In 1924, J.B.S. Haldane calculated, using a simple general selection model, the selective advantage necessary for the recorded natural evolution of peppered moths, based on the assumption that in 1848 the frequency of dark-coloured moths was 2%, and by 1895 it was 95%. The dark-coloured, or melanic, form would have had to be 50% more fit than the typical, light-coloured form. Even taking into consideration possible errors in the model, this reasonably excluded the stochastic process of genetic drift, because the changes were too fast. Haldane's statistical analysis of selection for the melanic variant in peppered moths became a well known part of his effort to demonstrate that mathematical models that combined natural selection with Mendelian genetics could explain evolution — an effort that played a key role in the foundation of the discipline of population genetics, and the beginnings of the modern synthesis of evolutionary theory with genetics.