The Meme Machine

MEME–GENE COEVOLUTION 101
for limited resources. Such conditions favour large size, long life and small
numbers of well-cared-for offspring. K-selected species include elephants and
humans. These are the extremes, but even in the most K-selected species many
copies of the genes are made.
Finally, genes are long lived. Individual molecules of DNA are well
protected inside cells, and those that are passed down through the germ line can
sometimes survive as long as the lifetime of the organism. Depending on the
size of unit you count as the gene, its lifetime varies, but in some sense genes are
immortal, since they are passed on from generation to generation to generation.
Genes are extremely high-quality replicators.
Were they always that way? Presumably not, although we do not know
much about the early history of DNA. However, it is reasonable to assume that
the first replicators were simpler chemicals than present-day DNA, and were not
packaged efficiently in chromosomes inside cell nuclei and with a complex
cellular machinery devoted to their maintenance and duplication. They may, for
example, have been simple autocatalytic systems that give rise to two identical
molecules, followed by polynucleotide-like molecules, and then RNA (Maynard
Smith and Szathmáry 1995). But why should these chemicals have evolved to
produce the high-quality replicating system that we have today?
Imagine the competition between various forms of early replicator in their
primeval soup. If a low-fidelity replicator and a high-fidelity replicator existed
at the same time, the high-fidelity one would win out. As Dennett (1995) puts it,
successful evolution is all about the discovery of ‘good tricks’. A replicator that
makes too many mistakes in copying soon loses any good tricks that it stumbles
across. A high-fidelity replicator would not stumble upon them any quicker
(and arguably could be slower) but at least it would keep any it found – and thus
outperform the competition. Similarly a highly fecund replicator would, simply
by virtue of making more copies, swamp its rivals. Finally, a long-lasting
replicator would still be around when its competitors had fizzled out. It is
obvious really. In this early environment there would have been selection
pressure for better and better replicators, and this could ultimately have resulted
in the exquisite cellular machinery for coming DNA.
The same principle can be applied to memes. Imagine early hominids who
have discovered the biologically ‘good trick’ of imitation. Initially, this good
trick allowed some individuals to profit by stealing the discoveries of others, and
these individuals therefore passed on the genes that made them imitators until
imitation became widespread. Then a new replicator was born and, using the