364 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
the inhabitants of different parts of the world have different 
reproductive rates. 
The selective forces which now act on the human species are natural, 
rather than artificial, selection. Itis of course conceivable that natural 
selection may some day be replaced by artificial selection. Indeed, 
“To replace natural selection by other processes that are more mer- 
ciful and not less effective’ (Galton) was the original theme of 
eugenics. To make this dream a reality, the contributions which 
various genotypes made to the gene pool of the next generation would 
have to be decided on the basis of genetic considerations either by 
parents themselves or by some outside authority. An alternative 
idea has been developed, especially by Osborn (1951); instead of 
substituting artificial selection for natural selection, he suggests a 
reorganization of social and economic institutions so that natural selec- 
tion could be relied upon to favor intelligence and social adaptability. 
The frequent allegation that the selective processes in the human 
species are no longer “natural” is due to persistence of the obsolete 
19th-century concept of “natural” selection. The error of this view 
is made clear when we ask its proponents such questions as, why 
should the “surviving fittest” be able to withstand cold and in- 
clement weather without the benefit of fire and clothing? Is it not 
ludicrous to expect selection to make us good at defending ourselves 
against wild beasts when wild beasts are getting to be so rare that it 
is a privilege to see one outside of a zoo? Is it necessary to eliminate 
everyone who has poor teeth when our dentists stand ready to provide 
us with artificial ones? Is it a great virtue to be able to endure pain 
when anesthetics are available? 
The words “fitness” and “adaptedness” are meaningless except in 
relation to some environment. Natural selection involves interaction 
between the genotype and the environment, and this interaction leads 
to furtherance of congruity between the interacting entities. For 
this reason, organic evolution has on the whole been adaptive. It 
is, nevertheless, a function of an imperfect world. One of its limita- 
tions is that it is opportunistic. Selection enhances the adaptedness of 
genotypes only to the currently existing environments. Therefore, 
the direction and the intensity of natural selection are as changeable 
as the environment. Selection in modern man cannot maintain our 
fitness for the conditions of the Old Stone Age, nor can it prepare us 
for novel conditions of the distant future except by increasing our 
general adaptability. 
Man’s environments are decisively influenced by his cultural devel- 
opments. For good or for ill, natural selection fits man to live in 
the environments created by his own culture and technology. In 
these environments, the ability to subsist on uncooked foods is prob- 
ably now less important than it once was; the ability to resist certain 
