THE PEOBLEM AMONG MEN 83 



the pre-human ancestor lived towards the conditions which now 

 exist. In order that we may consider the quantitative asj^ect of 

 the problem, it is evident that we require some knowledge 

 regarding fecundity and as full details as possible regarding 

 the factors which bear upon fertility and elimination. It is only 

 when we are provided with such information that we can hope 

 to be able to determine how it is that numbers are regulated 

 among men. 



In addition to such information, it will be desirable to have 

 information regarding various social customs and the general 

 conditions of life. As regards the inquiry into the qualitative 

 part of the problem, it is clear that facts regarding fertility and 

 elimination are again of value inasmuch as they throw light upon 

 the nature and intensity of selection. For the second part of the 

 problem it is also necessary to have in mind the main facts regard- 

 ing the changes which are summed up as history into the causes 

 of which we have to inquire ; and in addition it will be necessary, 

 in order that we may attempt some estimate of the relative 

 importance of change in the germinal constitution on the one hand 

 and of the other factor or factors of the nature indicated above on 

 the other hand, to make some inquiry into the conditions which 

 determine the nature of these latter factors. This wdll involve 

 a reference to certain elementary facts of psychology together 

 with some discussion of the origin, formation, preservation, and 

 so on, of tradition. 



If we first ask how far the data desired are available, we may 

 afterwards go on to discuss how the facts are best presented. Our 

 information is obviously very incomplete as regards the history of 

 social habits and customs. Historical records do not take us 

 farther back than at the most six thousand years, and the informa- 

 tion available with respect to social customs, except for the latter 

 part of the period, is very inadequate. If we take a broad view 

 of history, written records have reference only to relatively 

 modern times. There are two other sources of evidence upon 

 which we have to rely and they are as follows. 



Some indication of the bare outline of the course which history 

 has taken can be gathered from a study of the fossil and cultural 

 remains of man. The fossil remains are in the form of skeletons 

 or portions of skeletons and the cultural remains in the shape of 

 tools, weapons, and other traces of his mode of hfe that man has 



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