On the history page of the Mind-Mapping.org Blog I used to have an image of a branching structure that I thought was by Leonardo da Vinci - from one of his notebooks. Then, Pablo Marin-Garcia of the European Bioinformatics Institute just wrote and kindly gave me an authoritative reference to indicate that it was actually by Charles Darwin. It was Darwin's first attempt at drawing a tree of life and not a mind map at all because it indicates his early thinking on how species might be connected.
I've seen quotes from time to time, not least by Tony Buzan, that da Vinci was an early mind mapper but I haven’t been able to find any evidence to back that up. Can anyone help by pointing me towards some evidence that da Vinci did anything like mind mapping? Of course he illustrated his notes profusely, but that clearly is not enough.