One notable result of dulness and apathy is to make a person unattractive to the opposite sex and to be unattracted by them.  It is antagonistic to sexual affection, and the result is a diminution of offspring.  There exists strong evidence that the decay of population in some parts of South America under the irksome tyranny of the Jesuits, which crushed what little vivacity the people possessed, was due to this very cause.  One cannot fairly apply the term “misery” to apathy; I should rather say that strong affections restrained from marriage by prudential considerations more truly deserved that name.

EARLY AND LATE MARRIAGES

It is important to obtain a just idea of the relative effects of early and late marriages.  I attempted this in Hereditary Genius, but I think the following is a better estimate.  We are unhappily still deficient in collected data as regards the fertility of the upper and middle classes at different ages; but the facts collected by Dr. Matthews Duncan as regards the lower orders will serve our purpose approximately, by furnishing the required ratios, though not the absolute values.  The following are his results,[17] 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 Approximate average
    Marriage.  Fertility.
       17 9.00 = 6 x 1.5
       22 7.50 = 5 x 1.5
       27 6.00 = 4 x 1.5
       32 4.50 = 3 x 1.5

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 8.2 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[17]—­namely, 200.  Then the number of such children in the A and B classes respectively, being in the proportion of 8.2 to 5.4, will be 115 and 85.