 This brings us to a fourth ontological point: developmental plasticity, which is considered to bias or even guide evolutionary trajectories (West-Eberhard 2003; Radersma et al. forthcoming). The concept of plasticity states that development can be regulated in important ways by the environment. This rules out genetic determinism (but not necessarily environmental determinism; see Waggoner and Uller 2015). In the original conception of phenotype production (i.e., development), Wilhelm Johannsen (1909) had pointed out that the phenotype is the product of both the genotype and environmental circumstance, and Woltereck (1909; see also Sarkar 1999) argued that what was inherited is the “Reaktionsnorm”, a potential to generate phenotypic variations in response to environmental agents. In line with this view, many embryology texts in the late 1800s (e.g., Hertwig 1894) had promulgated the perspective that development demanded both the interactions between embryonic cells and the further interactions of those cells with the environment (see Nyhart 1995).