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It was with some enthusiasm that I read the title of an article in the November 11 issue of the journal Dog Behavior on the transformation of some wolves to dogs: “Scavenging Hypothesis: Lack of Evidence for Dog Domestication on the Waste Dump.”
Here were two forceful new voices—Christoph Jung of Vetwatch Halle, Germany, and Daniela Pörtl, a psychiatrist at Saale-Unstrut Klinikum teaching hospital, Leipzig and Jena Universities, Naumburg, Germany—raised against the notion that dogs self-domesticated while chowing down on the midden heaps of early humans in the Mesolithic, that transitional period between the Paleolithic and Neolithic Ages when our forebears were beginning to settle into something approaching permanent settlements.
Jung and Pörtl correctly attribute to the late Raymond Coppinger, a biologist at Hampshire College, the notion that the dump-diving wolves were a self-sorting lot who became increasingly non-threatening to the humans whose waste they consumed. Supposedly, in adapting to the new ecological niche of village offal eater, they became so tame and solicitous of attention that they became juvenilized in appearance and behavior—so much so that humans, who feared and loathed wild wolves, were seduced into taking them into their huts. Coppinger promoted this theory wherever he could, most notably in his book, Dogs: A Startling New Understanding of Canine Origin, Behavior, and Evolution, co-authored with his wife Lorna. As primary support for his theory Coppinger invoked a long-running experiment in domestication of fur-farm foxes being conducted by Soviet geneticist Dmitri Belyaev.
Regular readers perhaps recall that I began referring to Coppinger’s proto-dogs as “sniveling dump divers,” nearly as soon as he proposed the idea, and I have continued to do so because no matter how many times the fur-farm foxes have been shown to be a poor model for dog domestication, theorists have invoked them and put forward Coppinger’s dog version of them when discussing the transition from wolf to dog.
So it was with some hope that I pulled down Jung and Pörtl’s article (available online here) and read their critique of the scavenging model of dog domestication. For example, Jung and Pörtl note that early human hunters used nearly every part of the animals they killed. It would have been unlikely, then, that there would have been enough left over to support a group of wolves transitioning to dogs.
Jung and Pörtl write:
Paleolithic people and ancient wolves were living together closely in the same ecological niche hunting the same prey with the same cooperative methods. It is likely that they met very often and knew each other very well. We have some hints, that ancient wolves and people treated each other with respect. We have hints for an active cooperation from humans and dogs starting in the Upper Paleolithic period long before it would have even been possible scavenging human waste. We have hints for emotional bonds between ancient people and dogs. Emotional bonds would have been unlikely for an animal hanging around human settlements while scavenging carrion and feces, like the scavenging hypothesizes describe. Looking at recent dogs and humans we have evidence for strong unique similarities in the psychological and neurobiological structures eventually allowing interspecific bonding, communication and working. Interspecific cooperation decreased the level of the stress axis of both species in the Paleolithic period and even does so today, what improves our social and cognitive abilities.
It has long seemed to me that many journalists and students of dog evolution—especially those in English-speaking countries—have become so wedded to the “dump-diver theory” of dog domestication that they have become stuck in their efforts to understand what happened. They try to make the facts fit the theory, seldom a good idea in science or life. That may sound harsh, but as Jung and Pörtl show, the evidence does not support the theory—no matter how much you manipulate the former or revise the latter. “We think it is much more helpful to look at the psychological factors allowing a wild wolf to live voluntarily [sic] within human societies without stress on both sides,” they write, “without leashes and eventually working cooperatively with humans. We suggest genetic selection as a necessary prediction but not a sufficient explanation of dog’s domestication pathway.” They turn to new work in dog cognition and consciousness to demonstrate what they call “Active Social Domestication,” which posits that wolves and humans got together nearly as soon as they met on the trail of the big game they were pursuing. The divergence of dog from wolf, they say, was a process involving the active participation of both parties.
Marc Bekoff has posted an informative Q & A he conducted with the authors on his Psychology Today blog.
I, on the other hand, have been slow commenting on this paper for several reasons, not least because although there is much to admire, there are strong echoes of my own work throughout the paper—without any citation or acknowledgement. There are also clear parallels to the work of German ethologists Wolfgang Schleidt and Michael Shalter, who have argued that early modern humans learned how to hunt cooperatively and to live together peacefully from wolves.
Building on Schleidt and Shalter, I have argued that the enduring relationship of dogs and humans is based not on force and enslavement, but on a fundamental recognition of each other as sentient beings who can benefit from an alliance. Sociability lies at that heart of that process, including the ability to overcome fear and distrust and bond with the “other.” I have also argued since my 2011 book, How the Dog Became the Dog, that the friendship of wolves and humans initially may have emerged from the similar social structure of wolfpacks and human hunter and gatherer bands, as well as their shared purpose in raising and educating the young in the ways of the group.
I have proposed on several occasions that humans and wolves met on the trail of the big game they were hunting and recognizing kindred spirits in each other took up together and never looked back. Indeed, as they moved together into new worlds, the newly emergent dogs may have been more likely to have found mates among wild wolves than dogs, although that would have depended on availability. I have always emphasized that perhaps the greatest flaw in the dump-diver hypothesis lies in its insistence that dogs are the result of self-domestication, a self- sorting over garbage. That has the effect of leaving the big-brained biped out of the equation. The argument that a wild wolf became a sniveling, tail-wagging attention seeker in order to persuade humans to take it into their lives where its wolfish talents can re-emerge makes little sense. One doesn’t have to be a human exceptionalist to find something very wrong with that argument, primarily that it is based on the notion that between wolves and humans lies an undying enmity that can be overcome only by the total transformation of the wolf’s nature. Jung and Pörtl themselves note that even if such a character change had occurred, it is unlikely to have been embraced by humans. Why, they ask would humans adopt scavengers, as their “best friends.”
It is encouraging to see Jung and Pörtl advance arguments I have been making for 20 years. Their emphasis on sociability as holding the key to the transformation of wolves to dogs is of particular interest. Jung and Pörtl told Marc Bekoff, in answer to one of his comments, that they had been influenced by Wolfgang Schleidt, Michael Shalter, and me; such influence should have been clearly spelled out in the paper itself. Most scholars understand that everyone is better served when we recognize our debt to others. That is especially important because the theory of dump-diving evolution has come to have the entrenched force of received wisdom. Those of us working to diminish its undeserved popularity should recognize one another as a means of better crafting an alternative that fits the empirical reality far better.
