When did Darwin ‘clearly conceive’ his theory of evolution?

ABSTRACT

Darwin’s theory of evolution by natural selection as espoused in his classic book, On the Origin of Species, constitutes one of the most important scientific advances of the last millennium. In his autobiography, Darwin apparently claimed to have ‘clearly conceived’ the theory in 1839, but the Origin was not published until 1859, following a brief excerpt of his theorizing published in mid-1858. Much scholarship has been devoted to explaining this apparent gap. Yet, examination of Darwin’s explicit theorizing fails to support the generally accepted ‘clear conception’ by 1839 as an accurate reference to an immature version of the Origin theory, a theory of continuous and universal organic change. However, by articulating both broad and narrow versions of the theory, as well as considering the inevitable theory development over decades, Darwin’s ‘clear conception’ is explained in relation to two distinct broad theories and the enduring core element, the mechanism of natural selection. This explanation casts the famous ‘gap’ in an entirely new light.

KEYWORDS:

• Darwin
• evolution theory
• natural selection
• publication gap
• 1844 Essay
• Darwin’s delay

Acknowledgements

Whilst not explicitly focused on the present paper, I would like to thank Janet Browne, Jim Moore, John van Wyhe, Jon Hodge, George Beccaloni, Charles Smith and Jim Costa for entering into repeated, relevant, and helpful email discussions. However, their general support and guidance should not be taken as an endorsement of my views presented here. I also acknowledge the support of the University of Exeter, primarily by providing access to a variety of scholarly archives and libraries.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1. Sir David Attenborough’s television documentaries invariably credit Darwin with this early conception, e.g. ‘Attenborough: the forgotten story of Alfred Russel Wallace’, BBC Science, http://www.bbc.co.uk/science/0/24837130 (accessed 22/5/2017), states that when Darwin received Wallace’s paper ‘he himself had exactly the same idea some 16 years earlier’. This appears to be a reference to Darwin’s 1842 sketch, the immediate precursor of the 1844 Essay, a pre-theoretical document variously described by generally supportive commentators as ‘decidedly garbled … crabbed, elliptical scrawl’ (Browne 1995, p. 437), and for his son Francis it was ‘more like hasty memoranda … than material for the convincing of others’ (Darwin 1909, p. xx). Similarly, ‘Bill Bailey’s Jungle Hero’, a BBC television documentary, although founded upon lessening the ‘total injustice’ of Wallace’s obscurity, also accepted without question that ‘seventeen years before Wallace had sent off the Sarawak Law [1855] Darwin had already cracked the idea of natural selection … so fearful, he didn’t publish. He kept quiet’. This is true only if it is strictly confined to the ‘idea of natural selection’, but the subsequent reference to reluctance to publish implies the broad theory connotation. http://www.bbc.co.uk/iplayer/episode/p0160p2p/bill-baileys-jungle-hero-2-wallace-in-the-spice-islands (accessed 25 May 2017).

2. Although the Origin was explicitly only an abstract of his planned ‘species book’.

3. Darwin’s autobiographical claim (Barlow 1958, p. 120) of the key insight not gained until October 1838 from reading ‘Malthus on Population’, perhaps one of the ‘inconsistencies’ mentioned in general by Smith.

4. Ospovat’s 1981 book, which makes a strong case for two theories, was titled ‘The Development of Darwin’s Theory’, thereby implying the consensus, single theory, view that he was disputing. Replacing ‘Theory’ with ‘Theorizing’ might have been more appropriate without flying directly in the face of orthodox opinion.

5. In 1858, it was Wallace, not Darwin, that explicitly likened the principle of balance in nature – ‘a deficiency in one set of organs always being compensated by an increased development of some others’ – to the action of ‘the centrifugal governor of the steam engine’ (Darwin and Wallace 1858, p. 62).

6. It was proposed in an anonymous scholarly review that by inclusion of this phrase in 1857 ‘Darwin is indeed saying that his selection dynamic and the divergence principle operate universally in space and time’. Hence, the Origin theory was announced in mid-1858 – personal communication June 2017.

7. A progressive formulation in contrast to, for example, Edward Blyth’s (1835) conservative, status-quo preserving, formulation of natural selection as a mechanism for weeding out ill-adapted variants: ‘Intended by Providence to keep up the typical qualities of a species’. The difference hinges on the possibility of beneficial variants rather than only detrimental ones which would necessarily be the case in a world of perfectly adapted organisms.

8. As Richard England, for example, has argued persuasively: the focus of the 1858 presentation was on varieties and ‘must be understood in light of the content of the communication itself, and what they regarded as its zoological context: the question of the difference between varieties and species, rather than that of transmutation’ (England 1997, p. 268). The presentation was entitled ‘On the tendency of species to form varieties; and on the perpetuation of varieties & species by means of natural selection’, published with the running head ‘Tendency of species to form VARIETIES’.