AMERICAN MEN OF SCIENCE 



801 



the children to follow similar scientific 

 pursuits with an early start and favorable 

 opportunities. I shall be able to give the 

 percentage of fathers and sons, or of two 

 or more brothers, who have engaged in 

 scientific work, and it may be possible to 

 determine the effect when the mother also 

 has scientific interests and ability. 



III. Vital Statistics and the Com- 

 position OF Families 



It has been claimed that children of 

 older parents are physically and mentally 

 inferior. Conversely, C. L. Redfield in a 

 curious book entitled "Control of Hered- 

 ity" and in various articles argues that 

 men of distinction are likely to be born 

 when their fathers are old and that their 

 performance is due to inheritance of the 

 experiences gained by their fathers. If 

 the age of the parents affects the constitu- 

 tion of the children, this clearly is a 

 matter of importance, particularly if the 

 principles of eugenics are enforced either 

 by law or by sentiment. But at present 

 we have no scientific information on a 

 problem which could be solved by statis- 

 tical research. 



The fathers of 865 leading American 

 men of science were on the average 35 

 years old and their mothers were 29 years 

 and 8 months old when their sons were 

 born. The fathers married at the average 

 age of twenty-eiglit years, being somewhat 

 more than five years older than their 

 wives. The scientific men are conse- 

 quently born at an average interval of 

 seven years after the marriage of their 



parents. The ages are given separat-ly 

 for the four groups into which the scien- 

 tific men have been divided and are earl- 

 ier for both fathei-s and mothers (group I. 

 in the table) of those more distinguished. 

 The probable errors given in italics show 

 that the differences may be due to chance, 

 but that this is unlikely. It is the ca.se, 

 as shown below in Table XIV., that the 

 first-born son is the one most likely to be- 

 come a scientific man, and the parents of 

 first-born children are of course younger. 

 In Table XI, is also given the average 

 age at death of the parents, whence it ap- 

 pears that the fathers died at the average 

 age of 70.6 years, the mothers at 70.2 

 years, the chances being even tliat the.se 

 figures are correct within a third of a year. 

 The average age of the scientific men be- 

 ing about fifty years, most of their parents 

 are now no longer living. If, however, the 

 deceased parents only had been included, 

 the averages would have been too low, as 

 the more long-lived parents would l)e those 

 more likely to be living. The expectation 

 of life has been added to the age of each 

 of those still living, and the probable age 

 at death used in the averages. The ages 

 given do not mean that people of this class 

 live to those ages, or that the men live 

 longer than the women. A statistical 

 error such as this has often been made, a 

 distinguished scientific man having, for 

 example, urged that it is one of the ad- 

 vantages of the scientific career that sci- 

 entific men live much longer than the 

 averaiire, failing to note the circumstance 

 that there are no scientific men who die 



Table XI. The Ages of the Parents at the Birth of the Scientific Men and at Death, accord- 

 ing TO the Standing of their Sons 



51 



