NATURAL SELECTION IN MAN 187 



best regulated asylums the death rate "is hardly less than 7 per 

 cent, even under favorable conditions," which is about four times 

 as great as should exist hi well-regulated municipalities of the 

 ordinary population. If, however, we take out certain forms of 

 insanity, such as paresis and organic dementia, we have the ratio 

 somewhat reduced. In any case, however, it will decidedly exceed 

 that amongst the general population. The death rate in asylums 

 is less than that of the insane outside of these institutions. Barr 

 (Mental Defectives, p. 131) states that out of 625 cases of mental 

 defectives of whose deaths he had records, "the largest number of 

 deaths occurred between 10 and 20 years; but comparatively 

 few passed the 25th year and exceptional cases appeared from 30 

 to 40 years." According to Clark and Stowell in the New York 

 City Children's Hospitals and Schools the mortality among the 

 feeble-minded is double that of other children, and the mortality 

 of the lowest grades, idiots and imbeciles, is four times as great as 

 among the feeble-minded. With the higher grades of the feeble- 

 minded the expectation of life is much greater, but among these 

 natural selection takes a relatively heavy toll as is evinced by 

 their high infant mortality. 



It is a fair inference that natural selection causes a higher 

 mortality among those who, while not feeble-minded, are below 

 the general average of intelligence. Not only is their station in 

 life apt to be such as to raise their death rate, but through igno- 

 rance or lack of the ability to afford the proper surroundings for 

 their children they have a high infant mortality which tends to 

 offset, in a measure, their greater fecundity. 



Contrasted with the rather high general death rate of inferior 

 stocks is the relatively low death rate of the classes with excep- 

 tional intelligence. Sir Francis Galton has noted that English 

 men of science as a class are long lived, and Cattell finds that the 

 death rate and especially the infant mortality in the families of 

 American men of science is unusually low. The death rate is 

 relatively low in professional classes in general and among others 

 who have achieved a noteworthy success in other fields. If it is 

 said that their reduced death rate is due to better environment 



