UNDERSTANDING EVOLUTION
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Dr Eliot Gingold, lecturer in genetics at Hatfield Polytechnic, has sent
a Spectrum program to simulate the development of mixed populations
under evolutionary pressures. He believes that the use of computers for
the purpose has the great advantage over mathematical equations that
random influences can be included in the model.

The listing sets up a small, local population of black and yellow mice
and follows it for successive generations. The variation in colour in
controlled by two variant forms of a single gene, with the
black-inducing gene dominant over the yellow.

The user is invited to fix the population size and the differing
selection pressures on the two types. An interesting finding is that
small populations suffering no selection pressure eventually will
resolve into entirely black or yellow types. Such results show the
importance of the random element.

"This so-called 'genetic drift' is an important factor in discussions of
evolutionary theory. Many scientists believe that such random events are
the basis for many of the observed differences between species," he
says.

The listing is aimed at A level students but its avoidance of technical
terms should assure it wider usefulness. In the listing, the mice should
be entered as graphic M. (48K Spectrum).