324 Social Evolution 



propagate their kind equally, the average of each 

 generation would tend to fall below the preceding. 

 From this position he draws as a corollary, that 

 the wider the limits of selection, the keener the ri- 

 valry and the more rigid the selection, just so much 

 greater will be the progress ; while for any progress 

 at all there must be some rivalry in selection, so that 

 every progressive form must lead a life of continual 

 strain and stress as it travels its upward path. This 

 again is true in a measure, but it is not true as 

 broadly as Mr. Kidd has stated it. The rivalry of 

 natural selection is but one of the features in prog- 

 ress. Other things being equal, the species where 

 this rivalry is keenest will make most progress; but 

 then "other things" never are equal. In actual life 

 those species make most progress which are furthest 

 removed from the point where the limits of selection 

 are very wide, the selection itself very rigid, and the 

 rivalry very keen. Of course the selection is most 

 rigid where the fecundity of the animal is greatest; 

 but it is precisely the forms which have most fe- 

 cundity that have made least progress. Some time 

 in the remote past the guinea-pig and the dog had 

 a common ancestor. The fecundity of the guinea- 

 pig is much greater than that of the dog. Of a 

 given number of guinea-pigs born, a much smaller 

 proportion are able to survive in the keen rivalry, so 

 that the limits of selection are wider, and the selec- 

 tion itself more rigid ; nevertheless the progress made 

 by the progenitors of the dog since eocene days has 

 been much more marked and rapid than the progress 



