Not by Genes Alone: How Culture Transformed Human Evolution

"This fits in in an interesting way with Richard Dawkins’s book because at the same time he was writing The Selfish Gene for a popular audience, Robert Boyd and Pete Richerson, the two authors of Not by Genes Alone , had begun to hammer away at building mathematical models of cultural evolution. They were using mathematical tools from population genetics, epidemiology, and other parts of science to systematically think about how culture transmits from one generation to another — how that’s different from genetic evolution, and how it can give you different phenomena than you would get under rules of genetic transmission. “It’s a popular book, so it’s written to be digestible to readers who don’t have a biological background” They’re building on work by two population-geneticists-biologists, Mark Feldman and Luca Luigi Cavalli-Sforza, who were working on similar problems beginning just before Boyd and Richerson. But it is Boyd and Richerson who ended up writing a book, in 1985, called Culture and the Evolutionary Process , which is a highly technical book, but really lays out a framework for thinking about the interaction between genes and culture — how culture can give rise to different kinds of social phenomena, how it can explain human cooperation. Finally, Not by Genes Alone puts together 30 years of research in one place. It makes the case that culture is really important, that it is evolving, and that we can solve lots of problems—like explaining ‘the demographic transition’—by thinking about cultural evolution. The demographic transition is a big puzzle for evolutionary biology because since about 1870, Western populations have been having fewer and fewer babies. The richer you are, the more educated you are, the fewer babies you tend to have. So your fitness is lower, in an evolutionary sense. How can we explain that? One of the puzzles that Boyd and Richerson take on in Not by Genes Alone is this puzzle of why it is that Westerners, and now the rest of the world, is decreasing the number of their babies, especially among the rich. It’s an interesting way in which, once you understand cultural evolution, you can explain extravagantly maladaptive behaviour that wouldn’t make any sense from a purely gene’s eye view, from the view of Dawkins in 1976. Interestingly, in The Selfish Gene , he develops the idea of memes as a rhetorical tool. He is saying, ‘I’m talking about replicators and I’m trying to describe this abstract idea of a replicator. This is going to help us understand genes’ — which is really what he is trying to explain in that first book. So, as a kind of mental toy, he develops this idea that culture could be like that, that there can be memes that are passed from mind to mind, and the success of a meme depends on its ability to fertilise many different heads. So it’s interesting that it started off, for him, as a rhetorical prop, and then later, in his 1981 book The Extended Phenotype, he develops it into a fully-fledged idea. Independent of that memes lineage, there is this lineage of cultural evolution that starts with Feldman and Cavalli-Sforza. That is a highly technical mathematical branch that then blossoms into modern gene cultural co-evolution and cultural evolution. Debates continue, but the interesting case that Richerson and Boyd make in Not by Genes Alone is that once you have a meritocratic society in which hard work and effort and acquiring more skills, knowledge and know-how, lead you to have greater success—and part of that is going to be education—people begin putting off reproduction until later. As soon as you have women having babies later in life, you immediately reduce the total number of babies. They have a fixed window, so if you close the window a little bit, you are going to have fewer babies. In pre-industrial societies, children could be converted directly into economic production because they can work on the farm and they can have jobs. But as jobs demand more skill and pure labour power becomes less important, the economic value of children declines and so cultural norms of limiting family size, of having babies late, are able to spread in a way they couldn’t in earlier societies. So it is an interaction of technology, social institutions and people’s beliefs and preferences."