In the 1930s, Soviet economist Nikolai Kondratiev developed a theory of socio-technological cycles that he considered to be an integral aspect of the economic structure. Kondratiev waves may be understood as an inherent, dynamic component of economic development, one which occurs with certain regularity. At the same time, however, modern societies have become ever-more complex networks of policy, technology and economy. The financial crisis that began in 2008 was the turning point upon which the fifth Kondratiev wave reached its demise and the new socio-economic cycle began. In the early 1970s, a group of leading system analysts at the Massachusetts Institute of Technology (MIT) built the world's first simulation model, which used a set of parameters to evaluate global development over the course of the next 130 years. The model has been used to assess the impacts of alternative policies on global emissions and other parameters.