Page Two 



EVOLUTION 



November, 1928 



New Evidence of Man's Relationship 



To The Anthropoid Apes 



(IVilh Kind Permission from a Study in the Journal of Dental Rseardi, .Ipril, 1928) 



By J. Leon Williams 



MANY years ago I made a critical study of tooth form In 

 relation to race. The most obvious variations in human 

 teetii occur in the upper central incisors. Examination of over 

 one thousand specimens from all parts of the world showed wide 

 and marked variations in all races, with only vague indications 

 of racial peculiarities. 



Arranging these teeth according to the most striking pecu- 

 liarities and resemblances it soon became apparent that there 

 are three very distinct forms of human central incisors. Class 1, 

 with sides parallel for more than half their length; Class 2, with 

 sides rapidly converging from the cutting edge toward the root; 

 Class 3, with a double curve on one, and sometimes on both 

 sides. The great majority are various blendings of these typal 

 forms, but in most teeth one or the other 

 is clearly dominant. 



An examination of the skulls in the 

 large collection of the Museum of the 

 Royal College of Surgeons of London 

 showed all three of these types of teeth in 

 every racial group. The racial types of 

 teeth which I had expected to find were 

 non-existant. Instead, all races have three 

 types of teeth, with certain minor racial 

 variations. Subsequent study in other 

 large museums and more than fifteen 

 years experience in the examination of 

 teeth in the mouths of living people have 

 established this discovery beyond a doubt. 



These same three tj'pes of teeth, even 

 more strongly marked in their leading 

 characteristics, are found in the gorilla, 

 the orang-utan and the chimpanzee. As 

 yet these variations have not been found 

 in the teeth of any other animals. These 

 facts have a direct bearing on the con- 

 troversy now in progress as to the pre- 

 human ancestors of man. 



The accompanying photographs illus- 

 trate these statements. Figures 1, 2 and 3 

 are taken from three skulls of Sandwich 

 Islanders. The first exhibits teeth of 

 Class I, having proximal sides that are 

 nearly parallel for more than half their 

 length. The teeth in the second are of 

 the tapering sort, Class II, characterized 

 by sharply converging lines and conse- 

 quently by wide interdental spaces. The 

 third shows the double curved line on the 

 distal proximal surface. Class III, also 

 with wide interdental spaces. 



I have similar sets of photographs of 

 Australian, Ancient Egyptian, Kaffir, Chi- 

 nese, African, New Hebridean, Hindoo, 

 Spanish, German, Javanese, Fiji Islander, 

 Italian, Tasmanian and others. They all 

 prove conclusively that there is no single 

 form of tooth characteristic of race. For 

 half a century it was taught in college 

 text books that certain forms of teeth are 

 peculiar to certain temperaments. There 

 is not the slightest foundation in fact for 

 this teaching. All peoples, ancient and 

 modern, have three types of teeth. 



Furthermore, the previously held views 



that there is some particular tooth form characteristic of the 

 anthropoid apes, has no foundation whatever in fact. They 

 have the three types of teeth that we find in all human races, 

 with even more strongly marked or bold characteristics. The 

 accompanying illustrations, figures 4, 5 and 6 show all three 

 types of teeth perfectly represented in the orang-utan. Studies 

 of the gorilla and the chimpanzee show the same three tooth 

 types. 



How closely they resemble human teeth is shown by figures 

 7 and 8, showing teeth of Sandwich Islander and Gorilla. The 

 left central incisor of the gorilla was lost. Over the black space 

 in the enlarged print I pasted a photograph of the 'left central 



I II', 2 Sandwich Islander; Ci.iss II 



Tig. 3. i.a;J.^;Ji l-ljlijcl, C!j-. HI 



