. The Dental cosmos . itance (blended in-heritance) and of reversion (exclusive in-heritance). According to these laws,even in slow-breeding humanity, allowingbut four generations to a century andonly one hundred thousand years for theevolution of the human race, the inter-vention of four thousand generationsreduces the possibility of the direct in-heritance of even anthropoid charactersin the teeth to practically nil. Yetnumerical dental variations are so com-mon in man that they are observed byevery dentist. As Pearson points out,these supposed cases of atavism havenothing whatever to do wit
. The Dental cosmos . itance (blended in-heritance) and of reversion (exclusive in-heritance). According to these laws,even in slow-breeding humanity, allowingbut four generations to a century andonly one hundred thousand years for theevolution of the human race, the inter-vention of four thousand generationsreduces the possibility of the direct in-heritance of even anthropoid charactersin the teeth to practically nil. Yetnumerical dental variations are so com-mon in man that they are observed byevery dentist. As Pearson points out,these supposed cases of atavism havenothing whatever to do with inheritance,but are abnormal variations. CHARACTERISTICS OF SUPERNUMERARYTEETH. Supernumeraries all evidently belongto the same general class, and the explan-ation that will apply to a third incisor or OSBURN. ON SUPERNUMERARY TEETH IN MAN AND OTHER MAMMALS. 1195 premolar or a fourth molar in man ought tion, which of itself involves too great ato apply with equal force to a second stretch of the imagination. Fig. Right and left upper canines of a dog, showing extra canine on one side andpartially divided canine on the other. (After Bateson.) canine or a fifth premolar or molar in any Another important difficulty in the waymammal. The theory of atavism evi- of accepting this explanation is the fact Fig. 2.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentist, bookyear1912
