SELECTION BY MAN.
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. (20/1. 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'
October 1864 page 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.) 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 (20/2. 'On Sheep' 1838 page 60.) 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 (20/3. Mr. J. Wright on Shorthorn Cattle in 'Journal of Royal
Agricult. Soc.' volume 7 pages 208, 209.) 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 (20/4. H.D. Richardson 'On Pigs'
1847 page 44.) 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 (20/5. 'Journal of Royal Agricult. Soc.' volume 1 page 24.), "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 (20/6. 'On Sheep' pages 520, 319.) 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. (20/7. Loudon's 'Mag. of Nat. Hist.' volume 8 1835 page 618.) A
great winner of prizes at the Pigeon-shows (20/8. 'A treatise on the Art of
Breeding the Almond Tumbler' 1851 page 9.), 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 (20/9. 'Recreations in Agriculture' volume 2 page
409.) 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 (20/10.
'Youatt on Cattle' pages 191, 227.), 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 (20/11. Ferguson 'Prize Poultry' 1854 page 208.), 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 (20/12. Wilson in 'Transact. Highland
Agricult. Soc.' quoted in 'Gardener's Chronicle' 1844 page 29.) "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.
(20/13. Simmonds quoted in 'Gardener's Chronicle' 1855 page 637. And for the
second quotation see 'Youatt on Sheep' page 171.) 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 (20/14. Robinet 'Vers a Soie' 1848 page 271.) 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. (20/15. Quatrefages 'Les Maladies du Ver
a Soie' 1859 page 101.) 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. (20/16. M. Simon in 'Bull. de la Soc.
d'Acclimat.' tome 9 1862 page 221.)
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." (20/17. 'The Poultry
Chronicle' volume 1 1854 page 607.) 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 (20/18. J.M. Eaton 'A Treatise on Fancy Pigeons' 1852 page 14 and 'A
Treatise on the Almond Tumbler' 1851 page 11.) "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 (20/19. 'Journal Royal Agricultural Soc.'
volume 6 page 22.) 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." (20/20. 'Poultry Chronicle' volume 2 1855 page 596.)
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 (20/21. Isid. Geoffroy St.-Hilaire
'Hist. Nat. Gen.' tome 3 page 254.) 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 (20/22. 'Gardener's Chronicle' 1850
page 198.) how "many a patient hour was devoted," whilst he was young, to the
detection of differences in peas intended for seed. Mr. Barnet (20/23.
'Transact. Hort. Soc.' volume 6 page 152.) 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 (20/24. 'Journal of Horticulture'
1862 page 369.) "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 (20/25 'Transact. Hort. Soc.' volume 4 page 381.), 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. (20/26. 'Transact. Hort. Soc.' volume 4 page 285.) The Canterbury bell
(Campanula medium) was doubled by careful selection in four generations.
(20/27. Rev. W. Bromehead in 'Gardener's Chronicle' 1857 page 550.) In four
years Mr. Buckman (20/28. 'Gardener's Chronicle' 1862 page 721.), 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. (20/29.
Dr. Anderson in 'The Bee' volume 6 page 96; Mr. Barnes in 'Gardener's
Chronicle' 1844 page 476.) 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. (20/30. Godron 'De l'Espece' 1859 tome 2 page 69;
'Gardener's Chronicle' 1854 page 258.)
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 (20/31. 'On Sheep' page 18.), 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 (20/32. Volz 'Beitrage zur Kulturgeschichte' 1852 s. 47.) so
that at this early period other nations must have crossed the horse and ass.
It is said (20/33. Mitford 'History of Greece' volume 1 page 73.) 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. (20/34.
Dr. Dally translated in 'Anthropological Review' May 1864 page 101.) Alexander
the Great selected the finest Indian cattle to send to Macedonia to improve
the breed. (20/35. Volz 'Beitrage' etc. 1852 s. 80.) According to Pliny (20/36
'History of the World' chapter 45.), 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." (20/37. 'Gardener's
Chronicle' 1848 page 323.) 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. (20/38. Reynier 'De l'Economie des
Celtes' 1818 pages 487, 503.) 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." (20/39. Le Couteur on 'Wheat' page 15.)
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. (20/40. Michel 'Des Haras' 1861 page 84.)
Even in a country so little civilised as Ireland during the ninth century, it
would appear from some ancient verses (20/41. Sir W. Wilde an 'Essay on
Unmanufactured Animal Remains' etc. 1860 page 11.), 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." (20/42. Col. Hamilton Smith 'Nat. Library'
volume 12 Horses, pages 135, 140.) 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. (20/43. Michel
'Des Haras' page 90.) 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. (20/44. Mr. Baker
'History of the Horse' 'Veterinary' volume 13 page 423.) 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. (20/45. M. l'Abbe Carlier in 'Journal de Physique' volume 24 1784
page 181; this memoir contains much information on the ancient selection of
sheep; and is my authority for rams not being killed young in England.)
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 (20/46. 'Gardener's Chronicle' 1843 page 389.) 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." (20/47. 'Communications to Board of Agriculture'
quoted in Dr. Darwin 'Phytologia' 1800 page 451.)
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. (20/48. 'Memoire sur les Chinois' 1786 tome
11 page 55; tome 5 page 507.) 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. (20/49. 'Recherches sur l'Agriculture des Chinois' par L.
D'Hervey Saint-Denys 1850 page 229. With respect to Khang-hi see Huc's
'Chinese Empire' page 311.) 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. (20/50. Anderson in 'Linn. Transact.' volume 12 page 253.)
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
(20/51. 'Mem. de l'Acad.' (divers savants), tome 6 1835 page 333.), however,
describes in Columbia a naked race of cattle, which are not allowed to
increase, on account of their delicate constitution. According to Azara
(20/52. 'Des Quadrupedes du Paraguay' 1801 tome 2 pages 333, 371.) 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." (20/53. 'The Great Sahara' by the Rev. H.B. Tristram 1860 page 238.)
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. (20/54. Pallas 'Act.
Acad. St. Petersburg' 1777 page 249. Moorcroft and Trebeck 'Travels in the
Himalayan Provinces' 1841.)
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 Canidae, 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).
(20/55. Quoted from Raffles in the 'Indian Field' 1859 page 196: for Varro see
Pallas ut supra.) 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 (20/56. Erman 'Travels in Siberia'
English translation volume 1 page 453.); 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 (20/57. See also 'Journal of R.
Geograph. Soc.' volume 13 part 1 page 65.), 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. (20/58. Livingstone 'First Travels' pages 191,
439, 565; see also 'Expedition to the Zambesi' 1865 page 495, for an analogous
case respecting a good breed of goats.) 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." (20/59.
Andersson 'Travels in South Africa' pages 232, 318, 319.) 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. (20/60. Dr. Vavasseur in 'Bull. de La Soc.
d'Acclimat.' tome 8 1861 page 136.) 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. (20/61. 'The Natural History of Dee
Side' 1855 page 476.) 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 (20/62. 'Bull. de la Soc. d'Acclimat.' tome 7 1860 page 457.) 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 (20/63. 'Cattle'
page 48.) "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." (20/64. Livingstone
'Travels' page 576; Andersson 'Lake Ngami' 1856 page 222. With respect to the
sale in Kaffraria see 'Quarterly Review' 1860 page 139.) 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.
(20/65. 'Memoire sur les Chinois' by the Jesuits 1786 tome 11 page 57.) 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" (20/66. F. Michel
'Des Haras' pages 47, 50.); 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." (20/67. Col. Hamilton Smith 'Dogs' in 'Nat. Lib.'
volume 10 page 103.)
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. (20/68. Azara 'Quadrupedes du Paraguay' tome 2 page 324.) 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." (20/69. Sidney's edition of Youatt 1860 pages 24, 25.) 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."
(20/70. 'Rural Economy of Yorkshire' volume 2 page 182.) 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." (20/71. Moll et Gayot 'Du Boeuf' 1860 page 547.) 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?" (20/72. 'The India Sporting Review' volume 2 page 181; 'The Stud Farm'
by Cecil page 58.) 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 (20/73. 'The Horse' page 22.), 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 (20/74. 'History of England' volume 1 page 316.)
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 (20/75. 'Ueber Bestandigkeit der Arten.'), 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." (20/76. 'Youatt on Sheep' page 315.) 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. (20/77. 'Ueber Shorthorn Rindvieh' 1857 s. 51.) The
Hereford cattle assumed their present well-marked character soon after the
year 1769, through careful selection by Mr. Tomkins (20/78. Low 'Domesticated
Animals' 1845 page 363.) and the breed has lately split into two strains--one
strain having a white face, and differing slightly, it is said (20/79.
'Quarterly Review' 1849 page 392.), 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. (20/80. H. von Nathusius 'Vorstudien...Schweineschadel' 1864 s
140.) 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. (20/81. See also Dr. Christ in Rutimeyer's
'Pfahlbauten' 1861 s. 226.) 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 (20/82. The passage is given 'Bull. Soc.
d'Acclimat.' 1858 page 11.) 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
(20/83. 'Journal of Horticulture' 1862 page 394.), 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 (20/84. 'Gardener's Chronicle' 1857 page 85.), 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. (20/85. See
Mr. Wildman's address to the Floricult. Soc. in 'Gardener's Chronicle' 1843
page 86.) A steady and gradual change has been noticed in many other flowers:
thus an old florist (20/86. 'Journal of Horticulture' October 24, 1865 page
239.), 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.
(20/87. Prescott 'Hist. of Mexico' volume 2 page 61.)
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. (20/88. Sagaret
'Pomologie Physiologique' 1830 page 47; Gallesio 'Teoria della Riproduzione'
1816 page 88; Godron 'De l'Espece' 1859 tome 2 pages 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.)
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. (20/89. Godron 'De
l'Espece' tome 2 page 27.) 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." (20/90. 'The
Anthropological Treatises of Blumenbach' 1856 page 292.) 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 (20/91. Mr. J.J. Murphy in his opening address to
the Belfast Nat. Hist. Soc. as given in the 'Belfast Northern Whig' November
19, 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 page 33 preached before the British
Association at Nottingham 1866.) 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 (20/92. On the Vision of Fishes and Amphibia,
translated in 'Annals and Mag. of Nat. Hist.' volume 18 1866 page 469.), 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.' (20/93. Sixth edition 1872 page 144.)