558 HUMAN BIOLOGY 



Not only in respect to physical traits and mental traits do 

 races of mankind differ, but also in regard to temperament. 

 Common observation shows that the emotional output of 

 different peoples is very different. We note that the North 

 American Indian is httle given to emotional expression. 

 On the other hand, the African negro expresses his emotions 

 copiously. In Europe the Scotch Highlanders are character- 

 ized by a prevaihngly somber tendency, while the South 

 Itahans are characterized by lightness of spirit. Now there 

 can be no question that temperament is inherited, though in a 

 rather compHcated fashion. This was worked out some 

 years ago by the author, who found a factor for excitability 

 which is possibly a simple Mendehan dominant and a factor 

 for cheerfulness which may, or may not, be combined with 

 excitabihty. The combination of these two factors results 

 in persons who are, on the one hand, both cheerful and 

 excitable and, on the other hand, in those who are cheerful 

 and somewhat stolid; those who are of a depressed tempera- 

 ment and easily aroused and, finally, those who are both 

 depressed and unresponsive to stimuli. These conditions 

 are inherited and show definitely that when one parent 

 exhibits excitability, at least half of the children will 

 show a similar trait. Where both parents are depressed, 

 all of the offspring will show a general depression. The 

 differences in temperament of different peoples are not to be 

 ascribed to their environment but to differences in bodily, 

 physiological functions which determine unrestricted output 

 of the emotions on the one hand, or inhibitions of output 

 on the other. 



Not only in temperament but also in instincts do the races 

 of mankind differ. For example, it is well known that most 

 of the races of Europe are fairly stable and domestic, engaged 

 in agriculture or industry. However, from eastern Europe 

 and western Asia have come forth races of mankind with 

 a strong tendency to wander over the face of the earth. 

 Such are the Gypsies which have run through Europe and 

 America and such are some nomadic peoples who are scat- 

 tered across the face of Asia and Northern Africa and who even 

 before the time of Livingstone had penetrated into the heart 

 of Equatorial Africa. Now the instinct to wander, or nom- 



