134 MARRIAGE AND HEREDITY 



heredity teaches us to look for. The population of a 

 certain island or district acquires the taint of insanity, 

 and consanguineous marriages then tend to aggravate 

 the evil. In the primitive communities cited by 

 Huth, such as the island of St. Kilda, Pitcairn Island, 

 Iceland, etc., and indeed among all savage races, we 

 should naturally expect consanguineous unions to be 

 more or less harmless, because of the rarity of disease 

 which is so largely bred by the conditions of civilised 

 society. Insanity, for example, is a disease of civili- 

 sation, arising from the excessive wear and tear of 

 commercial, literary, and artistic life, or from the 

 enervating influences of wealth and luxury. Were 

 insanity in all its forms to be swept out of the world 

 to-morrow, says Maudsley, it would at once be bred 

 again in civilised communities. Other classes of 

 disease that may be said to dog the steps of civilisa- 

 tion are those arising from overcrowded and unsani- 

 tary dwellings and long hours of work. The puny 

 lads and the flat-chested girls swarming in great towns 

 and cities are essentially the product of civilisation; 

 and as each family group suffers from a particular de- 

 fect, which would be aggravated by the intermarriage 

 of its members, it is mathematically certain that 

 consanguineous unions, if as common, for example, in 



