for natural selection to take place. Darwin needed a solution to both the swamping argument for non-saltation’s and the earths age. Darwin theorized that ‘negative selection’ by the increased destruction of non-adapted specimens would further speed up the process of natural selection. Darwin added this to the fifth edition of “On the Origin of species”. This solved for him the problem of swamping in large numbers and would shorten the evolutionary process to fit his own calculated age of the earth. Because the ‘swamping argument’ was mostly anchored in the ‘blending inheritance’ theory. When the ‘blending inheritance’ theory was replaced by mendelian inheritance in the early 1900s the ‘swamping argument’ also became obsolete. Notes Susan W. Morris. “Fleeming Jenkin and ‘The Origin of Species’: A Reassessment.” The British Journal for the History of Science, vol. 27, no. 3, 1994, pp. 313–343. JSTOR, www.jstor.org/stable/4027601. See also Haldane's dilemma External links Bulmer, Michael. Did Jenkin’s swamping argument invalidate Darwin’s theory of natural selection? // The British Journal for the History of Science (2004), 37:3:281-297 Cambridge University Press Population genetics Evolutionary biology History of evolutionary biology