Why our facial expression changes when we cry? Have you
ever had a doubt why our facial expression is changed when we are in pain and
that expression is called as cry. Why would our facial expression turn like
that, why people called its as crying. Moving away from "the noisy,
promiscuous pronouncement of childhood," the subdued weeping of adulthood
"favors the face-to-face encounters of an intimate setting."
The human body is an extraordinary machine, and our
behavior an incessant source of fascination. In Curious Behavior: Yawning,
Laughing, Hiccupping, and Beyond (public library), psychology and neuroscience
professorRobert R. Provine undertakes an "analysis and celebration of
undervalued, informative, and sometimes disreputable human behavior" by
applying the lens of anthropologically-inspired, observational "Small
Science" -- "small because it does not require fancy equipment and a
big budget, not because it's trivial" -- to a wealth of clinical research
into the biology, physiology, and neuropsychology of our bodily behaviors.
Take, for instance, the science of what we call
"crying," a uniquely human capacity -- a grab-bag term that consists
of "vocal crying," or sobbing, and "emotional tearing," our
quiet waterworks. Provine explains:
As an adult, you cry much less than when young, and your
crying is more often subdued, teary weeping than the demonstrative, vocal
sobbing of childhood. . . [T]he trauma that causes your crying is now more
often emotional than physical. However, whether intentional or not, as adult or
child, you cry to solicit assistance, whether physical aid or emotional solace.
Paradoxically, your adult cry for help is more private than the noisy,
promiscuous pronouncement of childhood, often occurring at home, where it finds
a select audience. The developmental shift from vocal crying to visual tearing
favors the face-to-face encounters of an intimate setting. The maturation of
inhibitory control gives adults the ability to select where and when crying
occurs, or to inhibit it altogether, options less available to children.
To better illustrate the physiology of crying, Provine
contrasts it with that of laughing, pointing out that the two are complementary
behaviors and understanding one helps understand the other.
Specialists may argue whether there is a typical cry or
laugh, but enough is known about these vocalizations to provide vivid
contrasts. A cry is a sustained, voiced utterance, usually of around one second
or more (reports vary), the duration of an outward breath. Think of a baby's
'waaa.' . . . Cries repeat at intervals of about one second, roughly the
duration of one respiratory cycle . . . A laugh, in contrast, is a chopped (not
sustained), usually voiced exhalation, as in 'ha-ha-ha,' in which each syllable
('ha') lasts about 1/15 second and repeats every 1/5 second.
One curious feature crying and laughing have in common,
which any human being with a beating heart can attest to:
Crying and laughing both show strong perseveration, the
tendency to maintain a behavior once it has started. These acts don't have an
on-off switch, a trait responsible for some quirks of human behavior. Whether
baby or adult, it's easier to prevent a bout of crying than to stop it once
under way. Crying causes more crying. Likewise, laughter causes more laughter,
a reason why headliners at comedy clubs want other performers to warm up the
audience, and why you may be immobilized by a laughing fit that can't be
quelled by heroic attempts at self-control. In fact, voluntary control has
little to do with starting or stopping most crying or laughing.
So, if vocal crying evolved to attract help, what's the
evolutionary purpose of quiet tears? For one, they contain lysozyme, the body's
own antiseptic, which sanitizes and lubricates the eye. But, Provine argues,
there might be something much more interesting and neurobiologically profound
at work:
Several lines of evidence suggest that the NGF [nerve
growth factor] in tears has medicinal functions. The NGF concentration in
tears, cornea, and lacrimal glands increases after corneal wounding, suggesting
that NGF plays a part in healing. More directly, the topical application of NGF
promotes the healing of corneal ulcers and may increase tear production in dry
eye . . . Although more of a scientific long shot, I suggest that tears bearing
NGF have an anti-depressive effect that may modulate as well as signal mood.
Non-emotional, healing tears may have originally signaled
trauma to the eyes, eliciting caregiving by tribe members or inhibiting
physical aggression by adversaries. This primal signal may have later evolved
through ritualization to become a sign of emotional as well as physical
distress. In this evolutionary scenario, the visual and possibly chemical
signals of emotional tears may be secondary consequences of lacrimal secretions
that originally evolved in the service of ocular maintenance and healing.
If anything, Provine points to this as a direction of
curiosity for future research:
Emotional tearing is a uniquely human and relatively
modern evolutionary innovation that may have left fresh biological tracks of
its genesis. The contrast of the human lacrimal system with that of our
tearless primate relatives may reveal a path to emotional tearfulness that
involves NGF. NGF may be both a healing agent found in tears and a neurotrophin
that plays a central role in shaping the neurologic circuitry essential for
emotional tearing during development and evolution. A lesson of NGF research is
that pursuit of the scientific trail can lead to serendipitous discoveries both
broad and deep. Emotional tears may provide an exciting new chapter in the NGF
saga, and vice versa.
The rest of Curious Behavior goes on to explore such
seemingly mundane by, in fact, utterly fascinating phenomena as yawning,
sneezing, coughing, tickling, nausea, and, yes, farting and belching.
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