, be divided by the total
number of children represented, 2,259, the child mortality rate for this
population is found to be 5.27%, or 53 per thousand.

The smallness of this figure may be seen by comparison with the
statistics of the registration area, U. S. Census of 1880, when the child
mortality (0-4 years) was 400 per thousand, as calculated by Alexander
Graham Bell. A mortality of 53 for the first four years of life is
smaller than any district known in the United States, even to-day, can
show for the _first_ year of life _alone_. If any city could bring the
deaths of babies during their first twelve months down to 53 per 1,000,
it would think it had achieved the impossible; but here is a population
in which 53 per 1,000 covers the deaths, not only of the fatal first 12
months, but of the following three years in addition.

Now this population with an unprecedentedly low rate of child mortality
is not one which had had the benefit of any Baby Saving Campaign, nor
even the knowledge of modern science. Its mothers were mostly poor, many
of them ignorant; they lived frequently under conditions of hardship;
they were peasants and pioneers. Their babies grew up without doctors,
without pasteurized milk, without ice, without many sanitary
precautions, usually on rough food. But they had one advantage which no
amount of applied science can give after birth--namely, good heredity.
They had inherited exceptionally good constitutions.

It is not by accident that inherited longevity in a family is associated
with low mortality of its children. The connection between the two facts
was first discovered by Mary Beeton and Karl Pearson in their pioneer
work on the inheritance of duration of life. They found that high infant
mortality was associated with early death of parents, while the
offspring of long-lived parents showed few deaths in childhood. The
correlation of the two facts was quite regular, as will be evident from
a glance at the following tables prepared by A. Ploetz:

LENGTH OF LIFE OF MOTHERS AND CHILD-MORTALITY OF THEIR DAUGHTERS.
ENGLISH QUAKER FAMILIES, DATA OF BEETON AND PEARSON, ARRANGED BY
PLOETZ

Year of life in which mothers died At
all
0-38 39-53 54-68 69-83 84 up ages

No. of daughters 234 304 305 666 247 1846

No.