Two German art historians are proposing another possibility for Vincent's mutilated ear: that Gauguin did it (see the Guardian article). The book "Van Gogh's Ear and the Pact of Silence" suggests that Gauguin injured Vincent with one of his fencing swords during a fight, either accidentally or intentionally. The two artists, according to this hypothesis, agreed to keep the incident a secret. Now, I am not a big fan of Gauguin and think Vincent's life would have been very different had he not come to Arles, but I am not persuaded. First of all, given that Vincent's ear was sliced only partially, that would have been quite a feat with a fencing sword. Especially 'by accident.'
The Guardian also published a rebuttal blogpost by art and design critic Jonathan Jones.
UPDATE: The Daily Mail also has an article about the new book (thanks for the link, Julianne!) and reveals more of the theory: that the alleged fight between Gauguin and van Gogh was about Rachel. I still am not persuaded Gauguin wounded Vincent with a sword, but otherwise the connection with my novel is really fun...and that's all I'm saying...
UPDATE 2: Wow, this story is being picked up by a lot of news outlets. It's not every day Vincent winds up on TMZ. Martin Gayford, author of the book "The Yellow House," has a rebuttal at Bloomberg.com that I think is spot on (although I think he favors Gauguin more than I do...).