The molecular-clock hypothesis and the neutral theory were particularly controversial, spawning the neutralist-selectionist debate over the relative importance of mutation, drift and selection, which continued into the 1980s without a clear resolution.
A hipótese do reloxo molecular e a teoría neutralista eran especialmente polémicas, orixinando o debate entre neutralistas e seleccionistas sobre a importancia relativa da mutación, deriva e selección, que continuou na década de 1980 sen que se chegase a unha clara resolución.