The Evolution of Man 89 



the baby must — not from mere weakness of legs — crawl 

 on all fours. 



There is another remarkable group of indications that 

 tells us much about the evolution of man without any 

 recourse to the geologist. Pine as the human frame 

 undoubtedly is, from one point of view it may well be 

 regarded as an "old curiosity shop" or museum of 

 useless antiquities. It contains a number of organs and 

 tissues that have no function, yet absorb the precious 

 nourishment and are sometimes sources of mischief and 

 danger. These are the so-called " rudimentary " — a bad 

 word — or " vestigial " organs. 



Some of these may easily be brought home to the 

 inexpert. The fine coat of hair over the body is an 

 obvious instance. It cannot be understood except as 

 the degenerate relic of our ape-like ancestor's natural 

 "fur coat." Indeed, we shall see that it was still well 

 developed in prehistoric man less than 50,000 years ago. 

 An interesting special point in it is the fact that the hair 

 on the arm generally — not always — tends upward from 

 wrist to elbow and downward from shoulder to elbow. 

 We can only understand this as a reminiscence of the 

 days when our thick-haired ancestor, perched in his 

 primitive tree, made a thatched roof of his arms during 

 the rain, as apes do. Changes of habit and taste have 

 developed the hair luxuriously on the head and on the 

 male's chin — an instance of sexual selection, or prefer- 

 ence of females for bearded mates and males for 

 smooth-faced ladies — and led to its general degradation. 



The breasts of the human male provide another in- 

 stance. That these are genuine milk glands is shown by 

 the many known cases in which the male has suckled the 

 young. Haeckel examined a young man in Ceylon who 

 did this, and one of our English generals informs me that 

 he has seen an old man suckling an infant on the roadside 



