Intraspecific and Interspecific Attachment between Cohabitant Dogs and Human Caregivers

In recent years there has been growing interest in uncovering evolutionary and lifetime factors that may contribute to the domestic dog's (Canis lupus familiaris) success in anthropogenic environments. The readiness with which dogs form social attachments, their hyper-social focus, and social flexibility have all been areas of investigation. Prior research has demonstrated that many pet dogs form infant-caregiver type attachments toward human caretakers, even into adulthood. However, it is unknown if adult dogs form similar attachment bonds to other species, including cohabitant dogs, or if the dog-human relationship is unique in this respect. In the current study we used the Secure Base Test to evaluate behavioral indicators of stress reduction, proximity seeking and exploration, classifying dog-human and dog-dog dyads into attachment style categories. As in prior studies, we found that the majority of our dog-human dyads met the traditional criteria for infant-caregiver type attachment. However, the majority of dogs did not display this form of attachment toward cohabitant dog partners. Instead, behaviors observed in dog-dog relationships better matched attachment classifications described in human sibling attachment research. Overall, companion dogs were significantly less likely than human caretakers to elicit behaviors associated with attachment security in a focal dog. Dog-human attachment may play a distinct and important role in the success and resilience of adult dogs living in at least some anthropogenic environments. Bonds formed with other adult dogs, while important, likely serve a different function.