Over the Top Sociality

  • Taxa: Dogs and wolves

One advance in social theory is the capacity to draw a demarcation around a baseline version of sociality, against which some forms are characterized as excessive. Think of dogs. In contrast to their close cousins, wolves, dogs display exaggerated gregariousness or hypersociability, “a heightened propensity to initiate social contact that is often extended to members of another species.” This tendency is the subject of a study by vonHoldt et al. that seeks to explain how dogs diverged from wolves during domestication. This project also endeavors to link a complex behavior, like sociability, to a genetic basis. The strategy for doing so is to analyze a chromosomal region associated with canine sociability and under selection in domestic dog breeds. They argue that variation in two genes (GTF2I & GTF2IRD1), which are also implicated in Williams-Beuren syndrome (WBS) in humans, contribute to extreme sociability in dogs.

Like autism, WBS is one of those conditions that seem to highlight the biological and genetic basis for sociality in humans, in that the phenotypic requirements for socializing—controlling eye-contact, focusing attention, and maintaining a bodily disposition—are lacking or compromised. There are a suite of physical disabilities associated with WBS, including stunted or reduced facial features. The genetic cause stems from the deletion of some 27 genes on chromosome 7. But one of its hallmarks is an apparent lack of social inhibition. People with this condition are remarkably adroit at reading others’ eyes and gauging mental states or emotions. They often actively seek out and embrace strangers, and they possess impressive verbal abilities. Despite their ready capacity for friendliness, their gestures and attempts at interaction are frequently received or viewed as inappropriate, transgressing many implicit conventions involving social distance. The study by vonHoldt et al ask whether such genetic mutations generate a similar kind of excessive sociality in canines.

The “sociability metrics” here are “attentional basis to social stimuli,” “hypersociability,” and “social interest in strangers:” indices for “behavior under selection during dog domestication and analogous to behaviors that typify WBS in humans.” This is an intriguing frame for analyzing sociality across species, both for operationalizing these dimensions and for suggesting a scale on which some expressions are construed as abnormal. In each of these registers, dogs are over the top. In comparison with wolves in a series of sociability tests, “adult dogs were consistently more likely to engage in prolonged or excessive contact with humans than adult wolves.” The wolves in these tests were sociable, demonstrating an interest in their caretakers, approaching them for greetings at the start of the sociability test. “However, they then returned to other activities. This pattern of behavior might be considered a ‘typical’ social greeting for bonded adult animals, whereas the prolonged greeting of pet dogs, sometimes lasting the full 2 minutes, would be considered exaggerated or hypersocial.” Though vonHoldt et al are focused on genes, I suspect there’s also a cultural dimension here: conventions clearly pertain governing “too much” or transgressive expressions of sociality, and, given that these are social species, such boundaries are likely learned early. This is where ethologists could contribute to this inquiry.

The payoff in this project is a substantially different way to think about domestication. Instead of assuming that dogs developed advanced forms of social cognition through their interactions with us in the distant past, these findings suggest they were already transformed; that a genetic mutation in dogs generated an “exaggerated motivation to seek social contact, which is absent in adult wolves.” This is borne out by the way adult dogs increase their social engagement with humans, opposite of the situation with wolves in captivity. The implications are significant: rather than the process of domestication gradually producing a genetic change in the target species, which is how this dynamic is currently understood, a genetic alteration served as the predicate making domestication possible. Just as notable, though, is the suggestion that here lies part of the genetic basis for sociality: “Our findings suggest that the same region affected by structural variants in human WBS is associated with the exuberant sociability of domestic dogs.” In that case, our capacity for restrained sociability must also lie in aspects of our genetic makeup.

But if dogs are excessive in their sociality, such that they mainly model a bounded, normative version of the social, then what does that suggest, in turn, about our own species advanced sociability? Dogs are not alone here. In a surge of in recent works on cultural evolution, a consistently theme is the uniqueness of human sociality. As Agustín Fuentes writes, “Humans have evolved to be supercooperators.”[1] If that’s the case, then maybe we might not be the best species baseline for theorizing the social.

Abstract

vonHoldt, Bridgett M., Emily Shuldiner, Ilana Janowitz Koch, Rebecca Y. Kartzinel, Andrew Hogan, Lauren Brubaker, Shelby Wanser, et al., “Structural Variants in Genes Associated with Human Williams-Beuren Syndrome Underlie Stereotypical Hypersociability in Domestic Dogs,Science Advances 3, no. 7 (July 2017): e1700398, https://doi.org/10.1126/sciadv.1700398.

Although considerable progress has been made in understanding the genetic basis of morphologic traits (for example, body size and coat color) in dogs and wolves, the genetic basis of their behavioral divergence is poorly understood. An integrative approach using both behavioral and genetic data is required to understand the molecular underpinnings of the various behavioral characteristics associated with domestication. We analyze a 5-Mb genomic region on chromosome 6 previously found to be under positive selection in domestic dog breeds. Deletion of this region in humans is linked to Williams-Beuren syndrome (WBS), a multisystem congenital disorder characterized by hypersocial behavior. We associate quantitative data on behavioral phenotypes symptomatic of WBS in humans with structural changes in the WBS locus in dogs. We find that hypersociability, a central feature of WBS, is also a core element of domestication that distinguishes dogs from wolves. We provide evidence that structural variants in GTF2I and GTF2IRD1, genes previously implicated in the behavioral phenotype of patients with WBS and contained within the WBS locus, contribute to extreme sociability in dogs. This finding suggests that there are commonalities in the genetic architecture of WBS and canine tameness and that directional selection may have targeted a unique set of linked behavioral genes of large phenotypic effect, allowing for rapid behavioral divergence of dogs and wolves, facilitating coexistence with humans.


[1] Agustín Fuentes, The Creative Spark: How Imagination Made Humans Exceptional (New York: Dutton, 2017).