434 



SCIENCE 



[X. S. Vol. XXXIV. No. 875 



producing prime necessaries), so that prognos- 

 tications of growth in this country are appar- 

 ently safer than in any other. The very ex- 

 tent of territory contributes to its self -content 

 sad isolation; its magnificent distances in- 

 volve such cost in transportation (and must 

 •continue to do so, despite prospective improve- 

 ment in facilities) as to limit interchange 

 between producing areas and ports, and thus 

 to restrict foreign commerce; every transcon- 

 tinental traveler must be impressed by the vast 

 "tracts in the westward states unproductive 

 ■mnd nearly uninhabitable because of aridity, 

 ;^€t few realize that with half its area and the 

 present water supply equably distributed main- 

 land United States could sustain a population 

 equal to its present capacity and maintain 

 freer foreign commerce by reason of the re- 

 duced average distance and cost of domestic 

 traffic. The various factors affecting any 

 forecast of future production and population 

 in this country indicate that the growth will 

 be exceptionally independent and presumably 

 uniform. The highest numerical increment 

 in the accompanying tabulated estimate (for 

 a century and a half hence) is 44,000,000 in a 

 decade, only 2f times that of the last decade 

 with an estimated population sevenfold greater. 

 The maximum estimated population of about 

 1,000,000,000 is less than eleven times that of 

 1910; and any excess in the estimated incre- 

 ments may be balanced by extending the esti- 

 mated date (about A.D. 2200) a few decades 

 further into the future. By way of comparison 

 it may be noted that since the rainfall on the 

 lands of the globe is some 30,000 cubic miles 

 (or 100,000,000,000 acre-feet), the maximum 

 world population, computed on the same basis, 

 is 20,000,000,000, or about thirteen times the 

 present 1,500,000,000. 



Whatever the probability of error in the 

 forecast, it would seem timely to consider the 

 prospective population of this and other coun- 

 tries in the light of the leading lessons of 

 anthropology, (1) that the development of 

 mankind is progressive, (2) that the distinc- 

 tive attribute of the human realm is mentality 

 and (3) that through cumulatively advancing 

 mentality man (unlike other organisms) ad- 



justs himself to environment in increasing de- 

 gree by subjugation of lower nature. Accord- 

 ingly, the capacity for population of any coun- 

 try during any generation depends not merely 

 on the natural resources but on these resources 

 as modified and adapted to human needs by 

 human genius; while the food quest is fun- 

 damental, the sources of food (and of clothing 

 as well) for enlightened folk are not the nat- 

 ural fauna and flora but cultivated and vir- 

 tually artificialized plants and animals; while 

 tools and machines and mechanical power are 

 necessaries of industrial activity, their sources 

 are no longer those found ready-made in na- 

 ture but are secondary products gained by 

 artificial conversion of natural materials and 

 forces — and no end to this reconstruction of 

 nature is in sight save the limitation to life 

 first in water supply and then in other con- 

 stituents of atmosphere and earth. Meantime 

 the power and efficiency of humanity are ad- 

 vancing; throughout the world men now meet 

 in amity rather than instinctive enmity as in 

 savager,y and barbarism, and while there will 

 yet be bloody battles before warfare is made so 

 sanguinary by mechanical and chemical de- 

 vices that mankind will revolt against it, the 

 current trend is toward national no less than 

 individual obedience to law and hence toward 

 international peace; famine grows less fatal 

 with advancing solidarity of peoples; pestil- 

 ence is passing with the advance of science 

 and philanthropy; health and happiness and 

 viability have increased almost uninter- 

 ruptedly from the prime to the present, and 

 give every promise of continued increase; and 

 most significant of all, the social and govern- 

 mental institutions of all countries are stead- 

 ily rising from primitive types in which the 

 lives of the many were at the mercy of a 

 favored few to that plane on which all lives 

 are alike sacred — indeed the modern and pros- 

 pective governmental form is but the organ- 

 ized expression of the knowledge and opin- 

 ions and sentiments — i. e., of the essentially 

 human traits — of a constituent citizenry. In 

 the light of past progress, it is the manifest 

 destiny of the temperate and tropical zones to 



