Mutual Aid: A Factor of Evolution is a 1902 essay collection by Russian anarchist philosopher Peter Kropotkin. The essays, initially published in the English periodical The Nineteenth Century between 1890 and 1896, explore the role of mutually-beneficial cooperation and reciprocity (or "mutual aid") in the animal kingdom and human societies both past and present. It is an argument against the competition-centred theories of so-called social Darwinism, as well as the romantic depictions of cooperation presented by writers such as Jean-Jacques Rousseau, who argued it was motivated by universal love rather than self-interest. Mutual Aid is considered a fundamental text in anarchist communism, presenting a scientific basis for communism alternative to the historical materialism of the Marxists. Many biologists also consider it an important catalyst in the scientific study of cooperation.