154 BUREAU OF AMERICAN ETHNOLOGY [Bull. 197 



It is interesting to note that even with the wide allowances that are 

 provided in the postulated vital rates for each period, none of the four 

 crude birth rates derived from reported data between 1870 and 1900 

 falls within the postulated range of 40 to 50 per 1,000. Of the four 

 corresponding crude death rates reported for this period (table 29), 

 the rate for 1884 falls just above the postulated minimum of 20 per 

 1,000, while the rate for 1889 falls just above the postulated maximum 

 of 35 per 1,000. The other two crude death rates fall far wide of 

 these limits. 



For the period 1900 to 1930, definite ranges can be postulated. At 

 the lower extreme, a crude birth rate of 40, and a crude death rate 

 of 17.5 per 1,000 would produce a crude rate of natural increase of 

 2.25 percent per year. At the upper extreme, rates of 50 and 32.5, 

 respectively, would produce a crude rate of natural increase of 1.75 

 percent per year. Of the 19 reported crude birth rates for the Navaho 

 population in this period (as shown in table 29) , only 3 fall within the 

 postulated range of 40 to 50 per 1,000. Of the 19 reported crude death 

 rates for the same period, only 7 are seen to fall within the even wider 

 range of 17.5 to 32.5 that was postulated for this period. 



For the period 1930 to 1950, we can postulate, at the lower extreme, 

 a crude birth rate of 40, and a crude death rate of 12 per 1,000, giving 

 a crude rate of natural increase of 2.8 percent per year. The corre- 

 sponding upper limits would consist of rates of 50 and 26, respectively, 

 implying a crude rate of natural increase of 2.4 percent per year. 

 If we include the average vital rates for the years 1944-46 and 1948-52, 

 we have a total of 11 sets of vital rates reported for the Navaho during 

 this period. All of the reported crude birth rates (table 29) are seen 

 to fall well below the postulated minimum of 40 per 1,000. Similarly, 

 all but one of the 11 reported crude death rates fall below the postu- 

 lated minimum rate of 12 per 1,000.* 



Finally, for the period since 1950, we can postulate as lower limits 

 a crude birth rate of 40, and a crude death rate of 7 per 1,000, giving 

 a crude rate of natural increase of 3.3 percent per year. At the upper 

 limit, we can postulate rates of 50 and 26 per 1,000 respectively, im- 

 plying a crude rate of natural increase of 2.4 percent per year. All 

 of the reported crude birth rates for this period fall below the postu- 

 lated minimum, although the rates reported for 1956 and 1957 nat- 

 urally approach the minimum. The reported death rates for this 

 period, however, fall within the very wide limits of 7 to 26 per 1,000 

 (except for the rate reported in 1956). These reported death rates, 



* One of the earliest studies of Navaho mortality in the modern period was a survey of 

 about 4,000 Navahos on the reservation, conducted by Dr. Solon T. Kimball during the 

 period of the Human Dependency Survey In 1938-39. Dr. Kimball (1940, pp. 2-3) 

 obtained a crude birth rate of 37.6 and a crude death rate of 13.6 among this population 

 at this time and anticipated the growth rates recognized among the Navaho after World 

 War II. 



