EVOLUTION 999 



wing-reduction. But, to be quite fair, let us quote Darwin's precise 

 sentences from The Origin of Species (1859). "Several conditions 

 make me believe that the wingless condition of so many Madeira 

 beetles is mainly due to the action of natural selection, combined 

 probably with disuse. For during many successive generations each 

 individual beetle which flew least, either from its wings having been 

 ever so little less perfectly developed or from indolent habit, will 

 have had the best chance of surviving from not being blown out to 

 sea; and, on the other hand, those beetles which most readily took 

 to flight would oftenest have been blown to sea, and thus 

 destroyed." 



Failures in Adjustment. — ^The Barnacle Goose (Bernicla 

 sandivensis) of the Hawaiian Islands has become entirely a land 

 goose during the breeding season. Moreover, it shows an obstinate 

 rigidity in always going back to the same breeding-place, an attach- 

 ment which enemies, including hunters, recognise to their own 

 advantage. Moreover, the parents are moulting when they lead the 

 goslings about, so that they cannot fly away; and they have left 

 the vicinity of the sea in which they used to find refuge. There are 

 many instances of this sort of imperfection in habit-change. And the 

 apparent imperfections become striking, though fallaciously so, 

 when man enters into the plot. Thus the now much reduced Elephant 

 Seal, once very abundant on Califomian coasts, persisted in being 

 unafraid of man. But how can one expect giant animals to have a 

 tradition of timidity? How can one expect animals that have held 

 a position of security for tens of thousands of years to react adap- 

 tively to man's mischievousness in the course of a century? For 

 thousands of years they have known no fear; is it any imperfection 

 that they remain unafraid of a few men intruding from a ship's boat ? 

 We do not absolve them, so to speak, from being somnolent in 

 security, but we cannot think of them as stupid. 



Conclusion. — ^There is no doubt that animals can adjust them- 

 selves, and sometimes adapt themselves, to new conditions of life. 

 There may be changes in structure and changes in habit. The fact 

 that some animals are profitably plastic, while others are fatally 

 stereotyped, is probably because those "habits" that are based on 

 reflexes and instincts are very hard to change ; while those that are 

 based on intelligence and on individually-learned associations 

 remain effectively plastic. Animals that are predominantly instinc- 

 tive — a line of evolution with many advantages — tend to become 

 stereotyped. For effective change of habit we must look among 

 animals whose ways of life are chiefly based on intelligence. The 

 instinctive line of evolution led to extraordinarily effective results, 

 as in ants, bees, and wasps; but the intelligent line of evolution is 

 the open path of educability. 



