When humans talk to each other or walk alongside each other, we tend to match each other's subtle movements.
Called interpersonal movement synchrony in the science literature and mirroring in the popular media, it's an often-unconscious process during which we match our gestures and pace to that of our social partner of the moment.
Writing in the March issue of the journal Animal Cognition, Charlotte Duranton, Thierry Bedossa, and Florence Gaunet note that this process is "evolutionarily adaptive" for us: "It contributes to communication between individuals by signaling the convergence of their inner states and fostering social cohesion."
Then, these three researchers present evidence to show that dogs synchronize their walking pace with their humans in a way that may also reflect an evolutionary adaptation.
In an experiment, 36 pet dogs were brought to an open area in Maisons-Laffitte, France, with their owners. After a 15-minute free period, the owner-dog pairs experienced three testing conditions presented in random order. These were: stay-still (owner didn't move for 10 seconds), normal-walk (owners walked at normal speed for 10 seconds), and fast-walk (owner walked fast for 10 seconds). Importantly, the dogs were off-leash and, thus, not tethered in any way to the speed of the owners. The owners were told not to look at, or talk to, their dogs — or to show any evident emotion. The experimenters filmed the trials as they occurred.
The dogs synchronized their pace closely with their owners, speeding up when the owners walked at an unnaturally fast pace. (The dogs in their regular routines were used to walking at a normal pace, with the owners often pausing to chat with other people).
Does this finding, at first, seem unremarkable? I think, on the contrary, it shows the degree of incredible attunement that the dogs work to create with humans: Recall that the dogs had complete freedom of movement, and they received no encouragement or cues from their owners.
A second finding is also striking: The dogs spent more time gazing at their owners in the fast-walk condition than in the other two conditions. The dogs were carrying out a form of social referencing, checking in with their owners in a condition that was unusual and, thus, uncertain for them. (Cats check in with us, too, by the way.)
Where does the evolutionary adaptation part come in? In a broad way, all the results fit with this notion. It's reasonable to think that during the domestication process, dogs who attuned to and checked in with humans had higher rates of survival and, more significantly, reproduction.
There's a more specific link to evolution, too, though. Of the 36 dogs tested in this experiment, 18 were shepherds and 18 were molossoids, and their behavior varied. Across the three conditions, shepherd dogs looked for longer at their owners than molossoid dogs.
At this point, I was left with a pretty basic question: What exactly are shepherd dogs and, especially, molossoid dogs?
Ethologist and lead author Duranton told me, in an email message, that the breeds she used in this research can be understood through the contents of the "official breed book in France." In this classification scheme, shepherd dogs are dogs "selected to work with their owners," such as German, Belgian and Australian shepherds, border collies, and beaucerons. By contrast, molossoid dogs are selected to provide protection, and include rottweilers, great danes, Newfoundlands, cane corso, and dogo argentino.
Duranton explained further:
"Shepherds have been selected (and are trained during their life experiences) to work with their owner, to wait for instructions from the owner, on what to do, where to go, whereas molossoid dogs have been selected (and are trained) to be more autonomous, and are thus less checking with their owners."
Duranton described something of what it was like to work with all these dogs out in the open air:
"All dogs were very cooperative when participating in the study, but one dog, Izzy, was particularly enthusiastic, and when the owner was walking fast, she was running so fast and then suddenly she was rolling in the grass, out of joy. This dog has died from an acute disease since her participation in the study, and I will never forget her. I am really grateful to her, and of course to all dogs for their participation in all of the studies I conducted."
For Duranton, the real message of this new experiment for dog owners revolves around how much our behavior influences theirs every day.
We're being mirrored by our pets, and looked to for guidance. That's a joy and a responsibility, both.
Barbara J. King is an anthropology professor emerita at the College of William and Mary. She often writes about the cognition, emotion and welfare of animals and about biological anthropology, human evolution and gender issues. Barbara's new book is Personalities on the Plate: The Lives and Minds of Animals We Eat. You can keep up with her on Twitter @bjkingape.