Genetic Progress by Voluntarily Conducted 
Germinal Choice * 
HERMANN J. MULLER. 
cannot be hindered, no matter what we do, because the 
organisms that survive and multiply are of course, zpso facto, 
the fittest. The implication of this seems to be that we might 
as well have a good time in any way we like, and that there is 
nothing to be feared, or helped either, at least genetically, in 
this best of all possible worlds. 
This pseudo-philosophical literalism ignores the evidence that 
the great majority of species have perished without issue. Most 
often this has been because the natural selection in their line 
was outsmarted, or rendered outmoded, by developments else- 
where. In other cases it has been because the natural selection 
led to the adoption of traits that favoured the possessors of them 
and their immediate descendants, as compared with other indi- 
viduals of the same population, but worked to the disadvantage 
of the population as a whole, over the long term. True, the 
division of a species into many small groups or sub-groups, that 
eventually competed with one another, tended to check such 
miscarriages of natural selection to some extent, and could even 
exert an overriding influence in the opposite direction. How- 
ever, the type of balance or of flux attained between these con- 
flicting forces depended on the specific situation that existed. 
Hence, no generalization could be valid that declared all species 
to be foreordained to rise by natural selection. 
There were similar flaws in the naive egalitarianism accord- 
ing to which all species must be equally fit, at least for their 
I: HAS become a cliché in some circles that natural selection 
* This paper was read by Dr. Wolstenholme because Professor Muller was 
unfortunately prevented by illness from participating in the symposium. 
247 
