Rethinking Human-Canid Communication as a two-way street
For decades, we have seen dogs as expert interpreters of human cues – animals that we’ve shaped through artificial selection to fit in with our lifestyles. What if that was only half of the story? Recent findings from researchers of the NCCR Evolving Language challenge this one-sided model and propose a more reciprocal one: communication between humans and canids evolved not just as a linear result of human-driven selection, but rather developed through an interactive process of mutual influence.
By Célia Lazzarotto, Eloïse Déaux and Gwendolyn Wirobski.
Many characteristics we assume to be unique to dogs may be better seen as stemming from their shared ancestry with wolves and would have then been refined over millennia of selection by humans and the differing environments they each inhabit. However, thinking that dogs possess unique traits shaped by domestication rests on the implicit assumption that the human-dog history is a one-way process in which humans alone selected dogs’ characteristics.
Questioning this view are two recent studies by NCCR collaborators, Eloïse Déaux on speech perception in dogs (Déaux et al., 2024), and Gwendolyn Wirobski and Svenja Capitain on greeting behaviours in dogs and wolves (Capitain et al., 2025), which invite us to rethink domestication as an ongoing dialogue between species.
A grey wolf and a domestic dog. © Core Facility Wolf Science Center Austria, Rooobert Bayer
Same same but different
Separated only 10’000 to 15’000 years ago from a common ancestor, today’s wolves and dogs share a lot of similarities (Bergström et al., 2020). Genetically, the species’ DNA sequences are almost identical (Saetre et al., 2004). Both species can also interbreed and produce fertile offspring, highlighting their closeness (Vilà and Wayne, 1999). However, there is one domain where dogs show striking differences compared to wolves, and that is when communicating with humans.
For example, compared to wolves, dogs wag their tails much more frequently and from a younger age, particularly when interacting with humans (Gácsi et al., 2005). While the precise function remains unclear, one hypothesis proposes that the rhythmic movement of the tail was pleasing to humans and may have been selected during the domestication process. If so, then as suggested by Leonetti et al. (2024), tail wagging could be one of the earliest examples of a communicative behaviour shaped by aesthetic or affective human preference.
In recent research, Gwendolyn Wirobski and Svenja Capitain compared how dogs and human-socialized wolves respond to familiar humans during short greeting sessions. While dogs and wolves exhibited very similar behaviours there were also some important differences. Notably, dogs spent more time close to the humans than wolves, wagged their tails and whined more and overall showed more submissive and appeasement signals than their counterparts. They also used the “puppy eyes” expression – a facial expression thought to promote care-giving in humans.
Overall, it may seem that dogs are more skilled than their close cousins, the wolves, in communicating with humans. Indeed, it has been proposed that dogs are better at following human cues than wolves as a result of selection pressures during the domestication process (Hare et al., 2010). However, later comparative studies showed that, when given similar opportunities and experiences with humans from an early age, wolves are equally capable of following human cues, and of successfully communicating and cooperating with us (Range et al., 2022). So what if the difference lies in us, humans, and how we interact with wolves and dogs?
The human bias
In the recent aforementioned research (Capitain et al., 2025), the authors got interested in another parameter of the experiment. “We found that the humans involved acted slightly differently depending on the species they interacted with,” notes Gwendolyn Wirobski. “This happened although the humans were used to working with those dogs and wolves, and were instructed to treat both species in the same way.” Specifically, when interacting with dogs, human participants displayed more frequent, intense and positive facial expressions than with wolves.
These unconscious human biases may have brought this interactive and ongoing process of domestication, reinforcing characteristics we thought were positive, such as being docile, and in turn selecting them.
The “puppy eyes” expression is a striking example of this reinforcement. Dogs have long been thought to possess a unique facial muscle used to raise the inner part of the eyebrows. This allows them to display the characteristic “puppy eyes” expression, which is absent in wolves. This expression has been interpreted as an evolved cue to elicit caregiving behaviour from humans, thereby providing a selective advantage (Waller et al., 2013). However, recent research by Cunningham et al. (2024) and Smith et al. (2024) found that this inner brow raiser is also present in coyotes and African wild dogs, which separated from wolves and dogs more than 2 million years ago. This work shows that “puppy eyes” are not exclusive to domestic dogs after all. Indeed, this trait may not be a new adaptation to domestication, but rather an ancestral feature that initially evolved to promote intraspecific communication and sociality but has been adapted for interspecific communication in domestic dogs.
“The behaviours we often label as ‘domesticated’ and attribute to dogs may not be entirely new inventions but exaptations, i.e. refinements or amplifications of existing features to acquire functions for which they were not originally adapted or selected, enabled by dogs’ interactions and relationships with humans,” says Eloïse Déaux.
And while dogs may have evolved to interpret and respond to human signals, by interacting with us, humans have also evolved to interact with dogs, as the researcher shows.
Humans adapting to dogs
In her latest article, Eloïse Déaux (Déaux et al., 2024) examined how dogs perceive speech, and found that their natural vocal rhythm is significantly slower than the rhythm of human speech. “While dogs produce around 2 vocalizations per second, human speech is around 4 syllables per second,” the researcher explains. Recordings of dogs’ brain activity showed that dogs are most efficient at tracking speech in the delta frequency range (1-3 Hz), corresponding to their own vocal production. In contrast, human brains rely on theta rhythms (4-7 Hz) tuned to the natural speech flow.
Communication between canines and humans requires adaptations on the part of both species. © Adobe Stock.
“But when humans speak to dogs, they slow down their speech, producing a so-called dog-directed speech (DDS), which lands between both rhythms,” adds Eloïse Déaux. Whether this is a learned behaviour or an evolved adaptation remains to be seen, but it underscores a key point: humans actively adjust the way they speak to be better understood by dogs.
Taking a different angle, this human adaptation to dogs is also evident in Gwendolyn Wirobski and Svenja Capitain’s research (Capitain et al., 2025). “Humans become more expressive when they interact with dogs, even if it’s unconscious,” says Gwendolyn Wirobski. According to the researcher, humans may have learned to enhance their facial expressions in the presence of dogs, so the two species can better communicate with each other. However, it remains unclear who affects whom first: is it that dogs’ initial reaction towards us elicits this increased expressiveness, or do we interact with them differently than with wolves from the start? If so, is this unique to our communication with dogs, or would we find similar results with other domesticated species?
Dogs started barking and wagging their tails more… But we’ve also slowed down our speech, and exaggerated our facial expressions… This goes to show how today’s human-canid communication system is better thought of as the result of a two-way co-evolutionary relationship. “Future research must go beyond the binary comparison of dogs and wolves, exploring in more depth their behaviour, and including diverse canid populations from various environments,” both researchers say. “And most importantly, we must consider humans not just as observers, but as active participants in this system”. Indeed, communication does not reside in one species or the other, but in the space between.
References
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