 A second proposal, advanced by Paul Griffiths and Karola Stotz, explicitly suggests taking explanandum and explanans to be picked out by different uses of the expression "human nature". In both cases, the “nature” in question is that of the taxon, not of individual organisms. The former use simply refers to “what human beings are like”, where “human beings” means all species specimens. Importantly, this characterisation does not aim at shared characteristics, but is open for polymorphisms both across a population and across life stages of individual organisms. The causal conception of human nature, what explains this spectrum of similarity and difference in life histories, is equated by Griffiths and Stotz with the organism-environment system that supports human development. It thus includes all the genetic, epigenetic and environmental resources responsible for varying human life cycles (Griffiths 2011: 319; Stotz &amp; Griffiths 2018, 66f.). It follows that explanatory human nature at one point in time can be radically different from human nature at some other point in time.