-~13The second area of uncertainty has to do with the
ultimate effect of mutation rates on the welfare and
survival -of populations.
Since many of the important
mutations appear to be dominant lethals, their estimation has to be based, not upon the recognition of
anomalous characters, but on the estimation of the num-
bers of individuals who should exist but in fact do not.
The technique, which is very useful in laboratory experiments with animals, becomes very difficult of application to a human population for obvious reasons.
Some of the mutations may be recessive and consequently not be detectable until at some future time
when an individual carrying such a mutant gene should
mate with another individual carrying the identical
factor.
.
The mere occurrence of mutations may be only
part of the problem.
The fate of the mutations in populations is the important question.
These mutations will
be subjected to the same forces of natural selection that
now act against spontaneous mutations.
The extremely complicated and difficult genetic
problem in man constitutes a very important section of
the studies being conducted in Japan.
No firm conclusions can be given until the statistical work is
finished but it seems likely that some evidence of genetic
effect will have been obtained among the more highly irradiated survivors at Hiroshima and Nagasaki.
At the lower
exposure rates, it is quite evident that no changes can be
recognized.
This genetic problem which is one of the fundamental aspects of the adjustment of man to the world of
the future, is sometimes thrown into confusion by reckless
and uncritical pronouncements based upon assumptions which
go far beyond our knowledge.
We have dire predictions of
many monsters and even the obliteration of mankind itself
from radiation exposures which are only a small fraction of
that from cosmic radiation, from the radium and radon of the
soil and air, and from the naturally radioactive potassium
and carbon of which we all are partially composed.
Such
distortions of emphasis are comparable to contending that
meteors from outer space are a major threat to safety on
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