In the historical literature on Charles Darwin one of the commonest assertions (or assumptions) is that there was a long delay (of about twenty years) between Darwin's first formulation of the theory of natural selection, and his publication of that theory in 1858 (followed in 1859 by a fuller publication in the Origin of Species). Based on this assumption the historian or biographer then procedes to speculate on the psychological or social reasons for this extraordinary 'delay'.

I have long been sceptical about this approach. Of course, in one sense there was a delay: we know that Darwin formulated his first private version of natural selection in 1838, and didn't publish it until 1858. But to call this a 'delay' - with the implication that it requires some deep explanation - requires us to assume that everyone should publish the first idea that comes into their head. While this is undoubtedly a common practice - both now and in Victorian times - it isn't necessarily a good one, and it wasn't Darwin's. He liked to do things thoroughly, and most of his major works took years to prepare. As a well-known example, he took about 8 years over his study of barnacles. This isn't unduly long, when we consider that he described about 200 species in 30 genera, each requiring careful comparison and often dissection of many specimens, a reading of all the existing literature on the species, and careful writing up of the results. In fact, at an average of one species every two weeks, it might be considered a rushed job, though it was widely admired by experts at the time and since. (Added: for comparison, Thomas Davidson and Sydney Buckman each spent more than 40 years studying brachiopods and ammonites respectively, but at a higher rate of species per year than Darwin with his barnacles.)

I am therefore pleased to find that the common assumption of a 'delay' is strongly challenged in a recent article by John Van Wyhe, available here. Maybe he slightly protests too much, but in my view he is a great deal more right than wrong. At least there is now no excuse for glib repetition of the usual version.