One circumstance has struck me much; namely, that all the breeders of the
various domestic animals and the cultivators of plants, with whom I have
ever conversed, or whose treatises I have read, are firmly convinced that
the several breeds to which each has attended, are descended from so many
aboriginally distinct species. Ask, as I have asked, a celebrated raiser
of Hereford cattle, whether his cattle might not have descended from long
horns, and he will laugh you to scorn. I have never met a pigeon, or
poultry, or duck, or rabbit fancier, who was not fully convinced that each
main breed was descended from a distinct species. Van Mons, in his
treatise on pears and apples, shows how utterly he disbelieves that the
several sorts, for instance a Ribston-pippin or Codlin-apple, could ever
have proceeded from the seeds of the same tree. Innumerable other examples
could be given. The explanation, I think, is simple: from long-continued
study they are strongly impressed with the differences between the several
races; and though they well know that each race varies slightly, for they
win their prizes by selecting such slight differences, yet they ignore all
general arguments, and refuse to sum up in their minds slight differences
accumulated during many successive generations. May not those naturalists
who, knowing far less of the laws of inheritance than does the breeder, and
knowing no more than he does of the intermediate links in the long lines of
descent, yet admit that many of our domestic races have descended from the
same parents--may they not learn a lesson of caution, when they deride the
idea of species in a state of nature being lineal descendants of other
species?
Selection. -- Let us now briefly consider the steps by which domestic races
have been produced, either from one or from several allied species. Some
little effect may, perhaps, be attributed to the direct action of the
external conditions of life, and some little to habit; but he would be a
bold man who would account by such agencies for the differences of 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 teazle, 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 very 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 several 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
make 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 some 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 quite plastic, which they can model almost 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 agriculturalists than almost any other individual, and who was
himself a very good judge of an animal, 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.' That most skilful breeder,
Sir John Sebright, used to say, with respect to pigeons, that 'he would
produce any given feather in three years, but it would take him six years
to obtain head and beak.' 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 now been
exported to almost every quarter of the world. The improvement is by no
means 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, and 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 b
y 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 is not so in some 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, also followed; for hardly any one is so
careless as to allow his worst animals to breed.
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, perhaps
never, the case. The laws of correlation of growth, the importance of
which should never be overlooked, will ensure some differences; but, as a
general rule, I cannot doubt 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, I may add, 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 the full acknowledgment of the importance of the principle in works of
high antiquity. 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 shows how much good domestic breeds are
valued by the negroes of 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.
At the present time, eminent breeders try by methodical selection, with a
distinct object in view, to make a new strain or sub-breed, superior to
anything existing in the country. But, for our purpose, a kind of
Selection, which may be called Unconscious, and which results from every
one trying to possess and breed from the best individual animals, is more
important. Thus, a man who intends keeping pointers naturally tries to get
as good dogs as he can, and afterwards breeds from his own best dogs, but
he has no wish or expectation of permanently altering the breed.
Nevertheless I cannot doubt that this process, continued during centuries,
would improve and modify any breed, in the same way as Bakewell, Collins,
&c., by this very same process, only carried on more methodically, did
greatly modify, even during their own lifetimes, the forms and qualities of
their cattle. Slow and insensible changes of this kind could never be
recognised unless actual measurements or careful drawings of the breeds in
question had been made long ago, which might serve for comparison. In some
cases, however, unchanged or but little changed individuals of the same
breed may be found in less civilised districts, where the breed has been
less improved. There is reason to believe that King Charles's spaniel has
been unconsciously modified to a large extent since the time of that
monarch. Some highly competent authorities are convinced that the setter
is directly derived from the spaniel, and has probably been slowly altered
from it. It is known that the English pointer has been greatly changed
within the last century, and in this case the change has, it is believed,
been chiefly effected by crosses with the fox-hound; but what concerns us
is, that the change has been effected unconsciously and gradually, and yet
so effectually, that, though the old Spanish pointer certainly came from
Spain, Mr. Borrow has not seen, as I am informed by him, any native dog in
Spain like our pointer.
By a similar process of selection, and by careful training, the whole body
of English racehorses have come to surpass in fleetness and size the parent
Arab stock, so that the latter, by the regulations for the Goodwood Races,
are favoured in the weights they carry. Lord Spencer and others have shown
how the cattle of England have increased in weight and in early maturity,
compared with the stock formerly kept in this country. By comparing the
accounts given in old pigeon treatises of carriers and tumblers with these
breeds as now existing in Britain, India, and Persia, we can, I think,
clearly trace the stages through which they have insensibly passed, and
come to differ so greatly from the rock-pigeon.
Youatt gives an excellent illustration of the effects of a course of
selection, which may be considered as unconsciously followed, in so far
that the breeders could never have expected or even have wished to have
produced the result which ensued--namely, the production of two distinct
strains. The two flocks of Leicester sheep kept by Mr. Buckley and Mr.
Burgess, as Mr. Youatt re
marks, 'have been purely bred from the original
stock of Mr. Bakewell for upwards of fifty years. There is not a suspicion
existing in the mind of any one at all acquainted with the subject that the
owner of either of them has deviated in any one instance from the pure
blood of Mr. Bakewell's flock, and yet the difference between the sheep
possessed by these two gentlemen is so great that they have the appearance
of being quite different varieties.'
If there exist savages so barbarous as never to think of the inherited
character of the offspring of their domestic animals, yet any one animal
particularly useful to them, for any special purpose, would be carefully
preserved during famines and other accidents, to which savages are so
liable, and such choice animals would thus generally leave more offspring
than the inferior ones; so that in this case there would be a kind of
unconscious selection going on. We see the value set on animals even by
the barbarians of Tierra del Fuego, by their killing and devouring their
old women, in times of dearth, as of less value than their dogs.
In plants the same gradual process of improvement, through the occasional
preservation of the best individuals, whether or not sufficiently distinct
to be ranked at their first appearance as distinct varieties, and whether
or not two or more species or races have become blended together by
crossing, may plainly be recognised in the increased size and beauty which
we now see in the varieties of the heartsease, rose, pelargonium, dahlia,
and other plants, when compared with the older varieties or with their
parent-stocks. No one would ever expect to get a first-rate heartsease or
dahlia from the seed of a wild plant. No one would expect to raise a
first-rate melting pear from the seed of a wild pear, though he might
succeed from a poor seedling growing wild, if it had come from a
garden-stock. The pear, though cultivated in classical times, appears,
from Pliny's description, to have been a fruit of very inferior quality. I
have seen great surprise expressed in horticultural works at the wonderful
skill of gardeners, in having produced such splendid results from such poor
materials; but the art, I cannot doubt, has been simple, and, as far as the
final result is concerned, has been followed almost unconsciously. It has
consisted in always cultivating the best known variety, sowing its seeds,
and, when a slightly better variety has chanced to appear, selecting it,
and so onwards. But the gardeners of the classical period, who cultivated
the best pear they could procure, never thought what splendid fruit we
should eat; though we owe our excellent fruit, in some small degree, to
their having naturally chosen and preserved the best varieties they could
anywhere find.
A large amount of change in our cultivated plants, thus slowly and
unconsciously accumulated, explains, as I believe, the well-known fact,
that in a vast number of cases we cannot recognise, and therefore do not
know, the wild parent-stocks of the plants which have been longest
cultivated in our flower and kitchen gardens. If it has taken centuries or
thousands of years to improve or modify most of our plants up to their
present standard of usefulness to man, we can understand how it is that
neither Australia, the Cape of Good Hope, nor any other region inhabited by
quite uncivilised man, has afforded us a single plant worth culture. It is
not that these countries, so rich in species, do not by a strange chance
possess the aboriginal stocks of any useful plants, but that the native
plants have not been improved by continued selection up to a standard of
perfection comparable with that given to the plants in countries anciently
civilised.
In regard to the domestic animals kept by uncivilised man, it should not be