law of averages

darwins 'origin of the species' is often summed up in the phrase 'survival of the fittest'. it is easy to make the unspoken assumption that over time a population becomes fitter by most definitions of fitness that affect survival and competition - fertility, strength, speed, cunning, intelligence etc.

But l don't think that happens any more. In western societies with low birth rates (and just as low death rates) the overriding factor in the make up of the gene pool in the next generation is defined by the demographic that procreates most.

As it happens there is a correlation here: country dwellers and the lower income bracket come top of this chart, but also suffer badly in many studies of mental capacity (IQ, awareness of current affairs etc). Such tests are not to everybody's taste but that's not my point. It is: our species is unassailably dominant - so maybe the removal of survival threats is making our species less 'fit'. year on year it may be that the gene pool is dominated more and more by the average.

Have we already peaked?