6 4 



THE HUMAN SPECIES 



whose skulls are strikingly human in appearance in the arch, 

 the relatively slightly developed organ of smell and its probo- 

 scidate character and-in the breadth of the septum interorbitale 

 (see Figs. 17 and 19). 



The human teeth also possess distinctive characters. In 

 early zoological manuals we find it asserted that man alone 

 possesses an unbroken series of teeth, and that they are all of 

 the same size ; only the first part of this assertion is correct, it 

 being a fact that in man neither is a whole series of teeth 

 absent as in certain other mammals, nor does he possess certain 

 spaces into which the upper and lower canine teeth fit, as in 

 the carnivora, or only the lower canines, as in the apes. As 

 regards the uniform size of the teeth, however, man has in 

 reality no advantage over the other mammals, for, apart from 

 individual differences of size in the molars and incisors, we find 

 signs of a transition stage between the anthropoids and man, 

 both in the molars and canines, there being people in whom 

 the points of the canine teeth are considerably higher than the 

 rest. 



The milk molars of man and the anthropoids bear a great 

 resemblance to one another, but when we come to the canine 

 teeth the resemblance disappears. Man has shorter and 

 broader permanent molars than have the anthropoids, and the 

 form and height of the molar cusps are constant in man but 

 vary in the different anthropoids. Another human attribute is 



the lesser divergence of the molar 

 roots (see Fig. 20). In man and 

 in the anthropoids, the upper pre- 

 molars and molars proper have 

 three roots, the lower two ; further, 

 the four cusps of the upper molars 

 are generally the same in man and 

 the anthropoids, but in the Pro- 



simiae only the first molar has four 

 FIG. 20. Human Teeth. I. Incisor; t t_ ^.1 i_ u 



II. Canine ; III. Molar ; (a) CUS P S, the Other two having but 



crown, (b) root. three each. In man the inner 



anterior cusp is connected with the outer posterior cusp by 

 means of a ridge and the inner exterior cusp is separated, as it 

 were, from the rest of the tooth by a small furrow. 



