Did Darwin delay publishing his theory of evolution by natural selection because he feared an outcry from the establishment? This has been a popular belief, and has been stoked by the fact that although Darwin began formulating the theory in 1837, he did not publish On the Origin of Species until 1859.

Now John van Wyhe, a science historian at the University of Cambridge, UK, says that after a painstaking trawl through the letters, notes and books written by, to or about Darwin, he can rule out the idea once and for all. But van Wyhe's work has irritated several prominent historians, who argue that he has gone too far in downplaying ideas about Darwin's reluctance to publish. “Portraying Darwin as having no feelings or reactions to the outside world warps the biographical picture,” says David Kohn, editor of the Darwin Digital Library of Evolution.

Darwin scholars have long pondered over the time it took to publish Origin of Species. According to van Wyhe, the idea that Darwin delayed because he was scared to publish a theory that so obviously contradicted religious beliefs about creation has dominated both popular and scholarly accounts of the man for decades. But in a study published this week in Notes and Records of the Royal Society (doi:10.1098/rsnr.2006.0171; 2007), van Wyhe concludes that there is no direct evidence for the idea, and that it is simply a myth that has passed down the generations without question.

It has been thought that Charles Darwin (left) delayed publication of his theory of evolution because of concerns over the public's reaction to it. Credit: BETTMANN/CORBIS

Darwin and those who knew him never unambiguously referred to a delay in publishing.

To carry out his study, Van Wyhe searched for the word “delay” in primary and secondary sources covering the period in which Darwin was working on Origin of Species. He says Darwin and those who knew him never unambiguously referred to a delay in publishing, or gave any explanation for the 20-year 'gap'. Indeed, in all the texts on Darwin, he says, the earliest reference to a delay appears in the 1940s. Only in a 1948 popular book, Darwin: Before and After, in which Robert Clark describes how Darwin was made ill by “an uncertainty that he allowed to haunt him for twenty years”, do you see all the elements of the modern story, says van Wyhe.

The historian further argues that in letters to friends, family and colleagues, Darwin continually communicated his belief that species could change, and that this is inconsistent with the notion that he was keeping his heretical ideas secret during this period. He even paid copiers on at least two occasions to produce early drafts of his species theory.

By documenting exactly what he was doing during the 'gap years', van Wyhe makes the case that Darwin just didn't get down to writing Origin of Species until he had completed other work in hand, including an eight-year study of barnacles. He was determined to build a formidable mass of documentation supporting his theory and to solve major stumbling blocks, such as that posed by non-reproductive castes of social insects. This, together with a busy personal life but poor health, filled the years. In other words, Darwin did not postpone publication; he just didn't publish until he was ready. “In my view, this settles the question once and for all,” says van Wyhe.

Janet Browne, a science historian at Harvard University in Cambridge, Massachusetts, reckons that van Wyhe's study is a valuable piece of work. “It may not shake the world, but it's an important point to make,” she says.

But several Darwin scholars are not convinced. Kohn and others agree that the way in which cultural and social pressures influenced Darwin's decisions may have been overplayed, particularly in the public arena, with less attention being paid to the involved process of scientific discovery. But the consensus in the field is likely to remain that a multitude of factors underpinned Darwin's delay.

Kohn points out that searching for explicit references to a “delay” is a simplistic approach to the problem, and that other factors should be considered. For example, Darwin often criticized religion in his notebooks, which suggests that he would have been aware of the probable implications of his theory for religion. It is hard to see how the absence of specific references to a delay rules out any influence of cultural and societal factors on Darwin's decisions, agrees David Quammen, author of The Reluctant Mr Darwin.

Kohn also points out that in Darwin's later publication The Descent of Man, which applied the theory of evolution to humans, Darwin specifically states in the opening lines that he delayed publishing this tome until he was convinced that the climate was right. It seems likely, therefore, that he would have been aware of the controversy his theories would cause from the outset, and probably avoided discussing humans in Origin of Species for this reason.