Accepted manuscript of Meloni, M. (2017). Disentangling life: Darwin, selectionism, and the postgenomic return of the environment. Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences, 62, 10-19. Pls cite from final published version at: http://dx.doi.org/10.1016/j.shpsc.2017.02.002 1 Disentangling life: Darwin, selectionism, and the postgenomic return of the environment (2017) Maurizio Meloni Abstract In this paper, I analyze the disruptive impact of Darwinian selectionism for the century-long tradition in which the environment had a direct causative role in shaping an organism’s traits. In the case of humans, the surrounding environment often determined not only the physical, but also the mental and moral features of individuals and whole populations. With its apparatus of indirect effects, random variations, and a much less harmonious view of nature and adaptation, Darwinian selectionism severed the deep imbrication of organism and milieu posited by these traditional environmentalist models. This move had radical implications well beyond strictly biological debates. In my essay, I discuss the problematization of the moral idiom of environmentalism by William James and August Weismann who adopted a selectionist view of the development of mental faculties. These debates show the complex moral discourse associated with the environmentalist-selectionist dilemma. They also well illustrate how the moral reverberations of selectionism went well beyond the stereotyped associations with biological fatalism or passivity of the organism. Rereading them today may be helpful as a genealogical guide to the complex ethical quandaries unfolding in the current postgenomic scenario in which a revival of new environmentalist themes is taking place. Keywords: Environment- Darwin James- Weismann- Epigenetics- Postgenomics 1. The social significance of selectionism: revisiting the case in the postgenomic age We possess a well-defined picture of the way in which Darwin’s natural selection absorbed and projected some of the wider social values of his time onto nature, as well as many of the intellectual sources (Malthus in primis) behind this transfer of values. However, the reverse relationship, the impact of Darwinian selectionism on the wider social and intellectual landscape remains a much more problematic area of investigation. Here, truly bogeymen terms such as Social Darwinism or eugenics have historically hampered a balanced evaluation, regardless of the tenuous historical validity of the former (Bannister, 1988), and the less than direct relationship of Darwin with the latter (Paul, 2009). Selectionism remains mostly a bad word outside of biological circles, where the term is still associated with crude ideas of merciless competition, harsh mili- tarism, extermination of ‘inferior races’, or a sanction for the