Peter Valentinovich Turchin (/ˈtɜːrtʃɪn/; Russian: Пётр Валенти́нович Турчи́н, IPA: [ˈpʲɵtr vəlʲɪnʲˈtʲinəvʲɪtɕ tʊrˈtɕin]; born 22 May 1957)[1] is a Russian-American complexity scientist, specializing in an area of study he and his colleagues developed called cliodynamics—mathematical modeling and statistical analysis of the dynamics of historical societies.

Turchin developed an original theory explaining how large historical empires evolve by the mechanism of multilevel selection.

[5] His research on secular cycles[6] has contributed to our understanding of the collapse of complex societies as has his re-interpretation of Ibn Khaldun's notion of asabiyya as "collective solidarity".

[9][10] He subsequently cited the success of Donald Trump's 2016 presidential campaign as evidence that "negative trends seem to be accelerating" and that there has been an "unprecedented collapse of social norms governing civilized discourse".

[11] In 2020, Turchin and Jack Goldstone predicted that political and civic unrest in the United States would continue regardless of the party in power until a leader took action to reduce inequality and improve the social indicators that are tracked in their research.

He is the founder of the journal, Cliodynamics, "...dedicated to 'the search for general principles explaining the functioning and dynamics of historical societies'",[2] and manages a blog, Cliodynamica.