POPULATION GENETICS IS OFTEN THOUGHT TO BE A DIFFICULT SUBJECT. To some
extent, difficulties are inevitable in a field where some quite basic
points are controversial. However, problems are most acute when
theoretical points are discussed, despite the fact that there has been
very little controversy over the mathematics. In my experience, the
actual mathematical manipulations rarely cause much difficulty. Rather
it is that the biologist, lacking the physicist's or chemist's
experience in "reading" mathematical formulae, finds it difficult to
appreciate what is happening in a mathematical treatment and to grasp
the implications of the results obtained, when these are given in
mathematical form. Accordingly, I have followed a procedure, which
students seem to find helpful, of giving a rough-and-ready verbal
treatment of a problem before attempting a much more exact mathematical
treatment; when the results of the latter are not readily interpretable,
I have given an elucidation. Another problem which often concerns
students is the reliability of results obtained using approximate
methods; I have, therefore, discussed this in fair detail in critical
cases. When dealing with controversial issues, I have done my very best
to be fair. To conceal one's opinions entirely would probably make for a
very dull book. I trust, however, that I have given enough for the
reader previously unfamiliar with these controversies to form his own
judge- ment.