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Professor Evelyn Fox Keller,
Rethinking the Meaning of Biological Information
Throughout the history of molecular biology, the
primary meaning of biological information has been taken from the image of
a word based linguistic code. I want to argue that the metaphor of such a
code does not begin to capture either the variety or richness of the
processes by which nucleotide sequences inform biological processes.
Current research demonstrates that nucleotide sequences inform not only
development, but also heredity and evolution, and they do so in all sorts
of ways. I claim that, while still not exhausting the varieties of
biological information employed in these processes, the power of DNA
sequences to inform these processes is both richer and perhaps far greater
than the conventional understanding of genetic information permits,
indeed, richer than any of our images of simple linguistic codes, or of
senders and receivers, permit. Rather than a tape in a Turing machine, a
message or signal sent through the generations, DNA is first and foremost
a physical-chemical structure with a range of potential uses by the
physical-chemical arsenal of biological cells that is so large as to
expose the poverty of our most familiar metaphors. Recognition of this
fact leads us to conclude that DNA is both more and less than we thought.
More, because it carries both symbolic and non-symbolic information, and
less, because accepting that fact undermines its radical distinction from
other biological molecules.
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