…the question of what it means to be alive has flowed through four centuries of scientific history like an underground river… More than 150 years later, despite all that biologists have learned about living things, they still cannot agree on the definition of life.
I have had the pleasure of driving up a mountain through mist and cloud, and of walking in London through pea soup fog. Where exactly did the clear air end and the more particulate air begin? It is not entirely…um…clear. Sure, there is a difference between standing, or driving in air that one cannot visually penetrate and looking through a wide outdoor expanse on a cloud-free, crystalline winter day. But it is not a barrier drawn with a straight edge. Thus it appears with the line between living and not-living. With the examples detailed in Life’s Edge, it is clearer than ever that there are more things under heaven and earth than had been dreamed of in our philosophies. There are those, certainly, who proclaim that this or that specific location is where the thing called life begins. Rules have been drawn up to plant markers, to draw lines. But like an outdoor crime-scene police-tape, the fog of what lies within and without wanders freely past those lines, with no regard for the designs or preferences of humans.
Carl Zimmer – image from The Psychology Podcast
New York Times science columnist and multiple-award-winning science-writer Carl Zimmer’s fourteenth book takes readers on an exploration to that amorphous borderland between the living and the non-living. It is a journey that raises a lot more questions than it answers. Zimmer employs a tried and true approach, each chapter moving on to the next lab, the next researcher, the next wild bit of research, and filling in with nice chunks of science history, as he circles around the question.
Alysson Muotri – image from The Stem Cell Podcast
Many of the things Zimmer reports on are fascinating. Some, however, will disturb your sleep. For an example of the latter, Alysson Muotri, at the Sanford Consortium for Regenerative Medicine, takes skin samples and reprograms them into neurons to study neurological diseases and possible treatments. They are grown into miniature organs called organoids, and are allowed to reproduce, up to a point. When he started growing these things, he assumed that they could never become conscious. “Now I’m not so sure, he confessed.” Zimmer tells, also, of a researcher, a very long time ago, who was notorious for experimenting on living animals.
Cerebral organoid – image from European Research Council
Clearly a significant concern for our culture is where “life” begins, and further, where “human life” begins. It all comes down to definitions. Is Thomas Aquinas’s notion of the “ensoulment” of human embryos the same as defining when life becomes human life? There have been other notions employed in the history of Christianity. Zimmer looks at how legal definitions of life, for purposes including supporting abortion laws, and concerning a widening spectrum of medical and legal issues, fail to hold up under scientific scrutiny.
”It’s Alive!” (or is it?) – from Frankenstein – image from Buzzfeed
The concern here is not just what is life, but how can we tell when something actually is alive? He looks at how humans perceive life and react to it. We have a sense of life being present or absent, an intuition that is not unique to our species. Ravens hold what can only be seen as funerals for dead flock members. Chimps engage in group laments for late members, as do many other creatures.
To be alive is to not be dead…Humanity did not come to this realization through logic and deduction. Our understanding of death is not like Darwin’s theory of evolution or Thompson’s discovery of the electron. It has its origins in ancient intuitions.
Zimmer looks at metabolic rate. In the 17th century, there was a widespread fear of being afflicted with a death-like state that might leave its victims without detectable breath or heartbeat, thus generating a rampant terror of being buried alive. This concern inspired a well-known short story.
The boundaries which divide Life from Death are at best shadowy and vague. – Edgar Allan Poe, The Premature Burial
Zimmer reports on a woman who was pronounced dead, twice. (third time’s the charm?) Where is the line between brain death and true, no backsies, total death? Can a person meet the criteria for brain death one day, and later not meet it?
From The Night of the Living Dead – image from Wikipedia
But what constitutes life? How about adding some ingredients to agar, leaving it alone for a few hours and then finding a thriving slime mold, one with remarkable survival skills. What about spores, some of which can survive in space? Are spores alive? Or only potentially alive, or an ingredient in a recipe for making life?
Scientists have been arguing over whether viruses are alive for about a century, ever since the pathogens came to light. Writing last month in the journal Frontiers in Microbiology, two microbiologists (Hugh Harris and Colin Hill) at University College Cork took stock of the debate. They could see no end to it. “The scientific community will never fully agree on the living nature of viruses,” they declared. – from Zimmer’s Secret Life piece in the NY Times
“I vunder vut it vood be like to be really dead” – image from The Indy Channel
Whether you prefer your undead to be of the vampiric, zombie, or reanimated sort, or are more inclined to unicellular spore candidates, or maybe pre-conscious organoids, there are plenty of candidates for entities on the fringes of life.
In addition to providing readers with a better handle on the attempt to delineate the line between life and not-life, there are plenty of interesting questions raised and fun facts to be gleaned. We learn, for example, that Erwin Schrödinger was set up by the government at Trinity College. (But he may have simultaneously both been there and not, depending on whether any students saw him give a lecture.) We also learn that when Vitamin C was discovered, the discoverer wanted to name it “Godnose.” And how about meteorites as a possible source of Terran life? Or maybe they contributed one or more of the ingredients necessary for the recipe? I particularly enjoy when science writers imbue their work with a sense of humor. That is mostly lacking here, which is disappointing. But there is plenty of material to keep your brain cells flashing on and off.
Who decides on a definition of life? In an ideal world, science should lead on matters that are subject to physical investigation and repeatable experimentation. And yet…
It may be enough for you to align with Supreme Court Justice Potter Stewart who, when it came time to issue a ruling pertaining to pornography, said that he knows it when he sees it. We as a species tend to think that we know life when we see it. But it would be a good thing to recognize that all extant definitions of life are squishy, relying on philosophy or religion for their support. So I would appreciate it if no one would use their definition to tell me or anyone who does not share their perspective what they can or cannot do. Because when it comes to folks twisting science to political ends, I know it when I see it.
Life’s Edge may not provide a definitive guide to the line between living and nonliving. Such a line does not really exist in biology. But it does point out where the arguments lie about where those lines might be drawn, or, at least, where they might be investigated. It raises the larger question, though, of whether that line can, at least from a scientific perspective, be drawn at all.
Life is what the scientific establishment (probably after some healthy disagreement) will accept as life.
Review first posted – March 19, 2021
———-March 9, 2021 – hardcover
———-March 8, 2022 – trade paperback
I received an e-book ARE if Life’s Edge from Dutton in exchange for an honest review, and some of those interesting things that have been growing, unasked, in my basement.
This review has been cross-posted on GoodReads
I heartily recommend you check out Siddhartha Mukherjee’s amazing NY Times review What Does It Mean to Be a Living Thing?
Items of Interest from the author
—–What is Life – audio – A series of live conversations between writer Carl Zimmer and eight leading thinkers on the question of what it means to be alive.
—–Slate – excerpt – What on Earth are These Things? – on organoids
—–NY Times – The Secret Life of a Coronavirus – is it alive?
—–From Sondheim’s Company – Being Alive
—–Aerosmith – Livin’ On the Edge
—–Opening of Saturday Night Fever – The Bee Gees Stayin’ Alive
—–Madonna – Borderline
—–GaGa – Edge of Glory
—–Shruti Haasan – Edge
—–Monty Python’s The Meaning of Life – Every Sperm is Sacred