On the other hand, if only a few
die during the first year, one might expect a proportionately greater
number to die in succeeding years. If it is actually found that a high
death-rate in the first year of life is associated with a low
death-rate in succeeding years, then there will be grounds for believing
that natural selection is really cutting off the weaker and allowing the
stronger to survive.
E. C. Snow[56] analyzed the infant mortality registration of parts of
England and Prussia to determine whether any such conclusion was
justified. His investigation met with many difficulties, and his results
are not as clear-cut as could be desired, but he felt justified in
concluding from them that "the general result can not be questioned.
Natural selection, in the form of a selective death-rate, is strongly
operative in man in the early years of life. We assert with great
confidence that a high mortality in infancy (the first two years of
life) is followed by a correspondingly low mortality in childhood, and
vice-versa.... Our work has led us to the conclusion that infant
mortality _does_ effect a 'weeding out' of the unfit."
"Unfitness" in this connection must not be interpreted too narrowly. A
child may be "unfit" to survive in its environment, merely because its
parents are ignorant and careless.
Pages:
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213