The most comprehensive of the books by Richard Dawkins
, published in 1982. Whereas others of his such as The Selfish Gene
and The Blind Watchmaker
are popularizations, that is introductions to genetics
for a general audience, The Extended Phenotype
demands a significant knowledge of biology
. But although it's intended for his professional colleagues, it's written so that if you've understood The Selfish Gene
you should then be able to make it through this one also.
It has a number of different themes and messages, but the basic one is the one embodied in the title. The phenotype of an organism is its particular body, how it actually turns out, as opposed to its genotype, which is the collection of instructions its genes give as to what sort of body to try to develop into.
The body can be harmed, killed, or improved, but it cannot truly reproduce. All reproduction is done by the gene. Evolution is between genes trying to take better advantage of the world around them. The body, the phenotype, is something genes build for themselves to make their way through the world. The extended phenotype is everything that the genes can influence to gain advantage.
So the phenotype of beaver genes is a beaver's body. Its extended phenotype includes its dam as well, which the genes create by means of their intermediary the beaver body.
Parasites induce behaviour in host species, which is to the advantage of the parasite, but to the disadvantage of the host. So a feature of the host -- a thicker shell in snails, for example -- is detrimental to host (snail) genes, but beneficial to, and caused by, and promoted by, the genes of the parasitical snail fluke.
Cuckoos gape their mouths wide to trigger the genetic instinct to feed a gaping mouth. But the one who does the feeding, a warbler or whatever, is being manipulated into acting in favour of cuckoo genes and against its own warbler genes. The warbler's body is part of the cuckoo genes' extended phenotype.
There are a number of other important themes in the book. Chapter 2, Genetic Determinism and Gene Selectionism, is a strong attack on the absurd notion of genetic determinism, which no biologist believes in, but which some non-biologists believe some biologists believe in, if you follow me. Genes do not determine anything. To suggest they do is simply ignorance of elementary genetics, yet the idea somehow has arisen that there is a school in biology, of which Dawkins is supposed to be a member, that holds that genes can determine things. For example, if you had a gene for left-handedness, that would make you left-handed. Dawkins in this chapter thoroughly undermines that wrong idea.
He returns to the subject of memes in Chapter 6, Organisms, Groups and Memes: Replicators or vehicles?, in a general discussion of what kinds of things can be said to reproduce and/or replicate themselves: bodies, genes, thoughts, photocopies, species, computer viruses, selfish DNA, etc.; and which of them are instrumental in the replication of others: see my replicator selection and vehicle selection for more detail.
In Chapter 10, An Agony in Five Fits he spends a long time clarifying different ways the word fitness has been used in the history of biology. This undercuts anyone who thinks that Herbert Spencer's 19th-century phrase "the survival of the fittest" is in any way trivialized or made into a tautology by the late 20th-century technical sense(s) of "fitness".
A big, superbly intelligent, precise, far-reaching book. Richard Dawkins says of it, "It doesn't matter if you never read anything else of mine, please at least read this." -- It is certainly his most original and important work, but you'll need preparation beforehand. The best introductions to modern biology are his other books. This one is, if you like, an extended modern biology.