Life experience rather than domestication accounts for dogs\u2019 increased oxytocin release during social contact with humans

Rupert Palme,Friederike Range,Gwendolyn Wirobski,Sarah Marshall-Pescini,Tobias Deschner,Franka S Schaebs

doi:10.1038/s41598-021-93922-1

Abstract

Dogs’ increased human-directed sociability compared to wolves may be the result of increased oxytocin system activity and decreased stress responses, but comparative studies accounting for life experience are lacking. We compared hand-raised, pack-living wolves’ and dogs’ behavior and hormone concentrations after interacting with a closely bonded and a familiar human. Both preferred the bonded partner, but dogs showed less variability in human-directed sociability than wolves. Physical contact was not associated with oxytocin but correlated positively with glucocorticoids in the pack-living animals when the human was not bonded. To clarify the role of life experience, we tested pet dogs and found that oxytocin concentrations correlated positively with physical contact with their owners, while glucocorticoids remained unaffected. Results show that, given similar experiences, wolf-dog differences in human-directed sociability and associated hormones are subtle and indicate that factors related to life as a pet dog rather than domestication account for oxytocin release during human–dog interactions.

Highlights

Dogs’ increased human-directed sociability compared to wolves may be the result of increased oxytocin system activity and decreased stress responses, but comparative studies accounting for life experience are lacking
Both pack dogs and wolves spent significantly more time in body contact with the bonded than the familiar partner (GLMM; χ2 = 12.8, df = 1, P < 0.01; no interaction effect of species and relationship strength; χ2 = 1.7, df = 1, P = 0.2) and there was no significant species difference in the duration the animals spent in body contact with the partners (GLMM; χ2 = 3.2, df = 1, P = 0.08) (Figure S3, Table S4; dogs: 87.7% of the interaction time with the bonded partner and 68.6% with the familiar partner; wolves: 72.9% with the bonded partner and 31.7% with the familiar partner)
Time spent in body contact with the familiar but not the bonded partner was positively associated with SDB rate (Figure S4 a), whereas in wolves a contrasting pattern emerged: time spent in body contact with the bonded partner was positively associated with SDB rate (GLMM; χ2 = 4.9, df = 1, P < 0.05) (Table S5, Figure S4 b)

Summary

Introduction

Dogs’ increased human-directed sociability compared to wolves may be the result of increased oxytocin system activity and decreased stress responses, but comparative studies accounting for life experience are lacking. We compared hand-raised, pack-living wolves’ and dogs’ behavior and hormone concentrations after interacting with a closely bonded and a familiar human. Both preferred the bonded partner, but dogs showed less variability in human-directed sociability than wolves. Domesticated compared to wild-type animals are thought to show reduced fear and increased willingness to interact with humans (Emotional Reactivity and Selection for Tameness hypotheses:[1,2]; Hypersociability hypothesis:[3]; Table 1) Such changes are thought to be associated with an altered hypothalamo-pituitary-adrenal (HPA) axis and oxytocinergic system (re)activity resulting in a diminished stress response and greater inclination to approach humans (‘Domestication Syndrome’:4,5–9). Based on the wolf-dog comparison, the authors proposed a coevolved feedback loop between dogs’ and humans’ oxytocinergic systems, providing an interesting framework

Methods

Results

Conclusion