Charles Darwin only published his treatise "the Origin of Species" after a fellow naturalist, called Wallace, wrote him a letter to inform him that he had come up with a theory of natural selection.
(Before receiving this letter he'd been too scared to go to print because he was a devout Christian, and when he realised what his new scientific theory meant for Christian fundamentalism, he was scared of the backlash he'd receive.)
PS - Hindsight proves him right to have been worried as the 1925 Scopes Monkey Trial proves, and the controversy continues today.