The Extended Phenotype

"I chose this because I think it expresses a really important idea. Richard Dawkins wrote this book not long after The Selfish Gene came out. That was his landmark book, in which he argued for a gene-centric view of evolution. Genes build bodies. They build traits, which are known as phenotypes, in order to be replicated in the next generation. In this book Dawkins took this argument to the next level. He said that when we think of the phenotype, we think about fur or eyesight or the red blood cell’s ability to take in oxygen. But genes influence behaviour, and so behaviour is part of the phenotype. And that behaviour allows animals to change their environment in ways that can then raise their reproductive success. For example, a beaver can build a large dam. That dam is part of what the genes in the beaver are doing to get themselves replicated. The dam alters the whole ecosystem for the beaver’s benefit, so it can get the food it wants. If you look at the dam, you can say: This is really just an expression of beaver genes. Get the weekly Five Books newsletter A particularly strange example that Dawkins used was the way parasites manipulate their hosts. I find this to be one of the weirdest things in all of biology. When some parasites get into their hosts, they actually alter their behaviour to benefit the parasite. For example, there are flatworms that get into ants and then go to the next stage in their life cycle in cows and sheep. How do they get there? They influence the ant by releasing some kind of chemical that causes the ant to climb up a blade of grass and clamp down on the very tip of it. The ant sits there and waits to be eaten by the cow or sheep! Right. So the ant clamped there on the grass is an extended phenotype of the parasite inside of it."

"This is one of my favourite books by Richard Dawkins . I like them all, but this is the one that I think is the most imaginative and compelling. It is slightly more technical than The Selfish Gene, but it shows a highly imaginative approach to understanding the nature of the biosphere. The Extended Phenotype is really an explanation of why an organism should not be seen just in isolation, but rather as part of a wider community of organisms and entities. It is a very clever book. Because it is easier to read. But this one is worth grappling with. Yes, I do think that is a fair comment – although it is difficult to imagine how one could be harder than Richard. Well, Richard confines himself to the biosphere, and is much more cautious and has not very much to say about the physical world – on cosmology and all that sort of thing. I span both, and try to span them equally, but perhaps I have a little bit more emphasis on the physical world."