Abstract
Despite remarkable empirical and methodological advances, our theoretical understanding of the evolutionary processes that made us human remains fragmented and contentious. Here, we make the radical proposition that the cultural communities within which Homo emerged may be understood as a novel exotic form of organism. The argument begins from a deep congruence between robust features of Pan community life cycles and protocell models of the origins of life. We argue that if a cultural tradition, meeting certain requirements, arises in the context of such a “social protocell,” the outcome will be an evolutionary transition in individuality whereby traditions and hominins coalesce into a macroscopic bio-socio-technical system, with an organismal organization that is culturally inherited through irreversible fission events on the community level. We refer to the resulting hypothetical evolutionary individual as a “sociont.” The social protocell provides a preadapted source of alignment of fitness interests that addresses a number of open questions about the origins of shared adaptive cultural organization, and the derived genetic (and highly unusual) adaptations that support them. Also, social cooperation between hominins is no longer in exclusive focus since cooperation among traditions becomes salient in this model. This provides novel avenues for explanation. We go on to hypothesize that the fate of the hominin in such a setting would be mutualistic coadaptation into a part-whole relation with the sociont, and we propose that the unusual suite of derived features in Homo is consistent with this hypothesis.
Highlights
An improving empirical picture of hominin evolution is creating a growing theoretical challenge, namely that of piecing together fragments of insight from a wide variety of disciplines, methodologies, and contexts into coherent explanations—the stories of our deep prehistory
We propose that human evolution is best understood as an evolutionary transition in individuality (ETI; e.g., Michod 2007; Leigh 2010; Hanschen et al 2015) that combines evolutionary patterns familiar from earlier ETI but in a radically new type of substrate
We began by arguing the need for new “meta-narratives” and claiming that some variant of our hypothesis potentially may provide one
Summary
An improving empirical picture of hominin evolution is creating a growing theoretical challenge, namely that of piecing together fragments of insight from a wide variety of disciplines, methodologies, and contexts into coherent explanations—the stories of our deep prehistory. We propose that human evolution is best understood as an evolutionary transition in individuality (ETI; e.g., Michod 2007; Leigh 2010; Hanschen et al 2015) that combines evolutionary patterns familiar from earlier ETI but in a radically new type of substrate Key to this new theoretical proposition is the argument that the basic kinetics of early hominin communities closely parallels protocell models of the origin of cellular life: incidentally preadapted chemical vesicles that compartmentalized autocatalytic reaction networks, producing macrolevel evolutionary populations (Gánti 1975, 1997; Hanczyc and Szostak 2004; Rasmussen et al 2004; Filisetti et al 2010; Serra and Villani 2017). In the protocell model of the origin of cellular life, a key property of the phospholipid vesicle is its impermeability to the autocatalytic chemical networks that generate it (see above) This is what structures microlevel inheritance into macrolevel inheritance on the cellular level, it is what protects emerging internal adapted organization, and is what limits the options for components that undermine cooperation. We refer to such an important, generative, and universal tradition as an IGUT
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