66 CONTROLLED NATURAL SELECTION 
sideration because they are self-evidently a 
means whereby Natural Selection within a 
family is controlled. 
Many account for the parental sacrificing 
instinct by concluding that the young and 
the juvenile, because they are helpless and 
inexperienced in defence, require protection 
of their parents. But such an argument is 
not sound. They require protection because 
they are valuable to the species: their help- 
lessness adds nothing to their value. How- 
ever, apart from this question: the origin 
of these characters as variations confined to 
particular members of a society and their 
fixation, must have been through Natural 
Selection dealing with families, and not with 
individuals; and further, these characters 
must control Natural Selection in such a way 
that one set of individuals, the young, is 
rendered more liable to be selected for sur- 
vival than the other, the parents. 
