Tracing the Origins of Human Empathy

A pioneer in primate studies, Frans de Waal sees our better side in chimps, especially our capacity for empathy. In his research, Dr. de Waal has gathered ample evidence that our ability to identify with another's distress -- a catalyst for compassion and charity -- has deep roots in the origin of our species. It is a view independently reinforced by recent biomedical studies showing that our brains are built to feel another's pain.

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Chimpanzees console one another in ways that echo human behavior. Above, a mother chimp cuddles her offspring.

Like tuning forks, we reflexively respond to others' moods. We can weep at the plight of people we have never met or, spellbound by fiction, become caught up in the lives of people who never existed. Indeed, we may be hard-wired for empathy, University of Chicago researchers who studied children's neural responses to others reported last year. "It starts on day one, when a baby cries because it hears another baby cry," says Dr. de Waal.

In his new book -- "The Age of Empathy" -- Dr. de Waal, director of Living Links Center at Emory University's Yerkes National Primate Research Center in Atlanta, traces the origins of our ability to put ourselves in another's place. Drawing on his experiments and studies by other animal behaviorists, he highlights how chimpanzees and other primates console each other, prefer to share, and nurse the injured. There are no fossils of feelings, but as our closest living relatives, Dr. de Waal believes these primates are reminders of empathy's antiquity.

Despite our genetic similarity to chimpanzees, evolution has taken us on different paths since our ancestors diverged more than six million years or so ago. Our brains today are quite unlike a chimp's in size, organization and cellular complexity. A chimp's brain weighs as much as a can of baked beans -- only a quarter the average human weight. Our cerebral cortex, the brain's most highly evolved region, is three times larger than a chimp's. Our mind's emotional intelligence requires all that extra gray matter. And some neuroscientists consider empathy a uniquely human virtue.

Even so, Dr. de Waal contends that empathy, sympathy and compassion are traits shared by every species with a rudimentary capacity for self-awareness. While chimps can be combative and violent, they more often comfort and help each other. Capuchin monkeys enjoy giving to others. Elephants and dolphins aid companions in need. Whales can display something akin to gratitude. Even mice appear to have an ability to sense what their cage-mates are experiencing, says a recent study by researchers at McGill University.

"The old remains present in the new," Dr. de Waal says. "This is relevant to the story of empathy because it means that even our most thoughtful reactions to others share core processes with the reactions of young children, other primates, elephants, dogs and rodents."

"All mammals have some degree of it, and I think the origin is in maternal care," Dr. de Waal says. "I think mammals need a mechanism like this because a female needs to be very sensitive to emotional signals that come from offspring. We just have a more powerful imagination and that amplifies our capacity for empathy."

Empathy draws us into the life of another's mind. Synapses fire to marshal sensory cues, muster memories and weave intuitions that our conscious minds could never articulate. As a visceral response to others, empathy can manifest in unexpected ways -- through contagious yawning, for instance.

Most people can't help but yawn reflexively when someone else starts doing it first. No one knows why, but researchers at the State University of New York recently learned that people better able to identify with another's state of mind also yawn more readily in response to others. Children with autism -- a condition characterized by an inability to interact socially -- don't catch yawns, scientists at the University of London's Birkbeck College reported in 2007.

But monkeys do. Chimpanzees will yawn when shown a computer animation of another monkey yawning, Dr. de Waal and his colleagues reported earlier this month in the Proceedings of the Royal Society. "Yawn contagion is not completely understood, but it is related to empathy," he says.

Emotions are contagious, too. The suffering from a major natural disaster, such as the Indian Ocean tsunami, which in 2004 killed more than 200,000 people in 11 countries, can trigger a global pandemic of empathy and compassion. "You cry and I feel sad," says Dr. de Waal. "There is an echo of your feelings in me."

Recently, researchers started capturing these emotional echoes with functional magnetic resonance imaging devices that track the oxygenated blood flow associated with neural activity. In the process, they have mapped how empathy arises from the interaction of our oldest and newest brain structures.

Among our synapses, we do feel another's pain as our own, these brain imaging studies show.

Watching people being jabbed with a needle, shocked with an electrical cable or banged with a hammer activates the same brain networks as when we ourselves are hurt, researchers at the University College London and others have shown. In a similar way, our brain responds to seeing others being touched or expressing disgust as if we are experiencing those sensations ourselves.

"This may be the basis of how we understand each other," says cognitive neuroscientist Kevin Ochsner at Columbia University, who is researching the accuracy of our intuitions about others' feelings and state of mind.

Not surprisingly, we respond more readily to those with whom we already feel a bond, either through kinship, community or racial group, neuroscientists at Peking University in Beijing reported in June.

However it began, human empathy has evolved into a divining rod that enables us to understand other people's feelings and sensations even if we have never experienced them ourselves.

Not everyone, for instance, knows the sensation of pain. At the Pitié-Salpêtrière Hospital in Paris, neurophysiologist Nicolas Danziger studied empathy among people born unable to feel pain. To understand their sense of other people's injuries, he monitored their brains while they watched video clips of people in painful mishaps. The neural scans revealed that, with no memories of their own pain to guide them, they had to rely on their empathic ability to imagine the sensation.

"They crossed the bridge with empathy, to realize something that is completely exotic to them," says Dr. Danziger. "True empathy is the ability to imagine how others are feeling, especially people who are not the same as you."

Write to Robert Lee Hotz at sciencejournal@wsj.com