PHYSICAL CHARACTERS IN MAN 39 



this is obviousl}^ not the place to analyse such possi- 

 bilities from the evolutionary point of view. 



That the diminution in size of a species may happen 

 very quickly is shown by garden vegetables which 

 are allowed to run wild, or bv the immediate and 

 rapid increase in size of wild species taken into a 

 garden. This appears to be due to the fact that con- 

 ditions of culture permit of the rapid accumulation 

 of reserve material. Such instances as the following 

 in animals show rapid decrease in size: Dr. John D. 

 Caton (1887) tells how a male and four female wild 

 turkeys were sent from his grounds in Ottawa to 

 Santa Cruz Island, twenty miles off the coast of 

 California. This island is thirt}^ miles long and five 

 to ten miles wide. Here the turke^^s had no enemies 

 except a small grey fox. In a few years they became 

 ver}^ abundant and very much smaller, the largest 

 weighing not over 6 pounds, or less than one-third 

 the size of the first and second generations bred there. 

 In this case the mild climatic conditions could not 

 have been responsible, the food supply was abundant, 

 the birds were vigorous and healthy, and there was 

 no evidence of any epidemic. The wild turkey was 

 formerly abundant in Arizona, and birds introduced 

 on the mainland of California north of San Francisco 

 were prolific and of normal size. The cause of the 

 decrease in size of the Santa Cruz birds, therefore^ 

 remains unexplained. 



Davenport is inclined to conclude from his studies 

 of human stature that " in both ateliosis and achon- 

 droplasia in man there are multiple dominant (growth 

 inhibiting) factors, whose actions are often obscured 

 by opposing epigenetic growth factors, and which 

 are probably of a different sort in ateliosis than in 

 achondroplasia, for achondroplasia affects chiefly 

 or exclusively the appendages." Evidently much 

 has yet to be learned of the inheritance of these 



