84 



HEREDITY AND SOCIAL FITNESS 



3. Perseverance 



In dealing with the characteristic perseverance, we are well aware 

 of the great difficulty of defining its heritable elements. The persist- 

 ence with which anyone follows a line of activity is due mainly to his 

 capacity for forming habits and his dominating interests, and these, 

 although in the first instance generally innate, are affected by all 

 sorts of extraneous influences. Such native qualities as general health, 

 endurance, pride, independence, and obstinacy also have a role in its 

 manifestation. Still, it is known that children in their desultory 

 activities present very noticeable differences with regard to this char- 

 acteristic ; while imbeciles, who are incapable of conceiving ideals or a 

 chain of related purposes, may show a variety of grades of this trait 

 quite independent of their mental incapacity. Perseverance may 

 accordingly be looked upon as a trait-complex having heritable ele- 

 ments whose behavior may be profitably investigated. 



The progeny of 80 matings, numbering 269 individuals, was classi- 

 fied and the results compared with the theoretical expectation. This 

 comparison is shown in table 4. 



Here, again, there is some discrepancy between the actual and 

 theoretical results which may well be set down to exogenous factors. 

 Making due allowance for these exogenous factors, the conclusion 

 seems warranted that there is a heritable element in the trait-complex 

 called perseverance, which so far dominates it as to make it show 

 segregation. 



It is, then, to the segregation of determiners for these traits that we 

 may conceive the wide range of their manifestation to be due. On 

 the constructive side this principle has its chief importance in the 

 possibility it offers for the building up of the trait-complex from the 

 effective combination of different traits through matings of successive 

 generations. With proper selection these combinations may be so 

 many steps in the production of high native ability, or the evolution 

 of a line showing average ability superior to that of earlier generations. 



Our history furnishes many examples of both of these results, and 

 it will suffice here to refer once more to certain cases. An interesting 

 illustration of such a series of combinations is afforded by Line A, 



