THE CHANCES OF DEATH 93 



40 the lines cross, and from then on the expectation of 

 life was definitely superior in the early years of the 

 Christian era to what it is now. 



It should be said that the curious zigzagging of the 

 lines in all of these Koman tables of Macdonell is due to 

 the tendency, which ancient Eomans apparently had in 

 common with present day American negroes, towards 

 heavy grouping on the even multiples of 5 in the state- 

 ment of their ages. 



Summarizing the whole matter we see that during a 

 period of approximately 2,000 years man's expectation 

 of life at birth and subsequent early ages has apparently 

 been steadily improving, while at the same time his expec- 

 tation of life at advanced ages has been steadily worsening. 

 The former phenomenon may probably be attributed essen- 

 tially to ever increasing knowledge of how best to cope 

 with the lethal forces of nature.* Progressively better 

 sanitation, in the broadest sense, down through the centur- 

 ies has saved for a time the lives of ever more and more 

 babies and young people who formerly could not with- 

 stand the unfavorable conditions they met, and died in 

 consequence rather promptly. But just because this pro- 

 cess tends to preserve the weaklings, who were speedily 

 eliminated under the rigorous action of unmitigated nat- 



* No absolute reliance can, of course, be put upon Macdonell's or 

 Pearson's curves. Besides laboring under the serious actuarial difficulty 

 of being expectations calculated from a knowledge of deaths alone, the 

 randomness of the sampling, even on that basis, is extremely doubtful. 

 The only real evidence that these Roman curves represent a rough pic- 

 ture of the truth as to expectation of life in those days, arises from the 

 consideration that they show a difference from present-day expectations 

 which is of the same kind as that which is found between populations of 

 one and two centuries ago and the present, and of a greater amount, as 

 would be expected from the longer time interval, and from what we know 

 has occurred in the material development of civilization in the meantime. 



