THE NATURAL HISTORY OF MAN 61 



In the prenatal condition the child needs to produce very 

 little heat because so little is radiated and the mother supplies 

 all of the necessary food and oxygen and removes all the 

 wastes. After birth the radiation of heat is greater and the 

 child is obliged to produce much more in order to maintain its 

 body temperature. The alimentary canal must take in and 

 digest its own food; through its lungs the child must obtain 

 oxygen and free itself of carbon dioxide, and its excretory 

 organs must remove its own wastes. It is evident, from the 

 above, that there is a great contrast between the prenatal 

 and postnatal environment, and the fundamental changes in 

 circulation, nutrition, and excretion which occur at the time of 

 birth make this period a very critical one for the child. 



At birth the child weighs about seven pounds, and is twenty 

 inches in height. Its upper extremities are relatively long, and 

 the lower extremities short. The legs are partly flexed, the 

 great toe abducted and the soles of the feet turned in. The 

 latter is believed to be indicative of a persistence of the climb- 

 ing position which existed in arboreal man. Additional evi- 

 dence along this line is to be found also in the remarkable 

 power of the hand grip of the child during the first month of 

 its life. At this time the infant is able to hold its weight sus- 

 pended by its hands, a power which is later lost. When the 

 body proportions of the newly born child are compared with 

 those of the adult it is found that the child is four times its 

 head height while the adult is eight times; that the upper and 

 lower extremities of the infant are equal in length while in the 

 adult the lower extremities are longer than the upper. The 

 long arms, short legs, flat nose, inverted feet, and lack of 

 cervical and lumbar curves in the spinal column of a newly 

 born infant constitute a remarkable series of structural re- 

 semblances to the ape which later disappear as the adult condi- 

 tion is reached. The child at birth can feel, see, taste, and 

 suffer pain but it is deaf for about twenty-four hours. Its 



