Volume 56, Number 16 · October 22, 2009
The Mysterious Genome
By Michael Corner, Reply by Freeman Dyson
In response to When Science & Poetry Were Friends (August 13, 2009)
To the Editors:
By describing the genome as a "language" that still needs to be deciphered ["When Science & Poetry Were Friends," NYR, August 13], Freeman Dyson perpetuates a widespread misconception of the role of genes in the development and functioning of biological organisms. Ever since the cracking of the "genetic code" more than half a century ago, it has been clear that DNA sequences (genes) serve simply as templates for the manufacture (indirectly, via messenger RNA) of the structural proteins and enzymes that constitute the raw materials from which living cells construct and replenish themselves.
This means that, once the amino acid sequence of a given protein is known (and there are powerful methods for obtaining such knowledge), the sequence of nucleotides that coded for it will be easily derived. All that DNA sequencing of the genome can add to the picture is to enable the strand that coded for the protein in question to be precisely located on a particular chromosome—not a biologically crucial detail, any more than the spatial distribution of the pipes of an organ gives any insight into its working, let alone the music that is played upon it.[*]
Providing children of future generations with their DNA charts will thus be no more helpful to them for understanding their biological uniqueness than were the horoscopes made for children of earlier generations: not only is the vast majority of DNA "junk" that doesn't code for any proteins that are actually synthesized, but all except a minuscule part of everybody's genome will turn out to be exactly the same, since identical biochemical mechanisms for making the same range of cell types are present in all individuals, indeed in most species. I think that a correct(ed) picture of the genetic component of our biological inheritance, and of the subsidiary part it plays in the totality of life processes, would be a vastly more useful gift for the children of the future!
Michael Corner
Professor Emeritus of Developmental Physiology
University of Amsterdam
The Netherlands
Freeman Dyson replies:
I am grateful to Michael Corner for raising an important question. We agree that the genome of a higher organism consists of two parts, a smaller part which is fully deciphered, consisting of genes, and a larger part which is undeciphered. The question is whether the larger part is "junk DNA" without any important meaning, or whether the larger part is a text that carries as much meaning as the genes, written in a language that we have still to learn. Michael Corner favors the first alternative. I favor the second. Since he is an expert and I am not, he may well be right.
One of the reasons why I stick to my opinion is the fact that a human being has only a few more genes than the primitive roundworm C. elegans. It seems that some component of the genome other than the genes is responsible for the enormous difference in complexity between human and roundworm. This unknown component of the genome must be deciphered and understood before the artists of the new Age of Wonder can master their craft, creating new varieties of animals and plants.
Notes
[*]See Denis Noble, The Music of Life: Biology Beyond Genes (Oxford University Press, 2006).