SELECTION A DIFFICULT ART—METHODICAL, UNCONSCIOUS, AND NATURAL
SELECTION—RESULTS OF METHODICAL SELECTION—CARE TAKEN IN
SELECTION—SELECTION WITH PLANTS—SELECTION CARRIED ON BY THE ANCIENTS
AND BY SEMI-CIVILISED PEOPLE—UNIMPORTANT CHARACTERS OFTEN ATTENDED
TO—UNCONSCIOUS SELECTION—AS CIRCUMSTANCES SLOWLY CHANGE, SO HAVE OUR
DOMESTICATED ANIMALS CHANGED THROUGH THE ACTION OF UNCONSCIOUS
SELECTION—INFLUENCE OF DIFFERENT BREEDERS ON THE SAME
SUB-VARIETY—PLANTS AS AFFECTED BY UNCONSCIOUS SELECTION—EFFECTS OF
SELECTION AS SHOWN BY THE GREAT AMOUNT OF DIFFERENCE IN THE PARTS MOST
VALUED BY MAN.
The power of Selection, whether exercised by man, or brought into play
under nature through the struggle for existence and the consequent
survival of the fittest, absolutely depends on the variability of
organic beings. Without variability nothing can be effected; slight
individual differences, however, suffice for the work, and are probably
the chief or sole means in the production of new species. Hence our
discussion on the causes and laws of variability ought in strict order
to have preceded the present subject, as well as inheritance, crossing,
etc.; but practically the present arrangement has been found the most
convenient. Man does not attempt to cause variability; though he
unintentionally effects this by exposing organisms to new conditions of
life, and by crossing breeds already formed. But variability being
granted, he works wonders. Unless some degree of selection be
exercised, the free commingling of the individuals of the same variety
soon obliterates, as we have previously seen, the slight differences
which arise, and gives uniformity of character to the whole body of
individuals. In separated districts, long-continued exposure to
different conditions of life may produce new races without the aid of
selection; but to this subject of the direct action of the conditions
of life I shall recur in a future chapter.
When animals or plants are born with some conspicuous and firmly
inherited new character, selection is reduced to the preservation of
such individuals, and to the subsequent prevention of crosses; so that
nothing more need be said on the subject. But in the great majority of
cases a new character, or some superiority in an old character, is at
first faintly pronounced, and is not strongly inherited; and then the
full difficulty of selection is experienced. Indomitable patience, the
finest powers of discrimination, and sound judgment must be exercised
during many years. A clearly predetermined object must be kept steadily
in view. Few men are endowed with all these qualities, especially with
that of discriminating very slight differences; judgment can be
acquired only by long experience; but if any of these qualities be
wanting, the labour of a life may be thrown away. I have been
astonished when celebrated breeders, whose skill and judgment have been
proved by their success at exhibitions, have shown me their animals,
which appeared all alike, and have assigned their reasons for matching
this and that individual. The importance of the great principle of
Selection mainly lies in this power of selecting scarcely appreciable
differences, which nevertheless are found to be transmissible, and
which can be accumulated until the result is made manifest to the eyes
of every beholder.
The principle of selection may be conveniently divided into three
kinds. _Methodical selection_ is that which guides a man who
systematically endeavours to modify a breed according to some
predetermined standard. _Unconscious selection_ is that which follows
from men naturally preserving the most valued and destroying the less
valued individuals, without any thought of altering the breed; and
undoubtedly this process slowly works great changes. Unconscious
selection graduates into methodical, and only extreme cases can be
distinctly separated; for he who preserves a useful or perfect animal
will generally breed from it with the hope of getting offspring of the
same character; but as long as he has not a predetermined purpose to
improve the breed, he may be said to be selecting unconsciously.[1]
Lastly, we have _Natural selection,_ which implies that the individuals
which are best fitted for the complex, and in the course of ages
changing conditions to which they are exposed, generally survive and
procreate their kind. With domestic productions, natural selection
comes to a certain extent into action, independently of, and even in
opposition to, the will of man.
_Methodical Selection._—What man has effected within recent times in
England by methodical selection is clearly shown by our exhibitions of
improved quadrupeds and fancy birds. With respect to cattle, sheep, and
pigs, we owe their great improvement to a long series of well-known
names—Bakewell, Coiling, Ellman, Bates, Jonas Webb, Lords Leicester and
Western, Fisher Hobbs, and others. Agricultural writers are unanimous
on the power of selection: any number of statements to this effect
could be quoted; a few will suffice. Youatt, a sagacious and
experienced observer, writes[2] the principle of selection is “that
which enables the agriculturist, not only to modify the character of
his flock, but to change it altogether.” A great breeder of
Shorthorns[3] says, “In the anatomy of the shoulder modern breeders
have made great improvement on the Ketton shorthorns by correcting the
defect in the knuckle or shoulder-joint, and by laying the top of the
shoulder more snugly in the crop, and thereby filling up the hollow
behind it . . . The eye has its fashion at different periods: at one
time the eye high and outstanding from the head, and at another time
the sleepy eye sunk into the head; but these extremes have merged into
the medium of a full, clear and prominent eye with a placid look.”
Again, hear what an excellent judge of pigs[4] says: “The legs should
be no longer than just to prevent the animal’s belly from trailing on
the ground. The leg is the least profitable portion of the hog, and we
therefore require no more of it than is absolutely necessary for the
support of the rest.” Let any one compare the wild-boar with any
improved breed, and he will see how effectually the legs have been
shortened.
Few persons, except breeders, are aware of the systematic care taken in
selecting animals, and of the necessity of having a clear and almost
prophetic vision into futurity. Lord Spencer’s skill and judgment were
well known; and he writes,[5] “It is therefore very desirable, before
any man commences to breed either cattle or sheep, that he should make
up his mind to the shape and qualities he wishes to obtain, and
steadily pursue this object.” Lord Somerville, in speaking of the
marvellous improvement of the New Leicester sheep, effected by Bakewell
and his successors, says, “It would seem as if they had first drawn a
perfect form, and then given it life.” Youatt[6] urges the necessity of
annually drafting each flock, as many animals will certainly degenerate
“from the standard of excellence which the breeder has established in
his own mind.” Even with a bird of such little importance as the
canary, long ago (1780-1790) rules were established, and a standard of
perfection was fixed according to which the London fanciers tried to
breed the several sub-varieties.[7] A great winner of prizes at the
Pigeon-shows,[8] in describing the short-faced Almond Tumbler, says,
“There are many first-rate fanciers who are particularly partial to
what is called the goldfinch-beak, which is very beautiful; others say,
take a full-size round cherry then take a barleycorn, and judiciously
placing and thrusting it into the cherry, form as it were your beak;
and that is not all, for it will form a good head and beak, provided,
as I said before, it is judiciously done; others take an oat; but as I
think the goldfinch-beak the handsomest, I would advise the
inexperienced fancier to get the head of a goldfinch, and keep it by
him for his observation.” Wonderfully different as are the beaks of the
rock pigeon and goldfinch, the end has undoubtedly been nearly gained,
as far as external shape and proportions are concerned.
Not only should our animals be examined with the greatest care whilst
alive, but, as Anderson remarks[9] their carcases should be
scrutinised, “so as to breed from the descendants of such only as, in
the language of the butcher, cut up well.” The “grain of the meat” in
cattle, and its being well marbled with fat,[10] and the greater or
less accumulation of fat in the abdomen of our sheep, have been
attended to with success. So with poultry, a writer,[11] speaking of
Cochin-China fowls, which are said to differ much in the quality of
their flesh, says, “the best mode is to purchase two young
brother-cocks, kill, dress, and serve up one; if he be indifferent,
similarly dispose of the other, and try again; if, however, he be fine
and well-flavoured, his brother will not be amiss for breeding purposes
for the table.”
The great principle of the division of labour has been brought to bear
on selection. In certain districts[12] “the breeding of bulls is
confined to a very limited number of persons, who by devoting their
whole attention to this department, are able from year to year to
furnish a class of bulls which are steadily improving the general breed
of the district.” The rearing and letting of choice rams has long been,
as is well known, a chief source of profit to several eminent breeders.
In parts of Germany this principle is carried with merino sheep to an
extreme point.[13] So “important is the proper selection of breeding
animals considered, that the best flock-masters do not trust to their
own judgment or to that of their shepherds, but employ persons called
‘sheep-classifiers’ who make it their special business to attend to
this part of the management of several flocks, and thus to preserve, or
if possible to improve, the best qualities of both parents in the
lambs.” In Saxony, “when the lambs are weaned, each in his turn is
placed upon a table that his wool and form may be minutely observed.
The finest are selected for breeding and receive a first mark. When
they are one year old, and prior to shearing them, another close
examination of those previously marked takes place: those in which no
defect can be found receive a second mark, and the rest are condemned.
A few months afterwards a third and last scrutiny is made; the prime
rams and ewes receive a third and final mark, but the slightest blemish
is sufficient to cause the rejection of the animal.” These sheep are
bred and valued almost exclusively for the fineness of their wool; and
the result corresponds with the labour bestowed on their selection.
Instruments have been invented to measure accurately the thickness of
the fibres; and “an Austrian fleece has been produced of which twelve
hairs equalled in thickness one from a Leicester sheep.”
Throughout the world, wherever silk is produced, the greatest care is
bestowed on selecting the cocoons from which the moths for breeding are
to be reared. A careful cultivator[14] likewise examines the moths
themselves, and destroys those that are not perfect. But what more
immediately concerns us is that certain families in France devote
themselves to raising eggs for sale.[15] In China, near Shanghai, the
inhabitants of two small districts have the privilege of raising eggs
for the whole surrounding country, and that they may give up their
whole time to this business, they are interdicted by law from producing
silk.[16]
The care which successful breeders take in matching their birds is
surprising. Sir John Sebright, whose fame is perpetuated by the
“Sebright Bantam,” used to spend “two and three days in examining,
consulting, and disputing with a friend which were the best of five or
six birds.”[17] Mr. Bult, whose pouter-pigeons won so many prizes, and
were exported to North America under the charge of a man sent on
purpose, told me that he always deliberated for several days before he
matched each pair. Hence we can understand the advice of an eminent
fancier, who writes[18] “I would here particularly guard you against
having too great a variety of pigeons, otherwise you will know a little
of all, but nothing about one as it ought to be known.” Apparently it
transcends the power of the human intellect to breed all kinds: “it is
possible that there may be a few fanciers that have a good general
knowledge of fancy pigeons; but there are many more who labour under
the delusion of supposing they know what they do not.” The excellence
of one sub-variety, the Almond Tumbler, lies in the plumage, carriage,
head, beak, and eye; but it is too presumptuous in the beginner to try
for all these points. The great judge above quoted says, “There are
some young fanciers who are over-covetous, who go for all the above
five properties at once; they have their reward by getting nothing.” We
thus see that breeding even fancy pigeons is no simple art: we may
smile at the solemnity of these precepts, but he who laughs will win no
prizes.
What methodical selection has effected for our animals is sufficiently
proved, as already remarked, by our Exhibitions. So greatly were the
sheep belonging to some of the earlier breeders, such as Bakewell and
Lord Western, changed, that many persons could not be persuaded that
they had not been crossed. Our pigs, as Mr. Corringham remarks[19]
during the last twenty years have undergone, through rigorous selection
together with crossing, a complete metamorphosis. The first exhibition
for poultry was held in the Zoological Gardens in 1845; and the
improvement effected since that time has been great. As Mr. Bailey, the
great judge, remarked to me, it was formerly ordered that the comb of
the Spanish cock should be upright, and in four or five years all good
birds had upright combs; it was ordered that the Polish cock should
have no comb or wattles, and now a bird thus furnished would be at once
disqualified; beards were ordered, and out of fifty-seven pens lately
(1860) exhibited at the Crystal Palace, all had beards. So it has been
in many other cases. But in all cases the judges order only what is
occasionally produced and what can be improved and rendered constant by
selection. The steady increase in weight during the last few years in
our fowls, turkeys, ducks, and geese is notorious; “six-pound ducks are
now common, whereas four pounds was formerly the average.” As the time
required to make a change has not often been recorded, it may be worth
mentioning that it took Mr. Wicking thirteen years to put a clean white
head on an almond tumbler’s body, “a triumph,” says another fancier,
“of which he may be justly proud.”[20]
Mr. Tollet, of Betley Hall, selected cows, and especially bulls,
descended from good milkers, for the sole purpose of improving his
cattle for the production of cheese; he steadily tested the milk with
the lactometer, and in eight years he increased, as I was informed by
him, the product in proportion of four to three. Here is a curious
case[21] of steady but slow progress, with the end not as yet fully
attained: in 1784 a race of silkworms was introduced into France, in
which one hundred in the thousand failed to produce white cocoons; but
now after careful selection during sixty-five generations, the
proportion of yellow cocoons has been reduced to thirty-five in the
thousand.
With plants selection has been followed with the same good result as
with animals. But the process is simpler, for plants in the great
majority of cases bear both sexes. Nevertheless, with most kinds it is
necessary to take as much care to prevent crosses as with animals or
unisexual plants; but with some plants, such as peas, this care is not
necessary. With all improved plants, excepting of course those which
are propagated by buds, cuttings, etc., it is almost indispensable to
examine the seedlings and destroy those which depart from the proper
type. This is called “roguing,” and is, in fact, a form of selection,
like the rejection of inferior animals. Experienced horticulturists and
agriculturists incessantly urge every one to preserve the finest plants
for the production of seed.
Although plants often present much more conspicuous variations than
animals, yet the closest attention is generally requisite to detect
each slight and favourable change. Mr. Masters relates[22] how “many a
patient hour was devoted,” whilst he was young, to the detection of
differences in peas intended for seed. Mr. Barnet[23] remarks that the
old scarlet American strawberry was cultivated for more than a century
without producing a single variety; and another writer observes how
singular it was that when gardeners first began to attend to this fruit
it began to vary; the truth no doubt being that it had always varied,
but that, until slight variations were selected and propagated by seed,
no conspicuous result was obtained. The finest shades of difference in
wheat have been discriminated and selected with almost as much care as,
in the case of the higher animals, for instance by Col. Le Couteur and
more especially by Major Hallett.
It may be worth while to give a few examples of methodical selection
with plants; but in fact the great improvement of all our anciently
cultivated plants may be attributed to selection long carried on, in
part methodically, and in part unconsciously. I have shown in a former
chapter how the weight of the gooseberry has been increased by
systematic selection and culture. The flowers of the Heartsease have
been similarly increased in size and regularity of outline. With the
Cineraria, Mr. Glenny[24] “was bold enough when the flowers were ragged
and starry and ill defined in colour, to fix a standard which was then
considered outrageously high and impossible, and which, even if
reached, it was said, we should be no gainers by, as it would spoil the
beauty of the flowers. He maintained that he was right; and the event
has proved it to be so.” The doubling of flowers has several times been
effected by careful selection: the Rev. W. Williamson,[25] after sowing
during several years seed of _Anemone coronaria,_ found a plant with
one additional petal; he sowed the seed of this, and by perseverance in
the same course obtained several varieties with six or seven rows of
petals. The single Scotch rose was doubled, and yielded eight good
varieties in nine or ten years.[26] The Canterbury bell (_Campanula
medium_) was doubled by careful selection in four generations.[27] In
four years Mr. Buckman,[28] by culture and careful selection, converted
parsnips, raised from wild seed, into a new and good variety. By
selection during a long course of years, the early maturity of peas has
been hastened by between ten and twenty-one days.[29] A more curious
case is offered by the beet plant, which since its cultivation in
France, has almost exactly doubled its yield of sugar. This has been
effected by the most careful selection; the specific gravity of the
roots being regularly tested, and the best roots saved for the
production of seed.[30]
_Selection by Ancient and Semi-civilised People._
In attributing so much importance to the selection of animals and
plants, it may be objected, that methodical selection would not have
been carried on during ancient times. A distinguished naturalist
considers it as absurd to suppose that semi-civilised people should
have practised selection of any kind. Undoubtedly the principle has
been systematically acknowledged and followed to a far greater extent
within the last hundred years than at any former period, and a
corresponding result has been gained; but it would be a greater error
to suppose, as we shall immediately see, that its importance was not
recognised and acted on during the most ancient times, and by
semi-civilised people. I should premise that many facts now to be given
only show that care was taken in breeding; but when this is the case,
selection is almost sure to be practised to a certain extent. We shall
hereafter be enabled better to judge how far selection, when only
occasionally carried on, by a few of the inhabitants of a country, will
slowly produce a great effect.
In a well-known passage in the thirtieth chapter of Genesis, rules are
given for influencing, as was then thought possible, the colour of
sheep; and speckled and dark breeds are spoken of as being kept
separate. By the time of David the fleece was likened to snow.
Youatt,[31] who has discussed all the passages in relation to breeding
in the Old Testament, concludes that at this early period “some of the
best principles of breeding must have been steadily and long pursued.”
It was ordered, according to Moses, that “Thou shalt not let thy cattle
gender with a diverse kind;” but mules were purchased[32] so that at
this early period other nations must have crossed the horse and ass. It
is said[33] that Erichthonius, some generations before the Trojan war,
had many brood-mares, “which by his care and judgment in the choice of
stallions produced a breed of horses superior to any in the surrounding
countries.” Homer (Book 5) speaks of Aeneas’ horses as bred from mares
which were put to the steeds of Laomedon. Plato, in his ‘Republic’ says
to Glaucus, “I see that you raise at your house a great many dogs for
the chase. Do you take care about breeding and pairing them? Among
animals of good blood, are there not always some which are superior to
the rest?” To which Glaucus answers in the affirmative.[34] Alexander
the Great selected the finest Indian cattle to send to Macedonia to
improve the breed.[35] According to Pliny,[36] King Pyrrhus had an
especially valuable breed of oxen: and he did not suffer the bulls and
cows to come together till four years old, that the breed might not
degenerate. Virgil, in his Georgics (lib. 3), gives as strong advice as
any modern agriculturist could do, carefully to select the breeding
stock; “to note the tribe, the lineage, and the sire; whom to reserve
for husband of the herd;”—to brand the progeny;—to select sheep of the
purest white, and to examine if their tongues are swarthy. We have seen
that the Romans kept pedigrees of their pigeons, and this would have
been a senseless proceeding had not great care been taken in breeding
them. Columella gives detailed instructions about breeding fowls: “Let
the breeding hens therefore be of a choice colour, a robust body,
square-built, full-breasted, with large heads, with upright and
bright-red combs. Those are believed to be the best bred which have
five toes.”[37] According to Tacitus, the Celts attended to the races
of their domestic animals; and Caesar states that they paid high prices
to merchants for fine imported horses.[38] In regard to plants, Virgil
speaks of yearly culling the largest seeds; and Celsus says, “where the
corn and crop is but small, we must pick out the best ears of corn, and
of them lay up our seed separately by itself.”[39]
Coming down the stream of time, we may be brief. At about the beginning
of the ninth century Charlemagne expressly ordered his officers to take
great care of his stallions; and if any proved bad or old, to forewarn
him in good time before they were put to the mares.[40] Even in a
country so little civilised as Ireland during the ninth century, it
would appear from some ancient verses,[41] describing a ransom demanded
by Cormac, that animals from particular places, or having a particular
character, were valued. Thus it is said,—
Two pigs of the pigs of Mac Lir,
A ram and ewe both round and red,
I brought with me from Aengus.
I brought with me a stallion and a mare
From the beautiful stud of Manannan,
A bull and a white cow from Druim Cain.
Athelstan, in 930, received running-horses as a present from Germany;
and he prohibited the exportation of English horses. King John imported
“one hundred chosen stallions from Flanders.”[42] On June 16th, 1305,
the Prince of Wales wrote to the Archbishop of Canterbury, begging for
the loan of any choice stallion, and promising its return at the end of
the season.[43] There are numerous records at ancient periods in
English history of the importation of choice animals of various kinds,
and of foolish laws against their exportation. In the reigns of Henry
VII. and VIII. it was ordered that the magistrates, at Michaelmas,
should scour the heaths and commons, and destroy all mares beneath a
certain size.[44] Some of our earlier kings passed laws against the
slaughtering rams of any good breed before they were seven years old,
so that they might have time to breed. In Spain Cardinal Ximenes
issued, in 1509, regulations on the _ selection_ of good rams for
breeding.[45]
The Emperor Akbar Khan before the year l600 is said to have
“wonderfully improved” his pigeons by crossing the breeds; and this
necessarily implies careful selection. About the same period the Dutch
attended with the greatest care to the breeding of these birds. Belon
in 1555 says that good managers in France examined the colour of their
goslings in order to get geese of a white colour and better kinds.
Markham in 1631 tells the breeder “to elect the largest and goodliest
conies,” and enters into minute details. Even with respect to seeds of
plants for the flower-garden, Sir J. Hanmer writing about the year
1660[46] says, in “choosing seed, the best seed is the most weighty,
and is had from the lustiest and most vigorous stems;” and he then
gives rules about leaving only a few flowers on plants for seed; so
that even such details were attended to in our flower-gardens two
hundred years ago. In order to show that selection has been silently
carried on in places where it would not have been expected, I may add
that in the middle of the last century, in a remote part of North
America, Mr. Cooper improved by careful selection all his vegetables,
“so that they were greatly superior to those of any other person. When
his radishes, for instance, are fit for use, he takes ten or twelve
that he most approves, and plants them at least 100 yards from others
that blossom at the same time. In the same manner he treats all his
other plants, varying the circumstances according to their nature.”[47]
In the great work on China published in the last century by the
Jesuits, and which is chiefly compiled from ancient Chinese
encyclopaedias, it is said that with sheep “improving the breed
consists in choosing with particular care the lambs which are destined
for propagation, in nourishing them well, and in keeping the flocks
separate.” The same principles were applied by the Chinese to various
plants and fruit-trees.[48] An imperial edict recommends the choice of
seed of remarkable size; and selection was practised even by imperial
hands, for it is said that the Ya-mi, or imperial rice, was noticed at
an ancient period in a field by the Emperor Khang-hi, was saved and
cultivated in his garden, and has since become valuable from being the
only kind which will grow north of the Great Wall.[49] Even with
flowers, the tree paeony (_P. moutan_) has been cultivated, according
to Chinese traditions, for 1400 years; between 200 and 300 varieties
have been raised, which are cherished like tulips formerly were by the
Dutch.[50]
Turning now to semi-civilised people and to savages: it occurred to me,
from what I had seen of several parts of South America, where fences do
not exist, and where the animals are of little value, that there would
be absolutely no care in breeding or selecting them; and this to a
large extent is true. Roulin,[51] however, describes in Columbia a
naked race of cattle, which are not allowed to increase, on account of
their delicate constitution. According to Azara[52] horses are often
born in Paraguay with curly hair; but, as the natives do not like them,
they are destroyed. On the other hand, Azara states that a hornless
bull, born in 1770, was preserved and propagated its race. I was
informed of the existence in Banda Oriental of a breed with reversed
hair; and the extraordinary niata cattle first appeared and have since
been kept distinct in La Plata. Hence certain conspicuous variations
have been preserved, and others have been habitually destroyed, in
these countries, which are so little favourable for careful selection.
We have also seen that the inhabitants sometimes introduce fresh cattle
on their estates to prevent the evil effects of close interbreeding. On
the other hand, I have heard on reliable authority that the Gauchos of
the Pampas never take any pains in selecting the best bulls or
stallions for breeding; and this probably accounts for the cattle and
horses being remarkably uniform in character throughout the immense
range of the Argentine republic.
Looking to the Old World, in the Sahara Desert “The Touareg is as
careful in the selection of his breeding Mahari (a fine race of the
dromedary) as the Arab is in that of his horse. The pedigrees are
handed down, and many a dromedary can boast a genealogy far longer than
the descendants of the Darley Arabian.”[53] According to Pallas the
Mongolians endeavour to breed the Yaks or horse-tailed buffaloes with
white tails, for these are sold to the Chinese mandarins as
fly-flappers; and Moorcroft, about seventy years after Pallas, found
that white-tailed animals were still selected for breeding.[54]
We have seen in the chapter on the Dog that savages in different parts
of North America and in Guiana cross their dogs with wild Canidæ, as
did the ancient Gauls, according to Pliny. This was done to give their
dogs strength and vigour, in the same way as the keepers in large
warrens now sometimes cross their ferrets (as I have been informed by
Mr. Yarrell) with the wild polecat, “to give them more devil.”
According to Varro, the wild ass was formerly caught and crossed with
the tame animal to improve the breed, in the same manner as at the
present day the natives of Java sometimes drive their cattle into the
forests to cross with the wild Banteng (_Bos sondaicus_).[55] In
Northern Siberia, among the Ostyaks, the dogs vary in markings in
different districts, but in each place they are spotted black and white
in a remarkably uniform manner;[56] and from this fact alone we may
infer careful breeding, more especially as the dogs of one locality are
famed throughout the country for their superiority. I have heard of
certain tribes of Esquimaux who take pride in their teams of dogs being
uniformly coloured. In Guiana, as Sir H. Schomburgk informs me,[57] the
dogs of the Turuma Indians are highly valued and extensively bartered:
the price of a good one is the same as that given for a wife: they are
kept in a sort of cage, and the Indians “take great care when the
female is in season to prevent her uniting with a dog of an inferior
description.” The Indians told Sir Robert that, if a dog proved bad or
useless, he was not killed, but was left to die from sheer neglect.
Hardly any nation is more barbarous than the Fuegians, but I hear from
Mr. Bridges, the Catechist to the Mission, that, “when these savages
have a large, strong, and active bitch, they take care to put her to a
fine dog, and even take care to feed her well, that her young may be
strong and well favoured.”
In the interior of Africa, negroes, who have not associated with white
men, show great anxiety to improve their animals; they “always choose
the larger and stronger males for stock;” the Malakolo were much
pleased at Livingstone’s promise to send them a bull, and some Bakalolo
carried a live cock all the way from Loanda into the interior.[58] At
Falaba Mr. Winwood Reade noticed an unusually fine horse, and the negro
King informed him that “the owner was noted for his skill in breeding
horses.” Further south on the same continent, Andersson states that he
has known a Damara give two fine oxen for a dog which struck his fancy.
The Damaras take great delight in having whole droves of cattle of the
same colour, and they prize their oxen in proportion to the size of
their horns. “The Namaquas have a perfect mania for a uniform team; and
almost all the people of Southern Africa value their cattle next to
their women, and take a pride in possessing animals that look
high-bred. They rarely or never make use of a handsome animal as a
beast of burden.”[59] The power of discrimination which these savages
possess is wonderful, and they can recognise to which tribe any cattle
belong. Mr. Andersson further informs me that the natives frequently
match a particular bull with a particular cow.
The most curious case of selection by semi-civilised people, or indeed
by any people, which I have found recorded, is that given by Garcilazo
de la Vega, a descendant of the Incas, as having been practised in Peru
before the country was subjugated by the Spaniards.[60] The Incas
annually held great hunts, when all the wild animals were driven from
an immense circuit to a central point. The beasts of prey were first
destroyed as injurious. The wild Guanacos and Vicunas were sheared; the
old males and females killed, and the others set at liberty. The
various kinds of deer were examined; the old males and females were
likewise killed, “but the young females, with a certain number of
males, selected from the most beautiful and strong,” were given their
freedom. Here, then, we have selection by man aiding natural selection.
So that the Incas followed exactly the reverse system of that which our
Scottish sportsman are accused of following, namely, of steadily
killing the finest stags, thus causing the whole race to
degenerate.[61] In regard to the domesticated llamas and alpacas, they
were separated in the time of the Incas according to colour: and if by
chance one in a flock was born of the wrong colour, it was eventually
put into another flock.
In the genus Auchenia there are four forms,—the Guanaco and Vicuna,
found wild and undoubtedly distinct species; the Llama and Alpaca,
known only in a domesticated condition. These four animals appear so
different, that most naturalists, especially those who have studied
these animals in their native country, maintain that they are
specifically distinct, notwithstanding that no one pretends to have
seen a wild llama or alpaca. Mr. Ledger, however, who has closely
studied these animals both in Peru and during their exportation to
Australia, and who has made many experiments on their propagation,
adduces arguments[62] which seem to me conclusive, that the llama is
the domesticated descendant of the guanaco, and the alpaca of the
vicuna. And now that we know that these animals were systematically
bred and selected many centuries ago, there is nothing surprising in
the great amount of change which they have undergone.
It appeared to me at one time probable that, though ancient and
semi-civilised people might have attended to the improvement of their
more useful animals in essential points, yet that they would have
disregarded unimportant characters. But human nature is the same
throughout the world: fashion everywhere reigns supreme, and man is apt
to value whatever he may chance to possess. We have seen that in South
America the niata cattle, which certainly are not made useful by their
shortened faces and upturned nostrils, have been preserved. The Damaras
of South Africa value their cattle for uniformity of colour and
enormously long horns. And I will now show that there is hardly any
peculiarity in our most useful animals which, from fashion,
superstition, or some other motive, has not been valued, and
consequently preserved. With respect to cattle, “an early record,”
according to Youatt[63] “speaks of a hundred white cows with red ears
being demanded as a compensation by the princes of North and South
Wales. If the cattle were of a dark or black colour, 150 were to be
presented.” So that colour was attended to in Wales before its
subjugation by England. In Central Africa, an ox that beats the ground
with its tail is killed; and in South Africa some of the Damaras will
not eat the flesh of a spotted ox. The Kaffirs value an animal with a
musical voice; and “at a sale in British Kaffraria the low of a heifer
excited so much admiration that a sharp competition sprung up for her
possession, and she realised a considerable price.”[64] With respect to
sheep, the Chinese prefer rams without horns; the Tartars prefer them
with spirally wound horns, because the hornless are thought to lose
courage.[65] Some of the Damaras will not eat the flesh of hornless
sheep. In regard to horses, at the end of the fifteenth century animals
of the colour described as liart pomme were most valued in France. The
Arabs have a proverb, “Never buy a horse with four white feet, for he
carries his shroud with him”;[66] the Arabs also, as we have seen,
despise dun-coloured horses. So with dogs, Xenophon and others at an
ancient period were prejudiced in favour of certain colours; and “white
or slate-coloured hunting dogs were not esteemed.”[67]
Turning to poultry, the old Roman gourmands thought that the liver of a
white goose was the most savoury. In Paraguay black-skinned fowls are
kept because they are thought to be more productive, and their flesh
the most proper for invalids.[68] In Guiana, as I am informed by Sir R.
Schomburgk, the aborigines will not eat the flesh or eggs of the fowl,
but two races are kept distinct merely for ornament. In the
Philippines, no less than nine sub-varieties of the game-cock are kept
and named, so that they must be separately bred.
At the present time in Europe, the smallest peculiarities are carefully
attended to in our most useful animals, either from fashion, or as a
mark of purity of blood. Many examples could be given; two will
suffice. “In the Western counties of England the prejudice against a
white pig is nearly as strong as against a black one in Yorkshire.” In
one of the Berkshire sub-breeds, it is said, “the white should be
confined to four white feet, a white spot between the eyes, and a few
white hairs behind each shoulder.” Mr. Saddler possessed “three hundred
pigs, every one of which was marked in this manner.”[69] Marshall,
towards the close of the last century, in speaking of a change in one
of the Yorkshire breeds of cattle, says the horns have been
considerably modified, as “a clean, small, sharp horn has been
_fashionable_ for the last twenty years.”[70] In a part of Germany the
cattle of the Race de Gfoehl are valued for many good qualities, but
they must have horns of a particular curvature and tint, so much so
that mechanical means are applied if they take a wrong direction; but
the inhabitants “consider it of the highest importance that the
nostrils of the bull should be flesh-coloured, and the eyelashes light;
this is an indispensable condition. A calf with blue nostrils would not
be purchased, or purchased at a very low price.”[71] Therefore let no
man say that any point or character is too trifling to be methodically
attended to and selected by breeders.
_Unconscious Selection._—By this term I mean, as already more than once
explained, the preservation by man of the most valued, and the
destruction of the least valued individuals, without any conscious
intention on his part of altering the breed. It is difficult to offer
direct proofs of the results which follow from this kind of selection;
but the indirect evidence is abundant. In fact, except that in the one
case man acts intentionally, and in the other unintentionally, there is
little difference between methodical and unconscious selection. In both
cases man preserves the animals which are most useful or pleasing to
him, and destroys or neglects the others. But no doubt a far more rapid
result follows from methodical than from unconscious selection. The
“roguing” of plants by gardeners, and the destruction by law in Henry
VIII.’s reign of all under-sized mares, are instances of a process the
reverse of selection in the ordinary sense of the word, but leading to
the same general result. The influence of the destruction of
individuals having a particular character is well shown by the
necessity of killing every lamb with a trace of black about it, in
order to keep the flock white; or again, by the effects on the average
height of the men of France of the destructive wars of Napoleon, by
which many tall men were killed, the short ones being left to be the
fathers of families. This at least is the conclusion of some of those
who have closely studied the effects of the conscription; and it is
certain that since Napoleon’s time the standard for the army has been
lowered two or three times.
Unconscious selection blends with methodical, so that it is scarcely
possible to separate them. When a fancier long ago first happened to
notice a pigeon with an unusually short beak, or one with the
tail-feathers unusually developed, although he bred from these birds
with the distinct intention of propagating the variety, yet he could
not have intended to make a short-faced tumbler or a fantail, and was
far from knowing that he had made the first step towards this end. If
he could have seen the final result, he would have been struck with
astonishment, but, from what we know of the habits of fanciers,
probably not with admiration. Our English carriers, barbs, and
short-faced tumblers have been greatly modified in the same manner, as
we may infer both from the historical evidence given in the chapters on
the Pigeon, and from the comparison of birds brought from distant
countries.
So it has been with dogs; our present fox-hounds differ from the old
English hound; our greyhounds have become lighter: the Scotch
deer-hound has been modified, and is now rare. Our bulldogs differ from
those which were formerly used for baiting bulls. Our pointers and
Newfoundlands do not closely resemble any native dog now found in the
countries whence they were brought. These changes have been effected
partly by crosses; but in every case the result has been governed by
the strictest selection. Nevertheless, there is no reason to suppose
that man intentionally and methodically made the breeds exactly what
they now are. As our horses became fleeter, and the country more
cultivated and smoother, fleeter fox-hounds were desired and produced,
but probably without any one distinctly foreseeing what they would
become. Our pointers and setters, the latter almost certainly descended
from large spaniels, have been greatly modified in accordance with
fashion and the desire for increased speed. Wolves have become extinct,
and so has the wolf-dog; deer have become rarer, bulls are no longer
baited, and the corresponding breeds of the dog have answered to the
change. But we may feel almost sure that when, for instance, bulls were
no longer baited, no man said to himself, I will now breed my dogs of
smaller size, and thus create the present race. As circumstances
changed, men unconsciously and slowly modified their course of
selection.
With racehorses selection for swiftness has been followed methodically,
and our horses now easily surpass their progenitors. The increased size
and different appearance of the English racehorse led a good observer
in India to ask, “Could any one in this year of 1856, looking at our
racehorses, conceive that they were the result of the union of the Arab
horse and the African mare?”[72] This change has, it is probable, been
largely effected through unconscious selection, that is, by the general
wish to breed as fine horses as possible in each generation, combined
with training and high feeding, but without any intention to give to
them their present appearance. According to Youatt,[73] the
introduction in Oliver Cromwell’s time of three celebrated Eastern
stallions speedily affected the English breed; “so that Lord Harleigh,
one of the old school, complained that the great horse was fast
disappearing.” This is an excellent proof how carefully selection must
have been attended to; for without such care, all traces of so small an
infusion of Eastern blood would soon have been absorbed and lost.
Notwithstanding that the climate of England has never been esteemed
particularly favourable to the horse, yet long-continued selection,
both methodical and unconscious, together with that practised by the
Arabs during a still longer and earlier period, has ended in giving us
the best breed of horses in the world. Macaulay[74] remarks, “Two men
whose authority on such subjects was held in great esteem, the Duke of
Newcastle and Sir John Fenwick, pronounced that the meanest hack ever
imported from Tangier would produce a finer progeny than could be
expected from the best sire of our native breed. They would not readily
have believed that a time would come when the princes and nobles of
neighbouring lands would be as eager to obtain horses from England as
ever the English had been to obtain horses from Barbary.”
The London dray-horse, which differs so much in appearance from any
natural species, and which from its size has so astonished many Eastern
princes, was probably formed by the heaviest and most powerful animals
having been selected during many generations in Flanders and England,
but without the least intention or expectation of creating a horse such
as we now see. If we go back to an early period of history, we behold
in the antique Greek statues, as Schaaffhausen has remarked,[75] a
horse equally unlike a race or dray horse, and differing from any
existing breed.
The results of unconscious selection, in an early stage, are well shown
in the difference between the flocks descended from the same stock, but
separately reared by careful breeders. Youatt gives an excellent
instance of this fact in the sheep belonging to Messrs. Buckley and
Burgess, which “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 flock has deviated in any one instance from the pure
blood of Mr. Bakewell’s flock; yet the difference between the sheep
possessed by these two gentlemen is so great, that they have the
appearance of being quite different varieties.”[76] I have seen several
analogous and well marked cases with pigeons: for instance, I had a
family of barbs descended from those long bred by Sir J. Sebright, and
another family long bred by another fancier, and the two families
plainly differed from each other. Nathusius—and a more competent
witness could not be cited—observes that, though the Shorthorns are
remarkably uniform in appearance (except in colour), yet the individual
character and wishes of each breeder become impressed on his cattle, so
that different herds differ slightly from one another.[77] The Hereford
cattle assumed their present well-marked character soon after the year
1769, through careful selection by Mr. Tomkins[78] and the breed has
lately split into two strains—one strain having a white face, and
differing slightly, it is said,[79] in some other points: but there is
no reason to believe that this split, the origin of which is unknown,
was intentionally made; it may with much more probability be attributed
to different breeders having attended to different points. So again,
the Berkshire breed of swine in the year 1810 had greatly changed from
what it was in 1780; and since 1810 at least two distinct sub-breeds
have arisen bearing the same name.[80] Keeping in mind how rapidly all
animals increase, and that some must be annually slaughtered and some
saved for breeding, then, if the same breeder during a long course of
years deliberately settles which shall be saved and which shall be
killed, it is almost inevitable that his individual turn of mind will
influence the character of his stock, without his having had any
intention to modify the breed.
Unconscious selection in the strictest sense of the word, that is, the
saving of the more useful animals and the neglect or slaughter of the
less useful, without any thought of the future, must have gone on
occasionally from the remotest period and amongst the most barbarous
nations. Savages often suffer from famines, and are sometimes expelled
by war from their own homes. In such cases it can hardly be doubted
that they would save their most useful animals. When the Fuegians are
hard pressed by want, they kill their old women for food rather than
their dogs; for, as we were assured, “old women no use—dogs catch
otters.” The same sound sense would surely lead them to preserve their
more useful dogs when still harder pressed by famine. Mr. Oldfield, who
has seen so much of the aborigines of Australia, informs me that “they
are all very glad to get a European kangaroo dog, and several instances
have been known of the father killing his own infant that the mother
might suckle the much-prized puppy.” Different kinds of dogs would be
useful to the Australian for hunting opossums and kangaroos, and to the
Fuegian for catching fish and otters; and the occasional preservation
in the two countries of the most useful animals would ultimately lead
to the formation of two widely distinct breeds.
With plants, from the earliest dawn of civilisation, the best variety
which was known would generally have been cultivated at each period and
its seeds occasionally sown; so that there will have been some
selection from an extremely remote period, but without any prefixed
standard of excellence or thought of the future. We at the present day
profit by a course of selection occasionally and unconsciously carried
on during thousands of years. This is proved in an interesting manner
by Oswald Heer’s researches on the lake-inhabitants of Switzerland, as
given in a former chapter; for he shows that the grain and seed of our
present varieties of wheat, barley, oats, peas, beans, lentils, and
poppy, exceed in size those which were cultivated in Switzerland during
the Neolithic and Bronze periods. These ancient people, during the
Neolithic period, possessed also a crab considerably larger than that
now growing wild on the Jura.[81] The pears described by Pliny were
evidently extremely inferior in quality to our present pears. We can
realise the effects of long-continued selection and cultivation in
another way, for would any one in his senses expect to raise a
first-rate apple from the seed of a truly wild crab, or a luscious
melting pear from the wild pear? Alphonse de Candolle informs me that
he has lately seen on an ancient mosaic at Rome a representation of the
melon; and as the Rotnans, who were such gourmands, are silent on this
fruit, he infers that the melon has been greatly ameliorated since the
classical period.
Coming to later times, Buffon[82] on comparing the flowers, fruit, and
vegetables which were then cultivated with some excellent drawings made
a hundred and fifty years previously, was struck with surprise at the
great improvement which had been effected; and remarks that these
ancient flowers and vegetables would now be rejected, not only by a
florist but by a village gardener. Since the time of Buffon the work of
improvement has steadily and rapidly gone on. Every florist who
compares our present flowers with those figured in books published not
long since, is astonished at the change. A well-known amateur,[83] in
speaking of the varieties of Pelargonium raised by Mr. Garth only
twenty-two years before, remarks, “What a rage they excited: surely we
had attained perfection, it was said; and now not one of the flowers of
those days will be looked at. But none the less is the debt of
gratitude which we owe to those who saw what was to be done, and did
it.” Mr. Paul, the well-known horticulturist, in writing of the same
flower,[84] says he remembers when young being delighted with the
portraits in Sweet’s work; “but what are they in point of beauty
compared with the Pelargoniums of this day? Here again nature did not
advance by leaps; the improvement was gradual, and if we had neglected
those very gradual advances, we must have foregone the present grand
results.” How well this practical horticulturist appreciates and
illustrates the gradual and accumulative force of selection! The Dahlia
has advanced in beauty in a like manner; the line of improvement being
guided by fashion, and by the successive modifications which the flower
slowly underwent.[85] A steady and gradual change has been noticed in
many other flowers: thus an old florist,[86] after describing the
leading varieties of the Pink which were grown in 1813 adds, “the pinks
of those days would now be scarcely grown as border-flowers.” The
improvement of so many flowers and the number of the varieties which
have been raised is all the more striking when we hear that the
earliest known flower-garden in Europe, namely at Padua, dates only
from the year 1545.[87]
_Effects of Selection, as shown by the parts most valued by man
presenting the greatest amount of difference._—The power of
long-continued selection, whether methodical or unconscious, or both
combined, is well shown in a general way, namely, by the comparison of
the differences between the varieties of distinct species, which are
valued for different parts, such as for the leaves, or stems, or
tubers, the seed, or fruit, or flowers. Whatever part man values most,
that part will be found to present the greatest amount of difference.
With trees cultivated for their fruit, Sageret remarks that the fruit
is larger than in the parent-species, whilst with those cultivated for
the seed, as with nuts, walnuts, almonds, chestnuts, etc., it is the
seed itself which is larger; and he accounts for this fact by the fruit
in the one case, and by the seed in the other, having been carefully
attended to and selected during many ages. Gallesio has made the same
observation. Godron insists on the diversity of the tuber in the
potato, of the bulb in the onion, and of the fruit in the melon; and on
the close similarity of the other parts in these same plants.[88]
In order to judge how far my own impression on this subject was
correct, I cultivated numerous varieties of the same species close to
one another. The comparison of the amount of difference between widely
different organs is necessarily vague; I will therefore give the
results in only a few cases. We have previously seen in the ninth
chapter how greatly the varieties of the cabbage differ in their
foliage and stems, which are the selected parts, and how closely they
resemble one another in their flowers, capsules, and seeds. In seven
varieties of the radish, the roots differed greatly in colour and
shape, but no difference whatever could be detected in their foliage,
flowers, or seeds. Now what a contrast is presented, if we compare the
flowers of the varieties of these two plants with those of any species
cultivated in our flower-gardens for ornament; or if we compare their
seeds with those of the varieties of maize, peas, beans, etc., which
are valued and cultivated for their seeds. In the ninth chapter it was
shown that the varieties of the pea differ but little except in the
tallness of the plant, moderately in the shape of the pod, and greatly
in the pea itself, and these are all selected points. The varieties,
however, of the _Pois sans parchemin_ differ much more in their pods,
and these are eaten and valued. I cultivated twelve varieties of the
common bean; one alone, the Dwarf Fan, differed considerably in general
appearance; two differed in the colour of their flowers, one being an
albino, and the other being wholly instead of partially purple; several
differed considerably in the shape and size of the pod, but far more in
the bean itself, and this is the valued and selected part. Toker’s
bean, for instance, is twice-and-a-half as long and broad as the
horse-bean, and is much thinner and of a different shape.
The varieties of the gooseberry, as formerly described, differ much in
their fruit, but hardly perceptibly in their flowers or organs of
vegetation. With the plum, the differences likewise appear to be
greater in the fruit than in the flowers or leaves. On the other hand,
the seed of the strawberry, which corresponds with the fruit of the
plum, differs hardly at all; whilst every one knows how greatly the
fruit—that is, the enlarged receptacle—differs in several varieties. In
apples, pears, and peaches the flowers and leaves differ considerably,
but not, as far as I can judge, in proportion with the fruit. The
Chinese double-flowering peaches, on the other hand, show that
varieties of this tree have been formed, which differ more in flower
than in fruit. If, as is highly probable, the peach is the modified
descent of the almond, a surprising amount of change has been effected
in the same species, in the fleshy covering of the former and in the
kernels of the latter.
When parts stand in close relationship to each other, such as the seed
and the fleshy covering of the fruit (whatever its homological nature
may be), changes in the one are usually accompanied by modifications in
the other, though not necessarily to the same degree. With the
plum-tree, for instance, some varieties produce plums which are nearly
alike, but include stones extremely dissimilar in shape; whilst
conversely other varieties produce dissimilar fruit with barely
distinguishable stones; and generally the stones, though they have
never been subjected to selection, differ greatly in the several
varieties of the plum. In other cases organs which are not manifestly
related, through some unknown bond vary together, and are consequently
liable, without any intention on man’s part, to be simultaneously acted
on by selection. Thus the varieties of the stock (Matthiola) have been
selected solely for the beauty of their flowers, but the seeds differ
greatly in colour and somewhat in size. Varieties of the lettuce have
been selected solely on account of their leaves, yet produce seeds
which likewise differ in colour. Generally, through the law of
correlation, when a variety differs greatly from its fellow-varieties
in any one character, it differs to a certain extent in several other
characters. I observed this fact when I cultivated together many
varieties of the same species, for I used first to make a list of the
varieties which differed most from each other in their foliage and
manner of growth, afterwards of those that differed most in their
flowers, then in their seed-capsules, and lastly in their mature seed;
and I found that the same names generally occurred in two, three, or
four of the successive lists. Nevertheless the greatest amount of
difference between the varieties was always exhibited, as far as I
could judge, by that part or organ for which the plant was cultivated.
When we bear in mind that each plant was at first cultivated because
useful to man, and that its variation was a subsequent, often a long
subsequent, event, we cannot explain the greater amount of diversity in
the valuable parts by supposing that species endowed with an especial
tendency to vary in any particular manner were originally chosen. We
must attribute the result to the variations in these parts having been
successively preserved, and thus continually augmented; whilst other
variations, excepting such as inevitably appeared through correlation,
were neglected and lost. We may therefore infer that most plants might
be made, through long-continued selection, to yield races as different
from one another in any character as they now are in those parts for
which they are valued and cultivated.
With animals we see nothing of the same kind; but a sufficient number
of species have not been domesticated for a fair comparison. Sheep are
valued for their wool, and the wool differs much more in the several
races than the hair in cattle. Neither sheep, goats, European cattle,
nor pigs are valued for their fleetness or strength; and we do not
possess breeds differing in these respects like the racehorse and
dray-horse. But fleetness and strength are valued in camels and dogs;
and we have with the former the swift dromedary and heavy camel; with
the latter the greyhound and mastiff. But dogs are valued even in a
higher degree for their mental qualities and senses; and every one
knows how greatly the races differ in these respects. On the other
hand, where the dog is kept solely to serve for food, as in the
Polynesian islands and China, it is described as an extremely stupid
animal.[89] Blumenbach remarks that “many dogs, such as the badger-dog,
have a build so marked and so appropriate for particular purposes, that
I should find it very difficult to persuade myself that this
astonishing figure was an accidental consequence of degeneration.”[90]
Had Blumenbach reflected on the great principle of selection, he would
not have used the term degeneration, and he would not have been
astonished that dogs and other animals should become excellently
adapted for the service of man.
On the whole we may conclude that whatever part or character is most
valued—whether the leaves, stems, tubers, bulbs, flowers, fruit, or
seed of plants, or the size, strength, fleetness, hairy covering, or
intellect of animals—that character will almost invariably be found to
present the greatest amount of difference both in kind and degree. And
this result may be safely attributed to man having preserved during a
long course of generations the variations which were useful to him, and
neglected the others.
I will conclude this chapter by some remarks on an important subject.
With animals such as the giraffe, of which the whole structure is
admirably co-ordinated for certain purposes, it has been supposed that
all the parts must have been simultaneously modified; and it has been
argued that, on the principle of natural selection, this is scarcely
possible. But in thus arguing, it has been tacitly assumed that the
variations must have been abrupt and great. No doubt, if the neck of a
ruminant were suddenly to become greatly elongated, the fore limbs and
back would have to be simultaneously strengthened and modified; but it
cannot be denied that an animal might have its neck, or head, or
tongue, or fore-limbs elongated a very little without any corresponding
modification in other parts of the body; and animals thus slightly
modified would, during a dearth, have a slight advantage, and be
enabled to browse on higher twigs, and thus survive. A few mouthfuls
more or less every day would make all the difference between life and
death. By the repetition of the same process, and by the occasional
intercrossing of the survivors, there would be some progress, slow and
fluctuating though it would be, towards the admirably coordinated
structure of the giraffe. If the short-faced tumbler-pigeon, with its
small conical beak, globular head, rounded body, short wings, and small
feet—characters which appear all in harmony—had been a natural species,
its whole structure would have been viewed as well fitted for its life;
but in this case we know that inexperienced breeders are urged to
attend to point after point, and not to attempt improving the whole
structure at the same time. Look at the greyhound, that perfect image
of grace, symmetry, and vigour; no natural species can boast of a more
admirably co-ordinated structure, with its tapering head, slim body,
deep chest, tucked-up abdomen, rat-like tail, and long muscular limbs,
all adapted for extreme fleetness, and for running down weak prey. Now,
from what we see of the variability of animals, and from what we know
of the method which different men follow in improving their stock—some
chiefly attending to one point, others to another point, others again
correcting defects by crosses, and so forth—we may feel assured that if
we could see the long line of ancestors of a first-rate greyhound up to
its wild wolf-like progenitor, we should behold an infinite number of
the finest gradations, sometimes in one character and sometimes in
another, but all leading towards our present perfect type. By small and
doubtful steps such as these, nature, as we may confidently believe,
has progressed, on her grand march of improvement and development.
A similar line of reasoning is as applicable to separate organs as to
the whole organisation. A writer[91] has recently maintained that “it
is probably no exaggeration to suppose that in order to improve such an
organ as the eye at all, it must be improved in ten different ways at
once. And the improbability of any complex organ being produced and
brought to perfection in any such way is an improbability of the same
kind and degree as that of producing a poem or a mathematical
demonstration by throwing letters at random on a table.” If the eye
were abruptly and greatly modified, no doubt many parts would have to
be simultaneously altered, in order that the organ should remain
serviceable.
But is this the case with smaller changes? There are persons who can
see distinctly only in a dull light, and this condition depends, I
believe, on the abnormal sensitiveness of the retina, and is known to
be inherited. Now if a bird, for instance, receive some great advantage
from seeing well in the twilight, all the individuals with the most
sensitive retina would succeed best and be the most likely to survive;
and why should not all those which happened to have the eye itself a
little larger, or the pupil capable of greater dilatation, be likewise
preserved, whether or not these modifications were strictly
simultaneous? These individuals would subsequently intercross and blend
their respective advantages. By such slight successive changes, the eye
of a diurnal bird would be brought into the condition of that of an
owl, which has often been advanced as an excellent instance of
adaptation. Short-sight, which is often inherited, permits a person to
see distinctly a minute object at so near a distance that it would be
indistinct to ordinary eyes; and here we have a capacity which might be
serviceable under certain conditions, abruptly gained. The Fuegians on
board the Beagle could certainly see distant objects more distinctly
than our sailors with all their long practice; I do not know whether
this depends upon sensitiveness or on the power of adjustment in the
focus; but this capacity for distant vision might, it is probable, be
slightly augmented by successive modifications of either kind.
Amphibious animals which are enabled to see both in the water and in
the air, require and possess, as M. Plateau has shown,[92] eyes
constructed on the following plan: “the cornea is always flat, or at
least much flattened in the front of the crystalline and over a space
equal to the diameter of that lens, whilst the lateral portions may be
much curved.” The crystalline is very nearly a sphere, and the humours
have nearly the same density as water. Now as a terrestrial animal
became more and more aquatic in its habits, very slight changes, first
in the curvature of the cornea or crystalline, and then in the density
of the humours, or conversely, might successively occur, and would be
advantageous to the animal whilst under water, without serious
detriment to its power of vision in the air. It is of course impossible
to conjecture by what steps the fundamental structure of the eye in the
Vertebrata was originally acquired, for we know nothing about this
organ in the first progenitors of the class. With respect to the lowest
animals in the scale, the transitional states through which the eye at
first probably passed, can by the aid of analogy be indicated, as I
have attempted to show in my ‘Origin of Species.’[93]
REFERENCES
[1] The term _unconscious selection_ has been objected to as a
contradiction; but _see_ some excellent observations on this head by
Prof. Huxley (‘Nat. Hist. Review,’ Oct. 1864, p. 578), who remarks
that when the wind heaps up sand-dunes it sifts and _unconsciously
selects_ from the gravel on the beach grains of sand of equal size.
[2] ‘On Sheep,’ 1838, p. 60.
[3] Mr. J. Wright on Shorthorn Cattle, in ‘Journal of Royal Agricult.
Soc.,’ vol. vii. pp. 208, 209.
[4] H. D. Richardson ‘On Pigs,’ 1847, p. 44.
[5] ‘Journal of Royal Agricult. Soc.,’ vol. i. p. 24.
[6] ‘On Sheep,’ pp. 520, 319.
[7] Loudon’s ‘Mag. of Nat. Hist.,’ vol. viii., 1835, p. 618.
[8] ‘A treatise on the Art of Breeding the Almond Tumbler.’ 1851. p.
9.
[9] ‘Recreations in Agriculture,’ vol. ii. p. 409.
[10] Youatt on Cattle, pp. 191, 227.
[11] Ferguson, ‘Prize Poultry,’ 1854, p. 208.
[12] Wilson, in ‘Transact. Highland Agricult. Soc.,’ quoted in
‘Gardener’s Chronicle,’ 1844, p. 29.
[13] Simmonds, quoted in ‘Gardener’s Chronicle,’ 1855, p. 637. And for
the second quotation, _see_ Youatt on Sheep, p. 171.
[14] Robinet, ‘Vers à Soie,’ 1848, p. 271.
[15] Quatrefages, ‘Les Maladies du Ver à Soie,’ 1859, p. 101.
[16] M. Simon, in ‘Bull. de la Soc. d’Acclimat.,’ tom. ix., 1862, p.
221.
[17] ‘The Poultry Chronicle,’ vol. i., 1854, p. 607.
[18] J. M. Eaton, ‘A Treatise on Fancy Pigeons,’ 1852, p. xiv., and ‘A
Treatise on the Almond Tumbler,’ 1851, p. 11.
[19] ‘Journal Royal Agricultural Soc.,’ vol. vi., p. 22.
[20] ‘Poultry Chronicle,’ vol. ii., 1855, p. 596.
[21] Isid. Geoffroy St.-Hilaire, ‘Hist. Nat. Gén.,’ tom. iii. p. 254.
[22] ‘Gardener’s Chronicle,’ 1850, p. 198.
[23] ‘Transact. Hort. Soc.,’ vol. vi. p. 152.
[24] ‘Journal of Horticulture,’ 1862, p. 369.
[25] ‘Transact. Hort. Soc.,’ vol. iv. p. 381.
[26] ‘Transact. Hort. Soc.,’ vol. iv. p. 285.
[27] Rev. W. Bromehead, in ‘Gardener’s Chronicle,’ 1857, p. 550.
[28] ‘Gardener’s Chronicle,’ 1862, p. 721.
29[] Dr. Anderson, in ‘The Bee,’ vol. vi. p. 96; Mr. Barnes in
‘Gardener’s Chronicle,’ 1844, p. 476.
[30] Godron, ‘De l’Espèce,’ 1859, tom. ii. p. 69; ‘Gardener’s
Chronicle,’ 1854, p. 258.
[31] On Sheep, p. 18.
[32] Volz, ‘Beiträge zur Kulturgeschichte,’ 1852, s. 47.
[33] Mitford’s ‘History of Greece,’ vol. i. p. 73.
[34] Dr. Dally, translated in ‘Anthropological Review,’ May 1864, p.
101.
[35] Volz, ‘Beiträge,’ etc., 1852, s. 80.
[36] ‘History of the World,’ ch. 45.
[37] ‘Gardener’s Chronicle,’ 1848, p. 323.
[38] Reynier, ‘De l’Économie des Celtes,’ 1818, pp. 487, 503.
[39] Le Couteur on Wheat, p. 15.
[40] Michel, ‘Des Haras,’ 1861, p. 84.
[41] Sir W. Wilde, an ‘Essay on Unmanufactured Animal Remains,’ etc.,
1860, p. 11.
[42] Col. Hamilton Smith, ‘Nat. Library,’ vol. xii., Horses, pp. 135,
140.
[43] Michel, ‘Des Haras,’ p. 90.
[44] Mr. Baker, ‘History of the Horse,’ ‘Veterinary,’ vol. xiii. p.
423.
[45] M. l’Abbé Carlier, in ‘Journal de Physique,’ vol. xxiv., 1784, p.
181; this memoir contains much information on the ancient selection of
sheep; and is my authority for rams not being killed young in England.
[46] ‘Gardener’s Chronicle,’ 1843, p. 389.
[47] ‘Communications to Board of Agriculture’ quoted in Dr. Darwin’s
‘Phytologia,’ 1800, p. 451.
[48] ‘Mémoire sur les Chinois,’ 1786, tom. xi. p. 55; tom. v. p. 507.
[49] ‘Recherches sur l’Agriculture des Chinois,’ par L. D’Hervey
Saint-Denys, 1850, p. 229. With respect to Khang-hi _see_ Huc’s
‘Chinese Empire,’ p. 311.
[50] Anderson, in ‘Linn. Transact.,’ vol. xii. p. 253.
[51] ‘Mém. de l’Acad.’ (divers savants), tom. vi., 1835, p. 333.
[52] ‘Des Quadrupèdes du Paraguay,’ 1801, tom. ii. pp. 333, 371.
[53] ‘The Great Sahara,’ by the Rev. H. B. Tristram, 1860, p. 238.
[54] Pallas, ‘Act. Acad. St. Petersburg,’ 1777, p. 249; Moorcroft and
Trebeck, ‘Travels in the Himalayan Provinces,’ 1841.
[55] Quoted from Raffles, in the ‘Indian Field,’ 1859, p. 196: for
Varro, _see_ Pallas _ut supra._
[56] Erman’s ‘Travels in Siberia,’ Eng. translat., vol. i. p. 453.
[57] _See also_ ‘Journal of R. Geograph. Soc.,’ vol. xiii. part i. p.
65.
[58] Livingstone’s ‘First Travels,’ pp. 191, 439, 565; _see also_
‘Expedition to the Zambesi,’ 1865, p. 495, for an analogous case
respecting a good breed of goats.
[59] Andersson’s ‘Travels in South Africa,’ pp. 232, 318, 319.
[60] Dr. Vavasseur, in ‘Bull. de La Soc. d’Acclimat.,’ tom. viii.
1861, p. 136.
[61] ‘The Natural History of Dee Side,’ 1855, p. 476.
[62] ‘Bull. de la Soc. d’Acclimat.,’ tom. vii. 1860, p. 457.
[63] ‘Cattle,’ p. 48.
[64] Livingstone’s Travels, p. 576; Andersson, ‘Lake Ngami,’ 1856, p.
222. With respect to the sale in Kaffraria, _see_ ‘Quarterly Review,’
1860, p. 139.
[65] ‘Mémoire sur les Chinois’ (by the Jesuits), 1786, tom. xi. p. 57.
[66] F. Michel, ‘Des Haras,’ pp. 47, 50.
[67] Col. Hamilton Smith, Dogs, in ‘Nat. Lib.,’ vol. x. p. 103.
[68] Azara, ‘Quadrupèdes du Paraguay,’ tom. ii. p. 324.
[69] Sidney’s edit. of Youatt, 1860, pp. 24, 25.
[70] ‘Rural Economy of Yorkshire,’ vol. ii. p. 182.
[71] Moll et Gayot, ‘Du Boeuf,’ 1860, p. 547.
[72] ‘The India Sporting Review,’ vol. ii. p. 181; ‘The Stud Farm,’ by
Cecil, p. 58.
[73] ‘The Horse,’ p. 22.
[74] ‘History of England,’ vol. i. p. 316.
[75] ‘Ueber Beständigkeit der Arten.’
[76] Youatt on Sheep, p. 315.
[77] ‘Ueber Shorthorn Rindvieh,’ 1857, s. 51.
[78] Low, ‘Domesticated Animals,’ 1845, p. 363.
[79] ‘Quarterly Review,’ 1849, p. 392.
[80] H. von Nathusius, ‘Vorstudien . . . Schweineschädel,’ 1864, s
140.
[81] _See also_ Dr. Christ, in Rütimeyer’s ‘Pfahlbauten,’ 1861, s.
226.
[82] The passage is given, ‘Bull. Soc. d’Acclimat.,’ 1858, p. 11.
[83] ‘Journal of Horticulture,’ 1862, p. 394.
[84] ‘Gardener’s Chronicle,’ 1857, p. 85.
[85] _See_ Mr. Wildman’s address to the Floricult. Soc. in ‘Gardener’s
Chronicle,’ 1843, p. 86.
[86] ‘Journal of Horticulture,’ Oct. 24th, 1865, p. 239.
[87] Prescott’s ‘Hist. of Mexico,’ vol. ii. p. 61.
[88] Sagaret, ‘Pomologie Physiologique,’ 1830, p. 47; Gallesio,
‘Teoria della Riproduzione,’ 1816, p. 88; Godron, ‘De l’Espèce,’ 1859,
tom. 2 pp. 63, 67, 70. In my tenth and eleventh chapters I have given
details on the potato; and I can confirm similar remarks with respect
to the onion. I have also shown how far Naudin concurs in regard to
the varieties of the melon.
[89] Godron, ‘De l’Espèce,’ tom. ii. p. 27.
[90] ‘The Anthropological Treatises of Blumenbach,’ 1856, p. 292.
[91] Mr. J. J. Murphy, in his opening address to the Belfast Nat.
Hist. Soc., as given in the ‘Belfast Northern Whig,’ Nov. 19th, 1866.
Mr. Murphy here follows the line of argument against my views
previously and more cautiously given by the Rev. C. Pritchard, Pres.
Royal Astronomical Soc., in his sermon (Appendix, p. 33) preached
before the British Association at Nottingham, 1866.
[92] On the Vision of Fishes and Amphibia, translated in ‘Annals and
Mag. of Nat. Hist.,’ vol. xviii., 1866, p. 469.
[93] Sixth edition, 1872, p. 144.