Read Online The Extended Phenotype: The Long Reach of the Gene (Popular Science) by Richard Dawkins - Free Book Online Page B
Authors: Richard Dawkins
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‘individuals that perform X are fitter than individuals that do not perform X’ sounds much more respectable. Even if it is not known to be true, it will probably be accepted as a permissible speculation. But the two sentences are exactly equivalent in meaning. The second one says nothing that the first does not say more clearly. Yet if we recognize this equivalence and talk explicitly about genes ‘for’ adaptations, we run the risk of being accused of ‘genetic determinism’. I hope I have succeeded in showing that this risk results from nothing more than misunderstanding. A sensible and unexceptionable way of thinking about natural selection—‘gene selectionism’—is mistaken for a strong belief about development—‘genetic determinism’. Anyone who thinks clearly about the details of how adaptations come into being is almost bound to think, implicitly if not explicitly, about genes, albeit they may be hypothetical genes. As I shall show in this book, there is much to be said for making the genetic basis of Darwinian functional speculations explicit rather than implicit. It is a good way of avoiding certain tempting errors of reasoning (Lloyd 1979). In doing this we may give the impression, entirely for the wrong reason, of being obsessed with genes and all the mythic baggage that genes carry in the contemporary journalistic consciousness. But determinism, in the sense of an inflexible, tramline-following ontogeny, is, or should be, a thousand miles from our thoughts. Of course, individual sociobiologists may or may not be genetic determinists. They may beRastafarians, Shakers or Marxists. But their private opinions on genetic determinism, like their private opinions on religion, have nothing to do with the fact that they use the language of ‘genes for behaviour’ when talking about natural selection.
A large part of this chapter has been based on the assumption that a biologist might wish to speculate on the Darwinian ‘function’ of behaviour patterns. This is not to say that all behaviour patterns necessarily have a Darwinian function. It may be that there is a large class of behaviour patterns which are selectively neutral or deleterious to their performers, and cannot usefully be regarded as the products of natural selection. If so, the arguments of this chapter do not apply to them. But it is legitimate to say ‘I am interested in adaptation. I don’t necessarily think all behaviour patterns are adaptations, but I want to study those behaviour patterns that are adaptations.’ Similarly, to express a preference for studying vertebrates rather than invertebrates does not commit us to the belief that all animals are vertebrates. Given that our field of interest is adaptive behaviour, we cannot talk about the Darwinian evolution of the objects of interest without postulating a genetic basis for them. And to use ‘a gene for X’ as a convenient way of talking about ‘the genetic basis of X’, has been standard practice in population genetics for over half a century.
The question of how large is the class of behaviour patterns that we can consider to be adaptations is an entirely separate question. It is the subject of the next chapter.
3 Constraints on Perfection
In one way or another, this book is largely preoccupied with the logic of Darwinian explanations of function. Bitter experience warns that a biologist who shows a strong interest in functional explanation is likely to be accused, sometimes with a passion that startles those more accustomed to scientific than ideological debate (Lewontin 1977), of believing that all animals are perfectly optimal—accused of being an ‘adaptationist’ (Lewontin 1979a,b; Gould & Lewontin 1979). Adaptationism is defined as ‘that approach to evolutionary studies which assumes without further proof that all aspects of the morphology, physiology and behavior of organisms are adaptive optimal solutions to problems’ (Lewontin 1979b). In the first draft
A large part of this chapter has been based on the assumption that a biologist might wish to speculate on the Darwinian ‘function’ of behaviour patterns. This is not to say that all behaviour patterns necessarily have a Darwinian function. It may be that there is a large class of behaviour patterns which are selectively neutral or deleterious to their performers, and cannot usefully be regarded as the products of natural selection. If so, the arguments of this chapter do not apply to them. But it is legitimate to say ‘I am interested in adaptation. I don’t necessarily think all behaviour patterns are adaptations, but I want to study those behaviour patterns that are adaptations.’ Similarly, to express a preference for studying vertebrates rather than invertebrates does not commit us to the belief that all animals are vertebrates. Given that our field of interest is adaptive behaviour, we cannot talk about the Darwinian evolution of the objects of interest without postulating a genetic basis for them. And to use ‘a gene for X’ as a convenient way of talking about ‘the genetic basis of X’, has been standard practice in population genetics for over half a century.
The question of how large is the class of behaviour patterns that we can consider to be adaptations is an entirely separate question. It is the subject of the next chapter.
3 Constraints on Perfection
In one way or another, this book is largely preoccupied with the logic of Darwinian explanations of function. Bitter experience warns that a biologist who shows a strong interest in functional explanation is likely to be accused, sometimes with a passion that startles those more accustomed to scientific than ideological debate (Lewontin 1977), of believing that all animals are perfectly optimal—accused of being an ‘adaptationist’ (Lewontin 1979a,b; Gould & Lewontin 1979). Adaptationism is defined as ‘that approach to evolutionary studies which assumes without further proof that all aspects of the morphology, physiology and behavior of organisms are adaptive optimal solutions to problems’ (Lewontin 1979b). In the first draft
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