76 SMITHSONIAN M ISCEIXANEOUS COLLECTIONS VOL. 93 



GENERALIZATION IN MAN 



Aside from the fact that ear exostoses are Hmited to the human 

 family, the next major reahzation is that of the generahzation of the 

 tendency to these growths over many if not all the human races. So 

 far the formations have heen found in all branches of the human 

 family from which large cranial collections are available. They have 

 not yet been reported in a Negro skull, in that of a Chinese, nor in 

 those of a few other groups, but the numbers of specimens in no 

 one of these cases has been adequate. When sufficient material is 

 availa])le, there are indications that the growths will be found ab- 

 sent in no human aggregate. 



VARIED FREOUENCY 



Though a tendency toward ear exostoses is probably a pan-human 

 condition, the incidence of the growths varies greatly in different races 

 and groups, and even in different localities. This may be due to dif- 

 ferences in the tendency, or to the quantity or effectiveness in a given 

 group or locality of the exciting causes ; or both these factors to- 

 gether. The most afflicted, in the order named, are some of the 

 American Indians, the Polynesians, and probably some groups of the 

 Whites ; the least affected are the African Negro, possibly the Chinese, 

 and the Eskimo. There is no racial concordance in this and no plain 

 significance, except perhaps as to the African Negro, wdio in general 

 represents one of the least advanced groups, so far as the brain and 

 head are concerned. 



The very marked difference in the incidence of ear exostoses among 

 the American Indians and probably also among the Whites indicates 

 that in some groups and localities the agencies that master the normal 

 status have been further weakened, or that conditions favoring the 

 production of the growths are more potent or common. The term 

 " racial inclination " must be understood in this manner. 



GENERAL SIMILARITY 



A survey of large and varied series of osteological material reveals : 

 I, that in general, ear exostoses display, regardless of race or place, 

 essential similarity ; and 2, that there is often distinguishable more 

 or less of group or place peculiarities. Thus in one tribe or locality 

 large growth may be frequent ; in another, equally involved, they may 

 be scarce. There are also group differences in the exostoses according 

 to their location, in their predominant forms, and in other respects. 



