Since my formal biology education consisted of a single high school course, my understanding of biology is somewhat sketchy. So, like most Christians examining evolution, understanding the evidence can sometimes be a difficult slog, particularly when the direction the evidence is pointing seems counter intuitive.
Take, for example, genetic mutations. Aren’t beneficial mutations too rare to account for the development of life through natural selection? Wouldn’t harmful mutations, at a minimum, counteract the good mutations? These are (the semi-rhetorical) questions that are asked frequently, particularly by those who wish to discredit the theory of evolution. And really, I don’t think I could have provided a succinct answer to these questions (or even pointed out that the questions themselves betray a misunderstanding of how natural selection and genetic mutations interact).
Maybe I can now. I recently encountered, almost simultaneously, 2 independent and simple explanations for the ability of helpful mutations to influence adaptation. For me, simple explanations are better. And since even simple doesn’t always seem to work, two simple explanations are twice as good.
The first explanation comes from Daryl Domning in his book Original Selfishness: Original Sin and Evil in the Light of Evolution. In his section on “Objections to the Darwinian View of Nature”, Domning addresses the question of the rarity of “favorable” mutations.
When a mutation is first exposed to selection, it may be selectively neutral (hence not eliminated), and only become favorable when circumstances change. Therefore the “window” of time within which an ultimately favorable mutation has to occur before it is needed may actually be quite generous. (page 37)In other words, these favorable mutations do not need to strike while the iron is hot. They can “wait” for a long, long time before affecting the course of evolution.
The second explanation comes from Stephen Matheson in his post Mutations, Selection, and Bacteria. Matheson first points out that the ratio of harmful to helpful mutations has been grossly overestimated. Secondly, although harmful mutations may be bad for an individual organism, they are not necessarily bad for a population. But the key point (for me anyways) was his comparison of two definitions for the process of adaptation. The first (inaccurate) definition is as follows:
Adaptive evolution occurs when natural selection favors certain mutations which are beneficial as opposed to harmful. When new challenges arise, new adaptations arise as new beneficial mutations are generated and selection favors these mutations.The implication here is that new mutations occur “just in time” like parts in an efficient Japanese auto factory. But, as Domning points out above, that is just not necessary. (And anyways, whoever said evolution was efficient?). As Matheson states, referring to the recent book Edge of Evolution by ID proponent Michael Behe:
[The] whole silly book is based on calculations that assume that new mutations must be generated, simultaneously, after the introduction of the new challenge.Mutating is not a strategy used by populations to address challenges. The occurrence of mutations is independent from a population’s environment. This is the random part of evolution. However, as the environment changes, so too the potential “usefulness” of the variation caused by a random mutation. Only then can one know whether a mutation was “useful” or not.
The second (much more accurate) definition for the process of adaptation is as follows:
Adaptive evolution occurs when natural selection favors previously-existing genetic combinations that are more fit than others. When new challenges arise, new adaptations arise as selection favors individuals whose genetic endowments are best suited to the new challenges.Natural selection does not act on mutations themselves, but on the variation caused by mutations.
Ok. If I was on a stage debating hucksters like Hovind, Safarti, or Ham, I’d probably badly mangle the argument and lose the debate. (Um, could I have a 30-minute time-out while I research that question please?) But at least I feel like I understand how the process of adaptation works, and why the arguments of anti-evolutionists are so badly flawed.