283 
Before all this progressive growth has been completed the 
male begins to lose hair from the head. It starts at the 
temples, on which, as I remarked, it appears last in an infant, 
thus illustrating the law of retrogression; then the scalp 
gradually becomes more and more bare; and finally only a 
fringe of hair is left round the lower part of the head. The 
resemblance, between the bald head of old age at this stage and 
the head of the infant after what may be called its moult, is 
extremely curious ; and it illustrates the law of retrogression— 
the part affected loses the latest acquired characters first 
(page 271). 
From the variations of hairiness above detailed, the 
following surmises may be made. The very complete hairiness 
of the fcetus points to descent from an animal completely 
clothed with hair. The loss of hair during early infancy is a 
retrogressive character, indicating the fact that the hairy 
ancestors of man lost their hair. This loss of hair was no 
doubt analogous to the baldness of the head at the present day. 
Now baldness presumably arises from the increased use of the 
brain—the extra nourishment required by the brain is afforded 
at the expense of the hair and scalp. Possibly for the same 
reason—some correlations of growth on the score of economy— 
man’s hairy ancestors began to lose their coats. It would 
commence as a developmental variation in maturity; it would 
pass by the law of earlier inheritance to immaturity, and 
presently to infancy. Such loss of hair may have been assisted 
by sexual selection—it may have been the fashion to prefer 
husbands or wives distinguished by being less hairy; but, 
without sexual selection, developmental variation and earlier 
inheritance would have caused this loss of hair in time. 
It is possible to surmise the places from which this hair 
went first. The front of the body in children is conspicuously 
smooth, while the back is hairy. Now although Man is 
descended from an animal completely covered with hair, yet 
going further back, the abdomen and chest of quadrupeds— 
the underside of the body—is nothing like so hairy as the 
back—which is the upper and more exposed side. It may be 
