What Is Life?: How Chemistry Becomes Biology by Addy Pross
My rating: 4 of 5 stars
Dr. Pross’s book shares a title (but not a subtitle) with the seminal work by the renowned physicist Erwin Schrödinger from 1944. While Schrödinger addresses a wide range of topics on how life might be explained in terms of physics and chemistry, Pross’s focus is narrower. Pross asks—and proposes an answer for—the straightforward (but thorny) question of how abiogenesis could occur. Abiogenesis is life from the non-living. Darwin did an excellent job of explaining how we could get from single-celled organisms to the great complexity we see in our own bodies, but Darwin didn’t touch the question of how that very first ancestor became animated.
The subtitle of this work, “How Chemistry Becomes Biology,” gives one insight into how Pross proceeds. There’ve been many ideas about how life came to be on planet Earth over the years. For a time, the idea of panspermia—life arriving from an extraterrestrial source—was popular. Of course, the most popular belief has been that there was a force of life (i.e. an “élan vital”) breathed into non-living matter by a, presumably, supernatural force / entity. While the awe-inspiring nature of life made this idea appealing / believable, it took a hit from the Urey-Miller experiments. Said experiment exposed the four materials believed to have been the most common in our pre-biologic atmosphere (hydrogen, ammonia, methane, and water vapor) to lightning, and the result included a range of organic materials—including amino acids–the building blocks of… well, us, among the other life forms of the planet. Of course, Urey-Miller didn’t make abiogenesis a foregone conclusion, but the production of ever more complex self-replicating molecules under laboratory conditions has made it easier to digest the notion that life developed without any intelligent or supernatural push.
While Pross’s ideas are at the stage of hypothesis, he develops a compelling explanation that revolves around the idea of dynamic kinetic stability. “Dynamic Kinetic Stability” is a mouthful, and so it’s necessary to break it down. The best place to start is with the “stability” part. This is because the biggest problem for an abiogenetical theory of life is the Second Law of Thermodynamics. The Second Law tells us that entropy increases. There are many ways of restating this, such as that chemical reactions move to states that are of lower free energy. However, the most intuitive way is to say that a beer mugs break but do not spontaneously pop into existence. So if everything is getting simpler by deteriorating, breaking, and decomposing, how does one get / maintain a stable state of complexity? First and foremost, the answer involves adding a lot of energy and resources, but there’s more to it than that–as the author explains. “Dynamic” can also be explained in complex terms, but it’s most easily thought of as being like a river in that the river’s existence is stable, but it’s always a different river—ever changing water molecules arranged differently. (Critically, our bodies are the same way. Except for neurons, our cells are constantly being replaced.) The term “kinetic” speaks to how said replacement takes place; replication must be fast and decay slow.
The appeal of the ideas put forth by Pross is that they’re conceptually consistent with Darwinian Evolution. That is, an entirely new set of principles isn’t necessary to make sense of the origins of life. Pross argues that the self-replicating molecules that can most effectively put resources to use succeed in doing so, and—in the process–they drive others into extinction.
I found this book interesting and readable. The author uses good analogies to make his points (which often deal in complex matter) as clearly as possible. I can’t disagree with the other reviewers who’ve pointed out that the book is a bit repetitive and drags out a relatively simple statement of the argument. It’s not so egregious that I could say that it’s necessarily the result of a desire to pad the book out to a length necessary to sell in hard-copy form. (But it might have been.) The understanding of this topic is in its infancy, but that doesn’t mean this book isn’t a valuable contribution to popular understanding of abiogenesis.
I’d recommend this book for anyone interested in reflecting on from whence we came in a fashion that is open-minded to explanations that eschew the supernatural.
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