THE PHYSICAL BASIS OF HEREDITY. 



35 



may be determined. "Of the individual we 

 can assert nothing as certain, only state the 

 probable." 



It is evident from these laws that, if 

 any fond parents feel that they are in 

 any way remarkable, their apparently re- 

 markable offspring are on an average only two 

 thirds as remarkable as they themselves. Also 

 if there are any fond sons or daughters who 

 rely on really gifted parents for their stand- 

 ing among their fellows, the sooner they begin 

 to look to themselves to make up by individual 

 effort their probable loss by the law of regres- 

 sion the better, for, on an average they are but 

 two thirds as gifted as their parents. I 

 should not mention this fool-killing law if it 

 did not have its bright side. If any individual 

 feels it in him to do and be something, a 

 mediocre parentage need not discourage him, 

 for, on the average, exceptional individuals, as 

 we all think ourselves to be, exceed the average 

 of humanity by one half as much again as 

 their parents exceeded this average. (Fig. 3.) 



It is a reassuring fact that, starting from 

 any standpoint above the average, our relatives 

 are on the average not quite equal to us. 

 Moreover, a gifted individual is more likely to 

 be the exceptional offspring of mediocre 

 parents than the average offspring of gifted 

 parents. "Among mankind we trust largely 

 for our exceptional men to extreme variations 

 occurring among the commonplace."* 



* Galton in his ' Hereditary Genius ' found one 

 hundred gifted men to possess on an average the 

 following number of relatives equally gifted: 



Gr. -grandfathers 3 



Grandfathers 17 



Brothers 41 Fathers 31 Granduncles 5 



Nephews 22 Gifted Men 100 Uncles 18 



Grandnephews.. 10 Sons 48 Cousins 13 



Grandsons 14 



Great-grandsons.. 3 



The isolation of gifted men is graphically illus- 

 trated by arranging the facts given in the middle 

 line in a frequency polygon. (Fig. 4.) 



Fig. 2. Galton's Forecast 

 Machine for Stature, set 

 at Mediocrity of the Race ; 

 The average height of men 

 being about 68.25, that of wo- 

 men 63 25. The circumference 

 of the wheels at the top are 

 to each other as two to three. 

 If the average height of the 

 parents is increased or de- 

 creased above or below medi- 

 ocrity by a given quantity the 

 average height of the offspring 

 is increased or decreased by 

 two thirds such amount. To 

 convert the female statures 

 into the corresponding male 

 stature, multiply the female 

 stature by 1.08. 



