 However, over 20 years after the diagnosis, it seems that the memetic approach has, by and large, been abandoned, with some of its insights incorporated into other evolutionary approaches to culture. Perhaps the most successful is dual-inheritance theory (Richerson &amp; Boyd 2008), also known as gene-culture coevolution. A very general characterization of sociocultural evolution has been attempted by El Mouden, André, Morin, and Nettle (2014). This approach, which relies on the most abstract formalism used by evolutionary theorists—namely, the Price equation (for an introduction to the Price equation see Okasha 2006: Chapter 1)—highlights some of the differences between biological and sociocultural evolution, and why a pure memetic approach seems difficult to implement as a general framework.