264 THE WORLD OF LIFE 



What we are seeking for is a cause which has been in 

 action over the whole earth during the period in question, 

 and which was adequate to produce the observed result. 

 AVhen the problem is stated in this way the answer is very 

 obvious. It is, moreover, a solution which has often been 

 suggested, though generally to be rejected as inadequate. It 

 has been so with myself, but why I can hardly say. In his 

 Antiquity of Man (4th ed., 1873, p. 418) Sir Charles Lyell 

 says: 



^^ That the growing power of man may have lent its aid as the 

 destroying cause of many Pleistocene species must, however, be 

 granted; yet, before the introduction of fire-arms, or even the use 

 of improved weapons of stone, it seems more wonderful that the 

 aborigines were able to hold their own against the cave-lion, hyena, 

 and wild bull, and to cope with such enemies, than that they failed 

 to bring about their extinction.'' 



Looking at the whole subject again, with the much larger 

 bodv of facts at our command, I am convinced that the above 

 somewhat enigmatic passage really gives the clue to the whole 

 problem, and that the rapidity of the extinction of so many 

 large Mammalia is actually due to man's agency, acting in 

 co-operation with those general causes w^hich at the culmina- 

 tion of each geological era has led to the extinction of the 

 larger, the most specialised, or the most strangely modified 

 forms. The reason why this has not been seen to be a suffi- 

 cient explanation of the phenomena is, I think, due to two 

 circumstances. Even since the fact of the antiquity of man 

 w^as first accepted by European geologists only half a century 

 ago, each fresh discovery tending to extend that antiquity has 

 been met with the same incredulity and opposition as did 

 the first discovery of flint weapons by Boucher de Perthes 

 in the gTavels near Amiens. It has been thought necessary 

 to minimise each fresh item of evidence, or in many cases to re- 

 ject it altogether, on the plea of imperfect observation. Thus 

 the full weight of the ever-accumulating facts has never been 



