EVOLUTIONAL PSYCHOLOGY 67 



groups invariably show greater wealth of species than carni- 

 vorous groups. Even amongst Insectivora and Carnivora, 

 there are some species which prefer plant food where they can 

 get it. Orthodox Biology, however, has not yet begun to realise 

 the importance of cross-feeding and of the symbiotic bond which 

 such feeding is calculated to maintain. 



Biological status, according to Bio-Economics, depends upon 

 biological service, the highest service producing also the highest 

 form of Sex. Upon the land, for instance, the Cryptogams, 

 amongst plants, with the exception of highly symbiotic lichens, 

 are of comparatively little service to the fauna ; and they are 

 also correspondingly backward as regards sex and status. 



We may, therefore, conclude that the good psychical effects 

 of gregariousness are due quite as much to the right kind of 

 sociological as of physiological conditions. Gregariousness is 

 the efflorescence as it were, of fruitful socio-physiological 

 relations. 



Foremost amongst such relations is the symbiotic relation, 

 which provides the best ground- work for psychological progress. 

 It entails a high degree of mutuality and of division of work 

 together with moderation, which factors ensure viability and 

 plasticity, whilst they are at the same time the most favourable 

 to continuous organic elevation. The predaceous habit, on the 

 other hand, represents the opposite pole the service of death 

 and of eternal emptiness. The latter, therefore, is incompa- 

 tible with the principle of Symbiosis and with that of 

 gregariousness. 



In previous chapters evidence was provided showing that the 

 biological origin of food, i.e., its " nurture," is as important in 

 the long run as its chemical composition or " nature ; " and 

 we have further seen that symbiotic food is a medium of pro- 

 gressive stimulation par excellence. If, as Spencer suggests, 

 certain foods " permit " associations more than others, we may 

 now state with more explicitness that the good effects of food 

 are largely due to the fact of its being normally engendered, 

 regulated and endowed by protracted bio-economic processes. 

 Not only is food thus capable of being " standardised " and 

 fitted to produce maximal harmony amongst inter-related parts, 

 but it is also capable, as we shall presently see good reason to 

 suppose, of conveying direct psychic influences. 



We look in vain to any of Spencer's writings for an 



