John Dupre is a notoriously non-orthodox philosopher of biology. In this latest book of his, he takes a stand against "evolutionary psychology", a fashionable doctrine that claims to explain contemporary human behavior based on pseudo-Darwinian arguments.
If the theory of evolution is now widely accepted, a number of issues remain unsolved: Is natural selection by itself sufficient for understanding evolution? Which parameters are optimized to achieve greater fitness? And what exactly is selected? Is it the single gene, as Richard Dawkins suggested in his influential book, The Selfish Gene? Is it the organism? The group? The species? Dupre believes that it is actually the entire developmental cycle. In other words, the unit of selection is "the ability to gather together and deploy the full set of resources necessary for producing the next generation". This theory is called developmental systems theory (DST), and it reconciles evolution (at the scale of the species) with development (at the individual scale).
Dupre then brings us one step farther: In the case of humans at least, evolution is not only genetic but also cultural. There is an evolutionary continuity of humans and other animals, but language (that Dupre calls "the most significant distinctively human feature") gives us the ability to develop complex thought and elaborate cultures. Our genome is probably Stone Age-old, but our cultural environment has considerably changed over the history of mankind and has an impact on contemporary humans that is hard to ignore. Without claiming, like Steven Pinker for example, that biology is entirely non-relevant and that only culture shapes an individual's mind (in the so-called "blank state" theory), Dupre believes that the cultural context tells us at least as much about human nature as does the genome. Evolutionary psychologists, on the other hand, choose to focus on humans' "structure" and to neglect their "context" (Dupre uses the words structure/context to avoid the controversial nature/nurture terms, which may or may not be a good thing).
The confounding fact, as very nicely demonstrated in Chapter 6, is the lack of evidence for evolutionary psychology. "The evolutionary psychologist is typically advancing a thesis about human nature at the same time as offering an explanation of the trait hypothesized" (page 89). Moreover, the analogies from humans to other animals are often arbitrary, not based on any verifiable evolutionary process, while conveniently overlooking counterexamples that would be no less relevant. The link to genetics is even weaker, if not completely speculative: Genetics should only be used to explain phenomena that are largely insensitive to environmental contingencies. Its misuse is prone to harmful misconceptions about our species.
Dupre reminds us that evolutionary psychology rose from the ash of sociobiology, decidedly inappropriate since E. O. Wilson's disreputable book (Sociobiology: The New Synthesis, 1975) and the ensuing accusations of racism, sexism and generally bad science. The same pitfalls await evolutionary psychologists when they claim that all men have a "natural" disposition to rape, for instance. I believe that the same goes with the "Men are from Mars, women are from Venus" frenzy. An important conclusion is that we are, so to speak, more "free" than evolutionary psychologists would like us to believe: "Biological explanations of social facts are frequently interpreted as having conservative implications. If it's part of our biology, the thought goes, we might as well just learn to live with it. No such implication is necessary, however" (page 115).
Overall, Darwin's Legacy is a great reading for anyone interested in mankind, or simply curious about the (lack of) scientific grounds for evolutionary psychology. I would give the book five stars if not for the following weak points: Dupre tends to repeat himself or to restate his previous books. He is probably right to be so skeptical towards reductionism, but his case was already made in his first book (The Disorder of Things: Metaphysical Foundations of the Disunity of Science). I was also unhappy with Chapter 4, a curious incursion into the debate of science (specifically, the theory of evolution) and religion. Although I find myself to agree with Dupre's "anti-supernaturalistic" (!) perspective, I was disappointed at his oversimplistic account of that famously complex issue. Even more disturbing is the fact that Dupre does not mention any other religion than Christianity, which makes his arguments even weaker. Let's hope he elaborates on evolution and religion(s) in a future publication.