July 22, 2010, marked the 100th anniversary of genetic investigations using fruit flies. The first such study appeared in Science in 1910 and described the unexpected appearance of a male fruit fly with white eyes after generations of flies with pigmented eyes.1 This began a century of focused studies on fruit fly mutations, but what has really been learned by all this tinkering?
For most of the past century–and especially since the discovery of DNA as a physical molecule carrying heritable information–the prevailing concept of neo-Darwinian evolution has held mutations to be the central generator of new and useful information. Thus, mutations have been given ample opportunity to prove themselves, if they are naturally selected, as having “the power to drive the evolution of all living things in the direction of positive improvement.”2
Fruit flies, with their short generation times and only four pairs of chromosomes, presented prime testing ground for evolution. In laboratories worldwide, they have been subjected to all manner of mutation-inducing phenomena, including hosts of chemicals and radiation treatments, to try and accelerate evolution-mimicking mutations. After all this, fruit flies should have certainly exemplified evolution by now.2 But they haven’t.