Darwiniana | Page 9

kind may
render derivation more improbable, and therefore specific creation
more probable, without settling the question either way. New facts, or
new arguments and a new mode of viewing the question, may some
day change the whole aspect of the case. It is with the latter that Mr.
Darwin now reopens the discussion.
Having conceived the idea that varieties are incipient species, he is led
to study variation in the field where it shows itself most strikingly, and
affords the greatest facilities to investigation. Thoughtful naturalists
have had increasing grounds to suspect that a reexamination of the
question of species in zoology and botany, commencing with those
races which man knows most about, viz., the domesticated and

cultivated races, would be likely somewhat to modify the received idea
of the entire fixity of species. This field, rich with various but
unsystematized stores of knowledge accumulated by cultivators and
breeders, has been generally neglected by naturalists, because these
races are not in a state of nature; whereas they deserve particular
attention on this very account, as experiments, or the materials for
experiments, ready to our hand. In domestication we vary some of the
natural conditions of a species, and thus learn experimentally what
changes are within the reach of varying conditions in Nature. We
separate and protect a favorite race against its foes or its competitors,
and thus learn what it might become if Nature ever afforded it equal
opportunities. Even when, to subserve human uses, we modify a
domesticated race to the detriment of its native vigor, or to the extent of
practical monstrosity, although we secure forms which would not be
originated and could not be perpetuated in free Nature, yet we attain
wider and juster views of the possible degree of variation. We perceive
that some species are more variable than others, but that no species
subjected to the experiment persistently refuses to vary; and that, when
it has once begun to vary, its varieties are not the less but the more
subject to variation. "No case is on record of a variable being ceasing to
be variable under cultivation." It is fair to conclude, from the
observation of plants and animals in a wild as well as domesticated
state, that the tendency to vary is general, and even universal. Mr.
Darwin does "not believe that variability is an inherent and necessary
contingency, under all circumstances, with all organic beings, as some
authors have thought." No one supposes variation could occur under all
circumstances; but the facts on the whole imply a universal tendency,
ready to be manifested under favorable circumstances. In reply to the
assumption that man has chosen for domestication animals and plants
having an extraordinary inherent tendency to vary, and likewise to
withstand diverse climates, it is asked:
"How could a savage possibly know, when he first tamed an animal,
whether it would vary in succeeding generations and whether it would
endure other climates? Has the little variability of the ass or
Guinea-fowl, or the small power of endurance of warmth by the
reindeer, or of cold by the common camel, prevented their
domestication? I cannot doubt that if other animals and plants, equal in

number to our domesticated productions, and belonging to equally
diverse classes and countries, were taken from a state of nature, and
could be made to breed for an equal number of generations under
domestication, they would vary on an average as largely as the parent
species of our existing domesticated productions have varied."
As to amount of variation, there is the common remark of naturalists
that the varieties of domesticated plants or animals often differ more
widely than do the individuals of distinct species in a wild state: and
even in Nature the individuals of some species are known to vary to a
degree sensibly wider than that which separates related species. In his
instructive section on the breeds of the domestic pigeon, our author
remarks that "at least a score of pigeons might be chosen which if
shown to an ornithologist, and he were told that they were wild birds,
would certainly be ranked by him as well-defined species. Moreover, I
do not believe that any ornithologist would place the English carrier,
the short-faced tumbler, the runt, the barb, pouter, and fantail, in the
same genus; more especially as in each of these breeds several
truly-inherited sub-breeds, or species, as he might have called them,
could be shown him." That this is not a case like that of dogs, in which
probably the blood of more than one species is mingled, Mr. Darwin
proceeds to show, adducing cogent reasons for the common opinion
that all have descended from the wild rock-pigeon. Then follow some
suggestive remarks:
"I have discussed the probable origin of domestic pigeons at some, yet
quite insufficient, length;