Conclusion
Philosophers of biology have long challenged the classical genes-”for ”-paradigm. The field of EvoDevo has traditionally benefitted from intense exchange between philosophers of biology, theoretical biologists, and empirical researchers. EvoDevo scientists now widely agree that the emergence of complex traits derive from developmental processes, often regulated by sensitive periods. Accordingly, “[neurotypic] brain function results from a conserved sequence of developmental processes of cell division, migration, network formation and maturation, directed by intrinsic genetic programs as well as by environmental and systemic cues, extrinsic to the nervous system. Within this sequence, appropriate stimuli induce events of heightened plasticity that are required to develop a given function” (Dehorter & Del Pino, 2020). These phases of heightened plasticity are particularly important in linking genetically guided developmental processes with intrinsic and extrinsic cues. By shaping traits in response to environmental inputs, sensitive periods can critically influence the trajectory of trait development. Alterations of neuroplastic processes can have advantageous effects as exemplified by heterochronic effects in hominid phylogeny that led to an evolutionarily driven expansion of the human neocortex. The dynamic aspects of traits are attributable to genetic and epigenetic regulation as well as environmental factors encountered in the species-specific niche. Complex interactions between genetic predispositions and environmental factors, such as upbringing, culture, or life experiences can have a tremendous impact on the manifestation of certain traits. Moreover, some behavioral traits might be more pronounced during stressful periods and manifest themselves in an extreme manner (Sullivan et al ., 2006). Yet, irrespective of extrinsic factors, traits can also exhibit significant variation due to varying expression that are intrinsically driven and occur at different developmental stages.
Developmental neuroscientists and developmental cognitive scientists have accumulated a wealth of data that corroborate the aforementioned framework. I believe that the time is right to get many more neuroscientists onboard. Rethinking the classical, deterministic paradigm of the gene–trait concept and working towards a philosophical reconceptualization of traits as dynamic attributes tied to ongoing developmental processes, will provide a three-fold advantage: