Weekend Reads | When Dogs and Their Humans Look Alike
This weekend’s read delves into one of the great mysteries of life: why some dogs look like their owners. In truth, it’s a bit broader than that, looking at patterns of similarities — in both appearance and personality — between dogs and their humans.
There is plenty of writing on the subject, as a team of German researchers discovered — side note: The Max Planck Institute of Geoanthropology, which is among the Max Planck Society’s highly respected research institutes, has a “dog studies” research team — but much of it wasn’t helpful. They wanted to do a “meta-review,” in which they add together all the research studies to create a much larger, more statistically meaningful sample to analyze, but in the end, they only found seven published research studies that were relevant to the questions they wanted to answer. So instead they settled on a “systematic review” of those seven papers, talking about each and looking for agreement and disagreement on their conclusions.
Beyond the anecdotal evidence we see on social media, is this a real phenomenon? Are there similarities between humans and their dogs? The research says yes — strong enough that given a set of photos and dogs, strangers have a better-than-random-chance likelihood to be able to match up dogs and their owners. Sometimes the similarity is clear and striking, but often it’s a bit more subtle; for example, women with long hair tend to prefer dogs with long ears, and more generally, there is a correlation between the human’s hairstyle and the dog’s ear shape.
There are similar correlations for dogs’ and humans’ personalities. Specifically, researchers found that “owners with high levels of extraversion report that their dogs also have high levels of extraversion.” Even more significant was the correlation for neuroticism in human–dog pairs. Researchers have found that the personality matches extend to the human owners’ satisfaction: Owners were more satisfied when they were similar to their dogs on sharing possessions, enjoyment of running outside, engaging in destructive activity, and ability to get along with their peers.
All of this leads to the bigger question: why? There seems to be some belief that the process of domesticating dogs over thousands of years has bred dogs to be at least more capable of adapting to individual humans, if not outright mimic human looks and behaviors. Still, with the huge range of appearances and personalities of dog breeds, how do we end up with humans and dogs pairing up based on similarities?
There are two hypotheses. One is “similarity because of choice”: Dogs and humans form a team because of their similarity. The other is “similarity over time”: Dogs and humans become more similar as they spend more time together.
Based on the limited research available, the researchers split the difference, concluding that external appearance similarities seem to be because of choice, whereas similarities in personality are driven by time spent together. This makes intuitive sense. At the time a human chooses a dog — for example, when they adopt a pet at a shelter — they know a lot about its external appearance, most of which, such as ear shape, is unlikely to change much over time. But they know little about the dog’s personality.
Further, the researchers found substantial evidence that an owner’s personality has a high impact on the dog’s personality. Though there is much less evidence that a dog’s personality influences their human’s.
The researchers note that there are clear weaknesses in the research, beyond the simple fact that there isn’t very much of it. First, unlike with humans, there is no standard for quantifying a dog’s personality. That leads to a lot of subjectivity and variability in how these kinds of studies are implemented. Second, they suggest that the existing studies have “low generalizability”: They tend to have small sample sizes and other kinds of limitations or biases in the humans and dogs selected for the study that limit our belief that the findings will hold true for most dog–human pairs. And there are plenty of exceptions, just as there are with human–human pairings where “opposites attract.”
Nevertheless, it’s an interesting look at an important social dynamic, and it gives us a peek into human behavior and preferences. Humans and dogs have been pairing up since before recorded history began, and in recent times — especially with the rise of DNA analysis — far more effort has gone into breeding dogs to be ideal companions. This is clearly an important relationship for many people (and dogs), and worthy of better understanding.
