Voices in the Ocean

by Susan Casey

  Marino was born and raised in Brooklyn, the oldest of two daughters in a traditional Italian family. She has a don’t-mess-with-me New York accent and an expressive way of speaking. Her voice roams across octaves. From an early age, Marino knew that science was her path, though she didn’t initially set out to study dolphins. The insects she found in her backyard, the family cat, her tank of guppies, the stars in the night sky—every creature, every question, every last bit of the natural world, everything enthralled her. Marino’s was a childhood filled with home telescopes, behavioral experiments with earthworms, wildly competitive science fairs: “the whole geek thing.” Did life forms exist on other planets? If yes, how would we talk to them? Did dogs dream? What was the mean size of a millipede? What was it like to be a bee? Her inquiries began.

  As a graduate student, Marino first glimpsed the dolphin brain in books; at the Smithsonian Institution, while collecting data for her PhD dissertation, she encountered actual specimens. More than anything, Marino was struck by the brain’s uniqueness—it was oversized, rounder…different. The dolphins’ ancestors had slipped into the water 55 million years ago, embarking on an evolutionary itinerary all their own. While humans took an express train and shot to their destination in no time flat, dolphins wound their way through geologic time, stopping often to take in their surroundings. In the end we both arrived at the same place—remarkable intelligence—but carrying different luggage. While everyone else in her field gravitated toward chimpanzees and other apes, the animals most reminiscent of ourselves, Marino was drawn to the weird, unfamiliar, and far more ancient architecture of the dolphin brain. “We’re primates—I get it,” she said, with a shrug. “But there is more than one way to be smart.”

  Marino was aware, of course, of John Lilly’s similar pronouncement, his celebrated swerve from human to dolphin neuroscience decades earlier, but in her case he was no inspiration. “When I was starting out, people used to bring up John Lilly,” she said, in an exasperated tone. “I had to fight for credibility to not be seen as a person who was just taking mushrooms and thinking dolphins were angels and all this crap. He really did a number on the profession.”

  Marino and her colleagues didn’t have their own Caribbean research labs, but they did have CT scans and MRI scans and other technologies that helped them delve into formerly unknown territories of the dolphin brain. In Lilly’s era, dissection was the main tool for investigating neuroanatomy, but that method had its limitations. It was like trying to wrangle Jell-O. (Large brains, in particular, are fragile and hard to keep intact.) Imaging solved that problem, allowing scientists to examine and rotate and peer into the entire structure in minute detail—charting the subtle diversities between sections, the exact measurements of regions, the precise stratum of cells. As our atlas of the dolphin brain is written, its terra incognita slowly becoming known to us, we are discovering that it is every bit as extraordinary as our own. “There’s folklore about dolphin brains that says they’re big but kind of simple,” Marino said, shaking her head. “That’s old stuff. We know now that it is a very complicated brain with a very wide range of types of cells. Their wiring’s different. But it is just as complex—it could be more complex.”

  One of the most striking things about the dolphin brain is that its neocortex—the most recently evolved part of the mammalian brain that enables us to do sophisticated stuff like reason, use our senses, consciously think, socialize—is constructed in an utterly original way. It’s a formidable structure: in humans, this area occupies 80 percent of our brain’s volume. “There’s a basic plan for the neocortex,” Marino explained. “In all mammals it’s layered.” Ours is made up of six distinct layers, each of which contain specific cells that interpret certain types of information. But dolphins and whales have only five layers. “They’re missing Layer 4,” she said. “And the reason that’s such a big deal is because, in primates, Layer 4 is where all the input for the lower parts of the brain come into the neocortex and get integrated.” She raised her eyebrows. “So if they don’t have a Layer 4, where’s the information coming in?” There were some theories, she added, but no one really knew the answer. “The way information enters their brain, gets tossed around, and out of their brain—it’s completely different.” Her voice trailed off in a theatrical whisper.

  If you pulled a neocortex out of a human or dolphin head, Marino told me, you could unfold it like a sheet. Ours is thicker, but theirs covers more real estate. The dolphin neocortex has more peaks and valleys, more crimps and wrinkles, more surface area for action to happen. In their brains, the region that deals with hearing is located at the top of their heads, while our hearing is processed in the temporal lobe, at the side of our heads. Dolphins have also rearranged the way they integrate sound and visual input. Instead of having that information zinging between the temporal and occipital lobes as it’s being analyzed, going for a bit of a ride the way it does in our brains, their processing areas are located right next to each other, resulting in lightning-quick responses. If you were designing a high-performance computer, you would choose the dolphins’ schematic, hands down. “This is a brain that is built for speed,” Marino said, admiringly. “The rate at which they process information is astounding. Everything’s faster! Their auditory fiber track is the diameter of this table!” This was said as a joke, a colorful exaggeration, but Marino was making an important point: “The bigger the fibers, the faster they conduct.” She leaned back and smiled, her eyes wide with awe. “I mean, are you kidding me? We can’t even imagine.”

  A fabulous neocortex is a kind of killer app for brainy animals, enabling the refined thinking and behavior that characterizes us as humans and distinguishes us from, say, lizards. It’s where we get our abilities to make tools, use language, devise plans. When Marino talks about the dolphin neocortex, enthusiasm pours out of her: “It’s got all kinds of different cells. There are columns, there are modules, shapes, clusters of cells. The structure in it! So many goodies. So much good stuff.”

  One group of brain cells neuroscientists find especially intriguing are spindle cells, also known as von Economo neurons (VENs). Humans and dolphins both have these cells in the areas responsible for high-level functions like judgment, intuition, and awareness—and so do whales, elephants, great apes, and even, it was recently discovered, macaque monkeys—but in the animal kingdom, VENs are unusual. Only the creatures with the most elaborate brains come equipped with them. Even their appearance is exotic: while many neurons look like wonky starbursts, their dendrite arms reaching across synapses to send and receive signals from nearby cells, VENs shoot out like bolts of forked lightning. They are also about four times bigger than most other brain cells. “They’re like superstar neurons,” Marino said. “And we see them in very interesting parts of the brain.”

  In new studies, researchers learned that when enough VENs are damaged in a human’s brain, dementia can result. Losing even a portion of these cells causes us to implode socially, to lose touch with all niceties. We seem to need our VENs to get along with one another, to empathize, to know if we’ve made a mistake, to modulate our emotions. VENs play a role, it appears, in our ability to trust, to joke around, even to love one another. Whatever their purpose, early estimates suggest that dolphins and whales have about three times more of these superstar neurons than we do. Marino and other researchers suspect VENs are an adaptation that arose in big-brained animals to help shunt large parcels of information around at high speeds: “It seems to be something that emerges when you go from a certain brain size up.”

  One of the key reasons anyone’s brain ballooned in the first place, scientists believe, was to deal with the intricacies of a thriving social life. Keeping track of family and friends and acquaintances in an extended community, figuring out who owes whom a favor and who once betrayed the group and who treated your grandma with special kindness but is also related to the guy who stole your brother’s girlfriend—the fine web of interactions between hundreds of indiv
iduals—is as challenging for dolphins as it is for us. We need every bit of our brainpower to navigate these relationships, using everything from memory to judgment to communication skills (even with Facebook). Dolphins juggle not only close alliances within their groups, but also form alliances with other alliances.

  So is their extroverted nature the reason dolphins developed such big brains? Likely, Marino said, but it’s not quite that simple. “When you say ‘social,’ well, you have to have good communication to have a social culture,” she said. “You have to have this, you have to have that. So it all gets wound together. And we’ll never know because you can’t directly test evolutionary hypotheses about complex behavior or cognition. But it’s probably the best story we have right now.” Doesn’t it make sense, I asked, that when dolphins became physically less ferocious, when their bodies became smaller and their teeth less intimidating, that they would begin to rely more on the group? “They would need each other,” Marino agreed. “Yeah.”

  In fact, dolphins are so tightly bound to their pods that they may be operating with a degree of interconnectedness far deeper than our own. “When you look at their brain you can definitely see how this could be an animal that takes sociality to another level,” Marino said, pointing out that scientists can’t explain why dolphins and whales strand en masse when only one or two individuals are sick; or why, when they’re herded into the cove, they huddle together and don’t jump the nets. “There is some sort of cohesiveness in them that I don’t think we get quite yet, but it accounts for a lot of the behavior that seems strange to us.” She took a sip of her tea and leaned over to pet a drooling St. Bernard that had wandered up to our table. In a field behind us, two horses cantered across the grass, whinnying and shaking their manes. “I think a lot of it comes down to emotional attachment,” she continued. “And I think there is a very strong sense in them that if something happens to the group, it happens to you.” She paused, and chose her words carefully: “I think the differentiation isn’t that great between self and other.”

  The possibility of a dolphin collective soul (my words, not Marino’s) is an astonishing idea, but not a brand-new one. It was first proposed in the eighties by paleoneurologist Harry Jerison, who studied brain evolution and its effects on intelligence and consciousness. Jerison, who was obviously unafraid to tackle life’s thorniest philosophical questions as part of his research, referred to it as “the communal self.” In this model an individual dolphin isn’t so rigidly defined; he doesn’t necessarily stop at the perimeter of his own body. His awareness, his concerns, even his survival instincts extend out into the world around him. He would relate to others in his pod at a level beyond empathy, in a kind of shared existence that we can’t fathom.

  The dolphin’s limbic system, Marino told me, might well have adapted for this type of connectivity. It is an ancient part of the brain: the seat of emotions, memory, and smell. While most vertebrates evolved this region early and kept it pretty much intact, once again the dolphins came up with their own design. Since odors are indistinguishable underwater, their hippocampus, a region linked to their olfactory sense, diminished. Meanwhile, their paralimbic area grew huge, so densely jammed with neurons that it blurped out an extra lobe. There’s a jubilee of tissue packed into this area, an exuberance of gray matter that scientists believe relates to all things feeling—and no other mammal has anything quite like it. In parts of the dolphins’ limbic system the structure erupts in whorls and curlicues, like baroque décor picked out by Marie Antoinette. “It suggests that these animals are doing something very sophisticated or complex while they’re processing emotions,” Marino said.

  That’s the thing about brains. You can guess what they’re up to, but right now, anyway, we really don’t know for sure. The human brain contains hundreds of billions of cells busily engaged in thousands of trillions of unknown, vital tasks. Only the universe itself can rival its incomprehensible dimensions. We stand about as much chance of deciphering our brain’s every last secret as we do of sitting down for a Starbucks venti latte with God. “There is no neuroscientist on the planet that can claim he or she knows how we go from this gray matter to being conscious,” Marino said. “Nobody knows. It is a complete mystery.”

  Yet we’re not entirely clueless. The anatomy itself has yielded rich information, tantalizing hints, and magnificent conjecture. We can examine how dolphin or human brains are constructed, and then match that to behavior. We can infer that a large brain size relative to body size makes for a more intelligent creature, although what intelligent means, exactly, is notoriously hard to define. It’s undeniable that pea-brained critters like crows or octopi are capable of some awfully clever feats, while humans, with our cantaloupe-size heads, engage in all kinds of self-destructive nonsense. “The human brain is the most unsuccessful adaptation ever to appear in the history of life on earth,” whale scientist Roger Payne once suggested. “What we call intelligence may only be a form of vandalism, just mischief on a grand scale.” Trying to rank dolphin intelligence against human intelligence is like comparing submarines to airplanes, or the color pink to the color purple. They can’t write things down; we suck at sonar. Rating animals’ brainpower is a slippery task.

  That doesn’t matter, Marino said. We need to try. “Everybody knows intelligence is a fuzzy concept. What we have to do is make sure that we’re being species appropriate and entirely empirical. In other words: dolphins recognize themselves in mirrors. Does this mean they are more brilliant than dogs, who do not? I don’t know. I just know this is a capacity they have that many other animals don’t have. And it means something.”

  The day had grown hotter as we talked, so we moved to a shaded patio overlooking a five-star canyon. A vegetarian lunch buffet had been laid out and was attracting numerous takers: high-school volunteers wearing Best Friends’ T-shirts, staff members emerging from offices trailing beagles and collies. Marino and I stopped to get salads. “The person who has probably done the most to help us understand dolphin intelligence is Lou Herman,” she said, after we sat down with our plates. “His work was superb.”

  Louis Herman is a psychology professor emeritus at the University of Hawaii. His studies on dolphin cognition, perception, memory, and communication were groundbreaking, jaw-dropping—any awesome adjective you’d care to insert. With scientific rigor and a lot of creativity, Herman showed just how smart dolphins can be. “My thought was, ‘Okay, so you have this pretty brain. Let’s see what you can do with it,’ ” he told National Geographic.

  Herman’s research, at the Kewalo Basin Marine Mammal Laboratory, was based in Honolulu. From 1970 to 2004, he worked with bottlenose dolphins, teaching them a gestural sign language and another language based on sounds, and then testing how well they grasped various concepts—including many tricky abstract notions that animals are really not supposed to be able to understand.

  Apparently, no one had informed Herman’s dolphins of this. His bottlenoses responded to complicated sentences and knew exactly how the word order, or syntax, changed their meanings. They got instantly that a command like “take the surfboard to the Frisbee” was different than “take the Frisbee to the surfboard,” and they adjusted their movements accordingly. “An important finding,” Herman wrote, “revealing the dolphin’s mastery of the sentence forms used, was that understanding was shown for novel instructions as well as for more familiar ones, with only a slight advantage to the latter.” When the dolphins were asked to do something impossible, like bring the tank window to the surfboard, they wouldn’t attempt any action. They just stared at their trainers, as if to say, “Come on. You and I both know that can’t be done.”

  Herman’s dolphins could distinguish left from right, even when the directions were reversed arbitrarily. They understood the concepts of presence and absence. Using their flippers to press paddles that indicated yes or no, the dolphins correctly responded when asked if a person or object—a boy, a particular dolphin, a ball, a box—was in thei
r tank or not. They could listen to a series of eight sounds and then indicate whether a ninth sound had been previously played. They discerned the ideas of “same” or “different,” and “less” or “more.” In other studies, they reported whether they were “sure” or “unsure” of an answer to a difficult question. When asked to create new behaviors—tricks they’d never done before—they immediately began to innovate, in perfect unison.

  Herman also proved that dolphins understand what we mean when we’re pointing; that they can identify their own body parts; that they realize television is a representation of reality. They can remember objects, locations, and instructions even over time, recalling information as necessary. They are masterful mimics, able to imitate sounds and movements with ease. With no prior instruction, when a trainer lifted a leg in the air and asked the dolphin to do the same, the dolphin lifted her tail. None of this is simple or easy behavior; all of it demonstrates, as Herman concluded, “wide-ranging intellectual competencies…an intellect that meets with some of the hallmarks of human intelligence.”

  Not only were the dolphins capable of all this (and probably far more), they picked everything up at warp speed. “When you work with them, you realize they’re on a completely different temporal plane than you,” Marino said. “They’re always one step ahead. They get things much quicker. They do things much faster.” She laughed. “I mean, you can tell they’re impatient because they have to deal with slow humans.”

  The night before I flew out I stayed in Las Vegas, doing some lackluster gambling and wishing I had a communal self so I could tell how the blackjack dealer was feeling about his hand. After an improbable win at slots, I quit while ahead and went back to my room. My own brain was spinning after talking to Marino. I felt as though I could have stayed at Best Friends for months, volunteering to clean out the pig pens if it meant the chance to ask Marino more questions about the inner lives of the sanctuary’s animals.