HEDLiCKA] PHYSIOLOGICAL AND MEDICAL OBSERVATIONS 41 



The above figures are remarkable in a number of particulars; how- 

 ever, they embody the complex results not only of natural but also of 

 social conditions. It is plain that in general the cycle of life with the 

 Indians and the native white Americans is nmch the same. In de- 

 tails, the Indian population shows a greater proportion per thousand 

 of young and again of very old people and a less proportion of those 

 of the intermediate years than whites. At present the Indians have 

 relatively more males than the whites during all the years up to 20, 

 and again during all the years above 80, and relatively fewer between 

 20 and 80; they also have relatively more females than the whites 

 during all. the years up to 15 and from 40 to 55, 60 to 65, and above 

 70, but relatively fewer during the intermediate periods. These facts 

 suggest a good Indian birth rate, a large death rate during adoles- 

 cence and adult life, and possibly somewhat greater longevity of those 

 who survive to old age. However, the Indian population still shows 

 to some extent the results of former w^ars, and, on the other hand, the 

 destructive Civil war may yet show its influence in some of the series 

 of whites. 



The proportion of nonagenarians and especially centenarians among 

 the Indians is far in excess of that among native white Americans. 

 It may be objected that the sources of error are apt to be greater 

 among the Indians in such cases, and that the low ratio for males 

 between 80 and 90 years of age may signify that some individuals 

 of this group were classed as older, but the objection is not so serious 

 as might be anticipated, on account of the marked general interest 

 centering about the oldest in every tribe; at all events, no ordinary 

 error could account for the extreme disproportion of centenarians 

 observed, viz, 224 per million of Indians to 3 per million of whites. 

 The relative excess of aged persons (80 years and above) among the 

 Indians can signify only that the infirmities and diseases known ordi- 

 narily as those of old age are less grave among them — a conclusion 

 in harmony with general observation. 



The sex ratio, while apparently following the same law in the two 

 races, presents, nevertheless, some interesting difl^erences, particularly 

 in more advanced age. A striking feature is the excess of males over 

 females among the whites up to the seventy-fifth year, among the 

 Indians up to the fifty-fifth year, and an excess of females over males 

 during all later years. The aged male of the Indians, as well as of the 

 whites, meets death on the average somewhat earlier than the aged 

 female. 



Size of Families 



Concerning the size of families of the Indians of the Southwest, 

 and particularly those in northern Mexico, official vital statistics 

 are lacking, and accurate individual observations are not yet exten- 



