It can't be said that this is the easiest of books to read, but I think it must be said that the reader is rewarded by a brilliantly written argument which puts evolution in a new context. What Dawkins calls the "central theorem" is this:
"An animal's behaviour tends to maximize the survival of the genes 'for' that behaviour, whether or not those genes happen to be in the body of the particular animal performing it." (p.233)
The book is a sequel to "The Selfish Gene", and pursues the theory that,
"to regard an organism as a replicator... is tantamount to a violation of the 'central dogma' of the non-inheritance of acquired characteristics." (p.97)
An organism is construed as a vehicle for replicators, which may be genes or memes, and, he argues, organisms are not the only vehicles. As can be readily appreciated by the reader of Ehrlich and Wilson, biodiversity is such that eco-systems are complex and hierarchical, and the entities serving as vehicles for replicators may subsist at various levels. This is what is meant by the extended phenotype: the bodily or behavioural expression of a genotype should not be assumed to be confined to an individual organism.
"From the viewpoint of this book an animal artefact, like any other phenotypic product whose variation is influenced by a gene, can be regarded as a phenotypic tool by which that gene could potentially lever itself into the next generation." (p.199)
This adds another interesting set of considerations to the discussion here about tools and design.
The strength and subtlety of Dawkins' argument seem to be lost on some of his critics, and a good example of this can be seen in the case of a recent book by Brian Goodwin.
© Paul Taylor 2001