Dogs Can Really Tell If A Person Is Untrustworthy, Science Suggests
If you’ve ever kept dogs as pets, you’ve probably experienced many occasions of your dogs reacting negatively to a seemingly non-threatening person, while letting other non-threatening people pass without so much as a low growl. According to research published in 2014, there may actually be something to that.
The story of dogs
Dogs have been a part of the lives of humans for an extraordinarily long time. Scientists estimated that the first dogs were domesticated between 20,000 and 40,000 years ago by humans living in Europe. This was concluded after researchers studied the DNA from the remains of three domesticated canines dating back between 4,700 and 7,000 years old.  All these thousands of years later, they are still man’s best friend.
In the intervening millennia, numerous breeds of dogs have been selectively bred for different tasks, from herding to protection, or in some cases their looks or personality.
Pet ownership in the United States is on the rise. According to data from the 2019/2020 National Pet Owners Survey conducted by the American Pet Products Association, 67% of US households own a pet. That’s up from just 56% in 1988. According to their survey, there are approximately 63 million kept as pets in the US. 
The perceptiveness of our best friends
If you spend time with a dog, you’ll find pretty easily that the dog is able to pick up on human emotions. Some research has suggested that dogs are able to smell fear and can tell the difference between happy, smiling faces and growing, angry faces. 
Canines, like elephants and dolphins, are able to understand pointing as well. They react to human pointing gestures by investigating the general area a human points to. If a human points to a dog’s favorite toy, for example, they are likely to react to this pointing gesture by retrieving the toy and playing with it.   
In October of 2014, a research team lead by Akika Takaoka from the Kyoto University in Japan released the results of a study of 34 dogs that connected these two canine attributes – understanding pointing gestures as well as human expression. The results pointed to an interesting conclusion: that dogs are able to identify when a pointing gesture is misleading. 
To test this theory, they conducted a couple different experiments where one container had a piece of food hidden in it and a second did not.
In the first experiment, the researchers pointed to a container filled with food, then showed each dog both containers, one being full and the other empty. The second step of the experiment was to point to the container that was not baited. In the third step of the experiment, the researchers pointed to the container filled with food.
They responded to the second step of the experiment, where they were fooled, by mostly ignoring the researchers in the third step. When the experiment was repeated with a new researcher doing the pointing, the dogs were eager to go along with it, indicating that they hadn’t lost interest in the experiment itself, but that they lost interest in the researcher that had fooled them.
In the study, researchers wrote: These results suggest that not only dogs are highly skilled at understanding human pointing gestures, but also, they make inferences about the reliability of a human who presents cues and consequently modify their behavior flexibly depending on the inference.
Dogs make astute snap judgements
Takoaka expressed surprise at how quickly the dogs assessed the reliability of the human researchers who participated in this experiment.
“Dogs have more sophisticated social intelligence than we thought. This social intelligence evolved selectively in their long-life history with humans,” she told the BBC.  Eventually, Takoaka hopes to extend this experiment to other animals, including wolves, in an effort to determine how much domestication has impacted the social intelligence of domesticated canines.
This research provides scientific evidence for something dog behaviorists have have long known – they prefer predictability.
“Dogs whose owners are inconsistent to them often have behavioral disorders,”said John Bradshaw, an honorary research fellow at the University of Bristol’s veterinary school. He adds that when gestures are inconsistent, dogs can become nervous or stressed. 
Dogs pick up on disrespect
Another study, published in November of 2017, found that dogs are able to tell if its human counterpart has been disrespected. In the study, dog owners were prompted to ask strangers for help. The dogs reacted negatively to people who behaved disrespectfully to their human companions. They continued to express an aversion to the disrespectful subjects, even if provided treats. 
Taken together, this research indicates that these loyal pets are able to observe human expression and behavior to paint a fairly complex portrait of whether or not a person is trustworthy.