Battlefield for parents' genes

Paul Harvey looks at some outrageous arguments that might just be correct.

E. O. Wilson's infamous book Sociobiology , published in 1975, explained social behaviour as the product of adaptive evolution by natural selection. Critics argued that the book was unscientific and that its fundamental claim had to be wrong. Others saw the book as providing a vision that mapped out a research agenda for the future. More than 20 years later, Wilson published Consilience (1998), which described how, because of research partially inspired by his earlier work, the social sciences had begun to accept the need for biological underpinnings. As if to underscore the issue, Christopher Badcock is a reader in sociology but his textbook, Evolutionary Psychology : A Critical Introduction , might as well have been written by a well-informed evolutionary biologist. While explaining psychology in terms of contemporary adaptationist evolutionary theory, it is as radical as Wilson's Sociobiology was.

The first two-thirds of Badcock's book are a very readable introduction to evolutionary psychology and can be recommended as inspirational and professional. But in the final third, things get really interesting.

Over the past decade, the notion that we receive about half our genetic make-up from either parent has received an important qualification: in some parts of the body only one of the parent's genes is active (genomic imprinting). The explanation, as understood at present, is that it is in the father's genes' interests to get the mother to invest more in the offspring than it is in her own interest. The reason is that over-investment in one offspring means the mother's ability to invest in subsequent offspring is reduced. Put crudely, the father may have the opportunity to mate elsewhere, but a mother who is too physically exhausted to produce new offspring can invest further only in those she already has. The paternally derived genes that are switched on in the offspring are the ones that help it to extract more resources from the mother than she has been selected to invest.

The concept of parent-offspring conflict accompanied by genomic imprinting might explain a host of features that have puzzled us in the past. And Badcock is as comfortable describing what we know as he is moving to a broader vision that explains what might be true. In young mice, there are genes responsible for the production of growth factors and other genes that produce receptors for those growth factors, thereby reducing their efficacy. An ingenious set of experiments has shown that the genes switched on are the father's for the production of growth factors and the mother's for growth-factor receptors. There is a conflict in each of us between our mother's and our father's genetic interests. The placenta seems designed by the foetus to extract the maximum amount of resources from its mother. Could it be that menstruation is an adaptation to allow the production of short-lived spirally coiled narrow arteries to counter the various measures by the foetus and placenta to widen them so as to increase the flow of blood?

This perspective is used by Badcock to explain much more. Examples include the reasons why some parts of our brain have our mother's genes switched on while for other parts it is the father's genes. Nobody knows whether the more extreme suggestions made in this book are correct or not, and Badcock is the first to point that out, but it contains excitement and vision that, when tempered by a mature critic such as a teacher or tutor, make this book stand out as one from which I should love to teach.

In contrast, Janet Radcliffe Richards's philosophical introduction to the limits of Darwinism is a carefully constructed introduction to logic, using the social implications of Darwinism as an example. The arguments I had with my contemporaries as a student have segued into those I have with my own children: what are the moral and ethical implications of Darwinism?

After nearly 300 pages of carefully developed argument, tested for clarity and instructional merit as an Open University course, the conclusion reached is that "the different depths of Darwinism have in themselves no implications for most ideas about ourselves and our situation". Of course, the exception comes when we divide people into materialists and non-materialists: we materialists have precluded ourselves from the comforts of "personal immortality and a morally ordered universe". Well, so be it.

I am very much in two minds about the value of this book. I could not fault the logic, but I am not at all sure that this philosophical approach is the way to teach students how to sort out an argument based on correct versus false premises. I prefer Badcock's methods: make seemingly outrageous arguments that might be correct, and let the students, together with their teachers and the scientists of the future, decide whether they are correct or not.

Paul Harvey is head of zoology, University of Oxford.