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Darwin Correspondence Project

To Charles Lyell   1 September [1860]

Down Bromley Kent

Sept 1.

My dear Lyell

I have been much interested by your letter of 28th, received this morning. It has delighted me, because it demonstrates that you have thought a good deal lately on Nat. selection. Few things have surprised me more than the entire paucity of objections & difficulties new to me in the published reviews. Your remarks are of a different stamp & new to me. I will run through them & make a few pleadings such as occur to me.

I put in the possibility of Galapagos having been continuously joined to America out of mere subservience to the many who believe in Forbes’ doctrine,1 & did not see the danger of admission; about small mammals surviving there in such case. The case of Galapagos, from certain facts on littoral sea-shells, (viz Pacific ocean & S. American littoral species) in fact convinced me more than in other case of other islands that Galapagos had never been continuously united with the mainland: it was mere base subservience & terror of Hooker & Co.—2

With respect to atolls I do not think mammals wd. hardly survive very long even if main islands (for as I have said in Coral-Book outline of groups of atolls do not look like a former continent)3 had been tenanted by mammals, from the extremely small area, the very peculiar conditions, & the probability that during subsidence all or nearly all atolls have been breached & flooded by sea many times during their existence as atolls.—

I cannot conceive any existing reptile being converted into a Mammal. From homologies I shd. look at it as certain that all Mammals have descended from some single progenitor. What its nature was, it is impossible to speculate. More like, probably, the Ornithorhynchus or Echidna than any known form as these animals combine Reptilian characters (& in lesser degree Bird character) with Mammalian. We must imagine some form as intermediate as is Lepidosiren now in between Reptiles & Fish, between Mammals & Birds on the one hand (for they retain longer the same embryological character) & Reptiles on the other hand. With respect to a mammal not being developed on any island, besides want of time for so prodigious a development, there must have arrived on the island, the necessary & peculiar progenitor having characters like the embryo of a mammal, & not an already developed reptile, Bird or Fish.— We might give to a Bird the habits of a mammal, but inheritance would retain almost for eternity some of the bird-like structure, & prevent our new creation ranking as a true mammal.—

I have often speculated on antiquity of islands, but not with your precision or at all under the point of view of Natural selection not having done, what might have been anticipated. The argument of littoral miocene shells at Canary Isd is new to me.— I was deeply impressed from amount of denudation of antiquity of St. Helena, & its age agrees with peculiarity of Flora.—

With respect to Bats at N. Zealand (N.B there are 2 or 3 Europeans Bats in Madeira & I think in Canary Islands) not having given rise to group of non-volant &c Bats, is, now you put the case surprising, more especially as the genus of Bats is in N. Zealand very peculiar, & therefore has probably been long introduced, & they now speak of Cretacean fossils there. But the first necessary step has to be shown, namely of a Bat taking to feed on the ground or anyhow & anywhere except in the air: I am bound to confess I do know one single such fact. viz of an Indian species killing frogs.

Observe that in my wretched polar bear case I do show the first step by which conversion into a whale “would be easy”—“would offer no difficulty.”!! So with Seals, I know of no fact showing any the least incipient variation of seals feeding on the shore. Moreover seals wander much: I searched in vain & could not find one case of any species of Seal confined to any island; & hence wanderers would be apt to cross with individuals undergoing any change on an island, as in case of land-birds of Madeira & Bermuda. The same remark applies perhaps even to Bats, as they frequently come to Bermuda from the mainland, though about 600 miles distant.

With respect to the Amblyrhynchus of Galapagos; one may infer as probable, from marine habit being so rare with Saurians & from the terrestrial species being confined to a few central islets, that its progenitor first arrived at the Galapagos; from what country it is impossible to say as its affinity (I believe) is not very close to any known species. The offspring of the terrestrial species was probably rendered marine. Now in this case I do not pretend I can show variation in habits; but we have in the terrestrial species a vegetable feeder (in itself a rather unusual circumstance) largely on lichens, & it would not be a great change for its offspring to feed first on littoral algæ & then on submarine algæ.

I have said what I can in defence; but yours is a good line of attack. We should, however, always remember that no change will ever be effected till a variation in habits or structure or of both chance to occur in right direction so as to give the organism in question an advantage over other already established occupants of land or water; & this may be in any particular case indefinitely long.—   I am very glad you will read my Dogs M.S; for it will be important to me to see what you think of balance of evidence.4 After long pondering on a subject it is often hard to judge.—

With hearty thanks for your most interesting letter. Farewell | My dear old Master | C. Darwin

Emma & self wrote a few days ago to you.—

Footnotes

Edward Forbes postulated the existence of former land-bridges to explain geographical distribution patterns between islands and neighbouring areas of Europe (E. Forbes 1846). The possibility of the Galápagos and Cape Verde Islands having been joined to the nearest continents by continuous land is mentioned in Origin, pp. 398–9. In the sixth edition, CD inserted the parenthetical phrase ‘though I do not believe in this doctrine’ (Peckham ed. 1959, p. 631).
CD stated his objections to Forbes’s theory in 1846 and again in 1856 when he vigorously debated the question with both Joseph Dalton Hooker and Lyell. CD believed there was insufficient geological evidence to be able to assume the existence of land-bridges and that Forbes and Hooker were misguided in laying so much emphasis on them. Between 1856 and 1858, CD conducted a long series of experiments on the means by which organisms could be transported across oceans to reduce the theoretical necessity for land connections. He discussed his findings at length with Hooker. See Correspondence vols. 3–6.

Bibliography

Coral reefs: The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle, under the command of Capt. FitzRoy RN, during the years 1832 to 1836. By Charles Darwin. London: Smith, Elder & Co. 1842.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Forbes, Edward. 1846. On the connexion between the distribution of the existing fauna and flora of the British Isles, and the geological changes which have affected their area, especially during the epoch of the Northern Drift. Memoirs of the Geological Survey of Great Britain, and of the Museum of Economic Geology in London 1: 336–432.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.

Summary

Discusses at length CL’s criticisms of natural selection.

Comments on possible former connection between the Galapagos and South America.

Discounts survival of mammals on atolls.

Discusses reptile origin of mammals.

Discounts development of a mammal on an island and the descent of mammals from a bird.

The antiquity of islands.

Comments on bats of New Zealand. Geographical distribution of seals. Discusses Amblyrhynchus.

Glad CL will read his MS on origin of dogs [Variation 1: 15–43].

Letter details

Letter no.
DCP-LETT-2903
From
Charles Robert Darwin
To
Charles Lyell, 1st baronet
Sent from
Down
Source of text
American Philosophical Society (Mss.B.D25.225)
Physical description
4pp

Please cite as

Darwin Correspondence Project, “Letter no. 2903,” accessed on 2 April 2020, https://www.darwinproject.ac.uk/letter/DCP-LETT-2903.xml

Also published in The Correspondence of Charles Darwin, vol. 8

letter