Why We Laugh—and Why It Is Good for Us
The neuroscience of laughter and smile.
Updated May 29, 2026 | Reviewed by Kaja Perina
After reading a New York Times article reporting that some patients find AI chatbots more helpful and compassionate than physicians, I asked an AI:
“Are you going to replace us doctors?”
We’ll still need someone to restart the Wi-Fi.”
Humans have been telling jokes for thousands of years. The oldest surviving collection of jokes, Philogelos (Greek for “Love of Laughter ”) was compiled around the fourth century AD. One joke aimed at physicians (a favorite target even then) goes like this:
A patient says to the doctor,
“Doctor, when I wake up for half an hour I feel dizzy.”
“Wake up half an hour later.”
Although humor and laughter are elemental to human experience, the neuroscience has only recently begun to reveal how laughter works and why it may be so important for our health.
Two Pathways to Laughter
I still remember a patient I saw during my neurology residency. She had suffered a stroke 6 months earleir which left her paralyzed on the left side, including her face. She could not smile symmetrically when I ask her to, as part of the routine neurological examination.
Yet later in the visit, a natural smile would appear while we were talking.
The answer lies in the fact that the brain contains two partially separate pathways for smiling and laughter.
The voluntary pathway allows us to smile or laugh on command. It originates at the motor cortex of the frontal lobe that control facial and vocal muscles.
The involuntary pathway originates in emotional centers such as the amygdala, hypothalamus, and anterior cingulate cortex. This network bypasses conscious control and generates spontaneous, emotionally driven laughter, the kind that erupts when we hear a funny joke or share a joyful moment with friends.
The brain distinguishes between the smile we choose and the smile we cannot help.
Why Did Humans Evolve to Laugh?
Why would evolution devote so much neural real estate to laughter?
Most humor follows a similar pattern. We build a mental model of what is happening, only to have that model suddenly overturned. A joke creates an expectation, then violates it in a surprising but harmless ways. That contrast makes us laugh.
Comedians, screenwriters, and literary scholars have decsribed many joke archetypes: misdirection, incongruity, false alarm resolution, superiority, and social bonding . Beneth these different forms lies a common structure: tension followed by release.
Neurologist V.S. Ramachandran proposed that laughter may have evolved as a signal of “averted danger.” When something initially appears threatening but turns out to be harmless, laughter communicates that realization to others; “False alarm. We are safe.”
He further speculated that the human smile may have evolved from an aborted threat display. A primate encountering another may initially bare its teeth, a threat gesture, but stop midway upon recognizing a friend, rather than a foe. He suggests this is why we show our teeth when we smile.
Whether or not this theory proves entirely correct, it highlights an important point. Laughter and smiling may have evolved not merely as expressions of pleasure, but as signals of safety and social connection.
Laughter Shapes Early Development and Social Bonds
Laughter precedes language. By six months of age, infants are engaging in rich social interactions with caregivers, including eye contact, smiling, giggling, and playful exchanges. These interactions promote bonding, are associated with oxytocin release, and help synchronize emotional states between parent and child. Such early social experiences help shape the developing brain, laying the groundwork for emotional regulation , resilience , and social competence.
Laughter may also enhance cognition and neuroplasticity . Processing humor is cognitively demanding. It requires the brain to activate working memory, detect conflicting interpretations, resolve ambiguity, and rapidly update expectations.
Laughter is contagious. When we hear someone laugh, our brains begin rehearsing the same behavior. The neural circuits involved in imitation and social understanding may help why laughter spreads so easily.
Taken together, these findings suggest that laughter is fundamentally a pro-social behavior. It regulates relationships, reduces social tensions and strengthens the bonds that hold communities together,
The Health Benefits of Laughter
Laughter lowers circulating stress hormones like cortisol and epinephrine. It increases oxygen intake and stimulates the release of neurochemicals associated with reward, connection, and well-being, including dopamine , serotonin, endorphins, and oxytocin.
Research suggests that laughter may also beneift cognitive function in older adults. In one study, laughter improved the short-term memory of adults over the age of 65. Simply anticipating humor decreased their cortisol levels by nearly 50 percent.
Laughter can also help navigate grief and adversity. By reducing physiological stress, humor may provide a physiological buffer during difficult times, fostering hope and resilience.
A recent research have revived interest in the “facial feedback hypothesis” , the idea that facial expressions influence emotional experience. While the popular advice to “just smile and you’ll be happy” is an oversimplication, this study showed that intentionally forming a smile produced a small but measurable effect in participant’s positive feelings.
This finding illustrates a broader principle of embodied cognition; the brain does not simply direct the body, it infer emotional state from signals coming back from the body.
We smile because we're happy, but smiling can also make us a little happier.
Laughter is more than entertainment. It is an ancient biological signal, a social glue, a developmental tool, and perhaps even a subtle form of medicine. Long before humans developed language, laughter helped us communicate safety, build trust, and strengthen social bonds.
Today, neuroscience is revealing that those same circuits continue to shape our emotional well-being.
Laughter maybe one of humanity’s oldest and most powerful social technologies.
Wild B, Rodden FA, Grodd W, Ruch W. Neural correlates of laughter and humour. Brain. 2003 Oct;126(Pt 10):2121-38. doi: 10.1093/brain/awg226. Epub 2003 Aug 5. PMID: 12902310.
This article is part of the Bringwise Psychology Journal — daily insights on human behavior, mental health, and personal growth.