(Copyright © 2000 Piero Scaruffi | Legal restrictions - Termini d'uso )
The main claim of Dawkins' book is that the gene is the unit
of natural selection. Genes are selected by their phenotypic effects. Such phenotypic effects are not limited to individual organism, but reach out to an "extended" phenotype, consisting of the world the organism interacts with. Genes ensure their survival by means of phenotypic effects on the world.
For Dawkins, the organism alone does not have biological relevance. What makes sense is an open system made of the organism and its neighbors. For example, a cobweb is still part of the spider. The control of an organism is never complete inside and null outside: there is rather a continuum of degrees of control, which allows partiality of control inside (e.g., parasites operate on the nervous system of their hosts) and an extension of control outside (as in the cobweb). The genome of a cell can be viewed as a representation of the environment inside the cell.
Conversely, within the boundaries of an organism there can be more than one psychology (as in the case of schizophrenics).
The same arguments apply to memes, which are nonbiological replicators. The extended phenotype of a meme is defined by phenotypic effects such as words, music, images, gestures, fashion, ...
Throughout the book, Dawkins downplays the importance of single organisms and emphasizes the "extended phenotype" which extends as far as its control reaches out.
The book is mainly written for biologists and debates numerous alternative theories.