The Evolutionists: The Struggle for Darwin's Soul

  • Richard Morris
W. H. Freeman: 2001. 272 pp. $22.95, £18.99

Nature or nurture? Chance or necessity? These dichotomies embody a controversy that has raged among the top thinkers in evolutionary biology. The question is: does adaptation by natural selection explain everything in nature, including human behaviour, or is the situation more complicated? The problem is that no one really believes the first proposition, but the second does not constitute a useful scientific hypothesis. And except as the impetus for a spate of books and articles, and lots of acrimonious debate, it may not matter much.

The spandrels of San Marco's basilica, symbols of a long-running debate on evolution. Credit: PAUL ALMASY/CORBIS

The contemporary debate started in 1979, when Stephen Jay Gould and Richard C. Lewontin published an article entitled “The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme”. This became the focus for the conflict between two lines of evolutionary thought. On one side are Richard Dawkins and like-minded evolutionary biologists, who believe that natural selection is adequate to explain virtually every observation in evolutionary biology. On the other are Gould and his followers, who believe that natural selection is a very important force in evolution, but not the only one. The most heated controversy arises when we attempt to apply our knowledge of evolutionary biology to the origin of human behaviour.

In The Evolutionists and Dawkins vs. Gould, Richard Morris and Kim Sterelny, respectively, recount this controversy in excruciating detail. Sterelny gets almost to the heart of the matter, and Morris's engaging style makes the history, politics and political motivations fun to read. Unfortunately, neither author really brings us any closer to a resolution, and neither really explains why the controversy may never be resolved.

Both try to dissect the argument into its component parts. They agree that Gould departs from “Darwinian fundamentalists” in his belief that evolution occurs by periods of stasis followed by periods of rapid evolution (“punctuated equilibria” or, as his detractors quip, a theory of “evolution by jerks”). Palaeontologist Gould sees evidence for rapid transitions, catastrophic extinctions and spectacular radiations in the fossil record, and thinks that a model of slow, steady change by natural selection acting on genetic variation is not adequate to explain history. In particular, Gould's notion of contingency in evolution may be important in understanding the origin of new species and higher taxa, and aspects of the broad pattern of evolutionary history that have never been fully explained by the neodarwinian synthesis.

Another area of disagreement concerns Gould and Lewontin's concept of 'spandrels' in evolution. Named after an architectural feature that is a by-product of the construction, evolutionary spandrels are biological structures or traits that are accidental by-products of history, not the results of natural selection. However, natural selection can clearly mould a spandrel into a useful structure. Spandrels, Morris and Sterelny agree, don't much change our understanding of anatomical evolution. But the issue becomes very heated where sociobiology or evolutionary psychology are concerned. Gould believes that many human behavioural traits are spandrels — by-products of the brain we evolved in the African savannah; the ability to read Nature is a spandrel, not a product of natural selection. The Dawkins party tends to think of the brain as a collection of traits moulded by natural selection. Morris gives an elaborate recipe, and even some preliminary data, for deciding between these two views by examining whether the brain is composed of isolated functions or parts or is an interacting whole. But anyone who thinks a brain is composed of interacting parts, whereas a body is not, has never suffered a stiff neck as a result of limping with a sprained ankle, yet no one is arguing that ankles and necks aren't largely products of natural selection.

Morris devotes a chapter to complexity theory, providing a lucid and enlightening explanation. Complexity scientist Stuart Kauffmann “believes that, although natural selection is important, it is not the sole cause of evolutionary change”, which is a “marriage between self-organization and selection”. Complexity science indicates that there are “emergent properties” that could not be predicted by a reductionist approach, a view that pleases Gould.

Dawkins vs. Gould: Survival of the Fittest

  • Kim Sterelny
Icon: 2001. 160 pp. £5.99, $9.95 (pbk)

Why is it so important that we know whether human behavioural traits are spandrels, and whether human brains have emergent properties? The answer lies more in politics and philosophy than it does in science. Sterelny explains most of the conflict between Dawkins and Gould in terms of two distinct ideologies. “In short,” Sterelny contends, “Dawkins, but not Gould, thinks of science as a unique standard-bearer of enlightenment and rationality.” Dawkins views the entire world in reductionist terms, and is dedicated to the scientific method as the only valid mode of analysis. Gould, as he has written elsewhere, sees science and religion as “non-overlapping magisteria”, as spheres in which different sorts of reasoning apply. He is probably right. But he also views some of science itself as outside the realm of investigation. Dawkins thinks that modern evolutionary theory provides a good model for the exposition of a natural system of morality, whereas Gould insists that morality is beyond the realm of science.

Morris and Sterelny both miss the opportunity to give us a bottom line on this argument. Gould, Lewontin and their followers believe that we should not take the application of evolutionary theory and genetics to human behaviour seriously, for otherwise we will see a resurgence of eugenics reminiscent of the Holocaust. Their fears may be correct. But no data on brain physiology, no studies on parallel evolution or rapid speciation, and no computer modelling of complex systems will ever change such perceptions.

These two slim and readable books target a well-defined problem in evolutionary theory. Sterelny could have accomplished more with an index, and both books could have profited from a thorough and organized bibliography. I found it easier to dig up my 20-year-old photocopy of the “Spandrels” article than to find a complete reference to it in either book. Both authors promise an unbiased summary of the arguments, but both come down predominantly in favour of Dawkins' perspective. Morris and Sterelny are on the cusp of an insightful analysis but never quite get to it. But the aficionado of evolutionary theory and the intense debate it engenders would do well to read both accounts. Whereas Morris stresses the divergent approaches of complexity and reductionism, Sterelny emphasizes other issues, such as common descent (or cladistics), which concerns Dawkins, and morphological similarity, which, to Gould, is of paramount importance. Longer, and with an elementary introduction to evolutionary science, Morris's book provides more of a stand-alone account and is suited to the non-specialist.

We have created an icon in Darwin, a god whose every printed word is canon. But Darwin knew that not everything he said would stand the test of time and new data in every detail. Darwin would be puzzled over the struggle for his soul, because the soul, like science, derives its strength not from rigidity but from fluidity. While some of today's most brilliant thinkers grope for the soul of Darwin, it is fortunate that so many experimental evolutionary biologists have decided not to wait for the resolution.