Pub. date: 2006 | Online Pub. Date: September 15, 2007 | DOI: 10.4135/9781412952453 | Print ISBN: 9780761930297 | Online ISBN: 9781412952453| Publisher:SAGE Publications, Inc.About this encyclopedia
James L. Gould
Darwin's theory of evolution by natural selection requires heritable variation for selection to work on. In Darwin's time, thinking about heritability centered on the idea of “blending inheritance”—the hypothesis that the offspring receive some average mix of the parental characters. If this were true, each generation would be more average than the last and variation would steadily decline. To make natural selection work, Darwin had to suppose that the frequency of mutations—“sports” as they were often called—was high. In 1900, the pioneering work of Gregor Mendel was independently rediscovered by Hugo De Vries, Carl ...