The Foundations of the Origin of Species Two Essays written in 1842 and 1844 · Charles Darwin
PART I.
Sec. I. <ON VARIATION UNDER DOMESTICATION, AND ON THE PRINCIPLES OF SELECTION.> An individual organism placed under new conditions [often] sometimes varies in a small degree and in very trifling respects such as stature, fatness, sometimes colour, health, habits in animals and probably disposition. Also habits of life develope certain parts. Disuse atrophies. [Most of these slight variations tend to become hereditary.] When the individual is multiplied for long periods by buds the variation is yet small, though greater and occasionally a single bud or individual departs widely from its type (example){36} and continues steadily to propagate, by buds, such new kind. {36} Evidently a memorandum that an example should be given. When the organism is bred for several generations under new or varying conditions, the variation is greater in amount and endless in kind [especially{37} holds good when individuals have long been exposed to new conditions]. The nature of the external conditions tends to effect some definite change in all or greater part of offspring,--little food, small size--certain foods harmless &c. &c. organs affected and diseases--extent unknown. A certain degree of variation (Mueller's twins){38} seems inevitable effect of process of reproduction. But more important is that simple <?> generation, especially under new conditions [when no crossing] <causes> infinite variation and not direct effect of external conditions, but only in as much as it affects the reproductive functions{39}. There seems to be no part (_beau ideal_ of liver){40} of body, internal or external, or mind or habits, or instincts which does not vary in some small degree and [often] some <?> to a great amount.
Therefore if in any country or district all animals of one species be allowed freely to cross, any small tendency in them to vary will be constantly counteracted. Secondly reversion to parent form--analogue of _vis medicatrix_{44}. But if man selects, then new races rapidly formed,--of late years systematically followed,--in most ancient times often practically followed{45}. By such selection make race-horse, dray-horse--one cow good for tallow, another for eating &c.--one plant's good lay <illegible> in leaves another in fruit &c. &c.: the same plant to supply his wants at different times of year. By former means animals become adapted, as a direct effect to a cause, to external conditions, as size of body to amount of food. By this latter means they may also be so adapted, but further they may be adapted to ends and pursuits, which by no possibility can affect growth, as existence of tallow-chandler cannot tend to make fat. In such selected races, if not removed to new conditions, and <if> preserved from all cross, after several generations become very true, like each other and not varying. But man{46} selects only <?> what is useful and curious--has bad judgment, is capricious,--grudges to destroy those that do not come up to his pattern,--has no [knowledge] power of selecting according to internal variations,--can hardly keep his conditions uniform,--[cannot] does not select those best adapted to the conditions under which <the> form <?> lives, but those most useful to him. This might all be otherwise.
Our experience would lead us to expect that any and every one of these organisms would vary if <the organism were> taken away <?> and placed under new conditions. Geology proclaims a constant round of change, bringing into play, by every possible <?> change of climate and the death of pre-existing inhabitants, endless variations of new conditions. These <?> generally very slow, doubtful though <illegible> how far the slowness <?> would produce tendency to vary. But Geolog<ists> show change in configuration which, together with the accidents of air and water and the means of transportal which every being possesses, must occasionally bring, rather suddenly, organism to new conditions and <?> expose it for several generations. Hence <?> we should expect every now and then a wild form to vary{49}; possibly this may be cause of some species varying more than others. {49} When the author wrote this sketch he seems not to have been so fully convinced of the general occurrence of variation in nature as he afterwards became. The above passage in the text possibly suggests that at this time he laid more stress on _sports_ or _mutations_ than was afterwards the case.
According to nature of new conditions, so we might expect all or majority of organisms born under them to vary in some definite way. Further we might expect that the mould in which they are cast would likewise vary in some small degree. But is there any means of selecting those offspring which vary in the same manner, crossing them and keeping their offspring separate and thus producing selected races: otherwise as the wild animals freely cross, so must such small heterogeneous varieties be constantly counter-balanced and lost, and a uniformity of character [kept up] preserved. The former variation as the direct and necessary effects of causes, which we can see can act on them, as size of body from amount of food, effect of certain kinds of food on certain parts of bodies &c. &c.; such new varieties may then become adapted to those external [natural] agencies which act on them. But can varieties be produced adapted to end, which cannot possibly influence their structure and which it is absurd to look <at> as effects of chance.
Can varieties like some vars of domesticated animals, like almost all wild species be produced adapted by exquisite means to prey on one animal or to escape from another,--or rather, as it puts out of question effects of intelligence and habits, can a plant become adapted to animals, as a plant which cannot be impregnated without agency of insect; or hooked seeds depending on animal's existence: woolly animals cannot have any direct effect on seeds of plant. This point which all theories about climate adapting woodpecker{50} to crawl <?> up trees, <illegible> miseltoe, <sentence incomplete>. But if every part of a plant or animal was to vary <illegible>, and if a being infinitely more sagacious than man (not an omniscient creator) during thousands and thousands of years were to select all the variations which tended towards certain ends ([or were to produce causes <?> which tended to the same end]), for instance, if he foresaw a canine animal would be better off, owing to the country producing more hares, if he were longer legged and keener sight,--greyhound produced{51}. If he saw that aquatic <animal would need> skinned toes.
If for some unknown cause he found it would advantage a plant, which <?> like most plants is occasionally visited by bees &c.: if that plant's seed were occasionally eaten by birds and were then carried on to rotten trees, he might select trees with fruit more agreeable to such birds as perched, to ensure their being carried to trees; if he perceived those birds more often dropped the seeds, he might well have selected a bird who would <illegible> rotten trees or [gradually select plants which <he> had proved to live on less and less rotten trees]. Who, seeing how plants vary in garden, what blind foolish man has done{52} in a few years, will deny an all-seeing being in thousands of years could effect (if the Creator chose to do so), either by his own direct foresight or by intermediate means,--which will represent <?> the creator of this universe. Seems usual means. Be it remembered I have nothing to say about life and mind and _all_ forms descending from one common type{53}. I speak of the variation of the existing great divisions of the organised kingdom, how far I would go, hereafter to be seen. {50} The author may possibly have taken the case of the woodpecker from Buffon, _Histoire Nat. des Oiseaux_, T. vii. p. 3, 1780, where however it is treated from a different point of view. He uses it more than once, see for instance _Origin_, Ed. i. pp. 3, 60, 184, vi. pp. 3, 76, 220. The passage in the text corresponds with a discussion on the woodpecker and the mistletoe in _Origin_, Ed. i. p. 3, vi. p. 3.
The unavoidable effect of this <is> that many of every species are destroyed either in egg or [young or mature (the former state the more common)]. In the course of a thousand generations infinitesimally small differences must inevitably tell{59}; when unusually cold winter, or hot or dry summer comes, then out of the whole body of individuals of any species, if there be the smallest differences in their structure, habits, instincts [senses], health &c, <it> will on an average tell; as conditions change a rather larger proportion will be preserved: so if the chief check to increase falls on seeds or eggs, so will, in the course of 1000 generations or ten thousand, those seeds (like one with down to fly{60}) which fly furthest and get scattered most ultimately rear most plants, and such small differences tend to be hereditary like shades of expression in human countenance. So if one parent <?> fish deposits its egg in infinitesimally different circumstances, as in rather shallower or deeper water &c., it will then <?> tell. {59} In a rough summary at the close of the Essay, occur the words:--"Every creature lives by a struggle, smallest grain in balance must tell." {60} Cf. _Origin_, Ed. i. p. 77, vi. p. 94. Let hares{61} increase very slowly from change of climate affecting peculiar plants, and some other <illegible> rabbit decrease in same proportion [let this unsettle organisation of], a canine animal, who formerly derived its chief sustenance by springing on rabbits or running them by scent, must decrease too and might thus readily become exterminated. But if its form varied very slightly, the long legged fleet ones, during a thousand years being selected, and the less fleet rigidly destroyed must, if no law of nature be opposed to it, alter forms.
Besides selection by death, in bisexual animals <illegible> the selection in time of fullest vigour, namely struggle of males; even in animals which pair there seems a surplus <?> and a battle, possibly as in man more males produced than females, struggle of war or charms{63}. Hence that male which at that time is in fullest vigour, or best armed with arms or ornaments of its species, will gain in hundreds of generations some small advantage and transmit such characters to its offspring. So in female rearing its young, the most vigorous and skilful and industrious, <whose> instincts <are> best developed, will rear more young, probably possessing her good qualities, and a greater number will thus <be> prepared for the struggle of nature. Compared to man using a male alone of good breed. This latter section only of limited application, applies to variation of [specific] sexual characters. Introduce here contrast with Lamarck,--absurdity of habit, or chance?? or external conditions, making a woodpecker adapted to tree{64}. {63} Here we have the two types of sexual selection discussed in the _Origin_, Ed. i. pp. 88 et seq., vi. pp. 108 et seq. {64} It is not obvious why the author objects to "chance" or "external conditions making a woodpecker." He allows that variation is ultimately referable to conditions and that the nature of the connexion is unknown, i.e. that the result is fortuitous. It is not clear in the original to how much of the passage the two ? refer.
Before considering difficulties of theory of selection let us consider character of the races produced, as now explained, by nature. Conditions have varied slowly and the organisms best adapted in their whole course of life to the changed conditions have always been selected,--man selects small dog and afterwards gives it profusion of food,--selects a long-backed and short-legged breed and gives it no particular exercise to suit this function &c. &c. In ordinary cases nature has not allowed her race to be contaminated with a cross of another race, and agriculturists know how difficult they find always to prevent this,--effect would be trueness. This character and sterility when crossed, and generally a greater amount of difference, are two main features, which distinguish domestic races from species.
Now wild animals, taken out of their natural conditions, seldom breed. I do not refer to shows or to Zoological Societies where many animals unite, but <do not?> breed, and others will never unite, but to wild animals caught and kept _quite tame_ left loose and well fed about houses and living many years. Hybrids produced almost as readily as pure breds. St Hilaire great distinction of tame and domestic,--elephants,--ferrets{72}. Reproductive organs not subject to disease in Zoological Garden. Dissection and microscope show that hybrid is in exactly same condition as another animal in the intervals of breeding season, or those animals which taken wild and _not bred_ in domesticity, remain without breeding their whole lives. It should be observed that so far from domesticity being unfavourable in itself <it> makes more fertile: [when animal is domesticated and breeds, productive power increased from more food and selection of fertile races]. As far as animals go might be thought <an> effect on their mind and a special case. {65} The meaning is "That sterility is not universal is admitted by all." {66} See _Var. under Dom._, Ed. 2, i. p. 388, where the garden forms of _Gladiolus_ and _Calceolaria_ are said to be derived from crosses between distinct species. Herbert's hybrid _Crinums_ are discussed in the _Origin_, Ed. i. p. 250, vi. p. 370. It is well known that the author believed in a multiple origin of domestic dogs.
Before leaving this subject well to observe that it was shown that a certain amount of variation is consequent on mere act of reproduction, both by buds and sexually,--is vastly increased when parents exposed for some generations to new conditions{82}, and we now find that many animals when exposed for first time to very new conditions, are <as> incapable of breeding as hybrids. It [probably] bears also on supposed fact of crossed animals when not infertile, as in mongrels, tending to vary much, as likewise seems to be the case, when true hybrids possess just sufficient fertility to propagate with the parent breeds and _inter se_ for some generations. This is Koelreuter's belief. These facts throw light on each other and support the truth of each other, we see throughout a connection between the reproductive faculties and exposure to changed conditions of life whether by crossing or exposure of the individuals{83}. {82} In the _Origin_, Ed. i. Chs. I. and V., the author does not admit reproduction, apart from environment, as being a cause of variation. With regard to the cumulative effect of new conditions there are many passages in the _Origin_, Ed. i. e.g. pp. 7, 12, vi. pp. 8, 14. {83} As already pointed out, this is the important principle investigated in the author's _Cross and Self-Fertilisation_. Professor Bateson has suggested to me that the experiments should be repeated with gametically pure individuals.
_Difficulties on theory of selection_{84}. It may be objected such perfect organs as eye and ear, could never be formed, in latter less difficulty as gradations more perfect; at first appears monstrous and to <the> end appears difficulty. But think of gradation, even now manifest, (Tibia and Fibula). Everyone will allow if every fossil preserved, gradation infinitely more perfect; for possibility of selection a perfect <?> gradation is required. Different groups of structure, slight gradation in each group,--every analogy renders it probable that intermediate forms have existed. Be it remembered what strange metamorphoses; part of eye, not directly connected with vision, might come to be [thus used] gradually worked in for this end,--swimming bladder by gradation of structure is admitted to belong to the ear system,--rattlesnake. [Woodpecker best adapted to climb.] In some cases gradation not possible,--as vertebrae,--actually vary in domestic animals,--less difficult if growth followed. Looking to whole animals, a bat formed not for flight{85}. Suppose we had flying fish{86} and not one of our now called flying fish preserved, who would have guessed intermediate habits. Woodpeckers and tree-frogs both live in countries where no trees{87}. {84} In the _Origin_ a chapter is given up to "difficulties on theory": the discussion in the present essay seems slight even when it is remembered how small a space is here available. For _Tibia_ &c. see p. 48.
The mental powers of different animals in wild and tame state [present still greater difficulties] require a separate section. Be it remembered I have nothing to do with origin of memory, attention, and the different faculties of the mind{88}, but merely with their differences in each of the great divisions of nature. Disposition, courage, pertinacity <?>, suspicion, restlessness, ill-temper, sagacity and <the> reverse unquestionably vary in animals and are inherited (Cuba wildness dogs, rabbits, fear against particular object as man Galapagos{89}). Habits purely corporeal, breeding season &c., time of going to rest &c., vary and are hereditary, like the analogous habits of plants which vary and are inherited. Habits of body, as manner of movement d^o. and d^o. Habits, as pointing and setting on certain occasions d^o. Taste for hunting certain objects and manner of doing so,--sheep-dog. These are shown clearly by crossing and their analogy with true instinct thus shown,--retriever. Do not know objects for which they do it. Lord Brougham's definition{90}. Origin partly habit, but the amount necessarily unknown, partly selection. Young pointers pointing stones and sheep--tumbling pigeons--sheep{91} going back to place where born. Instinct aided by reason, as in the taylor-bird{92}. Taught by parents, cows choosing food, birds singing. Instincts vary in wild state (birds get wilder) often lost{93}; more perfect,--nest without roof. These facts [only clear way] show how incomprehensibly brain has power of transmitting intellectual operations.
Faculties{94} distinct from true instincts,--finding [way]. It must I think be admitted that habits whether congenital or acquired by practice [sometimes] often become inherited{95}; instincts, influence, equally with structure, the preservation of animals; therefore selection must, with changing conditions tend to modify the inherited habits of animals. If this be admitted it will be found _possible_ that many of the strangest instincts may be thus acquired. I may observe, without attempting definition, that an inherited habit or trick (trick because may be born) fulfils closely what we mean by instinct. A habit is often performed unconsciously, the strangest habits become associated, d^o. tricks, going in certain spots &c. &c., even against will, is excited by external agencies, and looks not to the end,--a person playing a pianoforte. If such a habit were transmitted it would make a marvellous instinct. Let us consider some of the most difficult cases of instincts, whether they could be _possibly_ acquired. I do not say _probably_, for that belongs to our 3rd Part{96}, I beg this may be remembered, nor do I mean to attempt to show exact method. I want only to show that whole theory ought not at once to be rejected on this score. {94} In the MS. of 1844 is an interesting discussion on _faculty_ as distinct from _instinct_. {95} At this date and for long afterwards the inheritance of acquired characters was assumed to occur.
Bees again, distinction of faculty,--how they make a hexagon,--Waterhouse's theory{100},--the impulse to use whatever faculty they possess,--the taylor-bird has the faculty of sewing with beak, instinct impels him to do it. {100} In the discussion on bees' cells, _Origin_, Ed. i. p. 225, vi. p. 343, the author acknowledges that his theory originated in Waterhouse's observations. Last case of parent feeding young with different food (take case of Galapagos birds, gradation from Hawfinch to Sylvia) selection and habit might lead old birds to vary taste <?> and form, leaving their instinct of feeding their young with same food{101},--or I see no difficulty in parents being forced or induced to vary the food brought, and selection adapting the young ones to it, and thus by degree any amount of diversity might be arrived at. Although we can never hope to see the course revealed by which different instincts have been acquired, for we have only present animals (not well known) to judge of the course of gradation, yet once grant the principle of habits, whether congenital or acquired by experience, being inherited and I can see no limit to the [amount of variation] extraordinariness <?> of the habits thus acquired. {101} The hawfinch-and _Sylvia-_types are figured in the _Journal of Researches_, p. 379. The discussion of change of form in relation to change of instinct is not clear, and I find it impossible to suggest a paraphrase.
_Summing up this Division._ If variation be admitted to occur occasionally in some wild animals, and how can we doubt it, when we see [all] thousands <of> organisms, for whatever use taken by man, do vary. If we admit such variations tend to be hereditary, and how can we doubt it when we <remember> resemblances of features and character,--disease and monstrosities inherited and endless races produced (1200 cabbages). If we admit selection is steadily at work, and who will doubt it, when he considers amount of food on an average fixed and reproductive powers act in geometrical ratio. If we admit that external conditions vary, as all geology proclaims, they have done and are now doing,--then, if no law of nature be opposed, there must occasionally be formed races, [slightly] differing from the parent races. So then any such law{102}, none is known, but in all works it is assumed, in <?> flat contradiction to all known facts, that the amount of possible variation is soon acquired. Are not all the most varied species, the oldest domesticated: who <would> think that horses or corn could be produced? Take dahlia and potato, who will pretend in 5000 years{103} <that great changes might not be effected>: perfectly adapted to conditions and then again brought into varying conditions.
Think what has been done in few last years, look at pigeons, and cattle. With the amount of food man can produce he may have arrived at limit of fatness or size, or thickness of wool <?>, but these are the most trivial points, but even in these I conclude it is impossible to say we know the limit of variation. And therefore with the [adapting] selecting power of nature, infinitely wise compared to those of man, <I conclude> that it is impossible to say we know the limit of races, which would be true <to their> kind; if of different constitutions would probably be infertile one with another, and which might be adapted in the most singular and admirable manner, according to their wants, to external nature and to other surrounding organisms,--such races would be species. But is there any evidence <that> species <have> been thus produced, this is a question wholly independent of all previous points, and which on examination of the kingdom of nature <we> ought to answer one way or another. {102} I should interpret this obscure sentence as follows, "No such opposing law is known, but in all works on the subject a law is (in flat contradiction to all known facts) assumed to limit the possible amount of variation." In the _Origin_, the author never limits the power of variation, as far as I know. {103} In _Var. under Dom._ Ed. 2, ii. p. 263, the _Dahlia_ is described as showing sensitiveness to conditions in 1841. All the varieties of the _Dahlia_ are said to have arisen since 1804 (_ibid._ i. p. 393).
Ideas discussed in this chapter
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