304 THE TREND OF THE RACE 



rate is allowed to take its natural course large families offer some 

 evidence of physical vigor whatever they may indicate as to 

 mentality. A general reduction of the birth rate has, therefore, 

 its dangers, at least for the physical vigor of the population, since 

 it would probably involve a greater proportionate reduction of 

 healthy and vigorous stocks. 



It would indeed be unfortunate if a reduction of the birth 

 rate in the larger families would lead to the reduction of the 

 best members of the stocks in addition to the loss of physical 

 vigor otherwise involved. Whether ordinal position in the family 

 except in the matter of weight, size and infantile death rate, is 

 per se a handicap is a question which most of our data do not 

 enable us to decide. The fact that there is a greater percentage 

 of deaths among the first born than there is among the second or 

 third born does not prove that the second or third born member 

 of any particular family is less likely to die than the first bom. 

 The large percentage of deaths among the first born may be due 

 to the fact that a large proportion of early deaths occur in families 

 containing only one or two children. The data do not prove that 

 in families in which three or four children are born the later 

 children have any greater expectation of life than the first. As 

 we have already pointed out fecundity is correlated with longev- 

 ity. Families limited by the early death of one or both parents 

 would naturally show a high death rate on account of the prob- 

 ability that the offspring would inherit a diminished vitality. On 

 the other hand, large size of family very commonly has a very 

 undesirable relation to infant mortality, despite the vitality of 

 the stock from which large families come. This is due in part at 

 least to economic causes and in part to the correlation between 

 mental subnormality (this does not imply reduced physiological 

 vigor) with a high birth rate. Where large families occur among 

 intelligent and thrifty people as they did a century ago, there is 

 much less correlation between size of family and a high early 

 death rate. The following table from data collected by Dr. A. G. 

 Bell is instructive in this connection: 



