Friday, August 16, 2013

The Failure of Reductionism in Biology

From Charney and English, "Candidate Genes and Political Behavior," American Political Science Review, Feb. 2012:
Hence, a single gene can code for multiple proteins, something that is estimated to occur in 90% of all human genes. We cannot equate a particular allele straightforwardly with the production of a particular form of protein and from that with the production of a particular physiological effect and corresponding phenotype.

Once considered the paragon of stability, DNA is subject to all manner of transformation. For example, we retrotransposons or "jumping genes" comprise 45% of the human genome, that the genome play copy-and-paste mechanism changing DNA content structure, are regulated by the epigenome (and hence are potentially environmentally responsive), and appear to be particularly prevalent in the human brain...

"The dogma and collect their genetics until the 1990s was the genotype would predict phenotype. We thought that once we cloned and characterized the gene, the nature of the mutation in the gene would specify the individual's phenotype... This concept celebrated reductionism. However, nature had not informed the patients and their biology of this belief system..." (McCabe and McCabe, 2006, 160, emphasis mine)
It turns out that the trying to reduce everything to genes failed, and that one has to see genes in the context of the entire organism and its environment to understand their role. Rather than reducing to genes, the whole organism is in a real sense more fundamental than its genes.

But this is just what the actual scientists* say. What do they know?

* The authors of the paper quoted are not biologists, but they have four densely covered pages of citations from Human Genetics, Biological Psychiatry, Journal of Neurochemistry, Behavior Genetics, Journal of Medical Genetics, Biometrics, Human Molecular Genetics, Genome Biology, etc. etc.: They probably cite 200 papers from genetic literature defending claims like the above.


  1. If reductionism is the view that a complex system is nothing but the sum of its parts (that's how Wikipedia defines it) then how does this post demonstrate "The Failure of Reductionism in Biology"?

    It just demonstrates that "the parts" may interact with the environment in ways which lead "the sum" to be environmentally determined. But I don't think that disproves reductionist, just adds additional steps to the process of reduction.

    1. Well, no Rob, if the function if a gene depends upon the entire state of the organism in which it resides, as the actual scientists in the quote said, that is a repudiation of reductionism.

    2. Suppose that genes are indeed environmentally responsive but always respond in a pre-determined way to a given environment, and that environment includes what you call "the whole organism".

      How would that differ from reductionism ?

    3. Rob, I think you've confused reductionism with determinism. They're separate issues.

    4. Well , if something is deterministic is it not also an example of "a system that is nothing but the sum of its parts"?

  2. Replies
    1. Look at my new post to see why Rob.


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