26 DARWINISM AND HUMAN LIFE 



races from centres where they had their original 

 headquarters. Peculiar cases, such as the present- 

 day distribution of Camelidse, or the fauna of 

 Australia, or the population of oceanic islands, 

 readily admit of evolutionist interpretations. 



We have not given prominence to the so-called 

 evidences of evolution, partly because they have 

 been stated so often e.g. by Romanes and by 

 Mimes Marshall partly because none of the so- 

 called evidence is in itself demonstrative in the 

 strict sense. All that is shown is that the formula 

 fits a wide and representative series of facts, and 

 enables us to think of them in a clear and rapid 

 way. What can be securely said is this, that all 

 biological facts can be used as evidence of evolution 

 if we know enough about them, and there are no 

 biological facts which are inconsistent with it, 

 so far as we know. 



COMPARISON OF EVOLUTION FORMULA AND 

 GRAVITATION FORMULA. Let us compare the 

 evolution theory with one of the great physical 

 generalisations the gravitation formula. Both 

 are simple in statement, both are wide as the 

 world in their applicability. We are aware of 

 no facts contradictory to either. Furthermore, 

 they are alike in this, that neither proposes any 

 ultimate explanation, that both are examples 

 of intellectual shorthand, of thought-economising, 

 descriptive formulae. We do not know why 

 one body attracts another in the manner which 

 Newton formulated ; we do not know why 

 life should have its power of slowly creeping 

 upwards. It has been pointed out that, just as 

 Newton started with gravitation as a big funda- 

 mental fact, so Darwin started from variation, 



