684 THE POPULAR SCIENCE MONTHLY. 



tliat he can gallop with speed. Instead of coming into the world 

 with tlie general outline of an American bison (as he ought to do 

 upon accepted physiological dicta), he is, as is well known, pro- 

 portionately higher at the rump and lower at the shoulder than 

 in after-life. The mention of the American bison reminds me 

 that it is another capital illustration of the same fact ; for a 

 young buffalo calf must have speed from its earliest days to 

 enable it to keep up with the herd on the open prairie ; and, in 

 consequence, we find that it is much better developed behind (the 

 hind legs being the chief propellers in all galloping animals) than 

 the full-grown bull or cow, and has none of the comma-like, 

 whittled-off aspect of its adult parents. The massive fore end of 

 the bull bison arises from his habit of using himself as a projectile 

 wherewith to batter his rivals out of the overlordship of the herd ; 

 but the bison calf is almost as level-backed as the young of our 

 domestic cattle — though it is a much more active, wide-awake little 

 beast than an ordinary calf. 



Why, then, are the head and upper extremities so apparently 

 abnormally developed in the young infant ? I conceive the true 

 reason to be something like this : For untold ages the perfection 

 of the arms was a sine qua non of the continuance of the race ; 

 and as man, or the thing which was to be man, took to living by 

 his wits — when, that is, mind began to take precedence of brute 

 force and direct reflex action in the forefront of the struggle for 

 existence — it became an absolute necessity for the being that was 

 to live by his wits to be furnished with an abundant supply of 

 the raw material out of which wits are made — that is, brains. 

 Now, every man, actual or in ^osse— having elected, be it remem- 

 bered, to fight chiefly with his brains, and having renounced for- 

 ever the more gross and carnal weapons, such as huge canine teeth 

 and heavy, cla.w-armed limbs— would be certainly bested in the 

 struggle, and driven out of being, if his chosen armature were not 

 up to the mark. In other words, every incipient homo who was 

 born with deficient mind-material lived but a short time and left 

 no offspring. And, since the potentialities of the brain depend 

 far more upon its primary degree of development than do, for 

 instance, the potentialities of the muscles, only those infants 

 which were born with crania capacious and well-furnished would 

 attain that degree of excellence which would prevent them from 

 being fatally plucked in Nature's great perennial competitive 

 examination. Only those infants, then, survived and became our 

 ancestors which had from the first a good development of head 

 and arm, and, to insure this, Nature has provided for a suitable 

 blood-supply during the early period of growth. 



With regard to the forward bend of the thighs in young infants, 

 which is constant in all cases, as any one who has the opportunity 



