i6o READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



representative of similarly long and scattered hairs which occur 

 in the chimpanzee, macacus, and baboons. 



Lastly, it may be here more conveniently observed than in the 

 next chapter on Embryology, that at about the sLxth month the human 

 foetus is often thickly coated with somewhat long dark hair over the 

 entire body, except the soles of the feet and palms of the hands, which 

 are likewise bare in all quadrumanous animals. This covering, which 

 is called the lanugo, and sometimes extends even to the whole fore- 

 head, ears, and face, is shed before birth. So that it appears to be 

 useless for any purpose other than that of emphatically declaring man 

 a child of the monkey. 



9. Teeth. — Darwin writes: 



"It appears as if the posterior molar or wisdom teeth were tending 

 to become rudimentary in the more civiUzed 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 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 

 usually sound (i.e., not specially Uable to decay); they also differ from 

 the other molars in size, less than in the Caucasian races." 



Now, in addition to these there are other respects in which the 

 dwindling condition of wisdom-teeth is manifested — particularly with 

 regard to the pattern of their crowns. Indeed, in this respect it would 

 seem that even in the anthropoid apes there is the beginning of a 

 tendency to degeneration of the molar teeth from behind forwards. 

 For if we compare the three molars in the lower jaw of the gorilla, 

 orang, and chimpanzee, we find that the gorilla has five well-marked 

 cusps on all three of them; but that in the orang the cusps are not so 

 pronounced, while in the chimpanzee there are only four of them on 

 the third molar. Now in man it is only the first of these three teeth 

 which normally presents five cusps, both the others presenting only 

 four. So that, comparing all these genera together, it appears that 

 the number of cusps is being reduced from behind forwards; the 

 chimpanzee having lost one of them from the third molar, while man 

 has not only lost this, but also one from the second molar, — and it 

 may be added, likewise partially (or even totally) from the first molar, 

 as a frequent variation among civilized races. But, on the other hand, 

 variations are often met with in the opposite direction, where the 



