NO. 6 EAR EXOSTOSES— HRDLICKA 85 



This leaves as the most probable basic cause of ear exostoses a 

 weakening or derangement of the normal hereditary control of the 

 tympanic bone and parts adjacent. With this conclusion we must rest 

 for the present, for while it was possible to proceed thus far by the 

 use of logic, a further delving into the subject, until there have ac- 

 cumulated additional reliable data, would entail pure speculation. 



Only one thought, already touched upon, may here be permissible, 

 but that must not be taken for an assertion. It concerns man's astound- 

 ingly rapid evolution and changes — geologically and morphologically. 

 Within some 500,000 years man's progress, especially as concerns 

 his brain and head, has far outstripped that of all the rest of creation. 

 This rapid progress and differentiation, with a spread to all regions 

 and exposure to a multitude of new factors, has prevented in many 

 respects a full adjustment of all parts, a full harmonization and sta- 

 bility in all regions. There is a possibility that the central trophic con- 

 trol of the external meatal region, in the greatly enlarged, altered and 

 still altering skull, has not regained the full life-long adequacy that 

 it possessed before. This would mark the abnormality under con- 

 sideration as an incidental condition, one that might disappear in the 

 natural course of events, if further skull changes affecting the part 

 stopped and if direct inheritance of the abnormality did not meanwhile 

 become rooted. Should this conception prove to be true, then the 

 process of ear exostoses could be defined as that of irregular out- 

 growths of bone in the external bony auditory canal and principally 

 from its tympanic part, due primarily to evolutionarily-weakened 

 normal neuro-vascular control of the parts. 



One other item demands a brief consideration in these connections. 

 It is that of a possible disturbing, and hence causative, influence of the 

 sex hormones. As seen, ear exostoses develop most frequently during 

 the period of major sexual activity. Also they are more common in 

 the male, in whom the sex activity is more intense. This attractive 

 " clue "', however, proves disappointing. Perhaps no race, particularly 

 as regards the males, is more active sexually than the Negro^ — yet 

 ear exostoses are very rare if not absent. There are so many such 

 incongruities, racial and individual, that this promising lead must be 

 abandoned. 



SUMMARY 



Ear exostoses are neither a constitutional, nor infectious, nor malig- 

 nant disease. They do not even properly deserve the name of disease, 

 being but secondarily pathological and that mainly through obstruction 

 or pressure. They are abnormalities rather than a disease. 



