Data for the Problem of Evolution in Man. 



291 



inherited character. So far as we are aware, however, neither the 

 above-mentioned naturalists nor any other investigators have published 

 researches bearing on the problem of whether duration of life is or is 

 not inherited. We are accustomed to hear of a particular man that 

 " he comes of a long-lived family," but the quantitative measure of the 

 inheritance of life's duration does not yet seem to have been deter- 

 mined. This absence of investigation appears the more remarkable 

 as a knowledge of the magnitude of inheritance in this respect would, 

 we should conceive, be of primary commercial importance in the con- 

 sideration of life insurance and of annuities. The biological interest of 

 the problem, as we have already noticed, is very great. 



2. It will be well in the first place to point out that the problem is 

 by no means an easy or a straightforward one. The ages at death of 

 even close relatives must be found from records of some kind, or else 

 collected ab initio. Now if we take records like the Peerage, Baronetage,. 

 Landed Gentry, family histories, and private pedigrees, we find various 

 serious omissions. -In the first place the ages of the women are rarely 

 given, pages of the Peerage or Landed Gentry may be examined before 

 a single record is found of the ages of two sisters at death, or even of a 

 mother and a daughter. Further, the census and other returns show how 

 liable we are to find women's ages given erroneously. Family histories 

 and pedigrees suffer in the same way, the pedigrees are mostly taken 

 through the male line, and the women's ages can only be found in rare 

 cases. An exception must be made in the case of the Quaker family 

 histories, such as those of the Backhouse, Whitney, and other families. 

 Here the data are as full for the women as for the men, but naturally 

 the history of a single, even much-branched family, does not provide 

 anything like the material that the Peerage and Landed Gentry do in 

 the case of men. For this reason our first study is confined to inherit- 

 ance of longevity in the male line. We hope eventually to collect 

 enough data for inheritance in the female line, but it will take a longer 

 time to amass, and we fear will scarcely be as homogeneous. 



In the second place, the sources to which we have referred omit 

 more or less completely all record of the ages at death of infants and 

 children. The Quaker records give better results than the Peerage, 

 but even here the great bulk of child deaths appears to remain un- 

 recorded. Out of 1000 males born in this country more than 300 die 

 before they are 20 years of age. But when 1000 cases of ages of 

 father and son were taken out of the Landed Gentry, only 31 cases 

 showed the death of a son before 20 years of age. Of 2000 brothers 

 from the Peerage in 1000 pairs, only 21 individuals died before 20 

 years of age. In the Quaker histories we found about 16 per cent, of 

 deaths before 20 years of age. Clearly such early deaths are not 

 represented in anything like their proper proportions. They will 

 have to be found from other sources ; possibly by direct inquiry, and 



