The term “information” has become nearly omnipresent in modern biology (and medicine). One would probably not exaggerate if the famous saying of evolutionary biologist Theodosius Dobhzhansky, that “nothing in biology makes sense except in the light of evolution” should nowadays be reframed as “nothing in biology makes sense except in the light of information.” But are those two concepts, evolution and information, somehow internally related? And if so, how?

Information in evolution

In textbooks, newspapers, and even scientific papers, the meanings of the terms “evolution” and “information” are generally supposed to be well known, and they are rarely explained. And yet, there is no general consensus in science, or even in biology, about what they really mean. For instance, the preferred exemplar (in the Kuhnian sense) of evolution by natural selection is that of industrial melanism. In woodlands, where industrial pollution has killed the lichens and exposed the dark brown tree trunks, dark forms of the peppered moth – melanics – are supposedly better camouflaged against predation from birds than are the light gray forms that predominated before the Industrial Revolution. The observation by 1950 that darker forms had largely displaced lighter forms was thus taken as evidence for natural selection in action. This exemplar does indeed illustrate the effect of natural selection, but whether it shows evolution depends on your idea of evolution. Thus, if by the term “evolution” is meant something like “the origin of species,” then it is remarkable that no speciation has actually taken place here, and it is not obvious that any speciation would indeed occur in a case like this. So, populations do indeed change as a result of natural selection, but is this mechanism also behind speciation and evolution at large? The majority of biologists certainly feel assured that macroevolution – that is, evolution above the level of species – is in fact the tardy result of an infinitely ongoing microevolution (adaptation in populations), but there remains serious disagreement on this (Depew and Weber, 1995; Gould, 2002).