Thanks, Bruce, for giving me something else to be gloomy about.
Not knowing much about biology, I’m used to thinking of natural selection as something that improves species (at least by the measure of ability to successfully reproduce), but BC points out that, because of the continual accumulation of deleterious mutations, one actually needs a continual culling of the herd just to keep a species “in place”. As in, he thinks that before the Industrial Revolution of order 3/4 of humans died before successfully reproducing (most during childhood), with the more fit having a slight edge, and that this was necessary to avoid genetic decline. With the end of infant mortality and the ability of just about anyone to successfully reproduce, mutations are now accumulating and genetic IQ declining precipitously, a process that will continue until civilization collapses and the death of most children re-establishes itself as the norm. Industrial civilization is, thus, an intrinsically transient thing.
What to make of this? Bruce won’t appreciate the comparison (although it is meant positively), but I think the situation here is analogous to global warming. In both cases, the effect being described certainly exists to some degree. Nobody doubts that CO2 is a greenhouse gas or that humanity is dumping huge amounts of it into the atmosphere, and now that I’ve had mutation load explained to me, I must admit that turning off selection must have the effect BC describes, at least at some nonzero rate. What’s more, the mutation overload theory is impervious to many escapes. One can’t say “well, maybe modern civilization can get by with a lower-IQ population”, because the process continues until the disaster comes. One might actually hope that it takes a pretty high IQ to maintain industrial civilization, because although we hit “giga-death” sooner, we leave with more mental capacity intact. Saying that the accumulation of mutations is slower than BC thinks doesn’t help either, because with no positive selection one must hit the disaster eventually. One might imagine an aggressive eugenics program as a way to save civilization, but it would have to be more draconian than anything anyone today would stomach (although presumably not as bad as pre-industrial unguided eugenics, which measured fitness only by the loosely correlated economic status). For both global warming and BC’s scenarios, there remains a great deal of doubt regarding both observations and models. For example, I’m still not sold on the assumption that the relation between reaction time and intelligence is constant in time. (Not that I disbelieve it; I just remain agnostic, and because I haven’t really studied it, my agnosticism doesn’t mean much for the claim itself.) However, for both theories, just because there are uncertainties doesn’t give us any reason to assume that things must be less bleak than the models predict or observations indicate, that truth is always on the optimistic edge of all the error bars.
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