Forward genetics a bare minimum for the appearance of specific phenotypes. However, such initial screens were either incomplete as they were missing redundant loci and epigenetic effects, and such screens were difficult to undertake for certain phenotypes that lack directly measurable phenotypes. Additionally a classical genetics approach takes significantly longer. Gregor Mendel experimented with pea plant phenotypes and published his conclusions about genes and inheritance in 1865. Around the early 1900s Thomas Hunt Morgan was mutating Drosophila using radium and attempting to find heritable mutations Alfred Sturtevant later began mapping genes of Drosophila with mutations they had been following. In the 1990s
Heredity to work (noticing that traits that were not expressed explicitly in the parent at the time of reproduction could be inherited, that certain traits could be sex-linked, etc.) rather than suggesting mechanisms. Darwin's initial model of heredity was adopted by, and then heavily modified by, his cousin Francis Galton, who laid the framework for the biometric school of heredity. Galton found no evidence to support the aspects of Darwin's pangenesis model, which relied on acquired traits. The inheritance of acquired traits was shown to have little basis in the 1880s when August Weismann cut the tails off many generations of