"In 1926, Dr. Hermann Joseph Muller discovered that X-rays can
increase the mutation rate in living organisms, particularly in egg and sperm cells, by as much as 100 times. Because the major source of genetic variation is mutations, he reasoned he could drastically speed-up evolution by artificially creating new mutations by X-rays. His experiments involved placing fruit flies in petri dishes, turning on his X-Ray tube to irradiate the flies, then mating those that survived, and lastly, attempting to measure and evaluate the number of mutations in the offspring.The excitement this discovery produced in the scientific community was so great that the Nobel Prize in Physiology was awarded to Muller in 1946 “for the discovery of the production of mutations by means of X-ray irradiation.” In his acceptance lecture Muller wrote:
Not only is this accumulation of many rare, mainly tiny changes the chief means of artificial animal and plant improvement, but it is, even more, the way in which natural evolution has occurred, under the guidance of natural selection. Thus the Darwinian theory becomes implemented, and freed from the accretions of directed variation and of Lamarckism that once encumbered it.
All Muller got, however, were sick fruit flies or dead fruit flies. The
results had nothing to do with evolution or natural selection. And ever
since, no experiment has produced an improved fruit fly by increasing
the mutation rate." CEH