Alfred J. Lotka

Analytical Theory of Biological Populations

Principles: 1. On Evolution in Organic and Inorganic Systems. 2. On the Direction of Time. 3. On Energetics and Uncertainty. 4. Biological Stoichiometry. Demographic Analysis with Specific Application to the Human Species: 1. Introduction. 2. Relations Involving Mortality and Births. 3. Relations Involving Fertility. 4. The Progeny of a Population Element. 5. Indices and Measures of Natural Increase. 6. Relations Involving Fertility by Birth Order. 7. Relations Involving the Survival Functions of Two Individuals. 8. Extinction of a Line of Descent. 9. Conclusion. Appendix. Bibliography. Author Index. Subject Index.

THE TREND OF THE BIRTH RATE BY AGE OF MOTHER AND ORDER OF BIRTH

With this in view, an analysis is now presented of the trend of reproduction rates in the United States. The series of rates computed begins with 1920 and extends to 1938, and relates to all but a few states of the expanding Birth Registration Area.2 In computing the rates, no at

Trends in Longevity

LIVING conditions as we know them here today imply, among other things, a high standard of public health. But as we look back over the centuries, or look abroad over some of the more remote parts of the earth, we find a wide range of circumstances, for not all peoples have shared equally in the advancement of science and the technical arts. Some have been held back by adverse climatic conditions, as in the extreme north; others are handicapped by outmoded traditions or by sheer superstitions ; and still others have lagged in following the lead of the most progressive nations. And so, as contemporaries on this same globe, we find the white population of New Zealand enjoying an average length of life of about 67 years and, by way of contrast, the people of India and China living on an average a bare 30 years, corresponding perhaps to the conditions among the Romans in classic times. These divergences are not due to basic differences in human stock. The upper limit of life-the span of life as it is called-for those who do survive

Modern Trends in the Birth Rate

In Sweden, for example, for which an exceptionally long series of data is available, the annual birth rate about the middle of the eighteenth century was over 34 per thousand. A figure of about this order was maintained until the beginning of the nineteenth century, and as late as the sixties, rates of over 33 per thousand still occurred. From about 1865 on began a period of gradual decline, continued to about 1920, after which a decline so rapid set in that in the course of a single decade the birth rate fell from over 20 to a little more than 15, a decrease by over 25 per cent. About this rate of decrease has continued into the present decade, as far as can be judged from available data. The picture thus presented by Sweden is essentially characteristic of most of the leading civilized countries. Thus, England and Wales recorded birth rates of 32 to 35 per thousand until 1881-1885, but from that time on exhibited an almost uninterrupted decline, until in 1933 bottom was reached with a birth rate of 14.4. One would have to be very optimistic to ascribe any serious significance to the slight rise to 14.8 in 1934 and 14.7 in 1935.