Waddington, Conrad Hal (1905–1975)

English geneticist and biologist who examined the evolutionary significance of the interrelations between the genetic constitution, characteristics, and environment of an organism. Waddington performed experiments that demonstrated the theory that natural selection is the cause of hereditary change.

He was a champion of the principle of ‘organic selection’, in which environmentally induced changes in somatic (body) cells can result in hereditary changes, not because they affect the hereditary material (DNA) itself, but because they enable the population to survive long enough to allow the accumulation and selection of similar hereditary changes.

In one experiment, Waddington gave the pupae of the fruit fly Drosophila melanogaster a heat shock for several hours, resulting in part or all of a vein across the wing being absent (crossveinless). Flies that showed the variation, approximately 40% of the population, were crossed with each other. Matings eventually produced flies that were crossveinless without heat shock; the environmentally produced characteristic had become an inherited characteristic.

Waddington was born in Evesham in the UK and trained originally as a geologist at Cambridge University, graduating 1926. He then turned his attention to palaeontology and finally to embryology and evolution.