It is not enough, however, to consider the mechanism by which the birth-rate declines; to realize the significance of the decline we must consider the causes which set the mechanism in action.
We begin to obtain a truer insight into the meaning of the curve of a country's birth-rate when we realize that it is in relation with the industrial and commercial activity of the country. 34
It is sometimes stated that a high birth-rate goes with a high degree of national prosperity. That, however, is scarcely the case; we have to look into the matter a little more closely. And, when we do so, we find that, not only is the statement of a supposed connection between a high birth-rate and a high degree of prosperity an imperfect statement; it is altogether misleading.
If, in the first place, we attempt to consider the state of things among savages, we find, indeed, great variations, and the birth-rate is not infrequently low. But, on the whole, it would appear, the marriage-rate, the birth-rate, and, it may be added, the death-rate are all alike high. Karl Ranke has investigated the question with considerable care among the Trumai and Nahuqua Indians of Central Brazil.35 These tribes are yet totally uncontaminated by contact with European influences; consumption and syphilis are alike unknown. In the two villages he investigated in detail, Ranke found that every man over twenty-five years of age was married, and that the only unmarried woman he discovered was feeble-minded. The average size of the families of those women who were over forty years of age was between five and six children, while, on the other hand, the mortality among children was great, and a relatively small proportion of the population reached old age. We see therefore that, among these