Home > Work > The Extended Phenotype: The Long Reach of the Gene
81 " Why are genetic determinants thought to be any more ineluctable, or blame-absolving, than ‘environmental’ ones? "
― Richard Dawkins , The Extended Phenotype: The Long Reach of the Gene
82 " Finally, at the end of the chapter, we saw that genes ‘sharing’ a given extended phenotypic trait might come from different species, even different phyla and different kingdoms. "
83 " One is that phenotypes that extend outside the body do not have to be inanimate artefacts: they can themselves be built of living tissue. "
84 " The other idea is that wherever there are ‘shared’ genetic influences on an extended phenotype, the shared influences may be in conflict with each other rather than cooperative "
85 " If the parasite’s means of genetic exit from the host’s body is the same as the host’s, namely the host’s gametes or spores, there will be relatively little conflict between the ‘interests’ of parasite and host genes. "
86 " I have previously supported the case for a completely non-genetic kind of replicator, which flourishes only in the environment provided by complex, communicating brains. I called it the ‘meme’ (Dawkins 1976a). "
87 " They are the outward and visible (audible, etc.) manifestations of the memes within the brain. "
88 " They may be perceived by the sense organs of other individuals, and they may so imprint themselves on the brains of the receiving individuals that a copy (not necessarily exact) of the original meme is graven in the receiving brain. "
89 " The new copy of the meme is then in a position to broadcast its phenotypic effects, with the result that further copies of itself may be made in yet other brains. "
90 " It seems to follow from the thesis of this book that there is no important distinction between our ‘own’ genes and parasitic or symbiotic insertion sequences. Whether they conflict or cooperate will depend not on their historical origins but on the circumstances from which they stand to gain now. "
91 " Any effect that a meme has on the behaviour of a body bearing it may influence that meme’s chance of surviving. "
92 " It is, of course, true that ‘Memes are utterly dependent upon genes, but genes can exist and change quite independently of memes’ (Bonner 1980). But this does not mean that the ultimate criterion for success in meme selection is gene survival. "
93 " The point is the obvious one that selection at any one locus is not independent of selection at other loci. "
94 " Each gene works in a world of phenotypic consequences of other genes. Some of those other genes will be members of the same genome. Others will be members of the same gene-pool operating through other bodies. Yet others may be members of different gene-pools, different species, different phyla. "
95 " Functionally speaking, too, genes are gregarious. They have phenotypic effects on bodies, but they do not do so in isolation. I stress this over and over again in this book. "
96 " My thesis has been that the slight further conceptual step outside the immediate body is a comparatively minor one. Nevertheless it is an unfamiliar one, and I tried to develop the idea in stages, working through inanimate artefacts to internal parasites controlling their hosts’ behaviour. From internal parasites we moved via cuckoos to action at a distance. In theory, genetic action at a distance could include almost all interactions between individuals of the same or different species. The living world can be seen as a network of interlocking fields of replicator power. "
97 " The facts are as follows. The total amount of DNA in different organisms is very variable, and the variation does not make obvious sense in terms of phylogeny. This is the so-called ‘C-value paradox’. ‘It seems totally implausible that the number of radically different genes needed in a salamander is 20 times that found in a man’ (Orgel & Crick 1980). It is equally implausible that salamanders on the West side of North America should need many times more DNA than congeneric salamanders on the East side. "