HEREDITY 1 95 



cultural colleges became the most admirable organization for breeding of 

 better crops and farm animals based upon the principles of Mendelism. The 

 ideas developed by Mendel have found a new home here in the new world. 

 From 1905 to 19 10, 1 tried by lectures and by articles to renew the mem- 

 ory of Mendel in my home country and to explain the importance of A4en- 

 delism to the people. This was not always an easy task. Once I happened to 

 be standing beside two old citizens of Bruenn, who were chatting before a 

 picture of Mendel in a book-seller's window. "Who is that chap, Mendel, 

 they are always talking about now?" asked one of them. "Don't you know?" 

 replied the second, "it's the fellow who left the town of Bruenn an inherit- 

 ance!" In the brain of the worthy man the term "heredity" had no mean- 

 ing, but he understood well enough the sense of an inheritance or bequest. 



^ ^ \r %% TT 



HUMAN HERITAGE * 

 CARROLL LANE FENTON 



Man has been inheriting for a million years, but his study of the process 

 dates back a scant half century. At various times during the former period 

 he has lost color from skin, eyes, and hair, has reduced the thickness of his 

 jaw, enlarged the capacity of his skull, and improved his brain. The half 

 century of study, however, has been largely devoted to clearing away 

 ancient treasures of misconception. Much of this still remains to be done 

 before human beings will admit the results of their own genes and chromo- 

 somes. 



SIMPLE CHARACTERS MAY SEEM COMPLEX 



Our most obvious inheritance is sex, controlled by two X chromosomes 

 in women but an X and a Y in man. Much simpler, however, is tanning, a 

 character developed when sunshine causes cells of the skin to pile up grains 

 of brown pigment just beneath the surface. Though such grains are not in- 

 herited, the power to make them is controlled by one dominant gene in each 

 of two paired chromosomes. The opposite is a recessive gene that seems 

 to do nothing; fair-skinned whites who get two of these sunburn endlessly 

 since their cells cannot make protective pigment. 



If a fair-skinned recessive marries a person who is pure for tanning, their 

 children will get one gene of each kind, as any hybrid must. These children 

 are sure to tan, for one dominant gene can control the skin cells about as well 

 as two. 



It is not clear how many characters exist which involve one pair of genes. 

 They undoubtedly include certain types of nearsightedness and clubfoot, 



* From: Our Living World by Carroll Lane Fenton, copyright 1943 by Carroll 

 Lane Fenton, reprinted by permission of Doubleday & Company, Inc. 



