Spent by Geoffrey Miller 

Dylan Evans discovers humanity's unique selling points

It is hardly surprising that the latest popular book about evolutionary psychology has caused another rumpus. Nor are the responses to Geoffrey Miller's new book, Spent, particularly original. First came a lengthy piece in Newsweek by Sharon Begley entitled "Why Do We Rape, Kill and Sleep Around?" in which the usual straw men were lined up and decapitated: disregard of culture and context, genetic determinism, and - paradoxically - ignorance of recent genetic discoveries. David Brooks followed up with an equally misinformed opinion piece in the New York Times, in which he excoriated Miller for stating that "listening to Lynyrd Skynyrd is a sign of low intelligence".

Miller should have known that some reviewers would completely miss the humour in his whimsical remarks (example: "Play The Sims 2 for a couple of weeks, and consider whether your life as a consumer has any more meaning than that of your Sims"). The rest of us should be grateful, however, that he chose to write in such a playful fashion. I lost count of the times his book made me hoot with laughter.

It is particularly ironic that the critics have hurled all the conventional accusations at Miller, since his version of evolutionary psychology is so different from that of Steven Pinker and other key thinkers in the field. His theory, eloquently advanced in The Mating Mind (2000), that the evolution of human intelligence was shaped more by sexual selection than by natural selection, sets him apart from the mainstream. In this book Miller advances an equally original thesis - that our purchases are driven by the desire to display personality traits that have been shaped by our evolutionary history. When viewed through this lens, puzzling aspects of consumer behaviour suddenly make sense.

Take the value-density conundrum, for example. The value-density of a product is its retail price divided by its weight. Miller calculates the value-density of a variety of products and comes up with some interesting questions. Why, for example, does an implanted human egg cost 72 quadrillion times more per gram than tap water, even though the egg is constituted mostly of water? The answer is that the egg is the ultimate currency of Darwinian success, for which there is little supply and much demand. Miller's genius here lies not in the answers he provides but in the questions he asks. Once the questions are posed the answers are rather obvious, but before reading Miller's book, it had never even occurred to me to ask such questions.

Nor, it seems, have they occurred to most marketing consultants. Miller argues that marketers still use simplistic models of human nature that remain uninformed by the past 20 years of research by evolutionary psychologists and behavioural ecologists. As a result, they "still believe that premium products are bought to display wealth, status, and taste, and they miss the deeper mental traits that people are actually wired to display - traits such as kindness, intelligence, and creativity". This, Miller claims, limits their success rate.

But Miller does not preach; he also thinks evolutionary psychologists could learn a thing or two from marketers. Through their experience of selling real products, marketers develop an intuitive understanding of consumer behaviour that could help evolutionary psychologists refine their theories of evolved preferences and sexual signalling. If this dialogue develops as Miller hopes it will, a rich seam of new research might be opened up.

His newfound enthusiasm for marketing does not mean he has become an uncritical apologist for late capitalism. Alongside the punchy humour runs a darker stream of ideas that draws on the work of the Norwegian-American sociologist and economist Thorstein Veblen, which is somewhat at odds with Miller's winking, postmodern nonchalance. At times Miller gives the impression that, like Marx, he thinks many consumer products are designed to satisfy "false needs". His imaginary dialogue between a 21st-century consumer and a couple of Cro-Magnons from prehistoric France, while hilariously funny, betrays the very nostalgia for an idealised paradise of primitive small-group living that he rightly criticises only a few pages later.

Thankfully, Miller's leftwing scruples do not intrude too much on what is ultimately a considerable intellectual achievement. Do not let the fact that he wears his scholarship so lightly fool you into thinking that this is merely another popular science book. It is much more than that.