Are dolphins as smart as people? And if so, shouldn’t we be treating them a bit better?
Those were the questions scientists and philosophers debated at a session here on Sunday.
Dolphins, it turns out, are pretty darn smart. Panelist Lori Marino, an expert on cetacean
neuroanatomy at Emory University in Atlanta, said they may be Earth’s second smartest creature, after humans, of course.
Bottlenose dolphins have bigger brains than humans (1600 grams versus 1300 grams), and they have a brain-to-body-weight ratio greater than that of great apes (but smaller than that of humans), said Marino. “They are the second most encephalized beings on the planet.”
But it’s not just size that matters. Dolphins also have a very complex neocortex, the part
of the brain responsible for problem solving, self-awareness, and various other traits we
associate with human intelligence. And researchers have found spindle neurons in
dolphin brains called von Economo neurons that in humans and apes have been linked to
emotions, social cognition, and even theory of mind: the ability to sense what others are
thinking. Overall, said Marino, “dolphin brains stack up quite well to human brains.”
What dolphins do with their brains is also impressive. Cognitive psychologist Diana
Reiss of Hunter College of the City University of New York has been working with dolphins in aquariums for most of her career, and she said their social intelligence rivals that of the great apes. Dolphins can recognize themselves in a mirror, a sign of self-awareness. They can understand complex gesture “sentences” from humans. And they can learn to poke an underwater keyboard to request toys. “Much of their learning is similar to what we see with young children,” said Reiss.
“The very traits that make dolphins interesting to study,” said Marino, “make confining
them in captivity unethical.” She noted, for example, that, in the wild, dolphins have a
home range of about 100 square kilometers. In captivity, they roam one 10-thousandth of one percent of this area.
Far worse, Reiss said, is the massive dolphin culling ongoing in some parts of the world, which she documented with a graphic video of dolphins being drowned and stabbed in places like the Japanese town of Taiji.
Thomas White, a philosopher at Loyola Marymount University in Redondo Beach,
California, suggested that dolphins aren’t merely like people—they may actually be people,
or at least, “nonhuman persons.” Defining exactly what it means to be a person is difficult,
White said, but dolphins seem to fit the checklist many philosophers agree on. There are the obvious ones: They’re alive, aware of their environment, and have emotions; but they alsoseem to have personalities, exhibit self-control, and treat others appropriately, even ethically.
When it comes to what defines a person, said White, “dolphins fit the bill.”
Still, experts caution that the scientific case for dolphin intelligence is based on relatively
little data. “It’s a pretty story, but it’s very speculative,” says Jacopo Annese, a neuroanatomist at the University of California, San Diego. Despite a long history of research, scientists still don’t agree on the roots of intelligence in the human brain, he says. “We don’t know, even in humans, the relationship between brain structure and function, let alone intelligence.” And, Annese says, far less is known about dolphins. –DAVID GRIMM