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In How Dogs Love Us (2013), Gregory Berns chronicles the early days of his efforts to use brain imaging scans for the first time to study how dogs think and feel emotions including love. Berns argues that many dog owners and trainers limit their understanding of dog psychology to behavior, or how dogs physically react to different situations. This approach tends to ignore a dog’s thoughts and feelings. For a true understanding of dogs, and how they relate to humans, it’s important to consider what dogs think about, and how they think and feel. Berns called his attempt to do this the Dog Project.

Berns and a team of investigators at Emory University in Atlanta trained two dogs to participate in the Dog Project. Using a functional magnetic resonance imaging (fMRI) scan, the investigators digitally mapped the dogs’ brains while showing the dogs familiar hand gestures and smells to prompt a particular emotional reaction. The team compared the scans of each dog’s brain to the other dog’s and to previous scans of human brains. The team found the dogs had reactions in the same brain regions, indicating they had similar emotional reactions to the same experiences. By comparing the scans to scans of human brains, the team could also determine that certain experiences induced memories and positive emotions in dogs.

In the first set of experiments, the team trained the dogs to associate a particular hand gesture with the presence or absence of a hot dog. An upward hand meant to expect a hot dog, while a downward hand meant to expect a pea, and, later, to expect nothing at all. Using the fMRI, the team scanned the dogs’ brains to assess their reactions to the hand gestures with and without the presence of a treat. The dogs’ brain scans demonstrated that they became excited at the mere anticipation of a hot dog, even when it was not yet present.

For the second set of experiments, the team collected sweat samples from members of the dogs’ human families and others from people whom the dogs had never met. While conducting an fMRI scan of the dogs’ brains, they allowed the dogs to smell each sample. When smelling the samples from strangers, the dogs’ brains showed no reaction. When smelling the samples from people they lived with, they had a reaction in a part of the brain, called the inferior lobe, associated with memory, and another, called the caudate nucleus, associated with positive emotions. In this way, the Dog Project was able to demonstrate that dogs could recall memories of particular humans, and experience positive feelings, even when the person was not in the room. Berns says these brain reactions may evidence a form of love which dogs experience for their human companions.

Berns also discusses the ethical implications of the Dog Project. Because dogs have emotions and feelings, society should recognize them as sentient creatures and not as property.

Like humans, dogs have a “theory of mind” for humans, meaning they can read human emotions.

Humans depend on the ability to read one other’s emotions without people stating explicitly how they feel. This ability is called a “theory of mind,” and it’s what allows people to navigate social situations by modifying behaviors when interacting with others. Since dogs also depend on relationships with humans to survive, it makes sense that they would have an ability to read human emotions as well. However, dogs’ theory of mind is rudimentary compared to an adult human’s, possibly equivalent to a young child’s theory of mind.

Researchers have found evidence that dogs can read human emotions. In one 2016 study, five researchers working with Natalia Albuquerque, a biologist at London’s University of Lincoln, showed dogs photos of humans who appeared either angry or happy while playing voices of humans speaking in either an angry or a happy tone of voice. The researchers mixed the voices and images so the dogs saw and heard matching faces and voices as well as faces and voices that did not match, such as an angry face paired with a happy voice. As the researchers suspected, the dogs consistently looked at the photos for longer periods of time when the voice matched the emotional expression they saw. The researchers interpreted this as evidence of dogs’ ability to read emotions in other species, an ability that had not been scientifically documented in any other non-human species. Dogs, the researchers wrote, probably have “mental prototypes” of humans that allow them to distinguish between positive or negative emotions without any training.

Dogs probably have survived so long as a species because they evolved to understand humans.

Domesticated dogs are descendants of wolves, but they have co-evolved with humans for thousands of years. Humans have shared their lives and spaces with dogs because they value canine companionship. Dog owners often believe their relationship with a dog is based on an emotional connection, advancing the claim that their dogs know and love them.

The Dog Project found evidence to support this assumption. Dogs experience the affection of their owners and they feel that affection in return. This explains why humans have kept dogs in their lives for thousands of years.

Although the domestication of dogs was an important milestone for both dogs and humans, scientists are still uncertain when exactly it happened. Possibly the oldest remains of a domesticated dog were found in the Goyet cave in Belgium alongside the preserved footprints of a child. Carbon dating placed the age of the dog at 30,000 years, which would mean that humans had domesticated dogs by the time they began making art and wearing adornments such as jewelry. Penn State University anthropologist Pat Shipman has said these developments could have been related, and that people who had successfully domesticated dogs may have worn jewelry to signify their mastery of an animal.

However, not everyone is convinced the Goyet dog was domesticated. A 2015 study of the shape of the Goyet fossil argued it belonged to a now extinct wolf species.  Heidi Parker and Samuel Gilbert of the National Human Genome Research Institute have said the Goyet fossil could mark the beginning of what was a long process of domestication as dogs moved into human environments and gradually changed from wild animals to human companions. Fossil records from the Middle East indicate that domesticated dogs existed around 15,000 years ago, so the long process of domestication could have happened over a period between 30,000 and 15,000 years ago in different parts of the world.

By considering only a dog’s behavior, people overlook what dogs think.

Much of what goes on inside a dog’s brain can be reflected in a dog’s behavior: When a dog salivates at the smell of food, for instance, the dog shows hunger. But not everything a dog thinks reflects in the dog’s behavior, so limiting the study of dog psychology to physical reactions misses the big picture.

Nevertheless, studying animal behavior can reveal important insights into how an animal thinks. For a 2005 study, three researchers at Britain’s University of Portsmouth interviewed people who had lived or worked with a dog, cat, horse or other animal for at least two years about whether and how they observed an emotional life of their creature companions. The team readily acknowledged that these animals exhibit “primary emotions,” such as fear. But as the team suspected, many animal owners also reported “secondary emotions” in their animals, such as jealousy. Because secondary emotions are so closely associated with human psychology, scientists have typically rejected the idea they can exist in dogs. However, the owners could attribute their claims to a set of behaviors they recognized in the animals. When the owners had observed jealousy, it was typically due to some interference in the animals’ relationships with their owner. The owners’ description of an observed emotion in their animals consistently relied on a characterization of a consistent set of behaviors and contexts. That consistent link between the behavior witnessed and the emotions described suggested that there was a behavioral connection to these “secondary emotions.” The researchers concluded that the owners had not merely projected an emotion they experienced themselves onto their animal companions. Rather, they had observed an actual emotional expression.

Like humans, dogs are inherently social, and they learn from other animals, including other dogs.

Everyone knows that humans learn from each other. But as those who own more than one dog understand, dogs are capable of learning from their peers. Moreover, dogs are perhaps unusual among animals in that they can learn from other species. For instance, dogs who work with animals on farms or ranches, known as herding dogs, learn to follow the movements of cows and sheep by observing them.

While dog owners have long known that dogs can follow their cues to locate specific items or food, there is evidence that dogs can also take cues from each other, even from a very young age. In 1999, scientists at Emory University, the future site of the Dog Project, demonstrated this phenomenon. Researchers Brian Hare and Michael Tomasello set up barriers against a wall a few feet apart from each other, hid food behind one, and placed a leashed dog next to the barrier with the food. The team then revealed the scene to a second dog and let the dog find the food on its own. The team then repeated the experiment, but with a human standing next to the barrier with food, making eye contact with the dog, and then looking at the barrier.

The dogs found the food most easily with human help. But seeing another dog stand next to the right barrier and look at it also seems to have made it easier for the dogs to locate the food than when they went looking for it on their own. As the team pointed out, dogs seemed to have this ability to learn from each other even when they didn’t have much experience with other dogs. One six-month-old dog who hadn’t yet met many other dogs very easily acted on cues from his fellow dogs.

Dogs remember their human companions even when not in the room with them.

The Dog Project found that dogs could remember humans, and that the memory of them could invoke a positive association even when the person was not in the room. Being presented with material that smelled like some of the humans they lived with activated the inferior temporal lobes in the brains of two dogs, Callie and McKenzie. Human brains become active in a similar way when they are shown photos of loved ones. This pattern of brain activity indicated that dogs form mental models of the humans in their lives and store those mental models in their brains.

During the smell test, when the team presented the dogs with objects which smelled like humans in some of their lives, the caudate nucleus of Callie’s and McKenzie’s brains also became active. Since the caudate is an area associated with positive sensations in human brains, the team inferred that the dogs had a positive association with their memories.

Dog and human memory may be more closely associated than we realize. A 2004 study tested one dog’s ability to learn to associate words with specific objects and found the dog could do this at a rate comparable to human toddlers. In a series of tests, the research team placed a number of items whose names he already knew in a room, along with a single item he did not know. In each test, the team asked the dog to retrieve the new item using a word he did not know. In seven out of 10 tests, the dog successfully retrieved the new item. The dog could do this, apparently, through some process of elimination: either because he knew the other items in the room either had names already, so the new word must be associated with the new object, or because he knew the items were familiar and the team was asking for an unfamiliar item.

Although it seemed like the dog could understand language, the team concluded the dog was able to learn these associations using a memory ability that perhaps many animals possess. They added that some of the cognitive abilities that allow humans to talk to each other now may have existed in humans even before they developed language.

Dogs know how to read other species because they evolved from predators.

Hunting requires studying other animals, so dogs developed an ability to read other animals by tracking them in the wild as predators. But as they started to live with humans, dogs adapted this predatory skill set to reading humans, allowing them to coexist with their new companions.

Dogs descended from wolves, and there is evidence that wolves that have not lived in human homes can read and respond to human cues just like dogs. In a 2011 study, three researchers from the University of Florida had a group of tamed wolves that lived in captivity participate in a “begging exercise” to test the wolves’ ability to read human body language. In a series of tests, the wolves faced two humans: one whose back was turned, and one who was facing the wolf and looking at it. When the wolf approached the person who was facing it, the wolf received a treat. Most times, the wolves did exactly this, indicating the wolves were able to detect when humans were paying attention to them, even though they had not been domesticated and did not live in human homes. The findings suggest that domestication alone cannot explain dogs’ ability to read human body language.

Dogs are emotionally intelligent and can experience a range of emotions.

The fact that dogs can feel good in the company of humans indicates they can also love and feel loved. While dogs may experience love for the humans in their lives differently than humans do, that doesn’t mean it isn’t love. And if dogs can feel love, they can also feel sad or lonely.

The question of whether animals have emotions has inspired a heated discussion for centuries. Living in the seventeenth century, when early machines were just beginning to appear in Europe, the French philosopher René Descartes argued that animals were only sophisticated biological machines without thoughts or feelings of their own. His argument has been controversial ever since.

Since Descartes, many scientists have concluded that animals do have emotions. Charles Darwin was one of the first people to make this claim and base it on scientific observation. In his 1871 book The Descent of Man, Darwin wrote that the difference between the mind of humans and of “lower animals” is not a categorical difference but a difference of degree. Animals, he wrote, possessed some form of emotions and cognitive abilities, “such as love, memory, [and] attention” even if their minds were not as sophisticated as our own.

More recently, scientists have identified certain brain hormones in both humans and animals, including dogs, that correspond to positive emotions. In a 2003 study, researchers found that levels of one of these hormones, oxytocin, rose dramatically within a few minutes in both dogs and their owners when they were together.

Since that study, scientists have suggested that oxytocin may help dogs bond with each other and with their owners. In a 2013 study, researchers found that dogs became more sociable with their owners after they were sprayed with oxytocin. For instance, the dogs were more likely to look at their owners with a steady gaze instead of moving their heads around. The team hypothesized that dogs may have evolved to emit oxytocin when they were with humans and other dogs to promote social relationships, because social relationships are essential to dog survival.

Since dogs think and feel, humans should treat them as sentient beings and should reconsider the rights they are owed.

The results of the Dog Project provide further evidence that humans should recognize the rights of dogs in ways similar to how they recognize the rights of humans. Legal protections for dolphins and chimpanzees arose because scientists recognized these animals have mental abilities that are closer to humans’ than most animals. Most of the world’s 400 million dogs do not enjoy these protections. Now that scientists know that dogs can think and feel, as humans do, perhaps humans should do more to protect the world’s dogs.

While the Dog Project introduced neuroscience to this discussion, the idea that animals should enjoy the same rights as humans because they can think and feel as humans do dates back more than a century. In his 1894 book, Animals’ Rights: Considered in Relation to Social Progress, Henry S. Salt cited Darwin’s claims that animals have emotions to lay out one of the earliest cases for recognizing animal rights. Salt wrote, “[Animals] have individuality, character, reason; and to have those qualities is to have the right to exercise them, in so far as surrounding circumstances permit,” he wrote. As Salt argued, white people had once justified slavery by saying they could never have a friendship with people of African descent. People similarly dismiss animal rights on the same flimsy basis.

In his 1985 book The Case for Animal Rights, philosopher Tom Regan also argued that animals had emotions, and that by recognizing that fact, humans should also recognize the rights of animals to live as individuals. Even simple desires, like the desire for food, he wrote, should be recognized as an expression of an animal’s individuality. Moreover, Regan wrote, by acting on their desires, animals made choices, which also demonstrated individuality.

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