February 7, 2025 by Emily Cataneo
James was in his late 30s and weighed more than 500 pounds when he fell in the bathroom and found himself wedged between the wall and shower enclosure. Unable to get up because of his size, and too embarrassed to call for help, he lay there for three days. Firefighters eventually had to wreck the bathroom to free him. By the time he made it to the hospital in London, fungal infections had spread through the creases in his body, his oxygen-starved skin was disintegrating in places, and his breath was labored. His doctor struggled to find a vein from which to draw blood.
That doctor, Guy Leschziner, did something that he’s ashamed of now: Along with the other junior doctors in the hospital, he mocked James for his fatness, for his predicament. Many people in Leschziner’s shoes might have laughed at James: Obesity in the popular imagination, is “the most obvious marker of ‘gluttony’” and considered a “moral failure, indicative of laziness, a lack of self-control,” Leschziner writes in “Seven Deadly Sins: The Biology of Being Human.”
But what if we took a more nuanced view of “gluttony”? What if we took a more nuanced view of all human failings? In “Seven Deadly Sins,” Leschziner, a neurologist and sleep physician, interrogates the evolutionary, neurological, and psychological underpinnings of the seven greatest transgressions in Dante’s “Inferno”: wrath, lust, pride, greed, envy, sloth, and gluttony. He concludes that these so-called sins are inextricably interwoven with the experience of being a person, and that to understand them is “to gain insights into why we do what we do: the biology of being human.”
Leschziner had several personal reasons for wanting to understand humanity’s darkest side. His family was defined by the trauma of his grandfather’s narrow escape from the Holocaust, a “supreme expression of human sin.” Leschziner’s curiosity about sin was also sparked by his 25 years as a doctor in London hospitals, where he’s seen the best and worst of humankind on display. In writing this book, he sought to push himself beyond merely observing and treating his patients’ issues and instead “to see beneath the surface, to delve into the depths.”
Leschziner has written two other books that explore the oddest cases he’s treated as a neurologist, and in “Seven Deadly Sins,” some of the most fascinating passages involve patients, like James, whose lives have been derailed by a medical issue that presents as one of the “sins.”
Leschziner concludes that these so-called sins are inextricably interwoven with the experience of being a person, and that to understand them is “to gain insights into why we do what we do: the biology of being human.”
In the wrath chapter, we meet Sean, who rages “like a wild beast” in the aftermath of his unpredictable seizures, smashing glass and furniture. In the envy chapter, we meet Sarah, who regularly becomes consumed with the paranoid fear that her husband’s having an affair and flies into jealous fits, only to have little-to-no memory of these episodes after they conclude. In the lust chapter, we meet Simon, who received a diagnosis of Parkinson’s disease in his early 30s and who lost his friends and family because of his obsession with porn, sex workers, and happy ending massage parlors. (Leschziner changed all names to preserve these patients’ privacy.)
In addition to introducing us to people whose bodies and brains have tipped them into a pathological realm, Leschziner also explores the presence of the seven deadly sins in all of us — traits that, when tempered, have evolutionary benefits. If you are injured or sick, then it will behoove you to indulge in some sloth. Sometimes, we need wrath for our own protection. Without lust, none of us would be here at all. Issues arise “when disorders of the brain disrupt the delicate equipoise between our basic instincts and our virtuous nature” and “those normal emotions, fundamental to humanity, to our advancement individually or collectively, run amok.”
Leschziner’s narrative is most morally and philosophically interesting when it delves into the murky space between the normal and the pathological. As he explores the biological and neurological underpinnings of each transgression, it dawns on Leschziner and on the reader that perhaps there is no such thing as a sin separate from the biology and history that comprises each of us.
Rather, we are all subject to physical processes that render some of us more predisposed to, say, greed or pride than others. People arrested for exhibitionism, for example, might be labeled perverts by society, but up to 35 percent of them may have brain disorders that predispose them to this behavior. Men arrested for violent actions might be called crazy criminals — and they also might be suffering from Brunner syndrome, a genetic disorder that leads to an enzyme deficiency that in turn leads to increased aggression and wrath. So many of our actions, and what we might deem our morality and personality, arises from our genes, our upbringing, and ultimately our brains. It could be that what defines us is mostly out of our control.
In showing that human “sin” is driven by genetics, childhood, environment, brain malfunction, and other factors, Leschziner throws his hat into the ring of the never-ending debate over free will: whether humans have it, or whether physical factors beyond our control predetermine our destiny.
In his final chapter, appropriately called “Free Will,” he grapples with the scientific arguments for and against free will’s existence and although he doesn’t come down on one side of the debate or the other, he does argue that doctors and society at large should think more about why people are the way that they are. Even the American criminal justice system has started to recognize that criminality often lies beyond our control: In some jurisdictions in the U.S., genetic tests that show the aggression-causing Brunner Syndrome are now admissible as evidence.
Instead of labeling people good or evil, says Leschziner, perhaps we should ask if their brains are fixable — a question that, in my view, represents an important departure from the good/bad dichotomy, but brings up its own set of thorny moral questions nonetheless.
One weakness of Leschziner’s book is that even as it seeks to disrupt the bedrock of Western society’s understanding of sin, it sometimes unwittingly reinforces other values. For example, even while emphasizing that gluttony is often beyond an individual’s control, Leschziner still reinforces the idea that fat is bad and obesity is an “epidemic,” notions that various writers and thinkers have interrogated .
So many of our actions, and what we might deem our morality and personality, arises from our genes, our upbringing, and ultimately our brains.
In his chapter on greed, he explains that it’s difficult to find examples of pathological greed, since pathologizing this trait would involve medical professionals imposing their “own moral prism upon others,” which he claims many of his colleagues are loathe to do. But while doctors may go easy on greed, a trait commonly exhibited by the powerful and wealthy, they certainly have no issue imposing their own moral prism onto other “sins”: gluttony, for example, or, for women, lust.
Speaking of lust, Leschziner cites several claims rooted in evolutionary psychology that could use some interrogation: Men tend to evaluate women as potential partners based on sexual history. Women are drawn towards men with higher salaries because of evolutionary pressures dating back to the hunter-gatherer era. In a book that aims to unsettle our collective viewpoint on morality and the status quo, these blind spots weaken the narrative.
Even so, Leschziner’s overall project of examining the physical underpinnings of our “sins” is a worthwhile one. Like Robert M. Sapolsky’s “Determined: A Science of Life Without Free Will,” his book is an important reminder that these sins are a natural part of being human, and that for some, seemingly pathological sin is caused by issues beyond their control, issues that we should seek to understand from a scientific perspective. For the medical establishment especially, this seems a lesson well worth learning.
Emily Cataneo is a writer and journalist from New England whose work has appeared in Slate, NPR, the Baffler, and Atlas Obscura, among other publications.
This article was originally published on Undark. Read the original article.
