12 I People
Laughter:
The mechanism behind the best medicine BY PAULA HORNSTEIN, BIOCHEMISTRY, 2020
I
magine you are an alien visiting Earth. In a conversation with a human, you tell a knock-knock joke. The human responds to this by emitting rhythmic, repetitive noises from deep inside their bodies, seemingly by impulse. You later tell someone else the same joke, and receive the same response from a different human, although the noises he makes are slightly different and have a different rhythm. You think, Why do they do this? What causes this shared human reaction to something humorous? This is a subject of wonder spanning as long as humans have been laughing. In 1922, an article was published in the popular twentieth-century science magazine, The Scientific Monthly, entitled Why Do We Laugh? In this piece, Professor Wilson D. Wallis of Reed College addresses the sociological and theoretical evolutionary reasoning for our impulse to laugh. According to Wallis, laughter is both a social phenomenon and a language in and of itself. Laughter as a physical response is two-fold: it is uplifting for the individual and provides for social solidarity. While laughter is not necessarily reserved for only humorous situations--cue nervous laughter, or boastful laughter--it is representative of a person’s understanding of a joke, an anecdote, or a situation, giving humans a sociological reason for their reflex to let out a titter. Since this publication, much of the scientific reasoning for laughter has been discovered. Real laughter requires a
stimulus, either internal or external. This stimulus activates the ventromedial prefrontal cortex, and the stimulus processed by multiple regions in the brain, including the hippocampus and amygdala. Many theories of the precise neural pathway of laughter exist, and are still being studied to this day. A human’s physiological reaction to this stimulus is rhythmic, continuous contractions of the diaphragm. The regular proceedings of respiratory system are disrupted, causing the audible gasps that are characteristic of any laugh. A particularly intense bout of laughter can disrupt ventilation to such an extent that the person can turn blue as a result of hypoxia, or possibly activate the tear ducts. In fact, there are at least ten records of people who have “died of laughter,” usually due to a dangerously high respiratory rate that resulted in heart failure. The truth behind these stories are questionable, but there is no doubt that the mechanism behind laughter involves inherent disruption of homeostasis within the body. Despite the risks involved in laughter, laughter can certainly not be considered a dangerous act. In addition to its social benefits, laughter has been shown to have beneficial effects on the brain and the body alike, such as reducing stress hormone levels, releasing endorphins, relaxing the muscles, and lowering blood pressure. While laughter may not be the best medicine, it certainly provides health benefits that make it worth acknowledging the humor in the world.
Evolved from greatness: Studying the Grandmother Effect
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WRITTEN AND DESIGNED BY LILLIE HOFFART, ENVIRONMENTAL SCIENCE, 2022
hy do humans live long after their years of childbearing? Few other species experience the social connections humans do with their grandparents. A hypothesis known as the Grandmother Effect suggests this is not due to advances in healthcare, but rather is an integral aspect of human survival. University of Utah Anthropologist Kristen Hawkes is one of the leading advocates for this phenomenon. Her interest in the Grandmother Effect was sparked in the 1980s while on two field projects studying the behavioral ecology of hunter-gatherer populations in Paraguay and Tanzania. Grandmothers spent much time harvesting food for their grandchildren. From this, Hawkes concluded this event explains why humans have evolved to live long after their reproductive years. In earlier years, grandmothers could help provide for their grandchildren, which would allow the children’s mother to devote herself more to the next baby. “Vigorous grandmothers could help more and leave more descendants,” Hawkes wrote in a 2012 mathematical population analysis. Therefore, the most evolutionarily-fit grandmothers will pass on their longevity genes to the greatest number of grandchildren.
In a study combining data collected from great apes and huntergatherer populations, Hawkes, along with other researches, developed models illustrating differences in population growth and lifespan with and without grandmothering. On average, a theoretical population with birth intervals resembling those of apes — meaning no grandmothering — were 5 years between offspring. Added grandmothering decreased that to three, as mothers would hand off their children to grandmothers as the youngsters reached age 2. Comparing ape-like life expectancy to one with grandmothering, the new expectancy doubled — from 25 to 50 years. Hawkes proves that “grandmothering can move life spans from the great ape to the human range.” The added childrearing help offered by a grandmother makes all the difference in early humans success. This is just another reason to celebrate grandmas. So the next time grandma prepares lunch, slips you a five dollar bill, or tells you to put on a sweater, remember she is looking out for you. Nature (2004). DOI:10.1038/428128a Royal Society (2012). DOI:10.1098/ rspb.2012.1751 PHOTOS BY FLICKR, UNSPLASH
