Read Online The Extended Phenotype: The Long Reach of the Gene (Popular Science) by Richard Dawkins - Free Book Online Page A
Authors: Richard Dawkins
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‘unnecessary geneticizing’ of the language of functional ethology, betray a fundamental failure to face up to the reality of what Darwinian selection is all about.
Let me illustrate this failure by another anecdote. I recently attended a research seminar given by an anthropologist. He was trying to interpret the incidence among various human tribes of a particular mating system (it happened to be polyandry) in terms of a theory of kin selection. A kin selection theorist can make models to predict the conditions under which we would expect to find polyandry. Thus, on one model applied to Tasmanian native hens (Maynard Smith & Ridpath 1972), the population sex ratio would need to be male-biased, and partners would need to be close kin, before a biologist would predict polyandry. The anthropologist sought to show that his polyandrous human tribes lived under such conditions, and, by implication, that other tribes showing the more normal patterns of monogamy or polygyny lived under different conditions.
Though fascinated by the information he presented, I tried to warn him of some difficulties in his hypothesis. I pointed out that the theory of kin selection is fundamentally a genetic theory, and that kin-selected adaptations to local conditions had to come about through the replacement of alleles by other alleles, over generations. Had his polyandrous tribes been living, I asked, under their current peculiar conditions for long enough—enough generations—for the necessary genetic replacement to have taken place? Was there, indeed, any reason to believe that variations in human mating systems are under genetic control at all?
The speaker, supported by many of his anthropological colleagues in the seminar, objected to my dragging genes into the discussion. He was not talking about genes, he said, but about a social behaviour pattern. Some of his colleagues seemed uncomfortable with the very mention of the four-letter word ‘gene’. I tried to persuade him that it was
he
who had ‘dragged genes in’ to the discussion although, to be sure, he had not mentioned the word gene in his talk. That is exactly the point I am trying to make. You cannot talk about kin selection, or any other form of Darwinian selection,
without
dragging genes in, whether you do so explicitly or not. By even speculatingabout kin selection as an explanation of differences in tribal mating systems, my anthropologist friend was implicitly dragging genes into the discussion. It is a pity he did not make it
explicit
, because he would then have realized what formidable difficulties lay in the path of his kin selection hypothesis: either his polyandrous tribes had to have been living, in partial genetic isolation, under their peculiar conditions for a large number of centuries, or natural selection had to have favoured the universal occurrence of genes programming some complex ‘conditional strategy’. The irony is that, of all the participants in that seminar on polyandry, it was I who was advancing the least ‘genetically deterministic’ view of the behaviour under discussion. Yet because I insisted on making the genetic nature of the kin selection hypothesis explicit, I expect I appeared to be characteristically obsessed with genes, a ‘typical genetic determinist’. The story illustrates well the main message of this chapter, that frankly facing up to the fundamental genetic nature of Darwinian
selection
is all too easily mistaken for an unhealthy preoccupation with hereditarian interpretations of ontogenetic
development
.
The same prejudice against explicit mention of genes where one can get away with an individual-level circumlocution is common among biologists. The statement, ‘genes for performing behaviour X are favoured over genes for not performing X’ has a vaguely naive and unprofessional ring to it. What evidence is there for such genes? How dare you conjure up
ad hoc
genes simply to satisfy your hypothetical convenience! To say
Let me illustrate this failure by another anecdote. I recently attended a research seminar given by an anthropologist. He was trying to interpret the incidence among various human tribes of a particular mating system (it happened to be polyandry) in terms of a theory of kin selection. A kin selection theorist can make models to predict the conditions under which we would expect to find polyandry. Thus, on one model applied to Tasmanian native hens (Maynard Smith & Ridpath 1972), the population sex ratio would need to be male-biased, and partners would need to be close kin, before a biologist would predict polyandry. The anthropologist sought to show that his polyandrous human tribes lived under such conditions, and, by implication, that other tribes showing the more normal patterns of monogamy or polygyny lived under different conditions.
Though fascinated by the information he presented, I tried to warn him of some difficulties in his hypothesis. I pointed out that the theory of kin selection is fundamentally a genetic theory, and that kin-selected adaptations to local conditions had to come about through the replacement of alleles by other alleles, over generations. Had his polyandrous tribes been living, I asked, under their current peculiar conditions for long enough—enough generations—for the necessary genetic replacement to have taken place? Was there, indeed, any reason to believe that variations in human mating systems are under genetic control at all?
The speaker, supported by many of his anthropological colleagues in the seminar, objected to my dragging genes into the discussion. He was not talking about genes, he said, but about a social behaviour pattern. Some of his colleagues seemed uncomfortable with the very mention of the four-letter word ‘gene’. I tried to persuade him that it was
he
who had ‘dragged genes in’ to the discussion although, to be sure, he had not mentioned the word gene in his talk. That is exactly the point I am trying to make. You cannot talk about kin selection, or any other form of Darwinian selection,
without
dragging genes in, whether you do so explicitly or not. By even speculatingabout kin selection as an explanation of differences in tribal mating systems, my anthropologist friend was implicitly dragging genes into the discussion. It is a pity he did not make it
explicit
, because he would then have realized what formidable difficulties lay in the path of his kin selection hypothesis: either his polyandrous tribes had to have been living, in partial genetic isolation, under their peculiar conditions for a large number of centuries, or natural selection had to have favoured the universal occurrence of genes programming some complex ‘conditional strategy’. The irony is that, of all the participants in that seminar on polyandry, it was I who was advancing the least ‘genetically deterministic’ view of the behaviour under discussion. Yet because I insisted on making the genetic nature of the kin selection hypothesis explicit, I expect I appeared to be characteristically obsessed with genes, a ‘typical genetic determinist’. The story illustrates well the main message of this chapter, that frankly facing up to the fundamental genetic nature of Darwinian
selection
is all too easily mistaken for an unhealthy preoccupation with hereditarian interpretations of ontogenetic
development
.
The same prejudice against explicit mention of genes where one can get away with an individual-level circumlocution is common among biologists. The statement, ‘genes for performing behaviour X are favoured over genes for not performing X’ has a vaguely naive and unprofessional ring to it. What evidence is there for such genes? How dare you conjure up
ad hoc
genes simply to satisfy your hypothetical convenience! To say
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