The shadow of the world's future, or The earth's population possibilities & the consequences of the present rate of increase of the earth's inhabitants

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Monograph

Identifikator:: 1775636852

URN:: urn:nbn:de:zbw-retromon-164018

Document type:: Monograph

Author:: Knibbs, George Handley http://d-nb.info/gnd/1045010944

Title:: The shadow of the world's future, or The earth's population possibilities & the consequences of the present rate of increase of the earth's inhabitants

Place of publication:: London

Publisher:: Ernest Benn Limited

Year of publication:: (1928)

Scope:: 131 Seiten

Digitisation:: 2021

Collection:: Economics Books

Usage license:: Get license information via the feedback formular.

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Document type:: Monograph

Structure type:: Chapter

Title:: Chapter V. How population increases

Collection:: Economics Books

s4 THE SHADOW OF THE WORLD’S FUTURE reproductive impulse of constant intensity; but at every moment the effectiveness of the impulse is being reduced in the ratio that the further population- possibility of the region, at that moment, bears to the total number which can live therein. Recently Prof. Raymond Pearl and Dr Reed in the United States, Mr Udny Yule in England, and others have system- atically examined this supposition; have—following Verhulst—called the curve representing it a “logistic curve,” ! and have developed formule for its applica- tion. In character the curve is similar to the * cross- over ”” from one railway line to another line parallel thereto. Initially it is concave upwards; its middle is sensibly linear; after that it becomes convex upwards, and approaches a limiting value asymptotically. That is to say, as time goes on the population-numbers increase more and more rapidly, per unit of time; attain to a maximum rate of increase; then increase more and more slowly as the numbers approach the limiting number of the population. The plausibility of this view is such that it cannot be passed without comment. The underlying assump- tion, viz., that human beings can be regarded as organisms, exhibiting essentially constant qualities, living in an environment which also is essentially constant, is certainly not true to a sufficient degree of approximation to warrant its being accepted as repre- senting the facts. The instantaneous rates of increase for the United States for the 10-year periods, which are § years on either side of the middle of the years shown in the table hereunder, were actually as indicated t The axis of abscisse represents time, and the axis of ordinates represents population-numbers. The curve will undoubtedly repre- sent very approximately the growth of, say, micro-organisms, developing in a limited region, where they are exhausting their pabulum by developing. It was found also to represent the mode of increase of the fly Drosoplila melanogaster, similarly circumstanced.

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