The Evolution of Laughing and Crying

How have we humans come to be so skillful at smiling, laughing, and crying? Other notable human behaviors – reproducing, fighting, sharing, hunting –  have easily visible predecessors among most animals. But our repertoire of daily grins, laughs, and tears – except for some vaguely similar expressions among chimps, dogs, and rats – is unique. We express life’s joys and sorrows in ways that seem to have little ancestry.

But neuroscientist Michael Graziano proposes that we smile, laugh, and cry in useful mimicry of a protective, cringing reflex that is millions of years old.

In The Spaces Between Us: A Story of Neuroscience, Evolution, and Human Nature (2018), Graziano describes his team’s years of research at Princeton on how the brain monitors the personal space around us. This flexible buffer zone can extend out to the edges of the car we are driving or to our child who is leaning over a ledge. The buffer also shrinks to the physical closeness we allow with those we trust and even disappears altogether for pair bonding and sex. The buffer is a protective, not a social space. “Personal space is all about the zone where you keep people out, not the zone where you invite people in” (Kindle location 472).

Cringe (mikecrudge.com)

So where do smiling, laughing, and crying come in? Such expressive reactions are rooted in an ancient cringe posture that people still take on when their protective zone is suddenly and dangerously threatened – by seeing a stone thrown at them, for example. The posture reflects the brain’s first priorities: protect the eyes and the abdomen. “The forehead is mobilized downward and the cheeks are mobilized upward, dragging the upper lip with them.” As a result, the teeth are exposed. Hands cover the abdomen, the body hunches down, shoulders rise.

Smiles (Mount Pleasant Granary)

We think of a smile as being about teeth, but the display of teeth is only a consequence of the cheeks lifting upward to protect the eyes. Still, the sight of this wincing “smile” may have reassured an early enemy that the individual in the cringe posture was not a threat. But the potential victim learned even more: that the facial expression could be imitated, mimicked, in order to ward off injury, to play it safe. Millions of years later, we smile.

Graziano states his point carefully. “…[T]o be clear, the human smile is not a defensive cringe. When you smile, you are not thereby protecting your eyes from a flying stone. You’re not expressing fear. You’re not anticipating an attack. But the evolutionary precursor of a smile is a defensive cringe that protects the eyes in folds of skin. A smile is an evolutionary mimic” (2255).

 

Laughter (pngimage.net)

While the smile mimics a gesture that might have headed off a conflict before it started, laughter may have emerged as a way to prevent harmless play-fighting already in progress from getting too serious. Graziano connects laughter with tickling. When a child is tickled, the hand of the tickler moves into the child’s protective space, the cringe reaction begins to sound the alarm, the hand reaches an area of sensitive skin and “the touch evokes a full-blown laughter…an entire collection of alarm shrieks, defensive blocking and retracting, a pursing of skin around the eyes, upward bunching of the cheeks, upper lip pulling up, and secretion of tears”(2316). Laughter evolved from such an alarm reaction that tells a play-opponent that yes, you’ve touched me, touché, now that’s enough. Like the smile, laughter gradually became a social signal, read by others, mimicked by those who want to signal their good-natured agreeableness.

Graziano acknowledges that such speculation does not explain the many types of laughter – or the nature of humor itself. But it does suggest why, after the long road of its evolution, full and hearty laughter shares many of the facial markers of the defensive cringe.

Crying (youtube)

Crying, unlike smiling and laughing, adapts the cringe response to the loser’s need for friendly resolution after an all-out fight is over.  After an attack, a primate victor often comforts the loser. The loser’s cringing, moaning, and tears signal not only surrender but a plea to restore amity. After a million years of such reactions, we mimic the post-drubbing defensive cringe as a way to express pain and ask for consolation – even when we are crying alone.

Graziano’s book is very clear, very engaging, and at times very personal. And I value knowing how laughter and tears both link us to early ancestors while also displaying such an evolutionary distance from the original reflex.

Humboldt’s Vision of Nature

Humboldt portrait 1806 Friedrich Georg Weitsch (Wikipedia)

An artist’s imagining of  young Humboldt at work in 1806, by Friedrich Georg Weitsch (Wikipedia)

Our ecological imagination—our sense of nature as a global, interconnected and sacred whole—has roots in many sources. A relatively unfamiliar one is the work of Alexander von Humboldt (1769-1859), a manic, prolific explorer and naturalist of the German Romantic era. Humboldt’s life and work are the subject of an outstanding biography by Andrea Wulf, The Invention of Nature: Alexander von Humboldt’s New World (2015).

Humboldt’s trademark was the web of connections he drew around whatever he observed. Nature, he insisted, could not be grasped in the slices and pieces into which other scientists chopped it but only as a whole. He looked at each specimen, whether a plant or a human institution, in its relation to global patterns of terrain, weather, and behavior. Such a perspective called for not only information but imagination and emotion as well. His works are as full of poetry as they are of data.

His seminal journey during his thirties took him on a five-year exploration of Latin America. Wherever he traveled, he compared. In the Andes, a moss reminded him of a moss in northern Germany. In Mexico he found trees similar to those in Canada. Measuring temperature and altitude as he climbed stormy volcanoes and crawled across frozen ridges in the Andes, he envisioned the plants of the world in vegetation zones consistent around the planet. He published a large diagram of a mountain with labels for plants at their respective altitudes around the world, from mushrooms at the depths to lichens just below the snow line. No one had ever seen a graphic of ecosystems from a global perspective like this.

 

Humboldt (mappingthenation.com)

(mappingthenation.com)

Humboldt was the first to note that cutting down a forest set off a cascade of environmental problems, triggering the loss of topsoil, the rapid runoff of rainwater, the flooding of rivers, the drying up of springs, the decline of agriculture. He observed how the farming of single crops for trade, such as indigo in Peru, ruined the soil ‘like a mine,’ and impoverished the people. “He debated nature, ecological issues, imperial power and politics in relation to each other. He criticized unjust land distribution, monocultures, violence against tribal groups and indigenous work conditions” (105).

During his return from South America, Humboldt stopped by the White House to visit another scholar of agricultural economy, Thomas Jefferson. The two saw eye-to-eye on all subjects except one. Humboldt had seen enough slavery in South America to convince him that it was butchery without justification, economic or otherwise.  For Humboldt, “What is against nature is unjust, bad, and without validity,” and humans, like plants, all come from one root. “’Nature is the domain of liberty,’ Humboldt said, because nature’s balance was created by diversity” (108). Jefferson agreed but never freed all his slaves (106).

Humboldt noted similarities between the mountains of South America and Africa and argued that those continents had been joined in the past, anticipating the modern theory of plate tectonics.

In his later years in Berlin, he gave a series of free public lectures that packed halls with people from all walks of life. Traffic clogged the city on the lecture days. “He talked about poetry and astronomy but also about geology and landscape painting….He roamed from fossils to the northern lights, and from magnetism to flora, fauna, and the migration of the human race” (194). He spoke from notes layered with clippings, bits of book pages, scribbled post-its, illustrations.

humboldt kosmos(eternalexploration.wordpress.com)

From Kosmos, a map of cultures and peoples in South America (eternalexploration.wordpress.com)

He convened gatherings of scientists from across Europe to exchange information and ideas, establishing in effect the modern scientific conference. Fascinated by the earth’s magnetic field, he successfully urged governments to build a network of magnetic stations across the globe, setting a new level of international scientific cooperation.

In consultation with specialists, Humboldt spent his last years writing Kosmos, a multi-volume survey of what was then known about outer space, the climate and geology of earth, the relation among plants, animals, and humans, the history of science, and the perceptions of nature by artists and poets through the ages.

In 1831, the 22-year-old Charles Darwin boarded the Beagle for his own formative voyage and brought with him Humboldt’s seven-volume narrative of the Latin American expedition. Darwin followed Humboldt in seeing nature as a grand ecological system in constant flux and precarious balance. But while Humboldt looked for the integration of nature, Darwin looked for beginnings. On the Origin of Species appeared a few months after Humboldt’s death in 1859.

In her epilogue, Andrea Wulf writes that Humboldt’s name remains unfamiliar to many because, as the last scientist to study his field so broadly, he has been eclipsed by modern specialists famous for singular discoveries and theories. (Darwin is one example.) Yet when I read today about reverence for nature, anxiety about the climate, and the fused destinies of humans and the environment, I hear Humboldt loud and clear.