130 Years Later: Darwin’s Theories Stand

While Darwin theorized about it more than a century ago, scientists continue to study links between emotions in humans and in animals.

Published January 1, 2003

By Rosemarie Foster
Academy Contributor

Birds do it. Bees do it. Humans and chimpanzees do it. What do we have in common? Expressing our emotions, albeit in different ways. How we do it and why was the subject of a recent two-day conference called Emotions Inside Out, sponsored by The New York Academy of Sciences (the Academy) in November and held at The Rockefeller University.

The topic is not new: In his 1872 book The Expression of the Emotions in Man and Animals, Charles Darwin recounted his observations of animals, his own children and other people, linking particular expressions with specific emotions. His book was “radical for his time and for today,” explained Paul Ekman, PhD, of the University of California, San Francisco, and conference chair. “We all stand on the contributions this great man made in this extraordinary book.”

Face Value

The face is often our first encounter with another’s emotions. Frans B.M. de Waal, PhD, of Emory University’s Yerkes Primate Center, scrutinizes the facial expressions and gestures of chimpanzees and their cousins, the bonobos, and has found remarkable similarities with humans. They smile and laugh like we do. A chimp may even extend a hand to another chimp after having been fighting – as a sign of reconciliation.

At Yerkes, Lisa A. Parr, PhD, observes how chimpanzees respond to photographs and sound recordings of other chimps. She has found that they process both visual and auditory cues to interpret emotion, with certain facial expressions and sounds having more relevance than others.

The same goes for human infants. “The emotional signals of a mother influence her baby in very powerful ways, and some of those have long-lasting impact,” said Joseph J. Campos, PhD, of U.C., Berkeley. For example, a mother may use facial expressions and varying tones of voice to denote approval or disapproval of her young infant’s actions.

By 12 months, infants begin seeking out emotional information themselves as a means of interpreting what’s happening around them. Emotional sharing between the infant and the mother begins shortly thereafter.

Infants’ emotional expression also varies by culture. Linda A. Camras, PhD, of DePaul University, compares facial expressions and reactions among infants of different nationalities who are exposed to stimuli that elicit positive and negative emotions. She has found that European-American babies are more expressive than Chinese infants, with Japanese babies falling somewhere in between.

Liar, Liar?

“The face lies and the face leaks,” said Paul Ekman in his presentation on facial expressions and deception. He described the value of interpreting facial “micro-expressions,” which may only last 1/25th of a second but reveal a person’s true intent. Micro-expressions, and the messages they convey, become much more apparent when viewed using slow-motion video, though trained observers can spot them instantly. They are often involuntary muscular movements of which the speaker is unaware.

“Facial expressions that contain an involuntary movement that is difficult to make voluntarily are the most reliable,” added Ekman. Taken in context with the pitch of a person’s voice, micro-expressions are a “very real source of information.”

Such fleeting expressions were also addressed by Dacher Keltner, PhD, of U.C., Berkeley. In a study of the faces of women in Mills College yearbook photos taken more than 30 years ago, Keltner found that women who displayed strong, natural smiles in the photos later felt the happiest over the course of their lives, and had better marriages. “Very brief observations of the face can tell us a tremendous amount about life,” he concluded.

Calls of the Wild

Some animals rely more on auditory displays to express their emotions. Superb starlings, diana monkeys, and baboons of Botswana’s Okavango Delta all have a catalogue of alarm calls to differentiate airborne predators (such as an eagle) from those on the ground (such as a leopard), letting nearby animals know how to escape.

“These vocalizations are clearly emotional signals, given in highly emotionally charged situations,” explained Robert M. Seyfarth, PhD, of the University of Pennsylvania. The characteristic “wahoo” sound of the baboons also differentiates high- from low-ranking males, as well as young from old.

Jo-Anne Bachorowski, PhD, of Vanderbilt University, might argue that humans use laughter in a similar way, to influence the response of those who hear it. Her studies have shown that men laugh most strongly with other male friends, while women’s laughs are stronger in the presence of other males (friends as well as strangers). “Laughter is a tool to elicit affect, and thereby shape the behavior of the listener toward the laugher,” she concluded.

Blood, Sweat, and Fears

When we laugh or cry – and when we try to stifle those feelings – our bodies respond with measurable responses in the heart and brain.

“There is no single emotion center in the brain,” said Richard J. Davidson, PhD, of the University of Wisconsin. Rather, the seat of emotion stretches across several regions.

Much of emotion is regulated by various areas in the prefrontal cortex, a finding supported by Davidson’s functional MRI studies. Those investigations also demonstrated contractility in the heart in response to the threat of shock, as well as activation of the brain’s amygdala.

David G. Amaral, PhD, of U.C., Davis, has done studies in monkeys confirming the role of the amygdala as the fear-processing center of the brain. “The amygdala is a protection device that not only instills a fear response,” he explained, “but controls behavior so that an individual can evaluate a situation.”

In response to fear, some of us turn white. Robert W. Levenson, PhD, of U.C., Berkeley, explained how that response is regulated by the autonomic nervous system (ANS).

In addition to making us blush with embarrassment or turn red with anger, the ANS governs the physiological responses that occur when we try to suppress an emotion we are feeling. Levenson’s studies demonstrate that such suppression can cause increased heart rate and skin conductance.

Emotion in the Golden Years

We know our bodies begin to slow down as we age. But our emotional perception actually gets better. “Emotional experience and regulation improve with age, despite the losses that occur with aging,” noted Laura L. Carstensen, PhD, of Stanford University.

In the second half of life, people reprioritize their lives in pursuit of emotional balance and well-being. Her research shows they’re more likely to recall positive images and messages, and desire more time with their families. Concluded Carstensen, “As we age, we begin to focus on the positive, forget about the negative, and find a way to successfully navigate through life in our later years.” And that’s good news.

Also read: 165 Years of ‘On the Origin of Species’