[1] His work has made foundational contributions to the fields of cliodynamics, economic history and political demography.
[2][3][4] He was the first scholar to describe in detail and document the long-term cyclical relationship between global population and of political rebellion and revolution.
[5] He was also a core member of the "California school" in world history, which replaced the standard view of a dynamic West and stagnant East with a 'late divergence' model in which Eastern and Western civilizations underwent similar political and economic cycles until the 18th century, when Europe achieved the technical breakthroughs of industrialization.
[8][9][10] In 2013–2015 he was the founding director of the Research Laboratory in Political Demography and Macrosocial Dynamics at the Russian Presidential Academy of National Economy and Public Administration in Moscow.
He has also worked as a consultant of the US government, for example, serving as chair of the National Research Council's evaluation of USAID Democracy Assistance Programs.