704 THE EELATION OF INSTITUTIONS TO ENVIRONMENT. 



The forest of humid lands, the flora of the desert, the foeless buffalo 

 and rabbit and sparrow, and the mimetic insect illustrate the r^otency 

 and persistence and indeed the predominance of characters acquired 

 through interaction with environment, and the testimony of vestigial 

 organs accords with the testimony of the organisms; and thereby the 

 law of organic development is indicated. In general terms, this law is 

 that the characters of organisms are determined through interaction with 

 environment. It is to be observed that the law is general and that 

 exceptional instances are to be looked for, yet it is to be remembered 

 also that no indubitably exceptional instances are known. It is indeed 

 a legitimate and desirable postulate that there is an inherent and per- 

 sistent force in vitality, a force expressed in heredity and transcending 

 environmental interaction; the postulate is legitimate since this com- 

 ponent of vitality is represented in the life of each individual organism 

 and in many of the characters of species,* genera, and other groups of 

 organisms; the postulate is desirable since it yields a sort of datum- 

 plane from which the amount and kind of adaptive modification may 

 be measured ; yet it must not be forgotten that, as applied to the great 

 aggregate of living things on the earth, the postulate is a postulate 

 merely; and the law of organic development, individual, specific, and 

 general, is that the characters of organisms are ultimately shaped by 

 interaction with environment. 



When the law of biotic development is extended to mankind, it 

 appears to fail; for the men of desert and shoreland, mountain and 

 plain, arctic and tropic, are ceaselessly occupied in strife against envi- 

 ronmental conditions which transform their subhuman associates, and 

 yet men remain essentially unchanged — some taller, some stouter, some 

 swifter of foot, some longer of life than others, yet all essentially Homo 

 sapiens in every characteristic. More careful examination indicates 

 that the failure of the law, when extended to mankind, is apparent 

 only. The desert nomads retain common physical characteristics, but 

 develop arts of obtaining water and food, and these arts are adjusted to 

 the local environment; dwellers alongshore do not suffer modification 

 in bodily form, but their arts are modified and they become fishermen 

 and sailors; the mountaineers do not acquire the physical characters 

 of the subhuman animals of the mountains, but learn to use weapons 

 and to protect themselves from bodily injury by artificial devices; the 

 plainsmen remain human in body and limb, but learn to hunt and, bor- 

 rowing knowledge from the desert, to herd lower animals; the men of 

 the arctic do not emulate their fur-bearing and blubber-making associ- 

 ates, but adjust themselves to environment and begin the conquest of 

 the earth through the making of clothes and the building of houses; 

 and the dwellers beneath the equatorial sun hold to the human form, yet 

 invent multifarious devices for overcoming hard environment through 

 the aid of mind. Thus development, differentiation, transformation, 

 are no less characteristic of the human genus than of lower organisms — 



