Haldane and the primary limitation of positive (Darwinian) natural selection

A satisfactory theory of natural selection must be quantitative. In order to establish the view that natural selection is capable of accounting for the known facts of evolution we must show not only that it can cause a species to change, but that it can cause it to change at a rate which will account for present and past transmutations.
— J. B. S. Haldane

I’m really excited to share this critical review of Haldane’s Dilemma, published in Inference: International Review of Science. The topic is a mathematical limit on the rate at which evolutionary substitution can proceed – in other words, a limit on how fast a new beneficial mutation can replace its older version in a population. This is how evolution by positive (Darwinian) natural selection proceeds.

It cannot occur instantly. Just imagine a new beneficial mutation arising in a single human individual; obviously one person cannot have enough children to replace the rest of the human population in a single generation. At the same time, such a process might easily take place over some 100 thousand years. Somewhere in between, a most plausible rate exists. I show that this likely rate has problematic implications for models of population genetics which rely solely on positive selection to explain the majority of adaptive evolution. Other mechanisms, including a predominant role for random genetic drift, are necessary. Read the full text here.