32 HEREDITY IN RELATION TO EUGENICS 



2. Hair Color 



This character is due to the presence of brown granules 

 in the hair and sonaetimes also to the presence of a diffuse 

 reddish pigment. The study of heredity of hair color is 

 compUcated — ^more than that of eye color — by the fact 

 that the hair grows darker with age, at least until maturity 

 is achieved. If you compare the hght browns and the 

 blacks in children under 16 and over 16 you will find twice 

 as many Ught browns in the younger lot as in the older; 

 but only half as many blacks. In other words, half of the 

 persons who will eventually have black hair still have hght 

 to medium brown at 16 years of age.^ While this tends to 

 obscure the result yet the general fact of segregation in hair 

 color cannot be gainsaid. Let us examine the results of 

 various matings. (Table V). 



Table V 



The hair-color of the offspring of parents with different classes 



OP hair pigment. 

 One parent Other parent Offspring 



Little brown Little brown All with tow, yellow, golden or red hair. 



pigment pigment 



Brown pig- Little or no Half with light hair, half with brown; in 

 ment brown pigment other families all children may eventually . 



gain brown hair 

 Brown pig- Brown pigment Most children have brown hair; some (about 

 ment one-quarter) have light hair. In some 



famihes all children eventually gain brown 

 hair. 



The most striking result is that dark-haired children prob- 

 ably never come from flaxen-haired parents. Indeed, a 

 good practical rule is that the children will not acquire hair 

 darker than that of the darker parent. 



The inheritance of red-hair color has a certain eugenic 

 importance. There can be little doubt that a young person 



^ Holmes and Loomis, 1909, p. 55. 



