Our Ancient Laughing Brain Courtesy of Cerebrum
The Laughing Brain
Scientists have been studying the play behavior of young animals to identify its neural basis. Some
are also evaluating whether and to what extent early social experiences such as play or lack of it
influence neural structure and function. Although the neural bases of laughter are not fully
understood, we are slowly putting together a picture of the various brain regions involved in
producing laughter. The ancient limbic system of the brain, including two structures involved
with emotions - the hippocampus and the amygdala - is involved in laughter, suggesting that it is
deep in our animal nture. But our cortex, too, appears to have a role, relating laughter and speech
and bringing humor into the equation. A. Primitive brain (archipallium) - Self preservation,
aggression. B. Intermediate brain (paleopallium) - Limbic system, emotions. C. Rational brain
(neopallium) - Neocortex, intellectual tasks. Laughing in potentially aggressive or competitive
situations disarms our social companions. On the verge of becoming our adversaries, they pick up
from our laughter that the situation is not threatening
The evolving human brain acquired three major parts that developed in succession and became
superimposed (see illustration above). The archipallium, or primitive (reptilian) brain comprises
the structures of the brain stem; the paleopallium, or intermediate (old mammalian) brain comprises
the structures of the limbic system. The neopallium, also known as the superior or rational (new
mammalian) brain, includes almost the whole of the hemispheres (made of a more recent type of tissue
called the neocortex) and some subcortical neuronal groups. These three make up the brain of the
superior mammals, including primates and humans.
When we examine brain areas involved with laughter, the limbic system (part of the old mammalian
brain) seems central. It controls behaviors essential to the survival of all mammals—for example,
defending oneself and finding food. The same structures that are found in the human limbic system
are found in the brains of much earlier animals such as lizards, snakes, and toads. In them, the
limbic system, linked to the sense of smell, is involved in hunting, eating prey, and defending
territory. In humans, the limbic system is more important in motivation and emotional behaviors. Two
limbic structures involved with emotions are the hippocampus (a seahorse-shaped structure) and the
amygdala, a small, almond-shaped structure deep in the brain. The amygdala connects with the
hippocampus and the medial dorsal nucleus of the thalamus, enabling the amygdala to have an
important role in mediating and controlling mood expression and emotion-laden activities like
friendship, love, and affection. The hypothalamus, particularly its median part, has been identified
as a key contributor to the production of loud, uncontrollable laughter.
If laughter is such a primitive feature of the human primate, with origins in lower mammals, it
stands to reason that its neural substrate would be in areas of the brain we share with other
animals, probably the same places aggressive and emotional behaviors are organized.
Neurobiologist Provine believes that laughter emerges not from our conscious mind (in other words,
the cortex) but from a more primitive part that he calls the "pre-cognitive brain." He says, "We're
talking about something that's very deep in our animal nature." Panksepp, too, sees evidence that
laughter is triggered by genetically older structures of the brain. He writes that "it is not
exactly a cerebral activity. Then laughter must be an ancient response, part of our earliest
evolution into mammals, and is triggered by brain regions that evolved from ancient times."
Recently, however, scientists have discovered that the brain's cortex also plays a critical role in
creating laughter. Studying a young epileptic woman, researchers electrically stimulated a part of
the cortex called the supplemental motor area (SMA), and found that low-intensity current induced
her to smile (5). A higher-intensity current transformed her smile into a contagious fit of
laughter. The SMA, associated with the control of speech, lies just behind the pre-supplemental
motor area, which is also found in nonhuman primates. Neurophysiologists believe that the SMA is
part of a larger brain circuit responsible for processing emotions related to humorous things: the
cognitive part ("getting it"😉 as well as the motor part (smiling and laughing), which involves
muscles of the face and respiratory system.
Based on those observations, researchers conclude that there is a link among the motor, emotional,
and cognitive components of laughter. They propose that the SMA spot they found "is part of a
further development in humans to accommodate the specialized functions of speech, manual dexterity
and laughter." So, not surprisingly, there is a relationship in the brain between speech and
laughter. After all, both are communicative activities, for which we use the same muscles of the
face and need to control the way we breathe. Primates have highly mobile facial expressions, and we
rely on our faces more than any other body part for communication, including speech.
Tickling is a fascinating instance of the connection between playfulness and social bonding.
It begins in early infancy, when parents tickle their babies to evoke laughter and
pleasurable sensations in them. Although there are a few "unticklish" children and adults,
tickling almost always produces laughter. Probably tickling and laughter evolved in part to
help us relate to others.
One remarkable feature of tickling is that we do not laugh when we tickle ourselves, only when other
people tickle us. This implies that the brain may have a different mechanism for responding to the
two types of tickling. Charles Darwin first explored the link between tickling and social relations,
arguing that tickling provokes laughter through the anticipation of pleasure. If a stranger tickles
a child without any preliminaries, catching the child by surprise, the likely result will be not
laughter but withdrawal and displeasure. Darwin also noticed that for tickling to be effective, you
must not know the precise point of stimulation in advance. He reasoned that this is why you cannot
effectively tickle yourself.
Researcher Sarah-Jayne Blakemore confirmed Darwin's propositions by investigating how the brain
distinguishes between sensations we create for ourselves and sensations others create for us. She
used robotic arms to tickle people and found them to be as effective as real people in provoking
laughter. When her subjects used a joystick to control the tickling robot, however, they couldn't
make themselves laugh.6 Her studies suggest that when you try to tickle yourself, your cerebellum
sends to your somatosensory cortex precise information on the position of the tickling target and
therefore what sensation to expect. Apparently some cortical mechanism then decreases or inhibits
the tickling sensation.
Why is the brain built this way? "It may be that there is no point laughing to your own tickle
because it is not biologically important," says Blakemore. But tickling by your playful companions
is indeed socially important, as we have seen.
Humor: Evolved Ticklishness?
Quoted message said:From these studies an apparent contradiction arises.
If laughter can be triggered by stimulating highly developed cortical areas of the brain, how
could laughter be, at the same time, a primitive feature of both human and nonhuman brains? The
answer may lie in our prodigious human capacity for humor, which we do not seem to share with
other animals.
The main argument here is that laughter induced by a joke or by watching something funny may be a
highly evolved version of the laughter induced in our ancestors by play or tickling. Provine
suggests that the human brain is able to enlarge the capabilities of one of its ancient, more
primitive features by processing lower functions. in higher areas. "When we hear laughter, we are
hearing something that is very primitive. In the more modern version, laughter induced by jokes
involves cognitive systems, something that evolved long after speech and language."
Chimpanzees show laughterlike behavior in response to physical contact, such as wrestling, chasing,
or tickling, but humans laugh more in response to conversational and visual stimuli. Both Darwin
and German evolutionist Ernst Haeckel theorized that jokes were essentially "psychological
tickling." Haeckel believed that laughter was a kind of reflex, which relieved the irritation of
vasomotor nerves brought on by physical or mental tickling. Ethnologist Glenn E. Weisfeld, an
expert on humor, adds that "the subject matter of humor often pertains to ticklish situations." The
word humor is from the Latin humere, meaning "liquid" or "fluid," and betrays the Aristotelian
belief (continued into the Middle Ages) that all emotional states were related to the essential
four body fluids that drive us.
One definition of humor is "the mental faculty of discovering, expressing, or appreciating the
ludicrous or absurdly incongruous." Visual and verbal jokes often emphasize the exaggeration,
absurdity, eccentricity, or inconsistency of a situation, a behavior, or an outcome. This
exaggeration becomes the core element provoking laughter: the punch line. Rat pups emit short,
high frequency, ultrasonic vocalizations during rough and tumble play, and when tickled. They
"laugh" far more than olders rats.
Another key element of humor and laughter is the release after danger and surprise. When we laugh
our heads off at someone slipping on a banana peel or getting a pie in the face, we are laughing at
situations that involve surprise, incongruence, potential damage to the body, or an unexpected
outcome—all stimuli that trigger fight-or-flight in our primitive, jungle-primate selves.
Philosopher John Morreall believes that human laughter may have its biological origins as a kind of
shared expression of relief at the passing of danger. The relaxation of tension we feel after
laughing may help inhibit the fight-or-flight response, making laughter a behavioral sign of trust
in one's companions.
This connection between humor and the release of tension makes sense in brain terms. Animal (and
human) brains do not like novelty and change; they are hardwired to produce a certain amount of
tension when something unexpected occurs, because any environmental change could be a threat. A
sudden noise startles us. A playful lunge at our belly by a friend provokes instinctive recoil and a
suitably scared expression, then laughter. If the stimulus were a gunshot, however, or a real punch
in the gut, we would most assuredly not laugh but seek cover or defend ourselves.
Watch people laughing at an amusement park and you see this connection between release from danger
and laughter. A boat swooping down a steep chute into water first evokes expressions of horror and
fear. When no danger ensues, laughter erupts. In the same vein, slapstick comedies feature a lot of
head banging, falls, and edge-of-the-cliff situations to induce laughter. We enjoy make-believe
aggression and danger and we laugh to relieve the tension and signal to our companions that all is
well. Weisfeld notes that "lots of humor pertains to aggressive or competitive situations in which
someone gets hurt." See how professional comedians or clowns use stooges who are constantly
embarrassed, hit, and harassed. Release from danger or threat - or the civilized substitute for it
during the amusement park plunge down the water chute - is followed by an explosion of laughter as
we share our feelings of relief.
Appreciating Humor
The brain's right hemisphere appears to be important in appreciating humor (7). In particular, the
frontal lobe processes cognitive tasks needed for us to get to the joke, including abstract
interpretation of aspects of conversation such as irony, affective intonation, sarcasm, and
innuendo.8 The frontal lobe is part of a wider neural circuit involved in controlling emotion. Many
neural pathways connect it with the "emotional" part of the brain—that is, the limbic and
hypothalamic systems.
Recent studies by Prathiba Shammi and Donald T. Stuss at the University of Toronto suggest an
interesting asymmetry in the frontal lobe's function in humor. It seems that the right lobe is more
involved than the left, but why? PET (positron-emission tomography) studies have shown that the
right hemisphere, particularly the right frontal lobe, mediates the indirect interpretation of
information, a process key to so many forms of humor. Appreciation of humor also often requires
interpreting current information in the light of our past experience, and the right frontal lobe is
critical for the retrieval of memories.
Why Laughing Is Good Medicine
Laughter is not only associated with release of tension induced by danger and signaling
nonaggression but also with expressing good, positive emotions. It is a social glue that facilitates
approach, contact, and intimacy between people and decreases stress from potential conflict. This
could be the basis for the intuitive notion that "laughter is the best medicine."
Serious research is showing that this notion is true. Laughter and humor decrease stress and
anxiety, reinforce immunity, relax muscle tension, and decrease blood pressure and pain. Modern
medicine is beginning to take advantage of these positive effects; hospitalized children who see
clown shows have shorter hospital stays than those who do not. Laughter in humans serves as
social glue. It helps us break the ice, get closer to people, dampen hostility and aggression, or
soften a refusal.
Photo by Vietnam Travel-Pictures: Hanoi, Da Nang, Hue, Saigon
Laughter initiates a chain of physiological reactions. First, it activates the cardiovascular
system, so heart rate and blood pressure increase. The arteries then dilate, however, causing blood
pressure to fall. Repeated short, strong contractions of the muscles of the thoracic wall, abdomen,
and diaphragm increase blood flow into our internal organs. Forced respiration (the ha! ha! of
laughter) elevates the flow of oxygen into the blood. Muscle tension decreases, and we may
temporarily lose control of our limbs, as in the expression "weak with laughter."
People suffering from chronic anger have a higher incidence of elevated blood pressure, increased
cholesterol levels, and heart attacks. While anger, depression, and frustration disturb the function
of many bodily systems, including the immune system, laughter helps the immune system to increase
the number of type T leukocytes (T-cells) in the blood, which combat damage and infection. Some
researchers have dubbed T-cells the "happiness cells."
Laughter may also produce beneficial hormonal changes. Scientists speculate that laughter releases
neurochemical transmitters called "endorphins," which reduce sensitivity to pain and boost endurance
and pleasurable sensations.
Laughter's Social Power
Why does laughter have such pervasive power in our lives? Beyond its physical effects, I believe
that the answer lies in our social nature. Laughter appears to be a basic aspect of bonding.
We are creatures who need to build stable social structures to live well. Thus we need to enjoy
peaceful relations with the people around us. Laughter is a kind of message we send to communicate
this joyful disposition and a willingness to play. We rarely laugh when we are alone. We even feel
that someone laughing alone may be crazy.
Laughter has many subtle effects on our social companions. It breaks the ice, achieves closeness,
bonds us, generates goodwill, and dampens hostility and aggression. Observe how we laugh when we
want to deflate tension between strangers or need to say no to someone. We often laugh when we
apologize.
Laughter disarms people, creates a bridge between them, and facilitates amicable behavior. Even
babies laugh. Since they are too young to have a sense of humor, smiling and laughing must reinforce
their connections with their parents and others close to them. Laughter's function in social
relations may go still deeper. Studies have shown that socially dominant individuals like bosses or
tribal chiefs use laughter to control their subordinates.
When the boss laughs, everyone laughs. Is laughter, then, a form of asserting power? Morreall
speculates that in this way, bosses are "controlling the emotional climate of the group." Provine
and his colleagues observed that women in an audience laugh more often when the speaker is a man.
Does this suggest gender differences in how we use laughter? Or reflect men's generally more
powerful social role?
Age differences in laughter have also been noted. Adolescents use it more when they are playing or
flirting; executives use it more in a professional context, to increase rapport with someone or win
a negotiation. On the other hand, laughter may have a negative connotation, even in our own culture.
There is a widely appreciated difference between "laughing with" and "laughing at" someone. Using
sarcasm and scorn toward people may cast them out of a group or block their entry. Laughter then
becomes an instrument of social hostility.
Humor usually means trouble - preferrably for someone else. Humor and laughter can be a way to deal
with surprise, incongruence, and threat. As tension mounts, along with all the stimuli that trigger
the fight-or-fight response, laughter can be a release that we share with others.
When Laughter Is Not Funny
Some people have fits of abnormal laughter, producing an inappropriate, unrestrained, uncontrollable
laughter dissociated from any stimulus. To observers, the laughter often appears childish or
violent. Clinical researchers report pathological laughter in three main conditions: psychiatric
illnesses such as hysteria and schizophrenia; pseudobulbar palsy (a disorder affecting the muscles
that control the tongue, throat, and parts of the face); and gelastic epilepsy (a form of temporal
lobe epilepsy with fits of mirthless laughter).9 Scientists believe all these conditions involve
disinhibition of impulses in the higher brain stem.
Although the neuroanatomy of pathological laughter is not fully known, three levels of the brain are
probably involved: the cortical level, the bulbar level, and an integrative level probably at or
near the hypothalamus. Patients with pathological laughter almost invariably have brain damage.
Laughter may also cause neural pathology, however, leading to or aggravating some key symptom. For
example, in a disease called cataplexy, characterized by sudden lack of muscle tone that leads to
falls, laughter is a potent triggering stimuli.
Collective contagious laughter is also pathological. One of the most extreme cases occurred in 1962
in Tanganyika. It started among young girls who erupted in fits of laughter that did not stop,
spread to neighboring communities, and became so severe that schools were forced to close. The
epidemic persisted for almost six months and may not have been psychological—at least not
entirely—because victims had symptoms such as fever and headache.
The Risks of Not Playing
We have examined how important laughter is in our lives, how it forges social bonds, how it stems
from our playful behavior as children. In this light, the trend in modern Western societies to
restrict the play of children is worrying. What will be the consequences, if, indeed, play is
important in developing personality and social behavior?
Watching television and engaging in socially isolated, individual play with video games and
electronic toys has increasingly displaced social interaction and group play. Fear of crime, illegal
drugs, and automobile traffic makes many parents curtail the custom of sending children outdoors to
play freely. Parents who arrive home late from work have little time to play with their children in
the evenings. Schools cut into playtime to cram more classes and topics into the day; they use
detention or suspension of playtime to punish pupils for misbehaving or for getting poor grades.
Teaching children to compete seems to have overtaken teaching them to relax, play, and socialize.
Where will all this lead? There are indications that these shifts may have some bearing on many of
today's social ills: increasing violence in schools, very young children using weapons and drugs,
and social and racial intolerance. Scientists such as Panksepp speculate that the recent astounding
increase in the prevalence of attention deficit hyperactivity disorder may be fueled by restrictions
on play in American schools. Deprived of exercise and time to play, normal young children become
fidgety; their attention spans decrease.
A Better World of Laughter
Laughter and play are important in our human behavioral repertoire, a response both ancient and
modern. When we laugh spontaneously, we use a capacity rooted in our most primitive biology. When we
laugh at a subtle joke, we build on this primitive process, employing an advanced capacity of our
brains. In both cases, our laughter has a surprisingly important role. Panksepp summarizes this with
wisdom and beauty:
Play and laughter not only fertilize the brain but they fertilize the human spirit. These are
the types of systems that allow us to be joyous, sharing creatures that do the right things in
the world—or usually do the right things. If other people are interacting with us in positive
ways and we respect the way they feel and they respect the way we feel, if we read each other's
minds correctly, then I think we have a better world. And play and laughter are a big part of
that.