    haldane's dilemma is a limit on the speed of beneficial evolution, first calculated by j. b. s. haldane in 1957, and clarified further by later commentators. creationists, and proponents of intelligent design in particular, claim it remains unresolved. today, haldane's dilemma is raised mostly by creationists opposed to evolution, who claim it is evidence against large-scale evolution, and a supposed example of negligence on the part of the scientific community. though the scientific community in general no longer regards haldane's dilemma as a problem, there remains little clarity as to how it became dismissed, and as recently as 1992 the issue was still regarded as a challenge by evolutionary biologists.  haldane stated at the time of publication "i am quite aware that my conclusions will probably need drastic revision", and subsequent corrected calculations found that the cost disappears. he had made an invalid simplifying assumption which negated his assumption of constant population size, and had also incorrectly assumed that two mutations would take twice as long to reach fixation as one, while sexual recombination means that two can be selected simultaneously so that both reach fixation more quickly. == substitution cost == in the introduction to the cost of natural selection haldane writes that it is difficult for breeders to simultaneously select all the desired qualities, partly because the required genes may not be found together in the stock; but, writes haldane (p.&nbsp;511), especially in slowly breeding animals such as cattle, one cannot cull even half the females, even though only one in a hundred of them combines the various qualities desired. that is, the problem for the cattle breeder is that keeping
Dilemmas Evolutionary_biology Intelligent_design Mathematical_and_theoretical_biology Population_genetics Works_by_J._B._S._Haldane