Charles Darwin opened a notebook in 1837 and began to record his emerging ideas on ‘the species question’. He labeled this notebook, Transmutation of Species. On page 36 he sketched a Tree of Life with ‘I think ’ written above it:

Twenty-two years later, he set out his theory of evolution by natural selection to the public in On the Origin of Species which has become regarded as one of the greatest works in science and human understanding. In this book Darwin writes, amongst many things, about the antiquity of habitable earth, about the gaps in the historical record and about reading landscapes. Of the development of the Tree of Life, Darwin says:

“As buds give rise to fresh buds, these … branch out and overtop…many a feeble branch, so …it has been with the great Tree of Life, which fills with its dead … branches the crust of the earth, and covers the surface [of the earth] with its ever branching and beautiful ramifications.”

(Tree of Life page from Notebook B reproduced from Darwin-online http://darwin-online.org.uk/manuscripts.html, with thanks to Wilma M. Barrett, the Syndics of Cambridge University Library, The Natural History Museum and William Huxley Darwin.)

Thank you The Charles Darwin Trust www.charlesdarwintrust.org for providing this information.