PDF - Wallace Online

ii ON THE TENDENCY OF VARIETIES, ETC. 31ever in a state of domesticity. Our quickly fattening pigs,short -legged sheep, pouter pigeons, and poodle dogs couldnever have come into existence in a state of nature, becausethe very first steps towards such inferior forms would haveled to the rapid extinction of the race ; still less could theynow exist in competition with their wild allies. The greatspeed but slight endurance of the racehorse, the unwieldlystrength of the ploughman's team, would both be useless ina state of nature. If turned wild on the pampas, suchanimals would probably soon become extinct, or underfavourable circumstances might each gradually lose thoseextreme qualities which would never be called into action,and in a few generations revert to a common type, whichmust be that in which the various powers and faculties are soproportioned to each other as to be best adapted to procurefood and secure safety, that in which, by the full exercise ofevery part of its organisation, the animal can alone continueto live. Domestic varieties, when turned wild, must returnto something near the type of the original wild stock, orbecome altogether extinct}-We see, then, that no inferences as to the permanence ofvarieties in a state of nature can be deduced from the observationsof those occurring among domestic animals. Thetwo are so much opposed to each other in every circumstanceof their existence, that what applies to the one is almost surenot to apply to the other. Domestic animals are abnormal,irregular,artificial ; they are subject to variations whichnever occur, and never can occur, in a state of nature : theirvery existence depends altogether on human care so far aremany of them removed from that just proportion of faculties,that true balance of organisation, by means of which alone ananimal left to its own resources can preserve its existence andcontinue its race.Lamarck's Hypothesis very different from that now advancedThe hypothesis of Lamarck that progressive changes inspecies have been produced by the attempts of animals to1That is, they will vary, and the variations which tend to adapt them tothe wild state, and therefore approximate them to wild animals, will be preserved.Those individuals which do not vary sufficiently will perish.