Who's afraid of epigenetics? Habits, instincts, and Charles Darwin’s evolutionary theory

Abstract

Our paper aims at bringing to the fore the crucial role that habits play in Charles Darwin’s theory of evolution by means of natural selection. We have organized the paper in two steps: first, we analyse value and functions of the concept of habit in Darwin's early works, notably in his Notebooks, and compare these views to his mature understanding of the concept in the Origin of Species and later works; second, we discuss Darwin’s ideas on habits in the light of today’s theories of epigenetic inheritance, which describe the way in which the functioning and expression of genes is modified by the environment, and how these modifications are transmitted over generations. We argue that Darwin’s lasting and multifaceted interest in the notion of habit, throughout his intellectual life, is both conceptually and methodologically relevant. From a conceptual point of view, intriguing similarities can be found between Darwin’s (early) conception of habit and contemporary views on epigenetic inheritance. From a methodological point of view, we suggest that Darwin’s plastic approach to habits, from his early writings up to the mature works, can provide today’s evolutionary scientists with a viable methodological model to address the challenging task of extending and expanding evolutionary theory, with particular reference to the integration of epigenetic mechanisms into existing models of evolutionary change. Over his entire life Darwin has modified and reassessed his views on habits as many times as required by evidence: his work on this notion may represent the paradigm of a habit of good scientific research methodology.

Epigenetics Role in Spermatozoa Function: Implications in Health and Evolution—An Overview

“…The environmental effect in epigenetics [ 33 ] and its reversibility [ 29 ] may present adaptative intragenerational implications [ 4 , 10 , 30 ]. Taking also into account its heritability through germ cells, it arises the idea of “accelerated evolution”, whose attributes recall the evolution models of Landmark and the Pangenesis of Darwin and gives them a molecular explanation [ 10 , 21 , 27 , 50 , 54 ]. This phenomenon would consist of the organism’s adaptation to the environment by means of epigenetics and the subsequent transmission to the next generations via gametes of some of the acquired features (damaging, neutral or beneficial) [ 10 , 30 , 50 ].…”

From Environmental Epigenetics to the Inheritance of Acquired Traits: A Historian and Molecular Perspective on an Unnecessary Lamarckian Explanation

“…In the eighteenth century, the belief in the inheritance of acquired characters was universal, and it was cited by different Authors, including, for instance, Georges-Louis Leclerc, Comte de Buffon, and Erasmus Darwin [49]. The inheritance of acquired characters was also accepted by Johann Friedrich Blumenbach, Thomas Burnet, Pierre-Louis Moreau de Maupertuis, and Jacques DuBois [49], and it was also present in the early writings of Charles Darwin [50].…”

The behavioral origins of phylogenic responses and ontogenic habits

“…[B]ehavioral genetics and genomics, especially for animals in natural populations, lend some plausibility to the phenotypic plasticity view . (emphasis added)Much evidence supports the possibility that initial phenotypic variation may become fixed in an evolving population (e.g., Badyaev, 2009; Ginsburg & Jablonka, 2010; Haig, 2007; Heyes et al, 2020; Jablonka & Lamb, 2005; Moray & Connolly, 1963; Portera & Mandrioli, 2021; Tierney, 1986). Robinson & Barron (2017) point to the possibility that instinct and learning share cellular and molecular mechanisms.…”