The Foundations of the Origin of Species
But turning to plants we find same class of facts. I do not refer to seeds not ripening, perhaps the commonest cause, but to plants not setting, which either is owing to some imperfection of ovule or pollen. Lindley says sterility is the [curse] bane of all propagators, – Linnæus about alpine plants. American bog plants, – pollen in exactly same state as in hybrids, – same in geraniums. Persian and Chinese73 lilac will not seed in Italy and England. Probably double plants and all fruits owe their developed parts primarily «?» to sterility and extra food thus «?» applied74. There is here gradation «in» sterility and then parts, like diseases, are transmitted hereditarily. We cannot assign any cause why the Pontic Azalea produces plenty of pollen and not American75, why common lilac seeds and not Persian, we see no difference in healthiness. We know not on what circumstances these facts depend, why ferret breeds, and cheetah76, elephant and pig in India will not.
Now in crossing it is certain every peculiarity in form and constitution is transmitted: an alpine plant transmits its alpine tendency to its offspring, an American plant its American-bog constitution, and «with» animals, those peculiarities, on which77 when placed out of their natural conditions they are incapable of breeding; and moreover they transmit every part of their constitution, their respiration, their pulse, their instinct, which are all suddenly modified, can it be wondered at that they are incapable of breeding? I think it may be truly said it would be more wonderful if they did. But it may be asked why have not the recognised varieties, supposed to have been produced through the means of man, [not refused to breed] have all bred78. Variation depends on change of condition and selection79, as far as man’s systematic or unsystematic selection «has» gone; he takes external form, has little power from ignorance over internal invisible constitutional differences. Races which have long been domesticated, and have much varied, are precisely those which were capable of bearing great changes, whose constitutions were adapted to a diversity of climates. Nature changes slowly and by degrees. According to many authors probably breeds of dogs are another case of modified species freely crossing. There is no variety which «illegible» has been «illegible» adapted to peculiar soil or situation for a thousand years and another rigorously adapted to another, till such can be produced, the question is not tried80. Man in past ages, could transport into different climates, animals and plants which would freely propagate in such new climates. Nature could effect, with selection, such changes slowly, so that precisely those animals which are adapted to submit to great changes have given rise to diverse races, – and indeed great doubt on this head81.
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 conditions82, 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 individuals83.
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 vertebræ, – actually vary in domestic animals, – less difficult if growth followed. Looking to whole animals, a bat formed not for flight85. Suppose we had flying fish86 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 trees87.
The gradations by which each individual organ has arrived at its present state, and each individual animal with its aggregate of organs has arrived, probably never could be known, and all present great difficulties. I merely wish to show that the proposition is not so monstrous as it at first appears, and that if good reason can be advanced for believing the species have descended from common parents, the difficulty of imagining intermediate forms of structure not sufficient to make one at once reject the theory.
§ III. «On Variation in instincts and other mental attributes.»
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 mind88, 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 Galapagos89). 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 do. and do. Habits, as pointing and setting on certain occasions do. 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 definition90. Origin partly habit, but the amount necessarily unknown, partly selection. Young pointers pointing stones and sheep – tumbling pigeons – sheep91 going back to place where born. Instinct aided by reason, as in the taylor-bird92. Taught by parents, cows choosing food, birds singing. Instincts vary in wild state (birds get wilder) often lost93; more perfect, – nest without roof. These facts [only clear way] show how incomprehensibly brain has power of transmitting intellectual operations.
Faculties94 distinct from true instincts, – finding [way]. It must I think be admitted that habits whether congenital or acquired by practice [sometimes] often become inherited95; 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, do. 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 Part96, 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.
Every instinct must, by my theory, have been acquired gradually by slight changes «illegible» of former instinct, each change being useful to its then species. Shamming death struck me at first as remarkable objection. I found none really sham death97, and that there is gradation; now no one doubts that those insects which do it either more or less, do it for some good, if then any species was led to do it more, and then «?» escaped &c. &c.
Take migratory instincts, faculty distinct from instinct, animals have notion of time, – like savages. Ordinary finding way by memory, but how does savage find way across country, – as incomprehensible to us, as animal to them, – geological changes, – fishes in river, – case of sheep in Spain98. Architectural instincts, – a manufacturer’s employee in making single articles extraordinary skill, – often said seem to make it almost «illegible», child born with such a notion of playing99, – we can fancy tailoring acquired in same perfection, – mixture of reason, – water-ouzel, – taylor-bird, – gradation of simple nest to most complicated.
Bees again, distinction of faculty, – how they make a hexagon, – Waterhouse’s theory100, – the impulse to use whatever faculty they possess, – the taylor-bird has the faculty of sewing with beak, instinct impels him to do it.
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 food101, – 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.
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 law102, 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 years103 «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.
PART II 104
§§ IV. & V. «On the evidence from Geology.»
I may premise, that according to the view ordinarily received, the myriads of organisms peopling this world have been created by so many distinct acts of creation. As we know nothing of the «illegible» will of a Creator, – we can see no reason why there should exist any relation between the organisms thus created; or again, they might be created according to any scheme. But it would be marvellous if this scheme should be the same as would result from the descent of groups of organisms from [certain] the same parents, according to the circumstances, just attempted to be developed.
With equal probability did old cosmogonists say fossils were created, as we now see them, with a false resemblance to living beings105; what would the Astronomer say to the doctrine that the planets moved «not» according to the law of gravitation, but from the Creator having willed each separate planet to move in its particular orbit? I believe such a proposition (if we remove all prejudices) would be as legitimate as to admit that certain groups of living and extinct organisms, in their distribution, in their structure and in their relations one to another and to external conditions, agreed with the theory and showed signs of common descent, and yet were created distinct. As long as it was thought impossible that organisms should vary, or should anyhow become adapted to other organisms in a complicated manner, and yet be separated from them by an impassable barrier of sterility106, it was justifiable, even with some appearance in favour of a common descent, to admit distinct creation according to the will of an Omniscient Creator; or, for it is the same thing, to say with Whewell that the beginnings of all things surpass the comprehension of man. In the former sections I have endeavoured to show that such variation or specification is not impossible, nay, in many points of view is absolutely probable. What then is the evidence in favour of it and what the evidence against it. With our imperfect knowledge of past ages [surely there will be some] it would be strange if the imperfection did not create some unfavourable evidence.
Give sketch of the Past, – beginning with facts appearing hostile under present knowledge, – then proceed to geograph. distribution, – order of appearance, – affinities, – morphology &c., &c.
Our theory requires a very gradual introduction of new forms107, and extermination of the old (to which we shall revert). The extermination of old may sometimes be rapid, but never the introduction. In the groups descended from common parent, our theory requires a perfect gradation not differing more than breed«s» of cattle, or potatoes, or cabbages in forms. I do not mean that a graduated series of animals must have existed, intermediate between horse, mouse, tapir108, elephant [or fowl and peacock], but that these must have had a common parent, and between horse and this «?» parent &c., &c., but the common parent may possibly have differed more from either than the two do now from each other. Now what evidence of this is there? So perfect gradation in some departments, that some naturalists have thought that in some large divisions, if all existing forms were collected, a near approach to perfect gradation would be made. But such a notion is preposterous with respect to all, but evidently so with mammals. Other naturalists have thought this would be so if all the specimens entombed in the strata were collected109. I conceive there is no probability whatever of this; nevertheless it is certain all the numerous fossil forms fall in«to», as Buckland remarks, not present classes, families and genera, they fall between them: so is it with new discoveries of existing forms. Most ancient fossils, that is most separated «by» space of time, are most apt to fall between the classes – (but organisms from those countries most separated by space also fall between the classes «e. g.» Ornithorhyncus?). As far as geological discoveries «go» they tend towards such gradation110. Illustrate it with net. Toxodon, – tibia and fibula, – dog and otter, – but so utterly improbable is «it», in ex. gr. Pachydermata, to compose series as perfect as cattle, that if, as many geologists seem to infer, each separate formation presents even an approach to a consecutive history, my theory must be given up. Even if it were consecutive, it would only collect series of one district in our present state of knowledge; but what probability is there that any one formation during the immense period which has elapsed during each period will generally present a consecutive history. [Compare number living at one period to fossils preserved – look at enormous periods of time.]
Referring only to marine animals, which are obviously most likely to be preserved, they must live where «?» sediment (of a kind favourable for preservation, not sand and pebble)111 is depositing quickly and over large area and must be thickly capped, «illegible» littoral deposits: for otherwise denudation «will destroy them», – they must live in a shallow space which sediment will tend to fill up, – as movement is «in?» progress if soon brought «?» up «?» subject to denudation, – [if] as during subsidence favourable, accords with facts of European deposits112, but subsidence apt to destroy agents which produce sediment113.
I believe safely inferred «that» groups of marine «?» fossils only preserved for future ages where sediment goes on long «and» continuous«ly» and with rapid but not too rapid deposition in «an» area of subsidence. In how few places in any one region like Europe will «?» these contingencies be going on? Hence «?» in past ages mere [gaps] pages preserved114. Lyell's doctrine carried to extreme, – we shall understand difficulty if it be asked: – what chance of series of gradation between cattle by «illegible» at age «illegible» as far back as Miocene115? We know then cattle existed. Compare number of living, – immense duration of each period, – fewness of fossils.
This only refers to consecutiveness of history of organisms of each formation.
The foregoing argument will show firstly, that formations are distinct merely from want of fossils «of intermediate beds», and secondly, that each formation is full of gaps, has been advanced to account for fewness of preserved organisms compared to what have lived on the world. The very same argument explains why in older formations the organisms appear to come on and disappear suddenly, – but in [later] tertiary not quite suddenly116, in later tertiary gradually, – becoming rare and disappearing, – some have disappeared within man’s time. It is obvious that our theory requires gradual and nearly uniform introduction, possibly more sudden extermination, – subsidence of continent of Australia &c., &c.
Our theory requires that the first form which existed of each of the great divisions would present points intermediate between existing ones, but immensely different. Most geologists believe Silurian117 fossils are those which first existed in the whole world, not those which have chanced to be the oldest not destroyed, – or the first which existed in profoundly deep seas in progress of conversion from sea to land: if they are first they «? we» give up. Not so Hutton or Lyell: if first reptile118 of Red Sandstone «?» really was first which existed: if Pachyderm119 of Paris was first which existed: fish of Devonian: dragon fly of Lias: for we cannot suppose them the progenitors: they agree too closely with existing divisions. But geologists consider Europe as «?» a passage from sea to island «?» to continent (except Wealden, see Lyell). These animals therefore, I consider then mere introduction «?» from continents long since submerged.
Finally, if views of some geologists be correct, my theory must be given up. [Lyell’s views, as far as they go, are in favour, but they go so little in favour, and so much more is required, that it may «be» viewed as objection.] If geology present us with mere pages in chapters, towards end of «a» history, formed by tearing out bundles of leaves, and each page illustrating merely a small portion of the organisms of that time, the facts accord perfectly with my theory120.
Extermination. We have seen that in later periods the organisms have disappeared by degrees and [perhaps] probably by degrees in earlier, and I have said our theory requires it. As many naturalists seem to think extermination a most mysterious circumstance121 and call in astonishing agencies, it is well to recall what we have shown concerning the struggle of nature. An exterminating agency is at work with every organism: we scarcely see it: if robins would increase to thousands in ten years how severe must the process be. How imperceptible a small increase: fossils become rare: possibly sudden extermination as Australia, but as present means very slow and many means of escape, I shall doubt very sudden exterminations. Who can explain why some species abound more, – why does marsh titmouse, or ring-ouzel, now little change, – why is one sea-slug rare and another common on our coasts, – why one species of Rhinoceros more than another, – why is «illegible» tiger of India so rare? Curious and general sources of error, the place of an organism is instantly filled up.
We know state of earth has changed, and as earthquakes and tides go on, the state must change, – many geologists believe a slow gradual cooling. Now let us see in accordance with principles of [variation] specification explained in Sect. II. how species would probably be introduced and how such results accord with what is known.
The first fact geology proclaims is immense number of extinct forms, and new appearances. Tertiary strata leads to belief, that forms gradually become rare and disappear and are gradually supplied by others. We see some forms now becoming rare and disappearing, we know of no sudden creation: in older periods the forms appear to come in suddenly, scene shifts: but even here Devonian, Permian &c. [keep on supplying new links in chain] – Genera and higher forms come on and disappear, in same way leaving a species on one or more stages below that in which the form abounded.
«Geographical Distribution.»
§ VI. Let us consider the absolute state of distribution of organisms of earth's face
Referring chiefly, but not exclusively (from difficulty of transport, fewness, and the distinct characteristics of groups) to Mammalia; and first considering the three or four main [regions] divisions; North America, Europe, Asia, including greater part of E. Indian Archipelago and Africa are intimately allied. Africa most distinct, especially most southern parts. And the Arctic regions, which unite N. America, Asia and Europe, only separated (if we travel one way by Behring’s St.) by a narrow strait, is most intimately allied, indeed forms but one restricted group. Next comes S. America, – then Australia, Madagascar (and some small islands which stand very remote from the land). Looking at these main divisions separately, the organisms vary according to changes in condition122 of different parts. But besides this, barriers of every kind seem to separate regions in a greater degree than proportionally to the difference of climates on each side. Thus great chains of mountains, spaces of sea between islands and continents, even great rivers and deserts. In fact the amount «of» difference in the organisms bears a certain, but not invariable relation to the amount of physical difficulties to transit123.
There are some curious exceptions, namely, similarity of fauna of mountains of Europe and N. America and Lapland. Other cases just «the» reverse, mountains of eastern S. America, Altai «?», S. India «?»124: mountain summits of islands often eminently peculiar. Fauna generally of some islands, even when close, very dissimilar, in others very similar. [I am here led to observe one or more centres of creation125.]