Introduction
It’s incredible how attuned dogs can be to the emotions of their human companions. While we may communicate through language, dogs rely more on body language and vocal cues to understand our moods and feelings. There is mounting scientific evidence that dogs have the capability to recognize basic human emotions such as happiness, sadness, anger, and fear through various senses.
Dogs that form close bonds with their owners can even mirror our excitement, stress, and anxiety. This emotional synchronization allows dogs to empathize and comfort us when we’re down. Understanding how dogs perceive our nonverbal emotional signals can help strengthen the human-canine bond.
Dogs’ Superior Sense of Smell
Dogs have an incredibly powerful sense of smell compared to humans. According to the Phoenix Vet Center, dogs’ noses have up to 300 million scent receptors, while humans only have about 6 million. This means dogs can smell odors that are up to 100,000 times fainter than what humans can detect. Their powerful sniffers are able to pick up scents from far away, even when the smell is not perceptible to us.
Research shows that because of their superior sense of smell, dogs can detect medical conditions like cancer or diabetes by smelling subtle changes in a person’s breath or bodily odors. Dogs are so adept at picking up scents that their noses are put to work daily by police departments, the military, and search and rescue teams. According to CareCredit, dogs can be trained to sniff out drugs, bombs, chemicals, missing people, and much more that we can’t detect.
Odor and Emotion
It is well established that human emotions produce subtle chemical changes that dogs can smell. Research has shown that human sweat and tears contain chemical signals known as chemosignals that communicate emotional states (https://pubmed.ncbi.nlm.nih.gov/23019141/). When we experience happiness, fear, or stress, our bodies release chemicals that dogs can detect.
One study found that chemosignals in human sweat provokedemotion-specific responses in the brains of dogs (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218249/). The scents associated with human fear and happiness caused significant changes in the dogs’ brain activity, indicating they were picking up on these emotions.
Experts believe dogs’ superior sense of smell allows them to pick up on the subtle odor changes emitted when humans experience emotions. By detecting our chemosignals, dogs gain insight into our emotional states. Their ability to “smell” emotions is an adaptive trait that strengthens the powerful bond between humans and dogs.
Visual Cues
Dogs have the capability to recognize human facial expressions and body language. According to research from the University of Helsinki, dogs can distinguish between angry and happy expressions in both humans and other dogs (https://www.cbc.ca/radio/asithappens/as-it-happens-the-tuesday-edition-1.5752254/dogs-can-read-your-expression-but-study-finds-they-aren-t-super-excited-about-your-face-1.5752649). Another study from the University of Veterinary Medicine found that dogs reacted differently based on whether a human had an angry or neutral expression (https://www.rspca.org.uk/-/blog_how_dogs_know_what_were_feeling).
Visual cues like facial expressions and body language let dogs know how their human is feeling. A smiling human puts a dog at ease, while signs of anger or distress cause a dog to become concerned. Rather than focusing on exact facial features, dogs seem to recognize the overall tone and get a sense of the human’s emotional state.
Vocal Cues
Dogs have an amazing ability to understand the meaning behind tone fluctuations in human voices. According to research by Attila Andics and colleagues at Eötvös Loránd University in Hungary, dogs can distinguish praise from neutral tones, similar to humans (https://www.npr.org/sections/health-shots/2016/08/30/491935800/their-masters-voices-dogs-understand-tone-and-meaning-of-words). When praising a dog, humans tend to use higher-pitched, more varied vocalizations. Dogs not only pick up on this difference, but their brains show different patterns of activity in response to praise versus neutral tones. Parts of their brains associated with processing emotion and reward are activated more strongly when hearing praise.
This sensitivity starts early, as puppies can recognize the different tones their owners use when praising versus scolding. They associate the positive tone with rewards and good feelings. Over time, the meaning behind certain vocal tones becomes ingrained. An encouraging, high-pitched voice will get a dog’s tail wagging, while a stern tone can stop bad behaviors. Dogs learn to anticipate outcomes based on their owner’s tone of voice (https://vcahospitals.com/know-your-pet/human-canine-communication-tone-vs-volume). While they may not understand each word, they pick up on the fluctuating pitch, cadence, and emotion behind them.
Brain Scans
Scientists have looked at how dogs’ brains respond when viewing human emotions. A study by researchers at Kyoto University used MRI scans to analyze dogs’ brain activity when their owners displayed positive versus negative emotions. The results showed activation in the “reward center” of dogs’ brains only when their owner smiled (1). This indicates that dogs have the capability to understand and respond to human emotional displays.
Another study from Emory University also used MRI scans to examine activity in dogs’ brains when exposed to five different human and dog smells. The scans revealed that dogs possess a small region of their brain dedicated to processing emotional information specifically related to human smells (2).
These brain imaging studies demonstrate that dogs have developed sophisticated neural mechanisms for perceiving human emotions.
Sources:
(1) https://www.nature.com/articles/s41598-020-79247-5
(2) https://www.npr.org/sections/health-shots/2014/02/21/280640267/how-dogs-read-our-moods-emotion-detector-found-in-fidos-brain
Hormones
Dogs have an incredible sense of smell that allows them to detect subtle changes in human hormones that indicate different emotional states. One key hormone is oxytocin, sometimes referred to as the “love hormone,” which is associated with bonding, social interactions, and positive emotions. Research shows that when dogs interact with their owners, both the human and dog experience a surge in oxytocin levels (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6826447/).
This oxytocin feedback loop between dogs and humans is similar to the bond between mothers and infants. Dogs even have specific oxytocin receptors in their brains that respond to the oxytocin released when a dog interacts with its owner (https://www.science.org/content/article/how-dogs-stole-our-hearts). So when we feel happy, relaxed, or affectionate and our oxytocin levels increase, dogs can detect this through their highly advanced sense of smell.
Real World Examples
Dogs have been observed picking up on human emotions in some remarkable real world examples. In one case, a service dog was able to detect that a girl was about to have a diabetic seizure 45 minutes before it happened, likely due to the dog smelling chemical changes in the girl’s body odor. Service dogs have also been trained to detect anxiety and panic attacks in their owners.
There are many stories of dogs seeming to sense human grief and offering comfort – laying their head in their owner’s lap or giving them physical affection. Dogs may be responding to the lack of movement and tone of voice in these situations. Some dogs have been known to grieve themselves after losing a family member, refusing to eat or seeming depressed.
Dogs are also able to detect positive emotions like happiness and excitement through visual cues like smiling and laughing, as well as more active body language. They often mirror these emotions back through eager tail wagging and running around. The bond between dogs and humans allows dogs to be highly in tune with our emotional states.
How to Strengthen the Bond
There are many ways to deepen the emotional connection with your dog. Here are some tips for strengthening the bond between owner and pup:
Spend quality one-on-one time together. Set aside dedicated time for just you and your dog to play, train, groom, or cuddle without distractions. This focused attention helps cement the bond. (Source)
Train together using positive reinforcement. Teaching new behaviors and tricks is mentally stimulating and helps your dog look to you for guidance. Reward-based training increases trust. (Source)
Give your dog physical affection. Dogs who enjoy being petted, massaged, or cuddled release oxytocin, the bonding hormone. Make affection a consistent part of your interactions. (Source)
Play fun games together. Games like fetch, tug-of-war, or hide-and-seek satisfy your dog’s natural instincts for play while deepening your connection. (Source)
Take them new places together. Exploring parks, trails, beaches, or other dog-friendly spots provides new sensory stimulation you both can enjoy. (Source)
Conclusion
In summary, dogs have some remarkable abilities to detect human emotions. Their exceptional sense of smell allows them to pick up on emotional chemical cues that humans emit. Dogs can also read visual cues like facial expressions and body language. Their hearing picks up on subtle vocal tone changes that humans make when experiencing different emotions. Brain scans confirm dogs have regions specialized for processing emotions, while hormones like oxytocin strengthen the human-dog bond. Real world examples demonstrate dogs comforting their owners in times of sadness or stress. The close relationships between humans and dogs mean each is finely tuned to the other. With attention and care, dog owners can further enhance their bonds and help their pets become even more perceptive of their feelings.