Self-Domestication: From Analogy to Homology via Genomics

Abstract

This paper seeks to clarify central aspects of the “self-domestication” hypothesis and its implications for the evolution of our species. It does so by reconstructing the evolutionary trajectory of the intuition at the heart of the hypothesis, showing what the hypothesis is not, and then proceeding to a critical review of the molecular mechanisms that have been suggested to underlie domestication processes. We propose a pre-domestication phase which can solve several lines of criticism around (self)-domestication, schematically outline the most parsimonious set of events that could have led to domestication in our lineage, and highlight specific genes within this framework, that can serve as regulatory hubs for experimental testing of human evolution in physiologically relevant models that recapitulate the key cellular lineages involved. Crucially, we show how (ancient) genomics can help us go beyond analogies and make the original intuition behind “self-domestication” stronger.

What made us “hunter-gatherers of words”

“…My starting point to gain insight into the underpinnings of socio-demographic differences across closely related species comes from evidence in favor of a hypothesis that has gained traction in recent years, the “self-domestication” hypothesis (Hare, 2017 ; Theofanopoulou et al, 2017 ; Wrangham, 2019 ; Zanella et al, 2019 ; Boeckx et al, 2022 ; Spikins, 2022 ). Part of the reason this hypothesis is currently popular stems from the possibility of identifying deep homology and convergence of molecular mechanisms between canonical domesticated species like dogs and species claimed to have undergone a similar process of reduction in reactive aggression (possibly coupled with, or followed by a neurocristopathic process).…”

“…Specifically, he posits a first stage of domestication, relaxing constraints, which set the stage for a subsequent stage of (sexual) selection promoting song complexity within the Bengalese finch lineage. Such multi-step scenarios are also considered in the history of other domesticates (Boeckx et al, 2022 ; Herbeck et al, 2022 ). In the case of language evolution and change, they may correspond to the establishment and maintenance of norms or conventions (Hawkins et al, 2022 ), distinguishing communities of language users (Iacozza et al, 2019 ), in which, in Goldberg ( 2019 )'s terms, speakers balance between Expressiveness (communication) and Efficiency (compression) while conforming to conventions, resulting in the pervasive phenomenon of “partial productivity.”…”

Loquens : A characterization of “Hunter-Gatherers of Words”

“…My starting point to gain insight into the underpinnings of socio-demographic differences across closely related species comes from evidence in favor of a hypothesis that has gained traction in recent years, the "selfdomestication" hypothesis (Hare, 2017;Theofanopoulou et al, 2017;Wrangham, 2019;Zanella et al, 2019;Spikins, 2022;Boeckx et al, 2022). Part of the reason this hypothesis is currently popular stems from the possibility of identifying deep homology and convergence of molecular mechanisms between canonical domesticated species like dogs and species claimed to have undergone a similar process of reduction in reactive aggression (possibly coupled with, or followed by a neurocristopathic process).…”

“…Specifically, he posits a first stage of domestication, relaxing constraints, which set the stag for a subsequent stage of (sexual) selection promoting song complexity within the Bengalese finch lineage. Such multi-step scenarios are also considered in the history of other domesticates (Boeckx et al, 2022;Herbeck et al, 2022). In the case of language evolution and change, they may correspond to the establishment and maintenance of norms or conventions (Hawkins et al, 2022), distinguishing communities of language users (Iacozza et al, 2019), in which, in Goldberg (2019)'s terms, speakers balance between Expressiveness (communication) and Efficiency (compression) while conforming to conventions, resulting in the the pervasive phenomenon of "partial productivity".…”

Modelling of factors underlying the evolution of human language

“…The process of self-domestication refers to a complex process involving physiological, morphological and behavioural changes leading to a reduction in reactive aggression, characteristic of domesticated species (Wilkins et al, 2014;Hare & Woods, 2020;Wrangham, 2019). The physical manifestation of self-domestication, that is, the retraction of the face, has been linked to a reduced migration rate and production of neural crest cells (Zanella et al, 2019), but tameness itself may implicate a series of changes in key neurotransmitters (Boeckx et al, 2022). It has been argued that self-domestication is a plausible mechanism behind the evolution of 'ultrasocial' behaviours and higher levels of cooperation exhibited by our species (Hare & Woods, 2020).…”