Williams Syndrome, Human Self-Domestication, and Language Evolution

Abstract

Language evolution resulted from changes in our biology, behavior, and culture. One source of these changes might be human self-domestication. Williams syndrome (WS) is a clinical condition with a clearly defined genetic basis which results in a distinctive behavioral and cognitive profile, including enhanced sociability. In this paper we show evidence that the WS phenotype can be satisfactorily construed as a hyper-domesticated human phenotype, plausibly resulting from the effect of the WS hemideletion on selected candidates for domestication and neural crest (NC) function. Specifically, we show that genes involved in animal domestication and NC development and function are significantly dysregulated in the blood of subjects with WS. We also discuss the consequences of this link between domestication and WS for our current understanding of language evolution.

Abnormal features of human self-domestication in bipolar disorder

“…Further study of the role of imprinting effects, sex differences, and their interaction may also illuminate a conundrum that unfolds in the application of the self-domestication hypothesis to human psychiatric/neurodevelopmental disorders: why is it that human disorders able to be construed as hyperdomesticated phenotypes are characterized by hypersociability (as in the case of WS; see Niego and Benítez-Burraco, 2019) or hypermentalization (as in the case of SZ; see Benítez-Burraco et al, 2017), but rarely both? Psychosis, for example, is rarely seen in WS (though has been reported in a female patient by Salgado and Martins-Correia, 2014), and SZ is characterized by persistent and severe social deficits despite (or perhaps in part because of) hypermentalization (Savla et al, 2013).…”

“…Interestingly, complex genetic conditions involving cognitive deficits, behavioral anomalies, and abnormal socialization patterns, like SZ and ASD, are characterized by abnormal presentations of traits associated with (self-)domestication; moreover, candidate genes for domestication are overrepresented among the candidates for these conditions and/or exhibit altered expression profiles in the brains of affected people (Benítez-Burraco et al, 2016; Benítez-Burraco et al, 2017; Benítez-Burraco, 2020b). But the same pattern holds in conditions with a neat molecular etiology, like WS, as genes outside the affected genomic region that are differentially-expressed in patients are likewise enriched in candidates for domestication (Niego and Benítez-Burraco, 2019). Overall, this supports the view that a deep link exists between cognitive disease and self-domestication (as a crucial aspect of human evolution) and specifically, that examining the presentation of (self-)domestication features in people with BD can help unravel the etiology of this condition.…”

“…Inasmuch as domestication entails a selection for hypersociality and low reactivity—in effect, tameness, the basis of selection in the famous fox farm experiment (Trut, 1999)—personality traits such extraversion and openness are worth noting. For instance, WS has been proposed as a condition of hyperdomestication and is characterized by hypersociability (Niego and Benítez-Burraco, 2019), with the genetic locus involved being correlated with hypersociability in dogs compared to wolves (vonHoldt et al, 2017). Perhaps not surprisingly, in subjects with WS, basal OT and AVP levels are increased, and the increase correlates with the tendency to approach strangers and emotionality (Dai et al, 2012).…”

Autism and Williams syndrome: dissimilar socio-cognitive profiles with similar patterns of abnormal gene expression in the blood

“…Finally, the HPA axis (a major neuroendocrine system resulting from the interaction between the hypothalamus, the pituitary gland, and the adrenal glands) comes into play here, because of its involvement in stress response---particularly, the response to cortisol in the amygdala, the PFC, and the hippocampus--all of them areas implicated in situations of fear and social stress (see Martens et al, 2008;Dedovic et al, 2009;Lense and Dykens, 2013;Bitsika et al, 2015). Both ASD and WS individuals have been shown to exhibit interrupted HPA axis function (Spratt et al, 2012;Jacobson, 2014;Benítez-Burraco et al, 2016;Niego and Benítez-Burraco, 2019, among many others). This might explain in part the prevalence of anxiety in the two disorders, although as mentioned above, the anxiety generally seems to happen in separate arenas for each group: social in ASD and non-social in WS (see also Dykens, 2003;Graham et al 2005;Rodgers et al, 2012;Lense and Dykens, 2013).…”

Recent selection of candidate genes for mammal domestication in Europeans and language change in Europe: a hypothesis

“…Signs of self-domestication in humans have increased in recent times (reviewed in Hare, 2017). Interestingly too, features of domestication are found abnormal (either exacerbated or attenuated) in clinical conditions impacting on our cognitive abilities, including language, like autism spectrum disorder (Benítez-Burraco et al, 2016) schizophrenia (Benítez-Burraco et al, 2017), or Williams syndrome (Niego and Benítez-Burraco, 2019). At the same time, genomic regions associated with dog-human communication contain genes related to human social disorders, particularly autism spectrum disorder (Persson et al, 2016).…”