22 THE DESCENT OF MAN, 



covered by rather long silky hairs; and such cases probably 

 come under the same head. 



It appears as if tlie posterior molar or wisdom teeth were 

 tending to become rudimentary in the more civilized races 

 of man. These teeth are rather smaller than the other 

 molars, as is likewise the case with the corresponding teeth 

 in the chimpanzee and orang; and they have only two 

 separate fangs. They do not cut through the gums till 

 about the seventeenth year, and I have been assured that 

 they are much more liable to decay, and are earlier lost 

 than the other teeth; but this is denied by some eminent 

 dentists. They are also much more liable to vary, both in 

 structure and in the period of their development, than the 

 other teeth.* In the Melanian races, on the other hand, 

 the wisdom teeth are usually furnished with three separate 

 fangs, and are generally sound; they also diifer from the 

 other molars in size, less than in the Caucasian races, f 

 Prof. Schaaffhausen accounts for this difference between 

 the races by '* the posterior dental portion of the jaw being 

 always shortened " in those that are civilized, | and this 

 shortening may, I presume, be attributed to civilized men 

 liabitually feeding on soft, cooked food, and thus using 

 their jaws less. I am informed by Mr. Brace that it is 

 becoming quite a common practice in the United States to 

 remove some of the molar teeth of children, as the jaw 

 does not grow large enough for the perfect development of 

 the normal number. 



With respect to the alimentary canal, I have met with an 

 account of only a single rudiment, namely the vermiform 

 appendage of the caecum. The caecum is a branch or diver- 

 ticulum of the intestine, ending in a cul-de-sac, and is ex- 

 tremely long in many of the lower vegetable-feeding mam- 



* Dr. Webb, "Teeth in Man and the Anthropoid Apes," as quoted 

 by Dr. C. Carter Blake in "Anthropological Review," July, 1867, 

 p. 299. 



f Owen, "Anatomy of Vertebrates." vol. iii, pp. 320, 321 and 325, 



X"On the Primitive Form of the Skull," Eng. translat. in" Anthrop- 

 ological Review," Oct. 1868, p. 426. 



Prof. Montegazza writes to me from Florence, that he has lately 

 been studying the last molar teeth in the different races of man, and 

 has come to the same conclusion as that given in my text, viz. : that 

 in the higher or civilized races they are on the road toward atrophy 

 or elimination. 



