332 ANNUAL KEPORT SMITHSONIAN INSTITUTION, 1935 



has the cellular mechanism for the shuffling and sorting of the genes 

 in each generation. The approximately 50-50 ratio of normal 

 winged to yestigial winged flies appears generation after generation 

 with somewhat wearisome regularity. The demonstration of the 

 inherent stability of the genie mechanism of heredity that this ex- 

 periment has given is extremely impressive. 



Analogous phenomena of organic stability are observed in nature. 

 There are considerable numbers of firmly established instances of 

 organisms living today that are specifically identical with their pro- 

 genitors in earlier geological eras. Among the Foraminifera 1 spe- 

 cies {Lagena sulcata) has persisted unchanged from Silurian times 

 down to the present; 1 species {Glohigerina hulloides) from the 

 Devonian to the present; 2 species from the Carboniferous; 2 from 

 the Permian ; 4 from the Triassic ; 7 from the Jurassic ; and 15 from 

 the Cretaceous. The significance of these cases cannot be overem- 

 phasized. When it is comprehended that organisms now living have 

 not changed by a perceptible amount from what they were millions 

 upon millions of years ago in Paleozoic times in those minutiae of 

 structure upon which systematists base their specific distinctions 

 and descriptions, the conservatism and stability of nature begin to 

 be realized. 



In human biology the conservative and stable element of true 

 biological heredity is supplemented and reinforced by what has been 

 variously called " social heredity ", or tradition, or the mores of the 

 group to which the individual and his stirp belong. This is, of 

 course, not inheritance at all in a proper biological sense. It is 

 rather an environmental matter at bottom. A bom Englishman 

 transported to America as a child may, and in fact usually does, 

 come as a man to think and act like an American. But to make him 

 do this if he lives his whole life in England among the people of 

 his kind would be virtually impossible. And it is a matter of sta- 

 tistical fact that vastly more human beings live out their lives not 

 far from where they were born and among their kind of people 

 than migrate or are transplanted into realms of other traditions and 

 mores. In consequence " social inheritance " or tradition plays an 

 enormous but usually underestimated part in determining the indi- 

 vidual and collective behavior of human beings. Its effects have 

 not infrequently been confused with those of true biological heredity. 

 Masses of data have been collected to show that near relatives, par- 

 ticularly fathers and sons, frequently follow the same professions 

 or callings. It is often quite erroneously concluded that such facts 

 prove a biological inheritance of talent or ability, either in general, 

 or for a particular calling, or both. Such data are inherently in- 

 capable of proving any such a conclusion. The observations can be 



