Life is Emerging: Review of Siddhartha Mukherjee’s Song of the Cell
The DNA double helix is often the image spiraling at the center of 21st century advances in biomedicine and the growing bioeconomy. And yet, DNA is molecularly inert. DNA, the code for genes, is not alive and is not strictly necessary for life. Ought life be at the center of our communication of living systems? Is not the Cell a superior symbol of life and our manipulation of living systems?
A code for life isn’t a code without the life that instantiates it. A code for life must be translated. The cell is the basic unit of that translation. The cell is the minimal viable package of life as we know it. Therefore, cell biology is at the center of biomedicine’s greatest transformations, suggests Pulitzer-winning physician-scientist Siddhartha Mukherjee in his latest book, The Song of the Cell: The Exploration of Medicine and the New Human.
The Song of the Cell begins with the discovery of cells and of germ theory, featuring characters such as Louis Pasteur and Robert Koch, who brought the cell “into intimate contact with pathology and medicine.” This intercourse would transform biomedicine, leading to the insight that we can treat disease by thinking at the cellular level. The slightest rearrangement of sick cells might be the path toward alleviating suffering for the organism: eroding the cell walls of a bacterium while sparing our human cells; inventing a medium that coaxes sperm and egg to dance into cellular union for in vitro fertilization (IVF); designing molecular missiles that home to the receptors decorating the exterior of cancer cells; teaching adult skin cells to remember their embryonic state for regenerative medicines.
Mukherjee uses the bulk of the book to elucidate key cell types in the human body, along with their “connective relationships” that enable key organs and organ systems to function. This includes the immune system, the heart, the brain, and so on. Mukherjee’s distinctive style features compelling anecdotes and human stories that animate the scientific (and unscientific) processes that have led to our current state of understanding. In his chapter on neurons and the brain, for example, he integrates Santiago Ramon y Cajal’s meticulous black ink sketches of neurons into Mukherjee’s own personal encounter with clinical depression. In one lucid section, he interviews Dr. Helen Mayberg, a pioneering neurologist who takes seriously the descriptive power of her patients’ metaphors, as they suffer from “caves,” “holes,” “voids,” and “force fields” that render their lives gray. Dr. Mayberg aims to stimulate patients’ neuronal cells in a manner that brings back the color.
Beyond exposing the insight and inventiveness that has arisen out of cell-based thinking, it seems that Mukherjee’s bigger project is an epistemological one. The early chapters of The Song of the Cell continually hint at the potential for redefining the basic unit of biology as the cell rather than the gene. The choice to center biomedicine around cells is, above all, a conspicuous choice not to center it around genes (the subject of Mukherjee’s previous book, The Gene), because genes dominate popular science communication.
This choice of cells over genes is most welcome. Cells are alive. Genes are not. Letters—such as the As, Cs, Gs, and Ts that represent the nucleotides of DNA, which make up our genes—must be synthesized into a word or poem or song that offers a glimpse into deeper truths. A key idea embedded in this thinking is that of emergence. Whether in ancient myth or modern art, creation tends to be an emergent process, not a linearly coded script. The cell is our current best guess for the basic unit of life’s emergence, turning a finite set of chemical building blocks—nucleic acids, proteins, sugars, fats—into a replicative, evolving system for fighting stasis and entropy. The cell’s song is one for our times, for it is the song of biology’s emergence out of chemistry and physics, into the “frenetically active process” of homeostasis.
Re-centering our view of biology has practical consequences, too, for how we think about diagnosing and treating disease, and for inventing new medicines. Centering cells presents a challenge: which type of cell to place at the center? Rather than default to the apparent simplicity of DNA as a symbol because it represents the one master code for life, the tension in defining the diversity of cells—a mapping process still far from complete in cutting-edge biology laboratories—can help to create a more thoughtful library of cellular metaphors to shape both the practice and communication of biology.
Further, effective problem solving is often about operating at the right level, or the right scale. The cell feels like appropriate level at which to interrogate many of the diseases that ail us, because the senses that guide our own perceptions of sickness and health—the smoldering pain of inflammation, the tunnel vision of a migraine, the dizziness of a fluttering heart—are emergent.
This, unfortunately, is sort of where Mukherjee leaves the reader, under-exploring the consequences of a biology of emergence. Many practical and profound questions have to do with the ways that each scale of life feeds back on the others. In a tome on Cells and “the future human” I wished that Mukherjee had created more space for seeking the ways that cells will shape and be shaped by the future, of humanity and otherwise.
We are entering a phase of real-world bioengineering that features the modularization of cellular parts within cells, of cells within organs, of organs within bodies, and of bodies within ecosystems. In this reality, we would be unwise to assume that any whole is the mere sum of its parts.
For example, when discussing the regenerative power of pluripotent stem cells, Mukherjee raises the philosophical thought experiment of the Delphic boat, also known as the Ship of Theseus. The boat is made of many pieces of wood, each of which is replaced for repairs over the years, with the boat’s structure unchanged. Eventually none of the boat’s original wood remains: Is it the same boat?
Mukherjee raises the Delphic boat in one paragraph at the end of the chapter on stem cells, as a metaphor related to the possibility of stem cell-enabled regeneration in perpetuity. He does not follow any of the threads of potential answers. Given the current state of cellular engineering, about which Mukherjee is a world expert from his work as a physician-scientist, this book could have used an entire section dedicated to probing this question and, importantly, the ways this thought experiment falls apart.
We are entering a phase of real-world bioengineering that features the modularization of cellular parts within cells, of cells within organs, of organs within bodies, and of bodies within ecosystems. In this reality, we would be unwise to assume that any whole is the mere sum of its parts. Wholeness at any one of these scales of life—organelle, cell, organ, body, ecosystem—is what is at stake if we allow biological reductionism to assume away the relation between those scales.
In other words, Mukherjee succeeds in providing a masterful and compelling narrative of the lives of many of the cells that emerge to enliven us. Like his previous books, it is a worthwhile read for anyone curious about the role of cells in disease and in health. And yet, he fails to offer the broader context of The Song of the Cell.
As leading agronomist and essayist Wes Jackson has written, “The sequence of amino acids that is at home in the human cell, when produced inside the bacterial cell, does not fold quite right. Something about the E. coli internal environment affects the tertiary structure of the protein and makes it inactive. The whole in this case, the E. coli cell, affects the part—the newly made protein. Where is the priority of part now?” [1]
Beyond the ways that different kingdoms of life translate the same genetic code, the practical situation for humanity today relates to the ways that the different disciplines of modern life use values and culture to influence our genes, cells, bodies, and environment. It may be that humans will soon become a bit like the Delphic boat, infused with the buzz of fresh cells to repopulate different niches within our bodies, for healthier, longer lives. But in biology, as in writing, a mixed metaphor can cause something of a cacophony. For we are not boats with parts to be replaced piecemeal. And nor are whales, nor alpine forests, nor topsoil. Life isn’t a sum of parts, and neither is a song that rings true.
[1] Wes Jackson, "Visions and Assumptions," in Nature as Measure (p. 52-53).
The Friday Five: A new blood test to detect Alzheimer's
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
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Here are the promising studies covered in this week's Friday Five:
- A blood test to detect Alzheimer's
- War vets can take their psychologist wherever they go
- Does intermittent fasting affect circadian rhythms?
- A new year's resolution for living longer
- 3-D printed eyes?
Staying well in the 21st century is like playing a game of chess
This article originally appeared in One Health/One Planet, a single-issue magazine that explores how climate change and other environmental shifts are increasing vulnerabilities to infectious diseases by land and by sea. The magazine probes how scientists are making progress with leaders in other fields toward solutions that embrace diverse perspectives and the interconnectedness of all lifeforms and the planet.
On July 30, 1999, the Centers for Disease Control and Prevention published a report comparing data on the control of infectious disease from the beginning of the 20th century to the end. The data showed that deaths from infectious diseases declined markedly. In the early 1900s, pneumonia, tuberculosis and diarrheal diseases were the three leading killers, accounting for one-third of total deaths in the U.S.—with 40 percent being children under five.
Mass vaccinations, the discovery of antibiotics and overall sanitation and hygiene measures eventually eradicated smallpox, beat down polio, cured cholera, nearly rid the world of tuberculosis and extended the U.S. life expectancy by 25 years. By 1997, there was a shift in population health in the U.S. such that cancer, diabetes and heart disease were now the leading causes of death.
The control of infectious diseases is considered to be one of the “10 Great Public Health Achievements.” Yet on the brink of the 21st century, new trouble was already brewing. Hospitals were seeing periodic cases of antibiotic-resistant infections. Novel viruses, or those that previously didn’t afflict humans, began to emerge, causing outbreaks of West Nile, SARS, MERS or swine flu.In the years that followed, tuberculosis made a comeback, at least in certain parts of the world. What we didn’t take into account was the very concept of evolution: as we built better protections, our enemies eventually boosted their attacking prowess, so soon enough we found ourselves on the defensive once again.
At the same time, new, previously unknown or extremely rare disorders began to rise, such as autoimmune or genetic conditions. Two decades later, scientists began thinking about health differently—not as a static achievement guaranteed to last, but as something dynamic and constantly changing—and sometimes, for the worse.
What emerged since then is a different paradigm that makes our interactions with the microbial world more like a biological chess match, says Victoria McGovern, a biochemist and program officer for the Burroughs Wellcome Fund’s Infectious Disease and Population Sciences Program. In this chess game, humans may make a clever strategic move, which could involve creating a new vaccine or a potent antibiotic, but that advantage is fleeting. At some point, the organisms we are up against could respond with a move of their own—such as developing resistance to medication or genetic mutations that attack our bodies. Simply eradicating the “opponent,” or the pathogenic microbes, as efficiently as possible isn’t enough to keep humans healthy long-term.
Instead, scientists should focus on studying the complexity of interactions between humans and their pathogens. “We need to better understand the lifestyles of things that afflict us,” McGovern says. “The solutions are going to be in understanding various parts of their biology so we can influence how they behave around our systems.”
Genetics and cell biology, combined with imaging techniques that allow one to see tissues and individual cells in actions, will enable scientists to define and quantify what it means to be healthy at the molecular level.
What is being proposed will require a pivot to basic biology and other disciplines that have suffered from lack of research funding in recent years. Yet, according to McGovern, the research teams of funded proposals are answering bigger questions. “We look for people exploring questions about hosts and pathogens, and what happens when they touch, but we’re also looking for people with big ideas,” she says. For example, if one specific infection causes a chain of pathological events in the body, can other infections cause them too? And if we find a way to break that chain for one pathogen, can we play the same trick on another? “We really want to see people thinking of not just one experiment but about big implications of their work,” McGovern says.
Jonah Cool, a cell biologist, geneticist and science officer at the Chan Zuckerberg Initiative, says that it’s necessary to define what constitutes a healthy organism and how it overcomes infections or environmental assaults, such as pollution from forest fires or toxins from industrial smokestacks. An organism that catches a disease isn’t necessarily an unhealthy one, as long as it fights it off successfully—an ability that arises from the complex interplay of its genes, the immune system, age, stress levels and other factors. Modern science allows many of these factors to be measured, recorded and compared. “We need a data-driven, deep-phenotyping approach to defining healthy biological systems and their responses to insults—which can be infectious disease or environmental exposures—and their ability to navigate their way through that space,” Cool says.
Genetics and cell biology, combined with imaging techniques that allow one to see tissues and individual cells in actions, will enable scientists to define and quantify what it means to be healthy at the molecular level. “As a geneticist and cell biologist, I believe in all these molecular underpinnings and how they arise in phenotypic differences in cells, genes, proteins—and how their combinations form complex cellular states,” Cool says.
Julie Graves, a physician, public health consultant, former adjunct professor of management, policy and community health at the University of Texas Health Science Center in Houston, stresses the necessity of nutritious diets. According to the Rockefeller Food Initiative, “poor diet is the leading risk factor for disease, disability and premature death in the majority of countries around the world.” Adequate nutrition is critical for maintaining human health and life. Yet, Western diets are often low in essential nutrients, high in calories and heavy on processed foods. Overconsumption of these foods has contributed to high rates of obesity and chronic disease in the U.S. In fact, more than half of American adults have at least one chronic disease, and 27 percent have more than one—which increases vulnerability to COVID-19 infections, according to the 2018 National Health Interview Survey.
Further, the contamination of our food supply with various agricultural and industrial toxins—petrochemicals, pesticides, PFAS and others—has implications for morbidity, mortality, and overall quality of life. “These chemicals are insidiously in everything, including our bodies,” Graves says—and they are interfering with our normal biological functions. “We need to stop how we manufacture food,” she adds, and rid our sustenance of these contaminants.
According to the Humane Society of the United States, factory farms result in nearly 40 percent of emissions of methane. Concentrated animal feeding operations or CAFOs may serve as breeding grounds for pandemics, scientists warn, so humans should research better ways to raise and treat livestock. Diego Rose, a professor of food and nutrition policy at Tulane University School of Public Health & Tropical Medicine, and his colleagues found that “20 percent of Americans’ diets account for about 45 percent of the environmental impacts [that come from food].” A subsequent study explored the impacts of specific foods and found that substituting beef for chicken lowers an individual’s carbon footprint by nearly 50 percent, with water usage decreased by 30 percent. Notably, however, eating too much red meat has been associated with a variety of illnesses.
In some communities, the option to swap food types is limited or impossible. For example, “many populations live in relative food deserts where there’s not a local grocery store that has any fresh produce,” says Louis Muglia, the president and CEO of Burroughs Wellcome. Individuals in these communities suffer from an insufficient intake of beneficial macronutrients, and they’re “probably being exposed to phenols and other toxins that are in the packaging.” An equitable, sustainable and nutritious food supply will be vital to humanity’s wellbeing in the era of climate change, unpredictable weather and spillover events.
A recent report by See Change Institute and the Climate Mental Health Network showed that people who are experiencing socioeconomic inequalities, including many people of color, contribute the least to climate change, yet they are impacted the most. For example, people in low-income communities are disproportionately exposed to vehicle emissions, Muglia says. Through its Climate Change and Human Health Seed Grants program, Burroughs Wellcome funds research that aims to understand how various factors related to climate change and environmental chemicals contribute to premature births, associated with health vulnerabilities over the course of a person’s life—and map such hot spots.
“It’s very complex, the combinations of socio-economic environment, race, ethnicity and environmental exposure, whether that’s heat or toxic chemicals,” Muglia explains. “Disentangling those things really requires a very sophisticated, multidisciplinary team. That’s what we’ve put together to describe where these hotspots are and see how they correlate with different toxin exposure levels.”
In addition to mapping the risks, researchers are developing novel therapeutics that will be crucial to our armor arsenal, but we will have to be smarter at designing and using them. We will need more potent, better-working monoclonal antibodies. Instead of directly attacking a pathogen, we may have to learn to stimulate the immune system—training it to fight the disease-causing microbes on its own. And rather than indiscriminately killing all bacteria with broad-scope drugs, we would need more targeted medications. “Instead of wiping out the entire gut flora, we will need to come up with ways that kill harmful bacteria but not healthy ones,” Graves says. Training our immune systems to recognize and react to pathogens by way of vaccination will keep us ahead of our biological opponents, too. “Continued development of vaccines against infectious diseases is critical,” says Graves.
With all of the unpredictable events that lie ahead, it is difficult to foresee what achievements in public health will be reported at the end of the 21st century. Yet, technological advances, better modeling and pursuing bigger questions in science, along with education and working closely with communities will help overcome the challenges. The Chan Zuckerberg Initiative displays an optimistic message on its website: “Is it possible to cure, prevent, or manage all diseases by the end of this century? We think so.” Cool shares the view of his employer—and believes that science can get us there. Just give it some time and a chance. “It’s a big, bold statement,” he says, “but the end of the century is a long way away.”Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.