Peter Kropotkin (1842-1921) was not only a leading anarchist thinker but also a world-renown scientist. While a noted geographer, he also wrote extensively on evolutionary theory. In this lecture, translated into English for the first time since it was given in 1893, he discusses how ethics could develop by means of natural selection. As with Mutual Aid and its discussion of the role of co-operation in evolution, his arguments were pioneering and vindicated by later research. A new translation by Iain McKay.