Our Ancient Laughing Brain. 1. Why do we laugh?. What makes us laugh?. Is humor the main ingredient of laughter?. Scientific investigation of laughter. Public places - only 10 to 20% has to do with humour (1200 conversations ). Dr.Robert Provine Neurobiologist.
Is humor the main ingredient of laughter?
Laughter disarms people, creates a bridge between them,
and facilitates amicable behavior
The function of laughter is .....
It seems to be a message that we send to other
people communicating joyful
disposition, bonding, happiness, willining to play.
We need to build
social structures in order to live well in our society and laughter signalize this disposition.
We rarely laugh alone
“If we see someone laughing
alone he or she would seem to be crazy”
“Laughter has powerful influences on the body”
Dr. J. Mercola, MD
You must get unobstructed upper airways in order to laugh
Therefore a spasm occurs, so that neck and head are
thrown back to provide a free respiratory intake.
Laughter is accompanied by a strong increase of amplitude and frequency of respiratory movement with a consequent increase in the intake of oxigen and output of carbon dioxide
“Laughter is a good aerobic exercice that ventilates the lungs”
Dr. William Fry Jr.
The venous return from the face by the jugular veins is partially blocked due to a strong contraction of neck muscles
Arterioles in the face dilate provoking an increase in the blood flow
Shedding of tears
The repeated contraction of the muscles around the eyes compressess the lacrimal glands provoking the outflow of tears.
Repeated short, strong contractions of the muscles of thoracic wall, abdomen, and diafragm increase blood flow into our internal organs
Muscle tension decreases, and we may temporarily lose control of our limbs.
“Being weak with laughter”
heart rate and blood pressure increase
The arteries then dilate, causing blood pressure to fall
Loss of control of urinary sphincter
“Shared laughter creates a bond of friendship. When people laugh together, they cease to be young and old, master and pupils. They have become a single group of human beings, enjoying their existence."
W. Grant Lee
“Laughter is a powerful sound”
Dr. Joseph M. Mercola
A Sociobiological Perspective
detectorContagious laughter:Roots in the neurological mechanism of laugh detection and replication
"The old saying that \'laughter is the best medicine,\' definitely appears to be true”
Michael Miller, M.D.
University of Maryland Medical Center
Scientists wondered if there was any cross- cultural differences in social context of laughter.
Eibl-Eibesfeldt documented laughter’s universality recording unstaged and undisturbed social interactions in a number of traditional societies
Native Brazilians, African tribesmen, Greek fishermen, etc.
Do we learn to laugh?
Or is laughter innate in human beings?
Congenitally blind, deaf, and dumb
Apes open their mouths wide, expose their teeth, retract the corners of their lips, and emit loud and repetitive vocalizations
Produce a pant “ah” for every expiration and inspiration
Produced by interrupting a
single expirationContrast of chimpanzee and human laugh production.
"The true origins of laughter lie in the rough-and-tumble
play of our primate ancestors”
Fighting in make-believe aggression is not for real. Laughter indicates that aggressive play is just fun
Rats emit short, high-frequency, ultrasonic vocalizations during rough-and-tumble play.
“Laughter also can serve as a weapon to
humiliate and ostracize its victims”
Is there a common evolutionary origin of laughter
Laughter in primates may have originated as a group threatening behaviour against strangers
They mean to keep the stranger:
Outside the group
Inside the group
“I am no threat to you”
It is trying to sound bigger than it actually is. They mean that they can bite
Contrast between laughter and aggression
Both involve showing the teeth
Definite function: communicative signal
Laughter involves the whole brain
Pleasure, happiness, joy
Vocalization, respiration, gland excretion
Areas involved with
Damage provoked in the neural circuit
responsible for the motor expression of laughter, may cause a "desinhibition" of the laughter
Fits of abnormal laughter, producing an inappropriate, unrestrained, uncontrollable laughter dissociated from any stimulus.
It is a disorder of emotional expression
All these conditions provoke an imbalance in the laughter expression mechanism
Motor Area (SMA)
SMA - Is associated with the control of speech
Electrical stimulation in supplemental motor area triggered peals of mirthful laughter.
Anatomy of Tickling
(Area that registers touch)
Tickling stimulates touch receptors in the skin. These receptors, when stimulated carry information in sensory neurons that goes to the spinal cord.
Then this information travels up to the sensory cortex via the thalamus.
The sensory cortex is involved in processing information from the skin.
We do not laugh when we tickle ourselves, only when other people tickle us.
Brain region that helps to control voluntary movement and balance
Predicts the sensory consequences of movements - supplying the brain with information that reduces the sensation of touch information.
“For tickling to be effective, you must not know the precise point of stimulation in advance”
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.
She used robotic arms to tickle people and found it to be as effective as real people in provoking laughter.
However, when her subjects used a joystick to control the tickling robot, they couldn’t make themselves laugh.
Part of the brain that registers touch
fMRI detected more neuronal activity in somatosensory cortex, when people were tickled than when they tickled themselves.
To compare brain activity when a subject\'s hand was tickled by an experimenter or by himself.
Somatosensory cortex helps interpret external stimuli registered by nerve endings that sense touch.
“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, to build stable social structures and sharing creatures that do the right things in the world. If other people are interacting with us in positive ways and we respect the way they feel, then I think we have a better world. And play and laughter are a big part of that”.
Our ancient Laughing Brain
By Silvia Helena Cardoso
Avaliable on-line at:
Laughter: A Scientific Investigation
A Book by Robert R. Provine