Lastly, more than one writer has asked why have some animals had their mental powers more highly developed than others, as such development would be advantageous to all?
Azkenik, autore batek baino gehiagok galdetu du zergatik garatu diren buru-ahalmenak animalia batzuetan beste batzuetan baino gehiago, garapen hori guztientzat onuragarri izanik.