The aid of Francis Darwin, his son is important here. The chief sources of information are the two editions of the "Journal of Researches," and his early notes and queries printed after his death. The first edition of the "Journal" was finished in 1838, though not published till the following year. It was in October, 1838, that he read Malthus's "Essay on Population," the incident that started him on the road to natural selection. The first edition of the "Journal" was, consequently, practically uninfluenced by his famous causal hypothesis.
Discussing this early period of his father's ideas, the son writes:
After reading the second edition of the "Journal" (published in 1845) we find a strong sense of surprise at how far developed were his views in 1837.[1]
It will be observed that 1837 was the year before the Malthus essay was read. But the evidence from posthumous notes is more to the point. The son remarks:
We are enabled to form an opinion on this point from the note-books in which he wrote down detached thoughts and queries.
From these I quote a few.
Propagation explains why modern animals same type as extinct, which is law, almost proved.
If we choose to let conjecture run wild, then animals, our fellow brethren in pain, disease, death, suffering and famine—our slaves in the most laborious works, our companions in our amusements—they partake (of) our origin in one common ancestor—we all may be melted together.
It is a wonderful fact, horse, elephant, and mastodon, dying out about same time in such different quarters.
They die, without they change, like golden pippins; it is a generation of species like generation of indivduals.
. . . so with useless wings under elytra of beetles—born from beetles with wings, and modified; if simple creation merely, would have been without them.
So much for evidence that Darwin was an evolutionist before he was a natural selectionist or had any other causal hypothesis. As to the relative value set by him on his part in establishing the "mere fact" of evolution, and his effort to explanation of that fact, the son's testimony is again important. He writes:
It comes out very clearly that. . . my father did not rejoice over the success of his special view of evolution, viz., that modification is mainly due to natural selection; on the contrary, he felt strongly that the really important point was that the doctrine of Descent should be accepted.[2]
Any one who knows Darwin's life-work in spirit as well as in letter will accept this statement unhesitatingly. Utterances of like import by Darwin himself are numerous. For brevity's sake I give but one. Writing to Asa Gray in 1863, he said:
