The Foundations of the Origin of Species

Before concluding it will be well to show, although this has incidentally appeared, how far the theory of common descent can legitimately be extended517. If we once admit that two true species of the same genus can have descended from the same parent, it will not be possible to deny that two species of two genera may also have descended from a common stock. For in some families the genera approach almost as closely as species of the same genus; and in some orders, for instance in the monocotyledonous plants, the families run closely into each other. We do not hesitate to assign a common origin to dogs or cabbages, because they are divided into groups analogous to the groups in nature. Many naturalists indeed admit that all groups are artificial; and that they depend entirely on the extinction of intermediate species. Some naturalists, however, affirm that though driven from considering sterility as the characteristic of species, that an entire incapacity to propagate together is the best evidence of the existence of natural genera. Even if we put on one side the undoubted fact that some species of the same genus will not breed together, we cannot possibly admit the above rule, seeing that the grouse and pheasant (considered by some good ornithologists as forming two families), the bull-finch and canary-bird have bred together.

No doubt the more remote two species are from each other, the weaker the arguments become in favour of their common descent. In species of two distinct families the analogy, from the variation of domestic organisms and from the manner of their intermarrying, fails; and the arguments from their geographical distribution quite or almost quite fails. But if we once admit the general principles of this work, as far as a clear unity of type can be made out in groups of species, adapted to play diversified parts in the economy of nature, whether shown in the structure of the embryonic or mature being, and especially if shown by a community of abortive parts, we are legitimately led to admit their community of descent. Naturalists dispute how widely this unity of type extends: most, however, admit that the vertebrata are built on one type; the articulata on another; the mollusca on a third; and the radiata on probably more than one. Plants also appear to fall under three or four great types. On this theory, therefore, all the organisms yet discovered are descendants of probably less than ten parent-forms.

Conclusion

My reasons have now been assigned for believing that specific forms are not immutable creations518. The terms used by naturalists of affinity, unity of type, adaptive characters, the metamorphosis and abortion of organs, cease to be metaphorical expressions and become intelligible facts. We no longer look at an organic being as a savage does at a ship519 or other great work of art, as at a thing wholly beyond his comprehension, but as a production that has a history which we may search into. How interesting do all instincts become when we speculate on their origin as hereditary habits, or as slight congenital modifications of former instincts perpetuated by the individuals so characterised having been preserved. When we look at every complex instinct and mechanism as the summing up of a long history of contrivances, each most useful to its possessor, nearly in the same way as when we look at a great mechanical invention as the summing up of the labour, the experience, the reason, and even the blunders of numerous workmen. How interesting does the geographical distribution of all organic beings, past and present, become as throwing light on the ancient geography of the world. Geology loses glory520 from the imperfection of its archives, but it gains in the immensity of its subject. There is much grandeur in looking at every existing organic being either as the lineal successor of some form now buried under thousands of feet of solid rock, or as being the co-descendant of that buried form of some more ancient and utterly lost inhabitant of this world. It accords with what we know of the laws impressed by the Creator521 on matter that the production and extinction of forms should, like the birth and death of individuals, be the result of secondary means. It is derogatory that the Creator of countless Universes should have made by individual acts of His will the myriads of creeping parasites and worms, which since the earliest dawn of life have swarmed over the land and in the depths of the ocean. We cease to be astonished522 that a group of animals should have been formed to lay their eggs in the bowels and flesh of other sensitive beings; that some animals should live by and even delight in cruelty; that animals should be led away by false instincts; that annually there should be an incalculable waste of the pollen, eggs and immature beings; for we see in all this the inevitable consequences of one great law, of the multiplication of organic beings not created immutable. From death, famine, and the struggle for existence, we see that the most exalted end which we are capable of conceiving, namely, the creation of the higher animals523, has directly proceeded. Doubtless, our first impression is to disbelieve that any secondary law could produce infinitely numerous organic beings, each characterised by the most exquisite workmanship and widely extended adaptations: it at first accords better with our faculties to suppose that each required the fiat of a Creator. There524 is a [simple] grandeur in this view of life with its several powers of growth, reproduction and of sensation, having been originally breathed into matter under a few forms, perhaps into only one525, and that whilst this planet has gone cycling onwards according to the fixed laws of gravity and whilst land and water have gone on replacing each other – that from so simple an origin, through the selection of infinitesimal varieties, endless forms most beautiful and most wonderful have been evolved.

1

See the extracts in Life and Letters of Charles Darwin, ii. p. 5.

2

The second volume, – especially important in regard to Evolution, – reached him in the autumn of 1832, as Prof. Judd has pointed out in his most interesting paper in Darwin and Modern Science. Cambridge, 1909.

3

Obituary Notice of C. Darwin, Proc. R. Soc. vol. 44. Reprinted in Huxley's Collected Essays. See also Life and Letters of C. Darwin, ii. p. 179.

4

See the extracts in the Life and Letters, ii. p. 5.

5

Life and Letters, i. p. 82.

6

Obituary Notice, loc. cit.

7

Darwin and Modern Science.

8

Huxley, Obituary, p. xi.

9

In this citation the italics are mine.

10

Journal of Researches, Ed. 1860, p. 394.

11

F. Darwin’s Life of Charles Darwin (in one volume), 1892, p. 166.

12

Life and Letters, i. p. 83.

13

Life and Letters, ii. p. 8.

14

Avestruz Petise, i. e. Rhea Darwini.

15

A bird.

16

Life and Letters, i. p. 84.

17

It contains as a fact 231 pp. It is a strongly bound folio, interleaved with blank pages, as though for notes and additions. His own MS. from which it was copied contains 189 pp.

18

Life and Letters, ii. p. 116.

19

Life and Letters, ii. p. 10.

20

Life and Letters, ii. p. 146.

21

J. Linn. Soc. Zool. iii. p. 45.

22

It is evident that Parts and Chapters were to some extent interchangeable in the author’s mind, for p. 1 (of the MS. we have been discussing) is headed in ink Chapter I, and afterwards altered in pencil to Part I.

23

On p. 23 of the MS. of the Foundations is a reference to the “back of p. 21 bis”: this suggests that additional pages had been interpolated in the MS. and that it may once have had 37 in place of 35 pp.

24

Life and Letters, i. p. 153.

25

Life and Letters, i. p. 84.

26

In the footnotes to the Essay of 1844 attention is called to similar passages.

27

Life and Letters, ii. p. 15.

28

The passage is given in the Life and Letters, ii. p. 124.

29

The extract consists of the section on Natural Means of Selection, p. 87.

30

Life and Letters, i. p. 84.

31

Life and Letters, ii. p. 18.

32

Mrs Darwin’s brother.

33

After Mr Strickland’s name comes the following sentence, which has been erased, but remains legible. “Professor Owen would be very good; but I presume he would not undertake such a work.”

34

The words “several years ago, and” seem to have been added at a later date.

35

Life and Letters, ii. p. 9.

36

Evidently a memorandum that an example should be given.

37

The importance of exposure to new conditions for several generations is insisted on in the Origin, Ed. i. p. 7, also p. 131. In the latter passage the author guards himself against the assumption that variations are “due to chance,” and speaks of “our ignorance of the cause of each particular variation.” These statements are not always remembered by his critics.

38

Cf. Origin, Ed. i. p. 10, vi. p. 9, “Young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life.”

39

This is paralleled by the conclusion in the Origin, Ed. i. p. 8, that “the most frequent cause of variability may be attributed to the male and female reproductive elements having been affected prior to the act of conception.”

40

The meaning seems to be that there must be some variability in the liver otherwise anatomists would not speak of the ‘beau ideal’ of that organ.

41

The position of the following passage is uncertain. “If individuals of two widely different varieties be allowed to cross, a third race will be formed – a most fertile source of the variation in domesticated animals. «In the Origin, Ed. i. p. 20 the author says that “the possibility of making distinct races by crossing has been greatly exaggerated.”» If freely allowed, the characters of pure parents will be lost, number of races thus «illegible» but differences «?» besides the «illegible». But if varieties differing in very slight respects be allowed to cross, such small variation will be destroyed, at least to our senses, – a variation [clearly] just to be distinguished by long legs will have offspring not to be so distinguished. Free crossing great agent in producing uniformity in any breed. Introduce tendency to revert to parent form.”

42

The swamping effect of intercrossing is referred to in the Origin, Ed. i. p. 103, vi. p. 126.

43

A discussion on the intercrossing of hermaphrodites in relation to Knight’s views occurs in the Origin, Ed. i. p. 96, vi. p. 119. The parallelism between crossing and changed conditions is briefly given in the Origin, Ed. i. p. 267, vi. p. 391, and was finally investigated in The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom, 1876.

44

There is an article on the vis medicatrix in Brougham’s Dissertations, 1839, a copy of which is in the author’s library.

45

This is the classification of selection into methodical and unconscious given in the Origin, Ed. i. p. 33, vi. p. 38.

46

This passage, and a similar discussion on the power of the Creator (p. 6), correspond to the comparison between the selective capacities of man and nature, in the Origin, Ed. i. p. 83, vi. p. 102.

47

i. e. they are individually distinguishable.

48

See Origin, Ed. i. p. 133, vi. p. 165.

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.

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.

51

This illustration occurs in the Origin, Ed. i. pp. 90, 91, vi. pp. 110, 111.

52

See Origin, Ed. i. p. 83, vi. p. 102, where the word Creator is replaced by Nature.

53

Note in the original. “Good place to introduce, saying reasons hereafter to be given, how far I extend theory, say to all mammalia – reasons growing weaker and weaker.”

54

See Origin, Ed. i. pp. 62, 63, vi. p. 77, where similar reference is made to De Candolle; for Malthus see Origin, p. 5.

55

This may possibly refer to the amount of destruction going on. See Origin, Ed. i. p. 68, vi. p. 84, where there is an estimate of a later date as to death-rate of birds in winter. “Calculate robins” probably refers to a calculation of the rate of increase of birds under favourable conditions.

56

In the Origin, Ed. i. pp. 64, 65, vi. p. 80, he instances cattle and horses and certain plants in S. America and American species of plants in India, and further on, as unexpected effects of changed conditions, the enclosure of a heath, and the relation between the fertilisation of clover and the presence of cats (Origin, Ed. i. p. 74, vi. p. 91).

57

Origin, Ed. i. p. 74, vi. p. 91. “It has been observed that the trees now growing on … ancient Indian mounds … display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests.”

58

The simile of the wedge occurs in the Origin, Ed. i. p. 67; it is deleted in Darwin’s copy of the first edition: it does not occur in Ed. vi.

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.

61

This is a repetition of what is given at p. 6.

62

Compare Origin, Ed. i. p. 41, vi. p. 47. “I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend closely to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected.”

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.

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.

67

The argument from gradation in sterility is given in the Origin, Ed. i. pp. 248, 255, vi. pp. 368, 375. In the Origin, I have not come across the cases mentioned, viz. crocus, heath, or grouse and fowl or peacock. For sterility between closely allied species, see Origin, Ed. i. p. 257, vi. p. 377. In the present essay the author does not distinguish between fertility between species and the fertility of the hybrid offspring, a point on which he insists in the Origin, Ed. i. p. 245, vi. p. 365.

68

Ackermann (Ber. d. Vereins f. Naturkunde zu Kassel, 1898, p. 23) quotes from Gloger that a cross has been effected between a domestic hen and a Tetrao tetrix; the offspring died when three days old.

69

No doubt the sexual cells are meant. I do not know on what evidence it is stated that the mule has bred.

70

The sentence is all but illegible. I think that the author refers to forms usually ranked as varieties having been marked as species when it was found that they were sterile together. See the case of the red and blue Anagallis given from Gärtner in the Origin, Ed. i. p. 247, vi. p. 368.

71

In the Origin, Ed. i. p. 258, where the author speaks of constitutional differences in this connexion, he specifies that they are confined to the reproductive system.

72

The sensitiveness of the reproductive system to changed conditions is insisted on in the Origin, Ed. i. p. 8, vi. p. 10.

The ferret is mentioned, as being prolific in captivity, in Var. under Dom., Ed. 2, ii. p. 90.

73

Lindley’s remark is quoted in the Origin, Ed. i. p. 9. Linnæus’ remark is to the effect that Alpine plants tend to be sterile under cultivation (see Var. under Dom., Ed. 2, ii. p. 147). In the same place the author speaks of peat-loving plants being sterile in our gardens, – no doubt the American bog-plants referred to above. On the following page (p. 148) the sterility of the lilac (Syringa persica and chinensis) is referred to.

74

The author probably means that the increase in the petals is due to a greater food supply being available for them owing to sterility. See the discussion in Var. under Dom., Ed. 2, ii. p. 151. It must be noted that doubleness of the flower may exist without noticeable sterility.

75

I have not come across this case in the author’s works.

76

For the somewhat doubtful case of the cheetah (Felis jubata) see Var. under Dom., Ed. 2, ii. p. 133. I do not know to what fact “pig in India” refers.

77

This sentence should run “on which depends their incapacity to breed in unnatural conditions.”

78

This sentence ends in confusion: it should clearly close with the words “refused to breed” in place of the bracket and the present concluding phrase.

79

The author doubtless refers to the change produced by the summation of variation by means of selection.

80

The meaning of this sentence is made clear by a passage in the MS. of 1844: – “Until man selects two varieties from the same stock, adapted to two climates or to other different external conditions, and confines each rigidly for one or several thousand years to such conditions, always selecting the individuals best adapted to them, he cannot be said to have even commenced the experiment.” That is, the attempt to produce mutually sterile domestic breeds.

81

This passage is to some extent a repetition of a previous one and may have been intended to replace an earlier sentence. I have thought it best to give both. In the Origin, Ed. i. p. 141, vi. p. 176, the author gives his opinion that the power of resisting diverse conditions, seen in man and his domestic animals, is an example “of a very common flexibility of constitution.”

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.

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.

85

This may be interpreted “The general structure of a bat is the same as that of non-flying mammals.”

86

That is truly winged fish.

87

The terrestrial woodpecker of S. America formed the subject of a paper by Darwin, Proc. Zool. Soc., 1870. See Life and Letters, vol. iii. p. 153.

88

The same proviso occurs in the Origin, Ed. i. p. 207, vi. p. 319.

89

The tameness of the birds in the Galapagos is described in the Journal of Researches (1860), p. 398. Dogs and rabbits are probably mentioned as cases in which the hereditary fear of man has been lost. In the 1844 MS. the author states that the Cuban feral dog shows great natural wildness, even when caught quite young.

90

In the Origin, Ed. i. p. 207, vi. p. 319, he refuses to define instinct. For Lord Brougham’s definition see his Dissertations on Subjects of Science etc., 1839, p. 27.

91

See James Hogg (the Ettrick Shepherd), Works, 1865, Tales and Sketches, p. 403.

92

This refers to the tailor-bird making use of manufactured thread supplied to it, instead of thread twisted by itself.

93

Often lost applies to instinct: birds get wilder is printed in a parenthesis because it was apparently added as an after-thought. Nest without roof refers to the water-ousel omitting to vault its nest when building in a protected situation.

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.

96

Part II. is here intended: see the Introduction.

97

The meaning is that the attitude assumed in shamming is not accurately like that of death.

98

This refers to the transandantes sheep mentioned in the MS. of 1844, as having acquired a migratory instinct.

99

In the Origin, Ed. i. p. 209, vi. p. 321, Mozart’s pseudo-instinctive skill in piano-playing is mentioned. See Phil. Trans., 1770, p. 54.