Edited, and with emphasis added, from a lecture of 1996 entitled 'Between Shoreham and Downe: seeking the key to natural beauty'
...Both the externally driven infectious-disease version sex theory that I support, and that more internally-driven (and at present better accepted) pure mutation-elimination version, lead to a similar conclusion, that a high level of selective death of zygotes has been a normal and necessary part of the maintenance of the health of species.
The only escape from this for our own is either a level of genetic engineering and cellular intervention that is at present not remotely in sight, or a series of technological fixes after or before birth for both all the old diseases of humanity and the new ones that will increasingly appear and accumulate.
The problem is not only with the major new infectious diseases or the major gene defects. There will also be needed physiological fixes for all the small bad mutations that are constantly being added to the human gene pool.
The natural system of life was to arrange deaths after some sort of testing through competition.
Generally in a species with parental care these deaths will evolve to occur as early in life as their effects can be made to appear.
Such deaths eliminate multiply bad and/or currently inappropriate genotypes. The multiply disadvantaged genotypes are constantly being created by [sexual] recombination along with other “clean” genotypes that are likely to survive in their place. The idea that the elimination of the former class is natural and even eugenically necessary, of course, runs much against our humane instincts and it is doubtless partly for this reason that genetics is sometimes referred to as “the gloomy science.”
In the face of such a bleak outlook of constant deterioration, our instincts are almost guaranteed to be pre-set to tell us: “Even if that may true in general, of course it doesn't always apply and surely anyone can see it doesn't apply in my wonderful family.”
But according to the old system, which the new one of medical tinkering is very far as yet from being able to replace and perhaps, even in principle, never will replace (and certainly won't before the Malthusian crunch begins to make medical progress much more difficult), death must cull from almost every family.
No family is so intrinsically healthy against all infections or so shielded from mutations that it is not being carried steadily down hill, in need not at all of the “Rassenhygiene” [i.e. a Nazi term for 'racial hygeine'] of our mistakes of the past; but, as the least, of just a natural wild culling of badly endowed foetuses and neonates.
(End of quotation)
My notes and comments:
Hamilton misses at least three major factors from this account (mostly because their significance was not appreciated in 1996):
1. That for the past 200 years (in Britain, anyway) there has been positive selection to amplify the proportion of mutated genomes - since assortative mating and an inverse relationship between fertility (thus, in the modern world, reproductive success) and fitness indicators such as intelligence, level of education, health, longevity and occupational social class. In other words (except for lethal or very severely-crippling mutations), with each generation the group of people carrying the heaviest mutation loads have left behind a larger proportion of offspring in the following generation, and vice versa.
2. That the population in Britain (and other developed nations) has for several decades been shrinking in the sense of having lower than replacement fertility. This amplifies the concentration of mutations in each succeeding generation.
3. When he says 'death must cull from every family - this 'must' is probably correct in a context where an average women would be expected to have considerably more than six conceptions -with some ending early in development. But the culling falls very unequally - going from a 100 percent cull in some to a much smaller fraction of this - maybe guesstimating fifteen percent? - in others.
Viewed from Hamilton's secular perspective; even despite his implicit devotion to objective transcendental values of truth and beauty, this is an utterly horrible vision of Life.
What is missing from Hamilton's vision is an objective transcendental sense of virtue as something more than mere presence of pleasure/ absence of suffering - but absent far more significantly more than even this is a faith in the reality of Love as the primary reality in Life.
All the above may be factually correct - and I believe it probably is - yet in ultimately reality, properly-speaking, at the end of the day and as the bottom-line: all the above is no more (nor less) than a context for the operation of divine Love.
This is the situation: now Love.
See also Adam Greenwood's meditation on this theme: