Since dogs have same gestation period as the wolf it is likely that the wolf is the ancestral wild species, if it is just one species.
CD's belief that domestic dogs are descended from several distinct aboriginal species seems to contradict views on sterility of hybrids and variation in Origin. If domestic varieties came from hybrids of wild species it will be impossible to trace ancestry. Opponents will exploit these problems.
Oct. 28. 1859
My dear Darwin
Many thanks for yr clear explanation of Pallas's views. Carpenter tells me that the variations of period of gestation in cows rabbits
& some other domesticated animals is said by experimenters of authority, Qy
Gärtner? to vary as much as
As soon as I get your book I shall attentively reread it & try to reconcile the admission with several propositions there laid down as to sterility of hybrids & laws of variation which as I read them seemed to me fundamentally opposed to the admission of our existing races of the dog coming from several wild or aboriginal canine species.
I understand you to say that selection under domestication rarely does in a shorter time what Nature might do in a longer.
I also thought, to borrow Hooker's language, that variation was a centrifugal, & crossing or hybridism a centripetal force. This would all accord with the doctrine that after a wolf, fox & jackall existed descending from some remote prog-enitor, one of them, the wolf, might produce the Esquimaux dog, the bull dog, the Italian greyhound, the shepherd's dog & so on, but if the three wild species above mentioned could produce any or all these races of dogs (or incipient species) by coalescing & interbreeding, I find it impossible to hope to trace any clue to the past transformations of species or their probable birthplaces
I cannot help thinking that by taking this concession, one which regards a variable species, about which we know most (little tho' it be) an adversary may erect a battery against several of your principal rules, & in proportion as I am perverted I shall always feel inclined to withstand so serious a wavering. I marked your passage of northern species over tropical plains, & approved of it, as you may remember I once proposed to bring certain Madeira shells over Africa during the Glacial period.
- f1 2512a.f1See letter to Charles Lyell, 25 October .
- f2 2512a.f2Lyell refers to William Benjamin Carpenter and Karl Friedrich von Gärtner.
- f3 2512a.f3As originally coined by Antoine Nicolas Duchesne, the term ‘atavisme’ referred to the tendency for plant varieties to revert to the type. Augustin Pyramus de Candolle discussed the phenomenon in A. P. de Candolle 1832, 2: 737–40.
- f4 2512a.f4The terms were used by Joseph Dalton Hooker in Hooker 1844–7, p. 315. CD had discussed their meaning with Hooker in 1846 (see Correspondence vol. 3, letter from J. D. Hooker, 1 February 1846, and letter to J. D. Hooker, [16 April 1846]).