Sir

I take issue with the contention that Erasmus Darwin, the grandfather of Charles, tackled evolution only in poetic terms, as implied by Dan Graur and colleagues in their insightful Book Review ('In retrospect: Lamarck's treatise at 200' Nature 460, 688–689; 2009).

Erasmus Darwin's most important contributions to evolutionary thought will be found in the very unpoetic prose of the first volume of his major medical and zoological treatise, Zoonomia, published in 1794.

Here, notably in Section 39, are discussions of deep time and the descent of all life from a single ancestor, bauplan homology among vertebrates, the analogy of artificial selection as a means of understanding descent with modification, and a brief but clear enunciation of the process of sexual selection.

One need only to look at the backlash against Erasmus Darwin's evolutionary ideas, in the savage political cartoons of James Gillray in 1798 and of others, to understand that — years before Lamarck made his contributions to evolutionary thought — Erasmus Darwin was triggering strong reactions for promoting a transformist view of biodiversity.

This year is justly celebrating the history-altering contributions of Charles Darwin. But it is equally important to take stock of the critical intellectual steps before 1859 that made scientific and social acceptance of evolution possible.

Besides Erasmus Darwin and Jean Baptiste Lamarck, a host of other influential evolutionists, including Etienne Geoffroy Saint-Hilaire, Robert Chambers, Baden Powell, Herbert Spencer and Alfred Russel Wallace, deserve to be recognized (as well as read) for having laid a path to a modern view of descent with modification.