204 BIOLOGY OF DEATH 



poorest districts have the highest death rates, the richest 

 districts the lowest death rates, and districts interme- 

 diate in respect of poverty are also intermediate in res- 

 pect of mortality. On the face of the evidence there 

 would seem to be here complete proof of the overwhelm- 

 ingly important influence upon duration of life of degree 

 of poverty, which is perhaps the most potent single envi- 

 ronmental factor affecting civilized man to-day. But, 

 alas, pitfalls proverbially lurk in statistics. Before we 

 can accept this so alluring result and go along with our 

 author to his final somewhat stupendous conclusion that 

 if there were no poverty the death rate from certain im- 

 portant causes, as for example tuberculosis, would f orth- 

 with become zero, we must exercise a little inquisitive 

 caution. What evidence is there that the inhabitants of 

 the districts showing a high poverty rate are not biologi- 

 cally as well as economically differentiated from the in- 

 habitants of districts with a low poverty rate? And 

 again what is the evidence that it is not such biological 

 differentiation rather than the economic which determines 

 the death rate differences in the two cases ? Unfortunately, 

 our author gives us no whit of evidence on these obviously 

 so important points. He merely assumes, because of the 

 facts shown, that if some omnipotent spook were to trans- 

 pose all the inhabitants of the Menilmontant arrondisse- 

 ment to the Elysee arrondissement, and vice versa for 

 example, and were to permit each group to annex the 

 worldly goods of the dispossessed group, then the death 

 rates would be forthwith interchanged. There is no real 

 evidence that any such result would follow at all. One 

 cannot shake in the slightest degree from its solidly 

 grounded foundation the critically determined fact of 

 the paramount importance of the hereditary factor in 

 determining rates of mortality, which have been summa- 



