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Lewontin’s argument for why genes are not buckets

In Uncategorized on April 12, 2010 by Jenny

Lewontin argues that it is mistaken to characterize genes as determining one’s capacity.  But I’m confused as to why this is so; maybe someone can help me out.

He writes, “In a trivial sense every genotype must indeed have a maximum possible metabolic rate, growth rate, activity, or mental acuity in some environment, but, as we have just seen from the actual experimental data on reaction norms, the environment in which that maximum is realized is different for each genotype.  Moreover, the ordering of genotypes from ‘restricted’ to ‘enriched’ will change from genotype to genotype.  Obviously there will be some environments that will be lethal or severely debilitating for any conceivable genotype, but these are irrelevant to the problem” (28).

I don’t understand why the fact that the environment in which the maximum is realized is different for each genotype supports the idea that genes are not buckets.  Or why the ordering of genotypes, too, supports the conclusion that genes are not buckets.  Does anyone understand this argument who could explain it to me?

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One Response to “Lewontin’s argument for why genes are not buckets”

  1. I too share Jenny’s confusion. The only thing I can think of to explain Lewontin’s claim that genes are not buckets is that what he really means is that genes are not buckets of a certain sort. That is genes are not like various sized buckets each of which can be filled in the same sort of way. So for example, imagine a series of buckets A, B, and D which are laid out in an open field. Each subsequent bucket is wider and has a greater capacity than the previous. (i.e. C is bigger and wider than B. B is bigger and wider than A) If the environmental conditions are favorable (i.e. it rains), the buckets will be filled with water to some degree. However, regardless of how favorable the conditions are, bucket C will always have more water than bucket B, etc… except when it doesn’t rain at all. I think that Lewontin is arguing that genes are not like this particular bucket model.

    However, if this is what Lewontin is saying, it could still be the case that genes can be viewed as buckets of a different sort. Imagine a series of buckets X, Y, Z each of which can only be filled under certain conditions. For example bucket X could have a cover on the top of the bucket and holes on the side such it does not fill when rain falls straight down but fills quite well when rain falls at an angle due to windy conditions. Bucket Y could be such that it fills well when rain falls straight down but not at an angle. Bucket Z could be such that it only fills by condensation. This bucket model is different from the previous model insofar as the conditions which are optimal for a given bucket in this model is not also optimal for another given bucket.

    So I think that Lewontin is merely ruling out a specific bucket metaphor rather than any metaphor viewing genes as certain sorts of bucket. That is his original metaphor may have been ill-defined which would be ironic given his earlier warning on using metaphors. Does this sound right?

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