 One of the most central topics of early philosophy of biology in the 1960s and 1970s was the attempt to develop a suitable conceptual framework that would support the parting between development and evolution in line with the central assumption of the Modern Synthesis that evolution is a change in the genetic composition of populations only (Dobzhansky 1951: 16; see also Charlesworth et al. 2017). This means, as a consequence, that development does not (or not in significant ways) causally effect evolution. Over the decades this assumption has been supported by the historically influential conceptual distinction between proximate causes and ultimate causes (Mayr 1961).