What It's Like to Be a Dog

Introduction

Until bin Laden was killed, I hadn't given much thought to animal minds.

It wasn't bin Laden but Cairo, the dog on the mission, who caught my attention. Cairo was a military working dog who could do amazing things, like jump out of helicopters. His ability to tolerate noisy, chaotic environments gave me an idea that, in retrospect, seemed so obvious that it was strange no one had thought of it before: If dogs could be trained to jump out of helicopters, then surely they could be trained to go into an MRI scanner. And why would I want to do that? To figure out what dogs were thinking, of course.

The timing was serendipitous. I had spent thirty years in science, first training to become a bioengineer, then a physician, and eventually specializing in the use of MRI to study how the human brain makes decisions. My favorite dog—a pug named Newton—had died the previous year, and somewhere in the back of my mind I had been pondering what the dog-human relationship meant. Had Newton loved me in the same way I had loved him? Or had it all been a sham, an innocent duplicity propagated by dogs to act all cute and stuff in exchange for food and shelter?

In Newton's place, our family had adopted a skinny black terrier mix, whom we named Callie. She was as opposite a pug in appearance as in demeanor. Insecure and high-strung, she tended toward bullying the other dog in the house, a sweet golden retriever who didn't put up any resistance. But besides Callie's feistiness, she had another trait that no other dog I had owned had possessed: curiosity. Callie loved to learn new things. The usual dog tricks were a breeze, and Callie soon discovered interesting things about life in a human household. Useful tidbits like how door handles worked. No need to wait for the humans to get into the pantry. Callie figured out that if she rose up on her hind legs, she could use her front paws to pull the handle down and out. She did it with such alacrity that you would have thought she was a capuchin monkey with opposable thumbs. This skill, unfortunately, was a hard-earned one that landed her in the ER with a stomach filled to the brim with who-knew-what.

I needed to give Callie something to do. Why not put her skills to more productive use than finding creative ways to swipe food, such as training her to go into an MRI so I could figure out what she was really thinking?

I sought out the help of Mark Spivak, who ran a local dog-training company called Comprehensive Pet Therapy. Mark was up for the challenge, and we began working through all the little details necessary to train Callie to hold still inside an MRI long enough for us to see how her brain worked. Sedation was out of the question for two reasons. She would have to be completely awake so that we could see how her brain processed things like smells, sounds, and, most importantly, communication from her owner—me. And because we set out to treat her in the same way that we would treat a human participating in an MRI study, she had to be able to leave the scanner whenever she wanted. Like a human, our canine participant would be a volunteer. That meant no restraints.

I built an MRI simulator, which I parked in our living room. We constructed mockups of the "head-coil" that picked up signals from the brain, and Mark and I quickly taught Callie how to shimmy into it. Although the process was mostly trial-and-error, and we hit many speed bumps along the way, it turned out not to be as difficult as we initially thought it would be. With just a few months of training, Callie had graduated from a discarded dog in an animal shelter to the first dog to have her brain scanned voluntarily while fully awake and unrestrained.

Encouraged by our success, we solicited the help of the local dog community to join this groundbreaking project to investigate the workings of the canine mind. Much to my surprise, we had no shortage of volunteers. So many volunteered that Mark and I developed a tryout protocol so we could identify the dogs who would be most likely to succeed in MRI training. Within a year of Callie's first scan, the team had grown to nearly twenty dogs. To accommodate all these dogs and people, we held MRI practice every Sunday afternoon, alternating weeks between the "A-Team" and "Bravo Company."

We began with very simple experiments to see how dogs' brains responded to hand signals that cued the delivery of treats. In humans, it was already known that a key brain structure, called the caudate nucleus, responded in anticipation to things that people liked, such as food, money, and music. So when we discovered that the dog's caudate reacted similarly to hand signals, in anticipation of the treats, we knew we were on to something important. The dogs took this all in stride as just another fun activity they did with their owners, and their brains responded much as a human's would to a pleasurable experience. As the dogs became increasingly accustomed to the MRI, we were able to design more complex tasks for them to do. When we presented smells of people and other animals to the dogs, we found that the reward response occurred in the dogs' brains only for the smells of the people in the household, and not for the smells of the other dogs. Because food wasn't directly linked to these odors, this was the first hard evidence that dogs might experience something like love for the people in their lives.

The Dog Project soon consumed my life, eclipsing the human work in the lab. Because of its potential to improve the training of military working dogs, the Office of Naval Research began supporting our research, and we expanded the number of dogs in the project as well as the complexity of the tasks they performed in the MRI. Not only was it fun, but I had the feeling that we were on the verge of gaining new insights into the minds of our best friends.

As I learned more about the canine brain, I became convinced we had much in common with dogs at the deepest levels. The same basic structures for emotion could be found in both dog and human. But there was a bigger question here, beyond one of emotions, which I had conveniently suppressed as we had built up the Dog Project.

The question came to the surface at a conference on vegan issues. I had been reluctant to accept the invitation to speak because I wasn't a vegan, but the organizers assured me that they just wanted to hear what we were learning about the canine mind. Personal eating practices were not on the agenda. That might have been the plan, but it didn't turn out that way. After my talk on the Dog Project, a fellow speaker accused me of being a "speciesist" because I gave dogs special status, even to the point of feeding them the ground-up flesh of other animals in the form of hot dogs. It was an awkward moment, and I felt duped by the conference organizers.

Was I a speciesist? Probably.

Was that bad? I didn't know.

Four years into the project, there was no denying that our work had raised a bigger question: If we had evidence that dogs experienced emotions similar to those of humans, what about other animals?

People began asking me whether cats could be trained to go into the MRI, and occasionally about whether pigs might be trainable. I knew that wasn't likely, and scanning sedated animals didn't seem ethical or likely to yield much useful information about animal cognition. I was at an impasse: the possibility of studying other animals seemed a fantasy.

The turning point came when Peter Cook joined the lab. Peter had come to the project from Santa Cruz, California, where he had completed his PhD on sea lion memory. He was passionate about figuring out how animals' minds worked, especially in their natural environments. California sea lions, though, had been stranding in large numbers. Some of the sea lions could be rehabilitated, but others suffered from unremitting seizures and had to be euthanized. Peter arranged for us to get their brains. I never imagined I would be in the business of scanning dead brains, but I was surprised by what we learned about the animals they came from. It was some comfort to know that even in death, these animals could tell us something about the worlds they had inhabited. The sea lions were just the beginning. Using new MRI techniques, we started pushing the boundaries of what we could scan. Other animals. Specimens locked away on museum shelves. And even the brains of animals that were thought to be extinct.

What is it in a human brain that makes a human, or in a dog brain that makes a dog? For centuries, anatomists focused on size. Bigger meant more neural real estate, and the assumption had been that bigger was better. This principle had been taken to apply to the whole brain, where bigger brains were associated with greater intelligence. And it had also been applied to parts of the brain, where the size of specific structures was thought to indicate the importance of the function of that region to the animal. There was some truth to this. Dogs had a large olfactory bulb, indicating the importance of smell in the dog's world.

But size alone does not explain how brains work. What really matters is how the different parts of the brain are connected to each other. This is the new science of connectomics. Recent advances in MRI have allowed us to examine in exquisite detail the wiring diagram of human brains. If I, or anyone else, were to ever figure out animals' minds, it was going to come from the analysis of these connections and how they coordinated activity throughout the brain. That was where internal experiences, including emotions, came from.

These were exciting times to be a neuroscientist, and the Dog Project was just the beginning. The deeper I got into the dog brain, the more obsessed I became with learning about other animals. If we could learn about their inner experiences, maybe we could communicate with them better. What if a dog could tell us exactly how she felt? And what would a pig say about a slaughterhouse? What did a whale think about all the noise flooding the ocean from ships and submarines? The inevitable result of these investigations was not just that we were going to realize that the inner worlds of animals are a lot richer than we had imagined, but also that we need to rethink how we treat them.

This is a book about brains, and about the minds of the animals they come from. In academics, such investigations fall under the umbrella of comparative neurobiology. All neuroscience is comparative at some level, but few neuroscientists dig deep and ask why the brains of animals look the way they do and how that relates to their mental experiences. These are hard questions. They get at the heart of what makes us human, and they raise troubling issues about the possibility that we may not be that different from many of the creatures with whom we share the planet.

The book is organized in roughly the sequence in which I branched out from humans to dogs to other animals, but the similarity of brains is the thread binding these adventures together. Over and over, I found structures in the brains of animals that looked to be organized in the same way as the corresponding parts of our own brains. And not only did these parts look the same, but they functioned in the same way.

The relationship between brain structure and cognitive function is complex and frequently depends on the coordination of multiple brain regions. Until recently, it wasn't possible to describe in detail the interconnectedness of the brain. But this has changed in just the past few years. Advances in neuroimaging and the software used to analyze brain networks have yielded new insights into human brain function, and there is no reason why the same tools can't be applied to animals' brains.

These techniques also suggest a way to understand the subjective experiences of other animals. Where structure-function relationships in an animal's brain are similar to those in our brains, it is likely that the animal is capable of having a similar subjective experience as we do. This, I believe, is the path toward understanding what it's like to be a dog, or a cat, or potentially any animal.

Dogs figure prominently in several chapters because dogs are familiar to all readers and because I think they are the best research partners. I also venture into the ocean to discover what the minds of our marine relatives are like. There are chapters on the most doglike of marine mammals, sea lions and seals, and a chapter on one of the most mysterious animals on the planet: dolphins. With their great intelligence and sociality, dolphins have intrigued both the public and scientists for decades. But they have long been inscrutable. Now, using new imaging techniques, we are learning how dolphins' brains are wired and what this means for life underwater. We may soon be able to communicate with each other.

And then there is the Tasmanian tiger, officially known as the thylacine. The "Tassie tiger" was a carnivorous marsupial that looked strikingly like a small wolf. It is believed to have become extinct in 1936, when the last one died in the Hobart Zoo in Australia. But claimed sightings of this mysterious creature continue to this day. I began a quest to find intact thylacine brains to see what I could discover about their inner lives, and ultimately, I located a preserved brain in the vaults of the Smithsonian Institution—one of only four known to exist in the world. I received permission to scan it with the new MRI tools. But that was just the beginning of an odyssey that took me to Australia in search of more brains and to scan the thylacine's closest living relative, the Tasmanian devil.

The book ends as it begins—with dogs. Although I admit to being an unabashed speciesist, I have come to think of dogs not just as man's best friend, but as ambassadors to the animal world. They still have enough wolf in them for their brains to tell us something about being a wild animal. The challenge lies in creating a means to communicate with each other. I believe that we should look to their brains. And so, the final chapters are about probing the limits of canine understanding of human language and what that means for the rights not only of dogs, but of all animals.