244 PROBLEMS OF HUMAN EVOLUTION 



tive, less indiscriminate, but as ruthless as ever. Whereas among 

 civilised peoples the stress of Natural Selection is weakened not 

 only during infancy, but throughout life. 



To elimination of the weak by disease much of the physical 

 strength of Europeans is due. The circumstances of civilised 

 life tend to foster a particular kind of stamina. The growing 

 tendency under civilisation is to live herded together and thus 

 there is far greater risk of infection than in former times, when 

 population was sparse and the country was dotted with small 

 villages or isolated habitations ; when, . too, the difficulty of 

 travelling checked the spread of infection. The race has adapted 

 itself to its circumstances. In spite of the large number of 

 victims that fall to the various " civilised " diseases, there is a 

 rapid increase of population. When, on the contrary, savage 

 peoples are suddenly brought into contact with some disease 

 that we have come to look upon without much alarm, but which 

 is new to them, the consequences are often astounding. The 

 fact is easily explicable on the theory that it is only by a constant 

 elimination of the unfit that a race becomes adapted to its en- 

 vironment. The weeding out through a long series of genera- 

 tions of those who are unable to fight a disease at length 

 produces a race who, though not immune from it, yet are, the 

 majority of them, able to laugh at its attacks. 



Tuber- Tuberculosis has long been at work in England dealing 



ils destruction, but at the same time reducing its own power to 



destroy. Whether there are any definite records of earlier date 



I do not know, but I quote some of the earliest London bills of 



mortality. 1 



Deaths from consumption 



A D. and cough. 



1629 1827 



1630 IplO 



1631 1713 

 1649 2387 

 1656 3184 



No doubt the diagnosis was not in every case correct ; 



1 I quote from Walford's Insurance Cyclopedia. 



