34 



POPULAR SCIENCE MONTHLY. 



among Cubans until full maturity, as a means of raising their physical 

 standard. He found that at present the average Cuban man is, in size 

 and weight, the equal of the American female student. 



An illustration of environment, including education, overcoming 

 hereditary tendencies has recently been brought to my notice by Mr. 

 A. J. Eedmon. Mr. Redmon reared two murderous sparrow-hawks in 

 a cage with young larks and wrens. "They all grew up together; the 

 little wrens would creep under the sparrow-hawks for protection at 

 night. The two hawks never attempted to hurt the larks or wrens." 

 Mr. Redmon tried to starve the hawks into killing birds, but they 

 utterly refused to disgrace their education. 



Galton has determined just how much, on an average, each ancestor 

 contributes to the peculiarities of an individual. The parents together 

 contribute one half of the total heritage, the four grandparents to- 

 gether one fourth, the eight great-grandparents one eighth, the sixteen 

 great-great-grandparents one sixteenth and all the remainder of the 

 ancestry one sixteenth. 



This law explains another — 

 that the offspring of exceptional 

 parents are, on an average, less 

 exceptional than their parents. 

 Supposing that the average height 

 of two parents exceeds the aver- 

 age height of the race by three 

 inches. The average of the grand- 

 parents and remoter ancestors will 

 differ from the average height of 

 the race by much less than this. 

 Since the ancestors beyond the 

 parents contribute one half the 

 entire heritage of the individual, 

 they will act as a drag to pull the 

 individual toward mediocrity, in 

 the present case by one inch. 

 This law acts impartially, so that 

 the offspring of the extremely 

 good and the extremely bad are 

 both saved from the fate of their 

 parents. 



This regression toward mediocrity may readily be overcome by select- 

 ive breeding. In race-horse breeding if the ancestry has been good for 

 three or four generations the rest are not considered. 



Galton has devised a forecast machine by which, if the height of the 

 parents is known, the average height to which the offspring will grow 



Fig. 1. Average Contribution to the Pe 

 culiarities, or deviation from the aver- 

 AGE, of the Individual, by the first, second, 

 third, fourth and remaining generations; 

 father and mother each contribute one fourth 

 together one half of the total heritage. Each 

 one of the grandparents contributes one six- 

 teenth or together one fourth. The great- 

 grandp:irents together one eighth, the great- 

 great grandparents together one sixteenth, 

 and all the remoter ancestry together one 

 sixteenth. After Meston. 



