The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1898-01-27
NATURES CARE OF THE SEX
RATIO.
APof. W. K. Brooks of Johns Hopkins
In the Baltimore SUM-.

dProf. W. K. Brooks of Johns HopKlns
In the Baltimore Sum-
Data which have been gathered. through
long periods of time. in various countries
show that the ratio of boys to girls in the
birth rate is lower In cities and large
towns than among the overworked, scan
tilv fed and badly sheltered peasants of
Europe: that it is less among the we'll ITO
do in the cities than it is among. the poor;
that it increases after long wars and in
time of agricultural depression and low
wages. and after long famine, and that
while the normal birth-rate Is about l06
boys to 100 girls, 1t may rise as much as
one OF two per cent under conditions of
great hardship.
Young husbands are seldom able to
effect any great improvement in good liv-
ing. but all may experiment in hardships
and privations If they wish, and If the
head of house chooses to conduct it as If
his house and country were in a state Of
seige by relentless enemy, he may do
SO in the assurance we'll warranted by
science that II he have 1000 children he
may hope for about a dozen more sons
among them than his neighbors could ex
pect.
The birth rate of each species, like its
Natural term of life, is something which
is characteristic of the species, or natural
and it has been fixed for the advantage OF
the species. All know that, while men
die at old ages and for many causes.
there is a natural term of life, and that
while a cat Is old at 10 years, crow,
which does not differ much in size or
weight, or in general activity from cat,
may live for centuries So it is with the
birth-rate. Each species has character
istic birth-ra and that birthrate Is that
which on the average is most advantage
Gus to the species. Animals which live
long or ere little exposed to accident, and
those able to protect and care for the1f
young have low birth -rate. while those
which are much exposed to danger, or
short-lived or unfit for giving their young
parental care and protection, have high
birth-rate.
The hen, which ia short-lived and much
exposed to enemies, may lay 200 eggs
year, but the Mother Carey chickens
which are said to be the most numerous
of all birds, lay but one egg year, bus
these are laid on sapdbars in the ocean,
where there is little danger to the eggs Or
young.
So it Is with the ratio between the sexes
When a preponderance of one sex Is great
" advantageous to its species, that sex
predominates In the birth-rate. When
one sex is peculiarly exposed to- danger
during infancy and youth, this danger is
met and provided for by nature through
an excess in the birth. rate of that sex
Among young frogs there are about $40
females and 60 males in each 2cO, but
when frogs are three and four years old
the sexes are equal. AS female frogs are
exposed to danger in the early part of
their lives, an excess of female frogs is
produced. Among mankind infant NOR
tality is much greater among boys than
among girls. and the birth-rate is adjust
ed to this danger by an excess of boy
birth.
1t Is undoubtedly possible for man to
change by long generations of selective
breeding the bfrth-rate of domestioated
animals..or the ratio between the sexes,
but no one who is familiar with the sub
ject can hope for any sudden radical
change through the application of empiri-
cal rules.