362 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1958 
the evolution theory. But the rhetorical superlative misrepresents the 
actual situation by overstating the ferocity of the struggle for exist- 
ence. Nietzschean superman is biologically a dubious foundation on 
which to build the future of the species. In nature, even under most 
stringent conditions, the survivors are usually fairly numerous and 
possess a variety of genetic equipment. Without going into the de- 
tails of this matter, it can be stated that too severe a selection is likely 
to be less effective than a moderate one, because severe selection tends 
to deplete too soon the reserves of genetic variability. 
REPRODUCTIVE SUCCESS 
The version of the theory of natural selection which invokes sur- 
vival of the fittest in the competitive struggle for life was remark- 
ably well suited to the intellectual climate of Darwin’s times. It has 
often been pointed out (e.g., Barzun, 1941) that the popularity of 
Darwinism had more to do with the social and political implications 
which some people read into the theory than with its scientific va- 
lidity. Those who believed that limitless progress will inevitably re- 
sult from unrestricted competition of private enterprise were beguiled 
to learn that their economic views found support in a universal law 
of nature. With colonial empires in the expansion stage, it was a 
comforting thought that the exploitation of the weak by the strong 
was merely a part of “the stern discipline of nature which eliminates 
the unfit.” An eminent anthropologist was able to advocate with- 
holding education from most people, in order that competition might 
occur under “natural” conditions. This “social Darwinism” continues 
to exist even today, and it has recently been given a modern biologi- 
cal dress by Darlington (1953). 
With the development of genetics, and particularly of population 
genetics, the theory of natural selection has been recast in a more 
exact, though emotionally less impressive form. Consider a popula- 
tion of a sexually reproducing and cross-fertilizing species, such as 
man. A Mendelian population of this sort consists of individuals 
which differ from one another in certain genes. The population has a 
gene pool, in which different gene variants are represented with dif- 
ferent frequencies. Now, in any one generation, the carriers of the 
different genes are likely to make unequal average contributions 
to the gene pool of the next generation. Therefore, the gene fre- 
quencies in the gene pool will change from generation to generation. 
Some genes will be perpetuated at rates greater than their alternative 
genes. The former are, then, favored by selection, and the latter are 
discriminated against. The genes which are selected for may 
eventually be established in the population, while those selected 
against may be lost. 
