BRAIN DEVELOPMENT AND EVOLUTION. 535 



tween his inlierited cerebral capacity and tlie actual demand for 

 mental activity shall be restored. 



We have now only time left us to review briefly two or three 

 of the many peculiarities of savage life which stimulate increas- 

 ing mental activity and its physical manifestation in convolu- 

 tional development, and which peculiarities do not to the same 

 extent, if at all, affect civilized men, and especially the routine 

 laborers among them. To do this exhaustively would require a 

 volume, and we can therefore only glance at the matter in the 

 most cursory manner. 



It is an open question as to the extent that the use to which 

 learning is to be put constitutes a factor in determining the 

 value of the mental development received in acquiring such 

 learning. To whichever school of thought one may incline, it 

 can hardly be denied by either side that in the acquisition of the 

 same knowledge by two persons, the one for one purpose and the 

 other for an entirely different but equally important object, the 

 strengthening and developing effect, other things being equal, 

 would be the same. Now the common hunting savage of the 

 neolithic age takes up one branch of the study of natural history 

 and pursues it until he is able to teach an Agassiz, an Audubon, 

 or a Darwin. Not one of these learned men knew, after a life of 

 study and observation, as much about this one thing, the habits 

 of the wild beasts, birds, and fishes, as does the average savage 

 hunter. To him such knowledge means food and life, and the 

 lack of it hunger and starvation. He must know their color, 

 size, and movements ; when, where, and how they get their food 

 and water; where and how they make their nests or lairs or 

 homes ; when they rest and when they go forth, and where ; all 

 their cries and sounds, and the meaning of them ; and he must be 

 able to imitate them so exactly that they shall think these sounds 

 made by one of their own kind ; he must know when and where 

 they are moved about by winter and summer, by drought and 

 flood ; when and where they breed their young, and in each case 

 whether the young are protected by hiding, defense, or flight. 

 He must know what animals have leaders or sentinels, and how 

 to distinguish them, and how to interpret their sounds of alarm, 

 and distinguish them from the sounds of safety, and he must be 

 able to perfectly produce both; he must know their strength, 

 alertness, and acuteness of sense, speed, and endurance as related 

 to the species and to the age and sex of the individual ; he must 

 be familiar with their dispositions, their courage, cunning, intel- 

 ligence, and timidity, and be able to determine in advance what 

 they would probably do under all conceivable conditions. Then 

 it is not less necessary that he should know all the relations 

 of each species to each and all of the others. To acquire this 



