The Meme Machine

60 THE MEME MACHINE
affect the genes that you pass on – although it can affect whether you pass some
on or not. The genes your children will inherit are derived directly from the
genes you inherited and it is this continuous line that is known as the ‘germ
line’. Conceivably, if genes worked as some kind of stored blueprint or map
then changes in the phenotype could be fed back to change the map but this is
not the case. Conceivably, the process of meiosis, in which cells divide to make
ova and sperms, could be affected by changes in the phenotype, but this does not
happen and in any case, the ova a woman carries in her ovaries are already there
at her birth. We must imagine the germ line going on continuously, with the
genes being shuffled and recombined in each generation. These genes instruct
the phenotype which then set off on their own and are either successful or not,
but the phenotypes do not instruct the genes.
Even though Lamarckian inheritance cannot happen in such a system, there
have been many experiments looking for it. Weismann himself cut off the tails
of mice for many generations with no obvious effect on the length of their
offspring’s tails. However, this is not strictly a test of the theory because
Lamarck argued that organisms had to strive towards improvements, as when
giraffes stretch their necks, or birds practise flying, and Weismann’s mice
presumably did not strive to have their tails cut off. In Russia, the official
science of Lysenko was based on Lamarckism but produced no progress in
biology and was disastrous for Soviet agriculture because their plant breeding
programmes failed.
Lamarck’s idea is still popular and appears in many guises, including
memories of past lives being attributed to ‘genetic memory’, and psychic powers
being explained by ‘spiritual evolution’. Perhaps it is popular because it implies
that there is some point in all our hard work or some benefit to our children if we
struggle to improve ourselves. But from the purely genetic point of view there is
no such benefit. Popular it may be, but it is simply not true.
At least, Lamarckism is not true for sexual species. For other kinds of
organism the idea is simply inapplicable. The most common creatures on this
planet are unicellular organisms, such as bacteria, which reproduce by cell
division. For these ubiquitous creatures there is no clear distinction between
genotype and phenotype, genetic information is exchanged in various ways, and
there is no clear germ line. So the whole idea of Lamarckian inheritance is
irrelevant.
What then of cultural evolution? The answer depends critically on how you
draw the analogy between genes and memes and, as I have stressed before, we
must be very careful whenever we use this analogy.