THE ALIMENTARY CANAL AND ITS APPENDAGES 159 
Man’s adoption of a more delicate diet, those degenerating first 
which were the last to be added to form the compound tooth, 
In the upper jaw this is the posterior lingual and in the 
lower the posterior unpaired cusp. In the third molar, the 
so-called wisdom tooth, the process of reduction may go so far 
that finally, instead of a tooth with four or five cusps, a vestigial 
stump alone appears. In a relatively large number of cases, 
indeed, no wisdom tooth at all appears, it being either not 
formed, or, if formed, retained within the gum. 
Repeated investigations on this subject have all tended to 
show that these signs of degeneration, so marked in Europeans, 
are found in non-Kuropeans also, but not at all to the same 
extent as among the Aryan race. Quite apart from patho- 
logical cases, upper molars with three cusps, lower molars with 
four, and reduced wisdom teeth, occur more frequently in 
Europeans than in Negroes, Mongolians, or native Australians. 
The low race last named, in its dental formula, appears least 
removed from the hypothetical original type; for in it are still 
found complete rows of splendid teeth with powerfully developed 
canines and molars, the latter being either uniform, or even 
increasing, in size, aS we proceed backwards, in such a way 
that the wisdom tooth is the largest of the series. This is 
decidedly a pithecoid character, which is always found in Apes. 
The upper incisors of the Malay, apart from their prognathous 
disposition, have occasionally a distinctly pithecoid form, their 
anterior surface being convex, and their lingual surface slightly 
concave. The ancestors of the Europeans seem to have had the 
same form of teeth, for the oldest existing fragments of skulls 
from the Mammoth age (eg. the jaws from la Naulette and 
Schipka) reveal tooth forms which must be classed with those 
of the lowest races of to-day. 
Apart from those variations in the human dentition, which 
tend to approximate it to that of Anthropoids, still more 
startling ones are occasionally found. For example, the 
appearance of a third premolar is not very rare. In the Freiburg 
anatomical museum there is an upper jaw with three well- 
developed premolars on each side, thus showing the dental 
formula of the New World Apes. An increase in the number of 
molars is also not very rare in both Man and the Anthropoids. 
A fourth molar, in a more or less perfect form, is to be met with 
in every large collection of skulls. Zuckerkandl has shown that 
the epithelial germ of a fourth molar is not infrequently present 
