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Although not presented as such, Robert Richardson's book offers a persuasive argument that scientific anti-realism is the appropriate framework for conceptualizing the theories and models of evolutionary psychology. A scientific anti-realist would claim that the theories of the evolutionary psychologists may be molded to fit their observations, but those theories shouldn't be taken to be literally true. The anti-realist interpretation of evolutionary psychology is based on the lack of enough data to transform speculation into validated explanations.
Let me explore the problem a bit further by making a comparison with astronomy. Astrophysicists cannot directly observe the insides of stars, yet they have been able to infer that stars the size of our sun obtain their energy from hydrogen fusing into helium via the proton-proton chain. They know what the various steps in this chain are and at what temperature it begins. Some of the more impressive confirmations of these inferences come from the measurement of neutrinos – particles that are created during fusion and barley interact with other matter. The inferences that physicists use to study astronomical phenomena can be delicate, and any one of them might seem to be a leap, but they hang together and allow enough alternative hypotheses to be eliminated that many astrophysicists are realists about their inferences regarding the composition, age and life cycle of stars. Such is not the case in evolutionary psychology. To make a Richardsonian point, even information about massless and chargeless particles such as neutrinos is more available to scientists than is the data that would be needed for respectable realist theories in evolutionary psychology.
The title of the book is slightly enigmatic. Evolutionary psychology (EP) was introduced to explain human behaviors as adaptations to the Pleistocene environment, but it fails to do so and is hence a maladapted psychology. The focus of the book, however, is not on psychology per se; rather, the claim is that EP is not well-adapted to the broad paradigm of evolutionary science. Richardson observes that evolutionary psychology aspires to bring the resources of evolutionary biology to cognitive psychology. One might assume that when you bring evolutionary biology into a new field its level of rigor would be imported as well, but this is not the case with EP according to Richardson. The questions that the evolutionary psychologists ask about human reasoning and language cannot be addressed using the kind of evidence that is available in evolutionary biology. More specifically, the problems of the psychologists cannot be addressed within the constraints of physics, biology, and paleontology; therefore, evolutionary psychology should not be classified as one of the evolutionary sciences.
The book undermines any putative EP claim to be a species of evolutionary science by examining what Richardson calls three kinds of empirically motivated research programs: a) reverse engineering, b) perspectives on natural selection via population genetics, and c) theories of descent using cladistic methodology. In each case, he demonstrates how theories in evolutionary biology have substantial empirical heft, and hints at the futility of expecting the same in evolutionary psychology.
Reverse engineering involves studying the design of a particular trait and then inferring the 'reasons' for that design. As Richardson notes, reverse engineering asks “What is this adapted for?” He suggests that thinkers such as Dennett seem to believe that determining what a trait is designed for is easier than it might in fact be. There is good evidence, for example, that feathers did not originally evolve to aid flight. Design is not always obvious. Dennett is inclined to use artifacts such as widgets to illustrate design. One readily inferable point from Richardson's argument is that a bi-level dissociation between artifacts and organisms makes comparisons between them problematic. One, it is easier to determine the function of an artifact than the function of an organismic trait. Two, making inferences about the history of artifacts is not nearly as difficult as making inferences about the often convoluted evolutionary history of organismic traits. The implication is that the reverse engineering approach can underestimate biological complexity. At the very least, it is important to have independent information about history rather than relying on inferences from current design.
More succinctly, Richardson claims that current function alone does not provide reliable evidence for inferring the selection pressures responsible for design. In evolutionary biology proper, questions about function can sometimes be answered by triangulating data from independent domains such as physics, paleontology and geology, but these sister sciences are largely silent on psychology. Not only is there limited data on the actual Pleistocene environment, the very idea of 'The Pleistocene' as some kind of homogeneous time and place, says Richardson, is a construction of the evolutionary psychologists. Even less is known about the early hominid social environment. Still more troubling is a lack of information about cognitive and linguistic variation among our immediate ancestors
One of the inspirations for the book is Stephen Gould and Richard Lewontin's claim that thinkers in evolutionary psychology seek to test hypotheses about the adaptive value of traits, but never question the adaptationist paradigm itself. Richardson offers a particularly interesting argument that with respect to any particular species, an adaptation proper will be a unique feature of that species. To use an easy example, having DNA segregated within a cell nucleus is not an adaption in human beings. It is part of our design by means of descent, not by natural selection. We might talk about DNA as an adaptation in eukaryote cells in contrast to prokaryote cells such as bacteria, but not as an adaption in human beings. A lot of our 'human' characteristics are likely not adaptations for the same reason. An evolved trait is not synonymous with 'an adaptation.'
What happens in evolutionary psychology claims Richardson is that when one adaptationist hypothesis fails, another one is quickly offered to take its place. In the philosophy of science, highlighting the availability of alternative explanations is a common argument for adopting scientific anti-realism. A more rigorous science would put individual adaptationist hypotheses to the test by comparing them to scientifically respectable alternatives such as genetic drift, developmental constraints, allometry, pleiotropy, and descent. Richardson also points out that supportive factors can increase or decrease the rate of selection and these factors can be considered to be 'causes' of evolution in a larger sense. Examples include high heritability and random mating patterns. As others have argued, natural selection is not the only candidate explanation for evolution.
In one of the more closely argued chapters, Richardson reviews five different types of evidence that can be used to legitimately infer that a particular trait is an adaption (as outlined by the philosopher of biology Robert Brandon). Being able to validate each type of evidence for any particular problem is the kind of argument that can be used to prove the 'reality' of evolution by natural selection. First, there should be evidence that the trait increased fitness among select variants. Second, there should be evidence about the environment or the selection pressures operating. Third, there should be evidence that the trait in question is heritable. Fourth, there should be data about the structure of the population that underwent evolution and fifth, there should be evidence about the nature of the ancestral traits.
Richardson cycles through several combinations of this evidence for different cases such as metal tolerant grasses, reduced eyes in cave dwelling organisms, human language and reasoning. I'm not sure that something as global as 'reasoning' can be fairly compared to 'metal tolerance,' but after reading Richardson's presentation it is natural to conclude that if one wanted to dispute the claims of the creationists by making a convincing case for evolution by natural selection, it would be a mistake to use the data and theories of the evolutionary psychologists. They are not respectable examples of evolutionary science.
Richardson is not as explicit about this point, but one gets the impression that he believes that thinkers such as Cosmides, Tooby and Pinker get free passes because they are seen as being on the side of Darwin. Others have made similar claims. In response to the psychologist Paul Ekman's own Darwin-inspired theory of basic emotions, one of Ekman's most persistent critics has claimed to me that Ekman “uses Darwin as a shield.” According the Darwin as a shield strategy, to disagree with my theory is to disagree with Darwin, and by default to potentially give comfort to the creationists and the intelligent design theorists.
I won't spill much more ink than has already been spilled on this sensitive issue. It gets complicated because Dawkins, Dennett and Pinker etc. are committed foes of the various species of creationism and advocates of creationism/ID tend to believe that any criticisms of Dennett et al. provide support for creationism/ID. Such contrived dualism is unfortunate. Using the Darwin as a shield strategy, however, is still a fallacious line of argument and should not be tolerated. Perhaps in anticipation of this strategy, Richardson never passes up an opportunity to declare his acceptance of the evidence for both evolution, and the role of natural selection in evolution.
Another tactic Richardson adopts is to not make an idol of Darwin. Just as Newton could not foresee the postulates described in Maxwell's equations, many core aspects of evolution were hidden from Darwin. No good 'Darwinian' would adhere chapter and verse to Darwin's views on evolution, but Darwin's compass was pretty accurate relative the scientists of his own and succeeding generations. Making one's allegiances known is a complicated aspect of gamesmanship in this area, and it can be difficult to find the right balance. That so much care and space has to be given to presenting one bona fides is a sad commentary on the anemic state of and commitment to scientific literacy in current day society.
If readers have time to study only one chapter, a good choice would be the chapter titled Recovering Evolutionary History, the topic of which is descent. Richardson claims that we know quite a bit about human evolution, but not at the level of detail required by evolutionary psychology. He does not dispute that aspects of human reasoning and human linguist abilities are shared derived traits. There are, however, many gaps. Even if psychologists could find a valid way to decompose these phenomena into units of selection, it isn't clear what is unique to Homo sapiens or what is homologous throughout the genus Homo. The relative selection pressures refer to what? The social environment of Homo habilus? That of Homo erectus? We don't have much evidence of what those environments were like anyway, nor information about population structure or evolving neuroanatomy. Given that our cognitive and linguistic capacities are supposedly derived traits within Homo, studying other living primates is of limited value. The impression Richardson leaves is that evolutionary psychology is an interesting exercise, but does not and cannot rise to the level of empirical rigor demanded of a respectable evolutionary science.
Minus many details, such is the main argument of the book. Although it isn't a favorite tactic of mine, in this case there does seem to be some value in claiming that the questions asked by the psychologists are harder or more recalcitrant than they are in some of the other sciences. Evolutionary biologists don't have good theories about the development of the frontal lobes in dinosaurs from to the Triassic to the Cretaceous era or models of mating behaviors in Sabertooth cats Why not? Likely because they don't ask these kinds of questions as the fossil record doesn't provide much information about either soft tissue or behavior. These, however, are the kinds of questions that the evolutionary psychologists are asking.
It would be a mistake to underestimate how various strands of data could be fit together to allow some valid inferences about the evolution of our psychological capacities or how a relatively youthful field will develop over the next few decades. If some of the evolutionary psychologists have exaggerated their scientific merits a bit, such sins are likely minor. The vast monetary resources devoted to the neurosciences in recent years makes it pretty certain that the base rate of exaggeration is going to be higher in that direction.
This review began with some reflections on the superiority of measuring neutrinos over constructs such as cheater detection modules. Let us come full circle and close with astronomy, turning to one of the great scientific realists in history – Galileo. Andreas Osiander marketed the Copernican theory along anti-realist lines, a move which Galileo rejected. Everyone now knows that Galileo was correct about heliocentrism, but to some extent his model was literally false. For example, Galileo refused to accept Kepler's elliptical orbit hypothesis and without Kepler, the Copernican model still required epicycles. It is also more correct to say that the planets AND the sun revolve around their common center of mass, which in our solar system happens to lie within the boundary of the sun. Copernicus still had the better model relative to Ptolemy, and not only because it made the calculations easier. Like Darwin, Galileo had a good compass. His preferred model of the solar system wasn't literally correct, but still a decent approximation, comparatively. Given Galileo's situation, evolutionary psychologists shouldn't resist the anti-realist interpretation. It is not very disputable. They should keep working and hope that eventually a few of their compasses will be widely seen to have been good as well.
© 2008 Peter Zachar
Peter Zachar is Professor and Chair of the Department of Psychology at Auburn University Montgomery.