‘The evolution of consciousness’ begins with two questions. Firstly, which living creatures are conscious and in what way? Secondly, when and how did consciousness evolve? Consciousness could be an all-or-nothing phenomenon, with some creatures having it and others not. Or it might be a continuous variable, with some having more than others. The theories of evolution of consciousness range from those that place its origin way back with the emergence of life itself, through intermediates linking it with the evolution of perception, intelligence, or other general abilities, to those that tie it to language, imitation, or memes. The future of consciousness research is also considered.