PRESENT ASPECTS OF EVOLUTION 281 



It makes its verdict much as the judges at a great 

 poultry or dog show count the series of points, giving 

 each one of them a certain value on a certain scale, 

 and then award the prize to the individual having 

 the highest aggregate on the whole series. Any such 

 illustration is very liable to mislead ; I wish to empha- 

 size that fitness to survive is determined by the aggre- 

 gate of the qualities of an individual. 



But an animal having one organ of great value or 

 capacity may thus carry off the prize, even though its 

 other organs deserve a much lower mark. This is the 

 case with man. In almost every respect, except in 

 brain and hand, he is surpassed by the carnivora, the 

 cat, for example. But muscle may be marked, in mak- 

 ing up the aggregate, on a scale of 500, and brain 

 on a scale of 5,000, or perhaps of 50,000. A very slight 

 difference in brain capacity outweighs a great superi- 

 ority in muscle in the struggle between man and the 

 carnivora, or between man and man. 



The scale on which an organ is marked will be pro- 

 portional to its usefulness under the conditions given 

 at a given time. During the period of development of 

 worms and lower vertebrates much muscle with a little 

 brain was more useful than more brain with less 

 muscle. Hence, as a rule, the more muscular survived ; 

 the brain increasing slowly, at first apparently largely 

 because of its correlation with muscle and sense- 

 organs. At a later date muscle, tooth, and claw were 

 more useful on the ground ; brain and hand in the 

 trees. Hence carnivora ruled the ground, and certain 

 arboreal apes became continually more anthropoid. 

 At a later date brain became more useful even on the 

 ground, and was marked on a higher scale, because it 



