" ARBOREAL MAN " 221 



is after leaves or after fruit, makes a great difference, nay, it is well 

 known that conspicuous physiological and anatomical differences 

 arise even with differences of " soft " or " hard " feeding among 

 allied frugivorous birds for instance. All such differences are 

 associated with vitally important differences of service in 

 Symbiosis, with their far-reaching reactions upon the evolution 

 of the organism. 



Fruit-eating animals, among whom man is included, are the 

 friends of the fruit-tree. They do not, for instance, crunch up 

 the fruit, kernel and all, as a grazing animal would do. They 

 are more temperate and more symbiotic in disposition. They 

 work in harmony with the fruit-producing plant. And they like 

 the bright colours and sweet scents (which, according to Mr. 

 E. Kay Robinson, are danger signals to the eaters of green-stuff) 

 because they indicate that their favourite food is ripe and ready 

 to be eaten. Grazing and browsing animals, however, are 

 generally the enemies of the higher plant, and Mr. E. Kay 

 Robinson says : 



They are afraid of bright colours ; so the fruits are brightly coloured. 

 They dislike scents ; so the fruits are scented. The colours and scents 

 of fruits have, so far as they are concerned the same meaning as the colours 

 and scents of flowers. 



However this may be, we may feel certain that habitual 

 biological use or misuse in course of time is replete with physio- 

 logical and anatomical reactions. The buffalo grass has gradually 

 disappeared from the prairies, which are no longer roamed by 

 herds of buffaloes. The buffalo grazed down all the rivals of the 

 buffalo grass, and the latter, being especially adapted to survive 

 in such circumstances, flourished exceedingly. With the 

 departure of the buffaloes, however, the other plants are having 

 their turn of prosperity, and the buffalo grass is not adapted to 

 compete with them on equal terms. 



It may thus be said that by their food-adaptations animals 

 determine to a large extent their own evolution. Who will 

 doubt that it has always been thus ? We are too apt to think 

 that food counts for very little, so long as there is enough of it. It 

 is one of those " seemingly humble and unimportant " factors 

 that yet matters most in evolution. We are confirmed in our 

 prejudice by the observation that domesticated animals devour 

 almost anything they can obtain. I have indeed been taken to 

 task for my cross-feeding thesis by a learned critic, in view of the 



