The Extended Phenotype: The Long Reach of the Gene
Richard Dawkins
Top 10 Best Quotes
“Putting these three things together we arrive at our own ‘central theorem’ of the extended phenotype: 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.”
“The genes in one organism’s cells, then, can have extended phenotypic influence on the living body of another organism; in this case a parasite’s genes find phenotypic expression in the behaviour of its host.”
“Genes affect proteins, and proteins affect X which affects Y which affects Z which . . . affects the phenotypic character of interest.”
“An organism is the physical unit associated with one single life cycle. Replicators that gang up in multicellular organisms achieve a regularly recycling life history, and complex adaptations to aid their preservation, as they progress through evolutionary time.”
“A replicator may be said to ‘benefit’ from anything that increases the number of its descendant (‘germ-line’) copies.”
“the conclusion I wish to draw is not really disputable. If host behaviour or physiology is a parasite adaptation, there must be (have been) parasite genes ‘for’ modifying the host, and the host modifications are therefore part of the phenotypic expression of those parasite genes. The extended phenotype reaches out of the body in whose cells the genes lie, reaches out to the living tissues of other organisms.”
“the behaviour of an individual may not always be interpretable as designed to maximize its own genetic welfare: it may be maximizing somebody else’s genetic welfare, in this case that of a parasite inside it.”
“Why are genetic determinants thought to be any more ineluctable, or blame-absolving, than ‘environmental’ ones?”
“When we talk of a program as ‘doing better’ or as being ‘successful’ we are notionally measuring success as capacity to propagate copies of the same program in the next generation: in reality this is likely to mean that a successful program is one which promotes the survival and reproduction of the animal adopting it.”
“What does complementariness mean for genes? Two genes may be said to be complementary if the survival of each, relative to its alleles, is enhanced when the other is abundant in the population.”
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