Philosopher Thomas Hobbes called it ‘the lust of the mind.’ Former first lady Eleanor Roosevelt said it was ‘the most useful gift.’ And, yes, we all know what killed the cat. But ask a group of scientists to define curiosity and you’ll get a rousing debate. No more, argue researchers in a review of curiosity science. They propose it’s time for researchers to organize and focus on curiosity’s function, evolution, mechanism, and development.