"Our results suggest that dominance remains a robust component of domestic dog behaviour..." (Rebecca Trisko and Barbara Smuts 2015)
It's well known that domestic dogs form dominance relationships, with many researchers noting that the hierarchies that are formed are linear (for further discussion please see "Dogs Display Dominance: Deniers Offer No Credible Debate" and many links therein). In a linear hierarchy, if individual A dominates (>) B, and B > C, then A > C. There are no circular relationships such as C > A. In dogs and other animals, as few as three dogs can form a linear hierarchy, despite claims that it takes six or more individuals to do so.
Because of my own interests in the social behavior of dogs and the sorts of social relationships they form, I was thrilled to learn of a new study published in the journal Behavioral Ecology by Dr. Roberto Bonanni and his colleagues called "Age-graded dominance hierarchies and social tolerance in packs of free-ranging dogs." This essay is not yet available online, but I've read it through and below are the abstract and some important highlights of this significant and very detailed research project.
It is believed that domestic dogs rarely form packs with age-graded hierarchical structures similar to those found in wolves. Dog-wolf comparisons in captivity suggest that human control has reduced dog dependency on cooperation with conspecifics, resulting in a more despotic dominance order. However, free-ranging dogs are under stronger natural selection than purebred dogs. They are dependent on companions’ social support but usually exhibit lower reproductive skew than wolves, possibly because access to easily available human-derived food may have relaxed within-group competition. We investigated social dominance in 5 packs of mongrel dogs living in a free-ranging or semifree-ranging state. We aimed at replicating the findings of the few studies that detected a dominance hierarchy in dogs using a larger sample of packs. Additionally, we provided behavioral measures of social tolerance. We found that a linear hierarchy existed in all packs studied and that the rank order was positively related to age in all packs but one. In 2 packs in which testing was possible, age was a better predictor of dominance than body size. Potentially injurious aggression was very rare. Hierarchy steepness in dogs was similar to that found in wolves and in tolerant primates. Submissive reversals were more common in dogs than in wolves. These results suggest that age-graded hierarchies in dogs are more common than previously thought, that rank is not usually acquired through fighting because subordinates rely on the guidance of elders, and contradict the view that domestication has increased despotism in dogs.
In the original essay these researchers write:
Taken together, all these studies support the view that dominance hierarchies are common in domestic dogs. Furthermore, they strongly contradict the previously held notion of lack of social structure in this species ... which was never supported by detailed analysis of social interactions.
The authors' conclusion in the published paper reads:
With this work, we believe to have provided convincing evidence that free-ranging dogs possess the ability to form well-structured social groups and that such structure can be described reasonably well as an age-graded dominance hierarchy similar to that of wolves. Intragroup agonistic interactions in free-ranging dogs are usually characterized by low-intensity aggression, which is consistent with the fact that they are cooperative carnivores. Moreover, our preliminary dog–wolf comparison contradicts the view that domestication has reduced social tolerance in dogs relative to wolves. Future studies should explore the meaning of “unknown relationships” in free-ranging dogs. If egalitarian/unresolved relationships actually exist in free-ranging dog packs, then we should conclude that a linear hierarchy model is just an approximate one (although effective) to describe the social structure of these animals.
Dogs mean what they say in serious encounters
So, as a result of this very detailed analysis, we learn that age-graded linear hierarchies are common -- dominance is correlated with age -- and potentially injurious fighting among free-ranging dogs is very rare. Related to the lack of fighting, we also now know when dogs growl in serious contests they do so honestly, likely telling others that they mean what they say. During play, this is not the case (for more details please see "Dogs Growl Honestly and Women Understand Better Than Men"). The researchers in the study of growling conclude, "Our results indicate that dogs may communicate honestly their size and inner state in a serious contest situation, while manipulatively in more uncertain defensive and playful contexts."
In a previous essay called "Dominance in relation to age, sex, and competitive contexts in a group of free-ranging domestic dogs" by some of the same researchers, including Roberto Bonanni, we read, "We investigated the existence of a social-dominance hierarchy in a free-ranging group of domestic dogs. We quantified the pattern of dyadic exchange of a number of behaviors to examine to what extent each behavior fits a linear rank-order model. We distinguished among agonistic dominance, formal dominance, and competitive ability. The agonistic-dominance hierarchy in the study group shows significant and substantial linearity."
The researchers also note, "Agonistic-dominance relationships in the dog group remain stable across different competitive contexts and to the behaviors considered. Some individuals gain access to food prevailing over other dogs during competitions." Finally, they conclude, "The findings of this research contradict the notion that free-ranging dogs are 'asocial' animals and agree with other studies suggesting that long-term social bonds exist within free-ranging dog groups."
Dominance in dogs is alive and well so let’s get over it and understand what it’s all about
Dominance in dogs is real, not a myth. For more discussion please see "Social Dominance Is Not a Myth," "Dominance and Pseudoscience: Making Sense of Nonsense," renowned primatologist Dr. Dario Maestripieri's outstanding essay called "Social Dominance Explained: Part I" in which he mildly takes me to task for trying to accommodate the deniers, and many links therein.
Species-wide surveys clearly show that dominance hierarchies in animals are real, as do rigorous science and well-received evolutionary theory. Dr. Maestripieri concludes: "Bottom line: dominance between two individuals helps keep the peace and increases stability and predictability in the relationship, thereby allowing both partners to benefit from their relationship." The outstanding studies of Italian dogs fully support what he writes.
Beliefs don't substitute for facts
Beliefs don't substitute for facts, and it's time to put aside beliefs, pay close attention to what we know, and let the facts speak for themselves. When we do this, it'll be a win-win for dogs and humans in all of the social venues in which their and our lives cross and become intimately entwined. And, let's remember that there still is so much to learn about the cognitive and emotional lives of these most amazing beings, and there are no substitutes for watching and studying dogs in the various contexts in which they interact with their friends and foes and with us. What could be more exciting? In my view, clearly not much.
All in all, there are absolutely no credible reasons why dogs should be uniquely different from other species in which dominant individuals and dominance hierarchies have been observed. It's not a question of if dogs form dominance relationships, but rather why has dominance evolved and what sorts of relationships are established. I look forward to much more research on this topic for dogs living in different social and ecological settings.
Marc Bekoff’s latest books are Jasper’s Story: Saving Moon Bears (with Jill Robinson); Ignoring Nature No More: The Case for Compassionate Conservation; Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation; Rewilding Our Hearts: Building Pathways of Compassion and Coexistence; The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson); and The Animals’ Agenda: Freedom, Compassion, and Coexistence in the Human Age (with Jessica Pierce). Canine Confidential: An Insider’s Guide to the Best Lives For Dogs and Us will be published in early 2018. Marc's homepage is marcbekoff.com.