Navigation bar
  Home Start Previous page
 233 of 305 
Next page End  

galton.org 209
 
Early and Late Marriages
209
values. The following are his results,
[1]
from returns kept at the Lying-in
Hospital of St. Georges-in-the-East
Age of Mother at her
Marriage.
Average Fertility.
15—19
9.12
20—24
7.92
25—29
6.30
30—34
4.60
The meaning of this Table will be more clearly grasped after a little
modification of its contents. We may consider the fertility of each group
to refer to the medium age of that group, as by writing 17 instead of 15—
19, and we may slightly smooth the figures, then we have—
Age of Mother at her
Marriage.
Approximate average
Fertility.
17
9.00=6x1.5
22
7.50=5x1.5
27
6.00=4x1.5
32
4.50=3x1.5
which shows that the relative fertility of mothers married at the ages of
17, 22, 27, and 32 respectively is as 6, 5, 4, and 3 approximately.
The increase in population by a habit of early marriages is further
augmented by the greater rapidity with which the generations follow each
other. By the joint effect of these two causes, a large effect is in time
produced.
Let us compute a single example. Taking a group of 100 mothers
married at the age of 20, whom we will designate as A, and another group
of 100 mothers married at the age of 29, whom we will call B, we shall
find by interpolation that the fertility of A and B respectively would be
about 82 and 5.4. We need not, however, regard their absolute fertility,
which would differ in different classes of society, but will only consider
their relative production of such female children as may live and become
mothers, and we will suppose the number of such descendants in the first
generation to be the same as that of the A and B mothers together
[1]
Fecundity, Fertility, Sterility, etc., by Dr. Matthews Duncan A. & C. Black:
Edinburgh, 1871, p. 143.
http://www.purepage.com Previous page Top Next page