26 
THE DESCENT OF MAN. 
Part I. 
animals. As this can hardly be an accidental coinci- 
dence, we must consider the woolly covering of the 
foetus to be the rudimental representative of the first 
permanent coat of hair in those mammals which are 
born hairy. This representation is much more com- 
plete, in accordance with the usual law of etnbryological 
development, than that afforded by the straggling hairs 
on the body of the adult. 
It appears as if the posterior molar or wisdom-teeth 
were tending to become rudimentary in the more civi- 
lised 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 dentists. They are also much more 
liable to vary both in structure and in the period of 
their development than the other teeth. 31 In the 
Melanian races, on the other hand, the wisdom-teeth 
are usually furnished with three separate fangs, and 
are generally sound : they also differ from the other 
molars in size less than in the Caucasian races. 32 -Prof. 
Schaaff hausen accounts for this difference between the 
races by “ the posterior dental portion of the jaw bein«r 
“always shortened” iu those that are civilised, 33 and this 
shortening may, 1 presume, be safely attributed to civi- 
lised men habitually 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 
W Te ® th 111 Man a,ld tlie Anthropoid Apes,’ as quoted by 
Dr. C. Carter Blake in ‘ Anthropological Review,’ July, 1867, p. 299. 
“ Owen, * Anatomy of Vertebrates,’ vol. iii. pp. 320 , 321, and 325 
33 1 On tire Primitive Form of the Skull,’ Eng. translat. in ‘ Anthro- 
pological Jieviow,’ Oct. 1808, p. 426. 
