Woods: Significant Evidence for Mental Heredity 111 



or statistical test of the effect of a 

 peculiar social restraint or law on a 

 certain class of persons, in data which 

 I had collected for inheritance in the 

 royal families of Europe. Some mem- 

 bers of the family reach the throne and 

 become sovereign rulers, while others 

 do not. Here, then, are two distinctly 

 different psychological environments 

 acting on the same heredity, or more 

 strictly speaking, virtually the same 

 average heredity which we secure on 

 the same principle as the agricultural 

 experimenter who takes two handftils 

 of seed from the same bin. I think 

 everyone would have supposed that a 

 part, at least, of the intellectual emi- 

 nence of Frederick the Great, Peter the 

 Great, or Gustavus Adolphus was due 

 to the fortunate opportunity of an 

 exalted official position. Perhaps this 

 is true; I cannot say that it is not true; 

 but if it is true to any considerable 

 extent, why does it not show itself 

 between sovereigns and their younger 

 brothers? Here is a definitely measur- 

 able difference of environment, which, 

 as far as I have been able to see, has no 

 particular effect one way or another. 



The eminence of the younger sons is 

 just as great as that of the actual rulers. 

 In 403 cases' it does not show itself 

 to any significant degree. All this 

 sets us thinking. It does not disprove 

 that exceptional opportunity has fav- 

 ored the sovereign, for it may be that 

 opportunities of kingship have favored 

 him and other opporttmities just as 

 beneficial have favored the younger 

 sons. All it shows is that a certain 

 specific difference in opportunity has 

 been unable to make itself felt. There- 

 fore, it is not right to say that kings are 

 favored by their peculiar opportunity 

 of kingship. 



GREAT MEN AND THEIR KIN 



Another instance of failure of oppor- 

 tunity to produce a measurable differ- 

 ence is obtained from a comparison of 

 the great men of America with 

 the great men of Europe. The pro- 

 portionate number of great men in 

 European history who are related to 



other eminent persons is well known 

 from the investigations of Galton, 

 de Candolle and Ellis. The proportion 

 for men of the highest type is about 

 one in two. That is, one out of every 

 two has an eminent blood relation as 

 close as great-grandparent or great- 

 grandson. This is far greater than the 

 average expectation, but it does not 

 prove an>'thing against the influence of 

 nurture since these very men necessarily, 

 more than common men, were brought 

 up in exceptional environments. My 

 own investigations into the family 

 history of great men in the United 

 States show that the ratios are not differ- 

 ent in this country. This fact does not 

 prove that the Americans have not 

 also been benefitted by the traditions 

 and educational advantages of belonging 

 to good families, but it does prove that 

 supposed superior opportunities in the 

 newer country have not produced an 

 easily measurable difference. 



Where, then, can environment be 

 expected to be found working at its 

 maximum or surely making itself felt 

 to some measurable extent? Certainly 

 environment has some influence. The 

 present war teaches us that, for the 

 same men in Europe are very different 

 men in outward action and inward 

 thought from what they were in June, 

 1914. It is also highly probable to 

 my mind that not only great national 

 crises, but also slowly developing na- 

 tional forces, when under the firm and 

 constant leadership of some very great 

 man or collection of men, profoundh' 

 alter for a time the thoughts and 

 activities of large numbers of men. 



On the other hand, the significant 

 evidence for mental heredity is very 

 considerable. The correlation ratios for 

 mental and physical traits, the facts 

 of alternative mental heredity, all have 

 their significance and value, even if 

 they do not separate internal from 

 external forces. The justification for 

 all this is too long a story to enter into 

 here, and I have not attempted in this 

 paper to enumerate the results. My 

 aim has been, rather, to point out a 

 method of procedure for future re- 



^ Science, June 19, 1914. 



