202 General Discussion 



to be happening is that the adult height is unchanged, but that it is 

 reached at a considerably earher age. Now there are so many factors in 

 preventive medicine that have come in during the last century and 

 liave tended to increase the span of life, that it is impossible in the 

 study of a whole population to sort out the possible decrease of the span 

 of life that might be produced by this earlier maturation from the 

 enormous increase that advances in medicine have brought about. 

 One is arguing from lower animals to man in suggesting that in man also 

 earlier maturation, or earlier reaching of adult size, might decrease the 

 span of life, other environmental factors being the same. 



Parkes: Is it really fair to say that the span of life has increased? As 

 I understand it, the expectation of life at birth has increased greatly, 

 but the expectation of life at seventy is now only about six months 

 longer than it was a hundred years ago, and it seems to me therefore that 

 the expectation of life in the biblical sense at any rate is just about the 

 same, although there are many more people living long enough to 

 expect it. 



Franklin: Would Dr. Sinclair define maturation? 



Sinclair: I think that is a question for a biologist. 



Bartlett: Isn't it the case that maturation cannot possibly be defined 

 in terms of a point reached at the end of a process of change? If the rate 

 of maturation has any relation to length of life, it surely must have to do 

 with the rate of some of the processes in reaching this final point, be- 

 cause one cannot assume that every process that is involved is increasing 

 at the same rate. One would assume also that the earlier age ranges 

 must vary among themselves a great deal. Maturation is not one single 

 process, whatever it is, and I shouldn't have thought it could possibly 

 be defined in terms of a terminal point of some sort. 



Bruit: I feel it will be impossible to answer the question on human 

 beings, since they live so long, and there is the progress of medicine and 

 of hygiene. Before you can have the result of your experiment on the 

 children you are considering, medicine will have made more progress. 

 The reason why people live longer is only due to victory over infectious 

 diseases, not to improvement in nutrition. Grown-up people eat like 

 fools, or as their government lets them eat, or as advertisements tempt 

 them, but animals are fed scientifically, so studies must be made by 

 comparative physiology, there is no way out. 



Miescher: I agree with Sir Frederic, but I should like to ask Dr. Sinclair 

 if he thinks that early maturation in size means also early maturation in 

 capacity for reproduction, for instance. 



Sinclair: I had that in mind, naturally, but I think size is an easier 

 criterion for measurement, though of course it is only a small part of 

 maturation. We also took another criterion, namely the onset of 

 menstruation, and tried to get information about that in populations 

 that are undoubtedly on different planes of nutrition, but we have run 

 into the difficult problem of primitive undernourished girls not knowing 

 their ages. It is very diiUcult, as you arc only too well aware, to find out 

 what has happened in past years, because the figures are not obtainable. 

 I had hoped that I could get some of these figures from my own college 



