Extending the Evolutionary Synthesis: an Epigenetic Perspective

Abstract.  The construction of the “Modern Evolutionary Synthesis” in the mid-twentieth century involved the exclusion of soft inheritance – the inheritance of the effects of developmental modifications – and, by implication, the possibility of any form of “Lamarckian” evolution. However, in later decades, discoveries of molecular-epigenetic mechanisms that can support such inheritance led to a broadening of the notion of biological heredity. After discussing the historical context in which this change occurred, I present an extended notion of inheritance, focusing on epigenetic inheritance and its underlying mechanisms. I examine the evidence for the ubiquity of epigenetic inheritance, point to the emerging evidence suggesting that epigenetic inheritance contributes to adaptive evolutionary change and macro-evolution, and discuss the kind of models that can capture evolutionary dynamics that incorporate multiple paths and types of information acquisition and transmission. I argue that these considerations require an extension of the evolutionary synthesis beyond the current neo-Darwinian model.