Evolution is testable science

PUBLISHED : Friday, 14 May, 1993, 12:00am
UPDATED : Friday, 14 May, 1993, 12:00am

''EVOLUTION'' refers both to the product of a natural process - revealed by the fossil record - and the mechanism by which that process occurs - Darwin's theory of natural selection.

Living animals with intermediate characters (mammals which lay eggs, fishes with lungs) provide support for evolution. Moreover, there are observations that we can make which will allow us to test whether evolution has occurred. For example, the theory of evolution would be in serious difficulty (and would be rejected by scientists) if human fossils were found in 600 million year old rocks, a period preceding the rise of animals with backbones. Perhaps this is the reason why creationists are so keen on the fake human footprints which were carved in the dinosaur beds of Texas during the depression with the aim of fooling tourists.

The mechanism of evolution combines random genetic mutations with non-random variations in the survival and breeding success of organisms. Those organisms with ''good'' mutations (enhanced adaptations) leave more offspring than those with ''bad'' mutations, hence the ''good'' mutations spread. Because the mechanism of evolution depends on the differential success of individuals, it is clearly non-random. Note also, that evolution proceeds in a cumulative fashion, with a few genes being changed at a time, and thus change is gradual. This is quite different from the single-step process envisaged by those who liken evolution to a single gust of wind blowing through a scrap yard and assembling a 747 from a pile of junk.

In a nutshell, the fossil record provides both a record and a test of evolution. The mechanism of evolution is a cumulative process involving non-random survival of individuals with different genes.

Evolution is a testable science and thus wholly different from the imaginative literature of the first chapter of Genesis.

Dr DAVID DUDGEON Reader Department of Zoology University of Hongkong