250 DIVERSIONS OF A NATURALIST 



in relative size and in the order of their " cutting " or 

 growth, but these are trivial. The jaws of man show their 

 derivation by gradual dwindling from the larger projecting 

 jaws seen in apes and monkeys, in the close setting (that is 

 to say, " crowding ") of the teeth, and also in the dwindling 

 and late " cutting " of the last tooth, in each jaw above and 

 below, which we call the wisdom tooth. The " wisdom 

 teeth" are in the higher races of men on their way to 

 total disappearance. In lower races of men they are 

 larger than in the higher, and in the man-like apes are of 

 full size, and there is plenty of room in the jaw for them. 



In the highest apes as well as the lower, the bony 

 lower jaw slopes gradually backwards and downwards 

 from the palisade of front chisel-like teeth or incisors 

 (see Fig. 23 C, p. 277). There is no bony projection 

 below the front teeth in fact, no bony " chin." But in 

 all modern races of men the front part of the semicircle 

 arch of teeth has shrunk or " withdrawn " considerably 

 or more than has the bony jaw in which the teeth are 

 set. Consequently the bone projects in front of the 

 front teeth as the bony chin (see Fig. 23 A, p. 277, and 

 also " Science from an Easy Chair," 1910, pp. 404, 405). 

 This is characteristic of modern races of man and occurs 

 in no other animal. The very remarkable fact has 

 recently been established that in the ancient species of 

 man from the Middle and Lower Pleistocene the 

 Neander man and the Heidelberg man (Homo Neander- 

 thalensis) this extra or excessive shrinking of the dental 

 arch (the half-circle formed by the complete row of teeth) 

 had not taken place. Though the teeth are placed 

 closely side by side and have the same shape as in 

 modern man, they are a little bigger and form a larger 

 and longer arch more like a horse-shoe than a semi- 

 circle, and have not shrunk back so as to leave a project- 



