290 POPULATIONS 



youngest mothers (nineteen and under) sex, race, or occupation, dying within one 



had the highest fertihty or age-specific year, from any cause whatever, in a popu- 



birth rate and that this rate drops consist- lation constituted in respect of its age, sex, 



ently with age. These data, in abbreviated racial and occupational distribution, as the 



form, follow: population under discussion happens to be." 



Annual Births per *^^ P^ge 288 we Usted crude birth rates 



Age of Mothers 1000 Married Women by countries, and also the corresponding 



(Years) of Indicated Age mortahty rates. Certain points about the lat- 



19 and under 476 ter can now be made: 



20-24 394 1. The birth rate is higher than the 



25-29 305 death rate for these geographically widely- 



^r~r^ .„„ chosen countries. Thus, although the hu- 



AQAA 71 "^^11 population of the world may be de- 



45 and over 9 cHning in some restricted areas, it is in gen- 

 eral growing. Although not very valid 



Enough has now been said about specific statistically, the birth rates and death rates 



birth rates to suggest their various advan- of the table can be averaged for purposes 



tages and applications for the population of rough comparison. When this is done, the 



student. mean birth rate is 28.9 births per 1000, 



DATE ^^^ *^® mean mortality rate is 16.6 deaths 



THE DEATH RATE p^^. ^qqq j^^^^ j^^. ^j^^ y^^^. j^gg^ ^^^ ^^ 



As is true for birth rate, the demogra- the basis of the twenty-one samples, there 

 pher uses both a crude death rate and var- were on the average 12.8, or 55.8 per cent, 

 ious specific death rates. There is a prodi- more births for every thousand persons liv- 

 gious hterature on these rates as applied to ing than there were deaths. This difference 

 human populations, largely because of the would change, of course, with the size and 

 relation of deaths to actuarial, medical, and character of the sample and has a large 

 numerous socio-economic enterprises. The standard deviation and range, 

 population ecologist can also derive some- 2. In general, a country with a high 

 thing of value from a knowledge of such birth rate has a high death rate. In the table 

 statistics, since as mentioned in the last the countries are arranged according to de- 

 chapter, mortahty is one of the great forces creasing birth rates. With exceptions, this 

 underlying population operations and since arrangement follows along fairly well for 

 death rates provide a technique by which mortahty. Guatemala and Egypt, with birth 

 this force can be measured. When more rates of 50.8 and 43.7, have death rates of 

 complete data are available, birth and 22.8 and 27.3; while England and Sweden, 

 death rates will be more fully used in popu- with birth rates of 16.3 and 15.4, have 

 lation studies of other organisms, including death rates of 11.4 and 11.7. 

 plants. 3. There is a tendency for the "industrial 



caucasoid countries" to have lower death 



Crude Death Rate ,.^j.gg^ ■^^^. ^^ ^^^^^ -^ ^ tendency for them 



The crude death rate is defined as fol- to have lower birth rates. Again, no biologi- 



lows: cal explanation should be inferred from 



j^ this suggestion without particular study. 



Ro = p' It is equally interesting to examine the 



trends of death for countries over an ex- 

 where R^ is the crude death rate; D, the tended period of time. In the Middle Ages 

 deaths from all causes; and P, the total and early Renaissance, European death 

 population or D + {P — D). This rate is rates must have been excessively high, just 

 usually expressed "per 1000," "per 10,000" as those in certain primitive areas are to- 

 or "per 100,000" individuals. The crude day. In fact, so far as the evidence goes, 

 death rate is not a refined statistic, because, these rates did not start consistently down- 

 as Pearl (1940) puts it, "The deaths are ward until the middle of the nineteenth 

 not separated as to cause, and the entire century. From that time on, accurate statis- 

 population is assumed to be at risk of death. tics are available for certain countries, and 

 The annual crude death-rate measures the this downward trend can be examined with 

 probabihty of a person, regardless of age, considerable precision. To document the 



