that sense unique because of the possibility of: a) the details of communication; b) the notion of historical memory; well, everything about human thought. I really do think that if we want to understand evolution, the first species we should keep out of our consideration is Homo sapiens. I’m sorry, but that’s the way it is for me.
DSW: Well, but that’s genetic evolution. What if the principles of cultural evolution, although different in some respects–because another inheritance mechanism needs to be functionally an inheritance mechanism but need not resemble other inheritance mechanisms in detail–what if the basic way of going about genetic evolutionary reasoning also could be employed for cultural evolutionary reasoning? Wouldn’t that put evolution back in the game for the study of human cultural evolution?
RL: Well, let me ask you a question. Why do you use cultural evolution instead of cultural history? Why evolution instead of history? Can you avoid—let me put it another way—can you generally avoid the false similarities, the made up structures that we are criticizing, if we continue to use the word evolution when what we really mean is historical change?
DSW: I’ll actually take you on, on that issue. I’m not sure how much time we’ll have during this conversation. What the mechanisms of human cultural evolution do is adapt human populations to their environments, often with a fine degree of sophistication. When you just say cultural history you’re being agnostic about adaptation. Cultures adapt to their environments. [Without a history of adaptation] they could no more survive and reproduce in their environments than a genetically evolved species. Just to say history leaves out adaptation, don’t you think?
RL: But the problem, here, is that it’s a form of adaptation that hasn’t been studied enough in animals and plants, which is that each change in the species changes what we call the environment, so there is a co-evolution of organism and environment. Historical change in our species has been increasingly the consequence of the organism itself. We’re inventing it all. As the brain grew into what we now have, it became the chief mechanism by which organisms constructed their environment. Look, let me interject here. I think it is extremely important to go to a fundamental issue, which is organisms create their own environments. All organisms make their niches. The whole notion of ecological niche is a very bad notion. There are no niches without organisms. This notion that there is a hole in the world that the organism evolves to fill. The organism by its evolution changes the conditions of its life and changes what surrounds it. Organisms are always creating their own hole in the world, their own niche.
DSW: You pioneered the concept of niche construction, which has become a hot topic.
RL: I think that one mustn’t see niche construction as a special issue. There are niches and then there is reconstruction of the niches. My claim is a very strong one and I could be wrong: there is no niche without an organism.
DSW: I’ll accept that provisionally, but there is such a thing as a purely physical environment…
RL: A physical world, oh yeah, but let me tell you one of my favorite seminars that I ever heard. I can’t trace it any more, unfortunately. A guy came to Chicago and gave a talk in which he showed motion picture photographs of all kinds of organisms, plants and animals, using what are called Schlieren optics, which are sensitive to differences in optical density. What he showed was every organism of which he took moving pictures—both plants and animals—have around them a layer of warm moist air–even trees have it—which is being produced by the organisms themselves. So every organism, at least every terrestrial organism (I don’t know about aquatic ones) is by its metabolism producing a layer of warm moist air with certain gases in it that are its immediate environment.
DSW: I think that’s probably even more so for aquatic organisms. You make your point very nicely. Each organism is manufacturing its own local environment.
RL: Exactly. That’s the wind chill factor. That’s why it gets colder when the wind blows.
DSW: Right. But that makes it a complicated evolutionary story. It’s still an evolutionary story, and when you just say history you’re leaving all that out. History seems to me too broad. Sure everything is history but we’d like to say something more specific. If there is a process of adaptation going on, even if it’s one of rapid niche construction and coevolution, that’s still a more specific set of ideas than just plain history, which really does encompass everything and therefore nothing. Don’t we want to use some of those more specific ideas about adaptation and coevolution and niche construction? That’s more than just history!
RL: Oh no, I’m with you! If I could convince people to use that notion of niche, not as a fixed thing, but as something that is manufactured by the organism, I would be very very happy. But when I talk to biologists about it, they’re always surprised.
DSW: It is still a new idea, in part of course because it’s a complex idea. Complexity is complex, it’s hard to study. We’re always trying to keep things simple, even when we should be embracing complexity in some sense.
DSW: What a pleasure, Dick! Thank you so much for this conversation. Have a great day.
RL: You too.