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Oy ANTHROPOMETKIC lNVESTIGATIO^' IX THE I^RITISH ISLES. O(0 



ENVIRONMENT. 



INTRODUCTION. 



The environment may be regarded as affecting the e%olution of 

 mankind in two different ways : — 



(1) It may affect the growth and activity of living bodies, and thus 

 produce a more or less efficient population from any given stock. 



(2) It may change the quality of the stock by selection. 



The first controlling action of the environment may be called (rophic 

 action ; and the second, genetic action. 



The trophic factors of the environment include nutrition, physical 

 exercise and training, education, stimuli (physical and mental), inhibition 

 (physical and mental). 



The genetic factors of the environment include all those influences 

 which control the relative rate of increase of the more or less endogamous 

 grades or classes of varying efficiency into which every population may 

 be di\ ided. The rate of increase of any given class evidently depends 

 on the difference between its birth-rate and its death-rate. All factors of 

 the environment which influence the birth-rate or death-rate of a class of 

 the population have a genetic action, i.e., in the course of time they may 

 change the average quality of the stock. 



Any of the actual factors of the environment are pi-obably capable of 

 acting more or less both trophically and genetically. The kind of action 

 of each factor must be determined by observation of the changes which 

 they produce when they have been acting for a sufficiently long time on 

 sufficiently large groups of men. It would be impossible, therefore, to 

 rigidly classify the factor-s of the environment according to the kind of 

 their action on mankind, though we may fairly assume that the action of 

 some factors is mainly trophic, and of others mainly genetic. 



Factors of the environment may also be classified according as they 

 act mainly on the bodies or minds of men, as physical, or psijchological. 



The factors selected for observation should preferably be of such a 

 kind that a numerical estimate can be made cf their degi-ee or intensity. 

 In many cases where the degree cannot be given in the case of indi- 

 viduals the presence or absence of the factor may be noted. When this 

 has been done, in the case of a sufficient number of individuals, the 

 intensity of the action of the factor on the group may be estimated as a 

 percentage. 



In making observations on the environment of a group of individuals 

 we may know that many factors are common to all individuals in the 

 group. Such factors should not be noted on the individual schedule, but 

 should be noted on sheets or cards applying to the whole group. 



It is not sufficient to note the factors of the environment in which the 

 individual or gi-oup of individuals is living at the time of the observa- 

 tions. As far as possible a history of the past environment should be 

 obtained. 



LIST OF FACTORS OF THE ENVIRONMENT. 



The following is a list of the more important factors of the environ- 

 ment, with suggestions as to methods of observation : — 



Food. — The kind of food, whether, for oxamplo, vegetable or animal, 



