368 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
It can be granted that some genotypes which were being eliminated 
under primitive conditions are enabled to survive and to perpetuate 
themselves in civilized environments. As pointed out above, this 
necessarily means that the Darwinian fitness of these genotypes under 
civilized conditions has risen relative to what it was under primitive 
ones. The possessors of such genotypes, if they take proper care of 
themselves, may even be able to secure their share of the joy of living. 
Does it follow, however, that these genotypes may now be considered 
desirable in the human species? The answer may, unfortunately, be 
in the negative. Muller (1950) has portrayed the state of mankind 
which might result from failure to eliminate weakening mutant genes 
in the following way: 
This means that despite all the improved methods and facilities which will be 
in use at that time the population will nevertheless be undergoing as much 
genetic extinction as it did under the most primitive conditions. In corre- 
spondence with this, the amount of genetically caused impairment suffered by 
the average individual, even though he has all the techniques of civilization 
working to mitigate it, must by that time have grown to be as great in the 
presence of these techniques as it had been in paleolithic times without them. 
But instead of people’s time and energy being mainly spent in the struggle with 
external enemies of a primitive kind such as famine, climatic difficulties and 
wild beasts, they would be devoted chiefly to the effort to live carefully, to spare 
and to prop up their own feeblenesses, to soothe their inner disharmonies and, 
in general, to doctor themselves as effectively as possible. For everyone would 
be an invalid, with his own special familial twists. 
The outlook seems grim. Natural selection under civilized condi- 
tions may lead mankind to evolve toward a state of genetic overspeciali- 
zation for living in gadget-ridden environments. It is certainly up 
to man to decide whether this direction of his evolution is or is not 
desirable. If it is not, man has, or soon will have, the knowledge 
requisite to redirect the evolution of his species pretty much as he sees 
fit. Perhaps we should not be too dogmatic about this choice of direc- 
tion. We may be awfully soft compared to paleolithic men when 
it comes to struggling, unaided by gadgets, with climatic difficulties 
and wild beasts. Most of us feel most of the time that this is not a 
very great loss. If our remote descendants grow to be even more effete 
than we are, they may conceivably be compensated by acquiring geno- 
types conducive to kindlier dispositions and greater intellectual capaci- 
ties than those prevalent in mankind today. 
SELECTION OF WHOLE GENOTYPES 
The propensity of evolution to produce unfavorable changes in 
plants and animals may at first sight appear astonishing. Consider 
the absurd difficulty which the human female has in giving birth to her 
young. Here isa process which is assuredly essential for the perpetua- 
tion of the species. Natural selection could be expected to make it 
