Biological and digital messages are transmitted by linear sequences of interchangeable elements -- "alphabets" if you will. Cells use messenger molecules constructed of chains of simple chemical subunits. Computers use messages that are sequences of bytes.
Life has evolved two sorts of chain molecules: DNA or RNA, which are
chains of nucleotides that primarily carry the genetic
'program' of the cell, and proteins which are chains of amino acids
that fold tightly upon themselves to form a complex shape that
determines their functional/structural properties.
Protein chains tend to be from a few dozen to a few thousand amino
length. Once folded, they become the "parts" that make up the machinery
of the cell. In contrast, DNA when not active in its "code" role,
is folded tightly (to sequester it so that it cannot be "executed") and
only when playing its genetic coding role is it unfolded to expose its
coding sequence to the protein machinery that interprets its execution.
Chains of RNA can play both sorts of roles: they may fold into
functional shapes, much like a protein, to act as "parts" in larger
complexes, or their genetic sequence may be interpreted
programmatically (the details of the two roles of RNA are beyond the
scope of the current topic). In general, however, transfer of messenger
proteins causes the cell to select
behavior from its existing repertoire whereas transfer of genetic
changes the repertoire itself. Metazoan cells have predetermined
functions and can seldom if ever tolerate having their functional
The distinction between the two kinds of message is central to communication strategies in biology and communication strategies in computing. The parallels between the two realms can help us understand multicellular computing. Whereas single-cells and single computers computers can afford to exchange executable code, and often benefit by doing so, code exchange in multicellular systems is exceedingly dangerous -- it is all too often a vehicle for infection by a virus. That is why DNA exchange is taboo in multicellular life. In computing, we are learning the importance of that taboo the "hard way" as we cope with increasingly dangerous digital viruses and worms. Polymorphic non-executable messages are far better suited to communication in multicellular systems.
Contact: sburbeck at mindspring.com
Last revised 6/12/2012