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.