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Honoring Richard Lewontin, Famed Evolutionary Biologist and Sometime Critic of His Own Field

Photo credit: Casey Luskin.

As Paul Nelson noted here already, Richard Lewontin, the famed Harvard zoologist, has passed away. He was 92. Lewontin was an extremely influential evolutionary biologist in the 20th century, having pioneered many new ideas and techniques in evolutionary studies. Though he was an explicit critic of intelligent design and a strong defender of evolutionary thinking in science, he was also brave and willing to criticize his own field when he thought it was appropriate. 

“The Spandrels of San Marco”

One of Lewontin’s most famous contributions to science came in a 1979 paper he co-wrote with Stephen Jay Gould, titled “The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme.” The paper critiqued the standard Darwinian viewpoint that every feature of life must have an adaptive benefit. They introduced the term “spandrel” into evolutionary biology — based upon the gaps between supportive arches common in medieval architecture — as a feature that is not immediately adaptive but a natural byproduct of other features (which may be adaptive). Lewontin’s article with Gould was heavily critical of the “adaptationist programme” and its credulity, the tendency to embrace weak tales to “explain” the origin of features:

We fault the adaptationist programme for its failure to distinguish current utility from reasons for origin (male tyrannosaurs may have used their diminutive front legs to titillate female partners, but this will not explain why they got so small); for its unwillingness to consider alternatives to adaptive stories; for its reliance upon plausibility alone as a criterion for accepting speculative tales; and for its failure to consider adequately such competing themes as random fixation of alleles, production of nonadaptive structures by developmental correlation with selected features (allometry, pleiotropy, material compensation, mechanically forced correlation), the separability of adaptation and selection, multiple adaptive peaks, and current utility as an epiphenomenon of non-adaptive structures. … [E]volutionary biologists, in their tendency to focus exclusively on immediate adaptation to local conditions, do tend to ignore architectural constraints and perform just such an inversion of explanation. … We wish to question a deeply engrained habit of thinking among students of evolution. We call it the adaptationist programme … This programme regards natural selection as so powerful and the constraints upon it so few that direct production of adaptation through its operation becomes the primary cause of nearly all organic form, function, and behaviour. … We all say that not everything is adaptive; yet, faced with an organism, we tend to break it into parts and tell adaptive stories as if trade-offs among competing, well designed parts were the only constraint upon perfection for each trait. It is an old habit. … Too often, the adaptationist programme gave us an evolutionary biology of parts and genes, but not of organisms. It assumed that all transitions could occur step by step and underrated the importance of integrated developmental blocks and pervasive constraints of history and architecture.

They cite many examples of “spandrels” in biology which defy simple adaptationist explanations, including the zig-zag grooves, ribs, and, colors on clam or brachiopod shells; horns, antlers, and tusks in various vertebrates; colors and shapes of snail shells; and others. One would be hard pressed to find an adaptive purpose for the beautiful graphic texture on a sea snail shell (see above; I believe it belongs to Darioconus auricomus) that I bought as a gift for my wife last year.

Why “Darwinism” Remains Appropriate

We are sometimes told that the term “Darwinism” is passé and no longer used, but in an essay, “The evolution of Charles Darwin,” written for the bicentennial celebration of Darwin’s birth, Lewontin used this term and explained precisely why it remains appropriate:

Why do we call the modern theory of organic evolution Darwinism? Charles Darwin certainly did not invent the idea of evolution, that is, of the continuous change in time of the state of some system as a fundamental property of that system, or even the idea that a process of evolution had occurred in the history of life. … By the time of the appearance of the Origin, the physical sciences had become thoroughly evolutionary. … By the younger Darwin’s time, the idea of organic evolution had become a common currency of intellectual life. Two years before the publication of the Origin, Herbert Spencer argued for a belief in organic evolution on the basis of the agreed-upon universality of evolutionary processes … 

The answer to Lewontin’s question of course is that it was Darwin who proposed natural selection as the primary mechanism driving evolution. He thus notes: “The Darwin-Wallace explanation of evolution, the theory of natural selection,” and Darwin’s ideas in Origin of Species had “immediate success” because the theory purported to explain the adaptive complexity of life. But Lewontin simultaneously noted that explanations based upon natural selection often amount to “stories” that don’t always have a high level of “inferential strength.” He criticized Jerry Coyne, writing: 

Where he [Coyne] 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 (or 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 sceptical 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.

Lewontin reiterated criticisms of the strength of selection-based explanations in 2010, when he published a review of What Darwin Got Wrong by Jerry Fodor and Massimo Piattelli-Palmarini in The New York Review of Books. He said that natural selection fails to explain many things:

The trouble with this outline is that it does not explain the actual forms of life that have evolved. There is an immense amount of biology that is missing. It says nothing about why organisms with the evolved characteristic were more likely to survive or reproduce than those with the original one. Why, when vertebrates evolved wings, did they have to give up their front legs to do it? After all, insects can have two pairs of wings and six legs, so there cannot be any deep general biological constraint on development. Why don’t birds that live in trees make a living by eating the leaves as countless forms of insects do instead of spending so much of their energy looking for seeds or worms?

Lewontin even criticized the standard peppered moth story, saying: “One unfortunate feature of this case is that the caterpillars of the dark-winged forms also have a slightly higher survival rate than those of the speckled-wing form, even though they are not black, so something more is going on, but this fact is not part of the curriculum.” 

In the 2010 essay, Lewontin expressed concern that “To a degree never before experienced by the current generation of students of evolution, evolutionary theory is under attack by powerful forces of religious fundamentalism.” He noted that What Darwin Got Wrong got the attention of evolutionary biologists because in it “two accomplished intellectuals make the statement ‘Darwin’s theory of selection is empty.’” Because of existential threats to evolutionary biology, he wrote, they thereby “generate an anger that makes it almost impossible for biologists to give serious consideration to their argument.” But Lewontin agreed with Fodor and Piattelli-Palmarini that evolutionary explanations are often insufficient to generate certain scientific knowledge:

Even biologists who have made fundamental contributions to our understanding of what the actual genetic changes are in the evolution of species cannot resist the temptation to defend evolution against its know-nothing enemies by appealing to the fact that biologists are always able to provide plausible scenarios for evolution by natural selection. But plausibility is not science. True and sufficient explanations of particular examples of evolution are extremely hard to arrive at because we do not have world enough and time. The cytogeneticist Jakov Krivshenko used to dismiss merely plausible explanations, in a strong Russian accent that lent it greater derisive force, as “idel specoolations.”

Even at the expense of having to say “I don’t know how it evolved” most of the time, biologists should not engage in idle speculations.

These are intriguing statements, for they show that Lewontin was an honest scientist who said what he really thought and was willing to buck the trend in his own field. But the quote for which Lewontin has become best known appeared in his 1997 review of Carl Sagan’s book Billions and Billions of Demons, also in The New York Review of Books. In this famous passage he acknowledged that modern evolutionary science assumes materialism is true, regardless of the state of the evidence:

Our willingness to accept scientific claims that are against common sense is the key to an understanding of the real struggle between science and the supernatural. We take the side of science in spite of the patent absurdity of some of its constructs, in spite of its failure to fulfill many of its extravagant promises of health and life, in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism. It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated. Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door. The eminent Kant scholar Lewis Beck used to say that anyone who could believe in God could believe in anything. To appeal to an omnipotent deity is to allow that at any moment the regularities of nature may be ruptured, that miracles may happen.

God of the Gaps?

Methodological naturalism (MN) is the idea that when practicing science we must assume that there are no intelligent and/or supernatural forces that can interfere with the natural world. To do otherwise, according to defenders of MN, subjects scientific investigation to the “whim of a deity,” as biologist John A. Moore put it. It also protects science against the “God of the gaps” mistake, where we initially attribute something to intelligent causes only later to discover a natural cause. 

But what if there were a reliable, predictive method to detect intelligent causation? What if we could detect when an intelligent agent was at work by using reliable scientific methods — just as reliable as the methods we use to detect material causation? This would bring intelligent agency back into science proper. William Dembski explains that this is exactly what the theories of design detection provided by the intelligent design research community provide for us:

Scientists are beginning to realize that design can be rigorously formulated as a scientific theory. What has kept design outside the scientific mainstream these last 130 years is the absence of precise methods for distinguishing intelligently caused objects from unintelligently caused ones. For design to be a fruitful scientific theory, scientists have to be sure they can reliably determine whether something is designed. Johannes Kepler, for instance, thought the craters on the moon were intelligently designed by moon dwellers. We now know that the craters were formed naturally. This fear of falsely attributing something to design only to have it overturned later has prevented design from entering science proper. With precise methods for discriminating intelligently from unintelligently caused objects, scientists are now able to avoid Kepler’s mistake. 

William Dembski, Introduction, in Mere Creation (InterVarsity Press, 1998), p. 16, emphasis added

A Legitimate Competitor 

Lewontin was right to see science as based upon reliable methods that produce some degree of certainty. And he tried to be fair, applying these requirements not just to intelligent design but also to evolutionary biology. But if Dembski is correct, then the modern theory intelligent design has developed rigorous methods for detecting the prior action of an intelligence, based upon predictable and regular features we observe when intelligent agents are at work. This makes intelligent causation a proper subject for scientific study, and it threatens to make intelligent design a legitimate competitor to “Darwinism.” 

I have no doubt that Lewontin would have disagreed that intelligent design deserves a place in science. But I would argue that like Darwinian evolution, intelligent design is a historical science. Because historical sciences deal with events of the past, their inferences are often weaker than in empirical sciences that study modern-day processes. Lewontin recognized this weakness in explanations citing natural selection (or other evolutionary mechanisms). But if Lewontin’s criticisms of evolutionary “just-so stories” are correct, and if Dembski’s statements about the robustness and reliability of the design inference are correct, then I believe ID could satisfy Lewontin’s concerns about including intelligent agency in science. 

Perhaps saying so is the best way an ID theorist can honor him.