Born to Be Good: The Science of a Meaningful Life

How so? First of all, Porges notes that the vagus nerve innervates the muscle groups of communicative systems involved in caretaking—the facial musculature and the vocal apparatus. In our research, for example, we have found that people systematically sigh—little quarter-second, breathy expressions of concern and understanding—when listening to another person describe an experience of suffering. The sigh is a primordial exhalation, calming the sigher’s fight/flight physiology, and a trigger of comfort and trust, our study found, in the speaker. When we sigh in soothing fashion, or reassure others in distress with our concerned gaze or oblique eyebrows, the vagus nerve is doing its work, stimulating the muscles of the throat, mouth, face, and tongue to emit soothing displays of concern and reassurance.

Second, the vagus nerve is the primary brake on our heart rate. Without activation of the vagus nerve, your heart would fire on average at about 115 beats per minute, instead of the more typical 72 beats per minute. The vagus nerve helps slow the heart rate down. When we are angry or fearful, our heart races, literally jumping five to ten beats per minute, distributing blood to various muscle groups, preparing the body for fight or flight. The vagus nerve does the opposite, reducing our heart rate to a more peaceful pace, enhancing the likelihood of gentle contact in close proximity with others.

Third, the vagus nerve is directly connected to rich networks of oxytocin receptors, those neuropeptides intimately involved in the experience of trust and love. As the vagus nerve fires, stimulating affiliative vocalizations and calmer cardiovascular physiology, presumably it triggers the release of oxytocin, sending signals of warmth, trust, and devotion throughout the brain and body and, ultimately, to other people.

Finally, the vagus nerve is unique to mammals. Reptilian autonomic nervous systems share the oldest portion of the vagus nerve with us, what is known as the dorsal vagal complex, responsible for immobilization behavior: for example, the shock response when physically traumatized; more speculatively, shame-related behavior when socially humiliated. Reptiles’ autonomic nervous systems also include the sympathetic region of the autonomic nervous system involved in fight/flight behavior. But as caretaking began to define a new class of species—mammals—a region of the nervous system, the vagus nerve, emerged evolutionarily to help support this new category of behavior.

Historians of science have rated Charles Darwin as off-the-charts in terms of kindness and warmth relative to other groundbreaking scientists (he was the only passenger on the Beagle about whom not a negative word was said, and was friend to captain and ship hands alike). As Darwin wrote in his Down House, amid the noisy, loving spectacle of his ten children, he most certainly felt those sensations of expansive warmth in the chest associated with the vagus nerve. The humming of the vagus nerve may have led Darwin to his often neglected thesis that sympathy and the maternal instincts are the centerpiece of human social evolution, that they bring the good in others to completion and are a foundation of high jen ratios. Some hundred and thirty years later a new science has yielded similar insights.

NERVES OF COMPASSION

 

Steve Porges’s wild-eyed claims about the vagus nerve would have inspired William James. James was the progenitor of the notion that our emotions originate in patterned responses in the autonomic nervous system, which lies below the brain stem and coordinates basic tasks like the distribution of blood, digestion, sexual response, and breathing. What could be more compelling proof that our emotions are embodied in peripheral physiological response, “reverberations of the viscera,” in James’s Victorian language, than the notion that that loftiest of human emotions—compassion—has its own bundle of nerves located deep within the chest?

Walter Cannon, a student of William James’s, was not so convinced by his advisor’s provocative armchair musings. The responses of the autonomic nervous system, Cannon countered, do not carry enough specific meaning to account for the many distinctions people make in their emotional experience. Patterned changes in heart rate, breathing, goose bumps, pupil dilation, cotton mouth, and sweaty palms could never give rise to nuances in experiences of gratitude, reverence, compassion, pity, love, devotion, desire, and pride.