PEARSON,KARL MATHEMATIZATION OF INHERITANCE - FROM ANCESTRAL HEREDITYTO MENDELIAN GENETICS (1895-1909)

Long-standing claims have been made for nearly the entire twentieth ce ntury that the biometrician, Karl Pearson, and his colleague, W. F. R. Weldon, rejected Mendelism as a theory of inheritance. It is shown th at at the end of the nineteenth century Pearson considered various the ories of inheritance (including Francis Galton's law of ancestral here dity for characters underpinned by continuous variation), and by 1904 he 'accepted the fundamental idea of Mendel' as a theory of inheritanc e for discontinuous variation. Moreover, in 1909, he suggested a synth esis of biometry and Mendelism. Despite the many attempts made by a nu mber of geneticists (including R. A. Fisher in 1936) to use Pearson's chi-square (chi(2), P) goodness-of-fit test on Mendel's data, which pr oduced results that were 'too good to be true', Weldon reached the sam e conclusion in 1902, but his results were never acknowledged. The gen eticist and arch-rival of the biometricians, Williams Bateson, was ins tead exceptionally critical of this work and interpreted this as Weldo n's rejection of Mendelism. Whilst scholarship on Mendel, by historian s of science in the last 18 years, has led to a balanced perspective o f Mendel, it is suggested that a better balanced and more rounded view of the hereditarian-statistical work of Pearson, Weldon, and the biom etricians is long overdue.