INTENSIVE SEGREGATION. 335 



this point of view we see how largely the form of Parental Selec- 

 tion is determined by social custom, and how it is sometimes 

 enforced by Social Selection, which excludes from the benefits of 

 the caste or tribe all who have not been througli the ordeal. 



As Eilio -parental Selection is due to different degrees of adap- 

 tation between the parent and offspring, it may be characterized 

 not only by fatal departures in ofli'spriug from the characters 

 required in their relations to their parents, but by fatal depar- 

 tures in parents from the characters required in parents in their 

 relations to their offspring. As an example of the former, we 

 may refer to the death at birth of children with excessiA'ely large 

 heads ; and as an example of the latter, to the death at birth of 

 all the children of a mother with a contracted pelvis. 



Dominatioiial Selection. — Variations that are equally fitted to 

 cope with the environment maybe divided into two classes — those 

 better able, and those less able, to cope with other members of the 

 species in appropriating resources. Increase of population and the 

 consequent competition between members of the same species con- 

 demns the latter to premature death, or at least to failure in propa- 

 gating, unless they find new resources by migrating or by changing 

 their habits. Competition between kindred for the possession of 

 identical resources we find directly connected with three quite dis- 

 tinct principles of evolution : — (1) With the principle oi Superla- 

 tive Selection tending to the destruction of all forms except those 

 most f LiHy adapted to the environment ; (2) AVinh the principle 

 of Dominatioual Selection tending to discriminate between those 

 equally adapted to the environment, through the success and 

 consequent propagation of those only that are best able to cope 

 Avith their kindred in appropriating advantages ; (3) With the 

 principle of Competitive Disruption, tending to break up old 

 relations and old habits, and so preparing the way for the forma- 

 tion of new habits producing segregation and divergence. Of 

 these three principles, the last was referred to in the second 

 chapter of my paper on " Divergent Evolution through Cumu- 

 lative Segregation," p. 221, and the first has already been men- 

 tioned in this paper. The remaining one I shall here briefly 

 describe, without attempting to shoAv its important influence on 

 the transformation and divergence of species. 



Dominatioual Selection is the exclusive breeding of those better 

 able to appropriate natural resources, or mates, or the provision 



