CHAPTER I
VARIATION UNDER DOMESTICATION
Principles of Selection anciently followed, and their Effects
Let us now briefly consider the steps by which domestic races have
been produced, either from one or from several allied species. Some
effect may be attributed to the direct and definite action of the
external conditions of life, and some to habit; but he would be a bold
man who would account by such agencies for the differences between a
dray- and race-horse, a greyhound and bloodhound, a carrier and
tumbler pigeon. One of the most remarkable features in our
domesticated races is that we see in them adaptation, not indeed to
the animal's or plant's own good, but to man's use or fancy. Some
variations useful to him have probably arisen suddenly, or by one
step; many botanists, for instance, believe that the fuller's
teasel, with its hooks, which cannot be rivalled by any mechanical
contrivance, is only a variety of the wild Dipsacus; and this amount
of change may have suddenly arisen in a seedling. So it has probably
been with the turnspit dog; and this is known to have been the case
with the ancon sheep. But when we compare the dray-horse and
race-horse, the dromedary and camel, the various breeds of sheep
fitted either for cultivated land or mountain pasture, with the wool
of one breed good for one purpose, and that of another breed for
another purpose; when we compare the many breeds of dogs, each good
for man in different ways; when we compare the game-cock, so
pertinacious in battle, with other breeds so little quarrelsome,
with "everlasting layers" which never desire to sit, and with the
bantam so small and elegant; when we compare the host of agricultural,
culinary, orchard, and flower-garden races of plants, most useful to
man at different seasons and for different purposes, or so beautiful
in his eyes, we must, I think, look further than to mere
variability. We cannot suppose that all the breeds were suddenly
produced as perfect and as useful as we now see them; indeed, in
many cases, we know that this has not been their history. The key is
man's power of accumulative selection: nature gives successive
variations; man adds them up in certain directions useful to him. In
this sense he may be said to have made for himself useful breeds.
The great power of this principle of selection is not
hypothetical. It is certain that several of our eminent breeders have,
even within a single lifetime, modified to a large extent their breeds
of cattle and sheep. In order fully to realise what they have done, it
is almost necessary to read several of the many treatises devoted to
this subject, and to inspect the animals. Breeders habitually speak of
an animal's organisation as something plastic, which they can model as
they please. If I had space I could quote numerous passages to this
effect from highly competent authorities. Youatt, who was probably
better acquainted with the works of agriculturists than almost any
other individual, and who was himself a very good judge of animals,
speaks of the principle of selection as "that which enables the
agriculturist, not only to modify the character of his flock, but to
change it altogether. It is the magician's wand, by means of which
he may summon into life whatever form and mould he pleases." Lord
Somerville, speaking of what breeders have done for sheep, says:-
"It would seem as if they had chalked out upon a wall a form perfect
in itself, and then had given it existence." In Saxony the
importance of the principle of selection in regard to merino sheep
is so fully recognised, that men follow it as a trade: the sheep are
placed on a table and are studied, like a picture by a connoisseur;
this is done three times at intervals of months, and the sheep are
each time marked and classed, so that the very best may ultimately
be selected for breeding.
What English breeders have actually effected is proved by the
enormous prices given for animals with a good pedigree; and these have
been exported to almost every quarter of the world. The improvement is
by no generally due to crossing different breeds; all the best
breeders are strongly opposed to this practice, except sometimes
amongst closely allied sub-breeds. And when a cross has been made, the
closest selection is far more indispensable even than in ordinary
cases. If selection consisted merely in separating some very
distinct variety, and breeding from it, the principle would be so
obvious as hardly to be worth notice; but its importance consists in
the great effect produced by the accumulation in one direction, during
successive generations, of differences absolutely inappreciable by
an uneducated eye- differences which I for one have vainly attempted
to appreciate. Not one man in a thousand has accuracy of eye and
judgment sufficient to become an eminent breeder. If, gifted with
these qualities, he studies his subject for years, and devotes his
lifetime to it with indomitable perseverance, he will succeed, and may
make great improvements; if he wants any of these qualities, he will
assuredly fail. Few would readily believe in the natural capacity
and years of practice requisite to become even a skilful pigeon
fancier.
The same principles are followed by horticulturists; but the
variations are here often more abrupt. No one supposes that our
choicest productions have been produced by a single variation from the
aboriginal stock. We have proofs that this has not been so in
several cases in which exact records have been kept; thus, to give a
very trifling instance, the steadily-increasing size of the common
gooseberry may be quoted. We see an astonishing improvement in many
florists' flowers, when the flowers of the present day are compared
with drawings made only twenty or thirty years ago. When a race of
plants is once pretty well established, the seed-raisers do not pick
out the best plants, but merely go over their seed-beds, and pull up
the "rogues," as they call the plants that deviate from the proper
standard. With animals this kind of selection is, in fact, likewise
followed; for hardly any one is so careless as to breed from his worst
animals.
In regard to plants, there is another means of observing the
accumulated effects of selection- namely, by comparing the diversity
of flowers in the different varieties of the same species in the
flower-garden; the diversity of leaves, pods, or tubers, or whatever
part is valued, in the kitchen garden, in comparison with the
flowers of the same varieties; and the diversity of fruit of the
same species in the orchard, in comparison with the leaves and flowers
of the same set of varieties. See how different the leaves of the
cabbage are, and how extremely alike the flowers; how unlike the
flowers of the heartsease are, and how alike the leaves; how much
the fruit of the different kinds of gooseberries differ in size,
colour, shape, and hairiness, and yet the flowers present very
slight differences. It is not that the varieties which differ
largely in some one point do not differ at all in other points; this
is hardly ever,- I speak after careful observation, perhaps never, the
case. The law of correlated variation, the importance of which
should never be overlooked, will ensure some differences; but, as a
general rule, it cannot be doubted that the continued selection of
slight variations, either in the leaves, the flowers, or the fruit,
will produce races differing from each other chiefly in these
characters.
It may be objected that the principle of selection has been
reduced to methodical practice for scarcely more than three-quarters
of a century; it has certainly been more attended to of late years,
and many treatises have been published on the subject; and the
result has been, in a corresponding degree, rapid and important. But
it is very far from true that the principle is a modern discovery. I
could give several references to works of high antiquity, in which the
full importance of the principle is acknowledged. In rude and
barbarous periods of English history choice animals were often
imported, and laws were passed to prevent their exportation: the
destruction of horses under a certain size was ordered, and this may
be compared to the "roguing" of plants by nurserymen. The principle of
selection I find distinctly given in an ancient Chinese encyclopaedia.
Explicit rules are laid down by some of the Roman classical writers.
From passages in Genesis, it is clear that the colour of domestic
animals was at that early period attended to. Savages now sometimes
cross their dogs with wild canine animals, to improve the breed, and
they formerly did so, as is attested by passages in Pliny. The savages
in South Africa match their draught cattle by colour, as do some of
the Esquimaux their teams of dogs. Livingstone states that good
domestic breeds are highly valued by the negroes in the interior of
Africa who have not associated with Europeans. Some of these facts
do not show actual selection, but they show that the breeding of
domestic animals was carefully attended to in ancient times, and is
now attended to by the lowest savages. It would, indeed, have been a
strange fact, had attention not been paid to breeding, for the
inheritance of good and bad qualities is so obvious.
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