In our last post, we covered some of the genetic shifts that helped distinguish our dogs from their wolf ancestors – both physically and behaviorally. Today, we are going to discuss how this new relationship between dog and man has altered the development of both species. One of the most pertinent hallmarks our bond with dogs is our ability to communicate. Dogs can be trained to understand hundreds of commands, and many of them also learn other human words (such “walk” or “treat”). Many people swear that dogs understand nonverbal communication, too, such as when a usually independent pup won’t leave her heartbroken owner’s side. And this communication goes both ways – many dogs know exactly how to signal what they need, be that a trip outside or their dinner. Owners, too, often know to take their dogs to the vet even when they just “aren’t acting right.” Now we are going to dive into the neurology behind these behaviors. How do dogs understand us, and what makes this bond so incredibly strong?

Dogs as young as 6 weeks old can successfully use human-directed pointing cues to find hidden food, which is something that neither wolves, dogs’ closest relatives, nor chimpanzees, our closest relatives, can do (Riedel et al., 2008). Other studies have established that dogs can do this same task with as little as an eye glance from their person (Lakatos et al., 2012). It appears that domestication has had a profound impact on dogs’ willingness and ability to communicate and cooperate with humans. Behavioral studies have supported “the domestication hypothesis” which posits that dogs have fundamentally altered their communication as a direct result of domestication, and that they are as attentive and willing to cooperate with humans as wolves are to other wolves (Kaminski & Nitzschner, 2013). Genetic studies have supported this hypothesis. One group of researchers recently found that a structural variation in the genes associated with a rare human condition called Williams-Beuren syndrome is present in domesticated dogs, and likely controls their stereotypical hypersocialibility (VonHoldt et al., 2017). This hypersociability is likely largely responsible for dogs’ willingness to communicate and cooperate with their human companions. Recent fMRI studies have further supported this hypothesis, showing that dogs may even have formed distinct areas for processing human language sounds, which are different and distinct from areas used to process conspecific vocalizations and other environmental sounds (Andics et al., 2014). Neither this genetic variation nor human language processing analogs are found in either wolves or coyotes.

Not all communication is verbal. If you’ve ever felt a sudden swell of love and affection just by looking at your pup, you are not alone, and your dog is probably feeling it, too. Mutual gaze is a nearly uniquely human form of communication, but it appears that dogs may have developed it alongside us. In laboratory studies, when dogs gazed at their owners, their owners had increased oxytocin concentrations (Petersson et al., 2017). Oxytocin is sometimes referred to as the love hormone because of its link to social bonding (Emery, 2000). In response, the owners with higher oxytocin concentrations were more likely to gaze, touch, or talk to their dogs, all of which increased the dogs’ oxytocin concentrations. When the dogs’ had higher concentrations of oxytocin, they were more likely to gaze and otherwise seek attention from their owners. This is the first interspecific oxytocin feedback loop that has been discovered (Nagasawa et al., 2015). The same results were not found even with hand-reared wolves, implying that this loop is a direct response to coevolution between humans and dogs.

These incredible evolutionary changes are directly due to dogs’ need to communicate and cooperate with humans. Their ability to blend into and compliment our lives have created a truly unique bond, unlike that shared with any other species. In some cases, that bond goes beyond pet and owner. From herding sheep to detecting cancer, some dogs have important jobs. In the next few posts, we will look at some of dogs’ super senses, starting with their noses. We’ll see once again how genetics combine with behavior to make dogs an integral part of our lives.

References

Andics, A., Gácsi, M., Faragó, T., Kis, A., & Miklósi, Á. (2014). Voice-Sensitive Regions in the Dog and Human Brain Are Revealed by Comparative fMRI. Current Biology, 24(5), 574–578. https://doi.org/10.1016/j.cub.2014.01.058

Emery, N. J. (2000). The eyes have it: the neuroethology, function and evolution of social gaze. Neuroscience & Biobehavioral Reviews, 24(6), 581–604. https://doi.org/10.1016/S0149-7634(00)00025-7

Kaminski, J., & Nitzschner, M. (2013). Do dogs get the point? A review of dog–human communication ability. Learning and Motivation, 44(4), 294–302. https://doi.org/10.1016/j.lmot.2013.05.001

Lakatos, G., Gácsi, M., Topál, J., & Miklósi, Á. (2012). Comprehension and utilisation of pointing gestures and gazing in dog–human communication in relatively complex situations. Animal Cognition, 15(2), 201–213. https://doi.org/10.1007/s10071-011-0446-x

Nagasawa, M., Mitsui, S., En, S., Ohtani, N., Ohta, M., Sakuma, Y., Kikusui, T. (2015). Oxytocin-Gaze Positive Loop and the Coevolution of Human-Dog Bonds. Science (New York, N.Y.), 348, 333–336. https://doi.org/10.1126/science.1261022

Petersson, M., Uvnäs-Moberg, K., Nilsson, A., Gustafson, L.-L., Hydbring-Sandberg, E., & Handlin, L. (2017). Oxytocin and Cortisol Levels in Dog Owners and Their Dogs Are Associated with Behavioral Patterns: An Exploratory Study. Frontiers in Psychology, 8. https://doi.org/10.3389/fpsyg.2017.01796

Riedel, J., Schumann, K., Kaminski, J., Call, J., & Tomasello, M. (2008). The early ontogeny of human–dog communication. Animal Behaviour, 75(3), 1003–1014. https://doi.org/10.1016/j.anbehav.2007.08.010

VonHoldt, B. M., Shuldiner, E., Koch, I. J., Kartzinel, R. Y., Hogan, A., Brubaker, L., Udell, M. A. R. (2017). Structural variants in genes associated with human Williams-Beuren syndrome underlie stereotypical hypersociability in domestic dogs. Science Advances, 3(7), e1700398. https://doi.org/10.1126/sciadv.1700398