I recently read and reviewed (find it here) an excellent book on scientific attempts to discover life’s origins by Robert Shapiro, but it was twenty-five years old. I figured this book might update the developments in the field. So it did. But sadly enough, there’s not much new to report.
Hazen is a decent enough writer, conveying the complexities of origin of life theories in a workman-like manner that is mostly free of jargon. But like so many scientists, and writers on science, he routinely falls into the trap of personalizing the science, giving mini-biographies and descriptions of the scientists whose research he describes, as if the scientists and not the science were the story. This is a troubling perspective considering the objectivity required of doing good science. It can’t be about the people. It must be about the nature of the world.
Unlike Shapiro, Hazen is hopeful, instead of skeptical, that science will one day discover how life began. This hopefulness is another impediment to doing good science. All hopes need be abandoned when the gathered evidence is investigated. The scientist needs to allow, like Frances Bacon taught nearly half a millennium ago, the evidence to take him wherever it leads.
Combine hopefulness at finding proof of a theory with the personal acclaim that would come to him that proves it, and a noxious brew of observational bias stirs in the beaker when these Optimist-Club scientists conduct experiments to gather evidence. Origin of life science is particularly susceptible to this sort of bias, none more so than the famous, or infamous as you prefer, Miller-Urey experiment in 1951. The experiment was elegantly simple—just a beaker 2/3rds full of water, along with an atmosphere of hydrogen, ammonia and methane with two electrodes for simulating lightning. Within a short time of heating the water and sparking the atmosphere, two of the amino acids known to be necessary for today’s life appeared, though in minute quantities that never much increased in ratio, no matter how long the experiment was run.
There are a number of problems with the theory that life began in something of the manner described by the Miller-Urey experiment, not least that it now is believed highly unlikely that free hydrogen could have been a very significant part of the early atmosphere, as hydrogen is notoriously unstable, while also being so light as to be continually lost to space. But Stanly Miller defended his theory against all comers to the very end of his days, often in a rude and acerbic manner. The experiment formed the basis for his career in science (he was only a graduate student at the time it was conducted), being celebrated as another marker in a new age of science that held the promise of nothing being beyond our ability to understand and create. While in the public’s mind the experiment probably served to resolve that nagging question about how life began, for any reasonably skeptical scientist, it did nothing of the sort. It is a far cry from creating a couple of amino acids in a laboratory beaker to fashioning a functioning, self-replicating cell.
Which hints at another problem with origin of life science. What, exactly, is life? It is a question that at turns seems simpler, or more complex, than really it is. Hazen offers a number of possibilities for what might qualify as life. Allow me this summary: Life is a discrete in space-time cooperative collection of matter and energy capable of guiding its own self-replication that interacts with its environment to reduce to possession and usefulness the matter and energy it needs from its environment in order to continue as a discrete in space-time cooperative collection of matter and energy capable of guiding its own self-replication. Under this summary, viruses are alive, but growing crystals probably are not, losing the distinction based on their lack of a discrete barrier defining them and their inability to actively guide their self-replication. Some theorists put great emphasis on the need for life to evolve by natural selection. In my view, natural selection is a consequence of life’s nature, not an attribute necessary for something to be alive. If life were easily contrived, it could have arisen spontaneously in many environments without being able to adapt to changes in its environment once arisen.
Chemical cooperation seems to be critical (my views, not Hazen’s). What is a human being except a collection of several trillion cells cooperating to see the genetic code makes it to the next generation? What is a cell but a collection of proteins and amino acids that cooperate to do the same thing? What are amino acids but chemical elements cooperatively arranged just so, according to quantum laws and environmental inputs? Of course, I am stretching the concept of cooperation here to more or less mean chemicals that complement each other, but I don’t mean the chemicals have some sort of Leibnitzian consciousness that promotes cooperation among them.
Hazen details the three main theories on life’s origins:
1) Life began with metabolism, with genetic replication to follow later. He details experiments done to initiate the cascade of chemical reactions in the citric acid cycle as a possible means to prove this theory. Unfortunately, no experimental condition that was plausibly present in the early earth has proved capable of starting the cycle, never mind keeping it going. So far, another blind alley.
2) Life began with genetic replication, and metabolism followed later. This is even less plausible than the first, because creating a gene out of pre-biotic soup is nigh well impossible. The amino acids comprising RNA and DNA are notoriously unstable, and again, there haven’t been devised any experimental conditions where they simply arise of their own accord such that they can draw resources from their surroundings and begin replicating.
3) The last possibility is really just a mish-mash of the first two—that proto-metabolism arose simultaneously with proto-replication that then developed in complexity as nature selected the most fit among the proto-organisms to survive. The problem with this theory is that it most probably would be impossible to replicate. It lacks the elegance and simplicity of the previous two, which is why it seems most plausible to me. Life is nothing if not fantastically complicated. Even today, every discovery of the inner workings of the cell yields more questions than answers. The mystery of how life arose may be one of those things God simply refuses to reveal to our finite minds.
Hazen claims in his prologue that emergence is a recurring theme of origin-of-life science, and likewise his book. But except for explaining emergence in the prologue, we get very little more direct discussion of it. Since emergence really is important to the development of life, and any other complex systems, allow me to explain the idea a bit more extensively.
Emergence is sort of like synergy. The whole organism or system seems more complex than its individual parts. It has qualities that can not be predicted by simply understanding the qualities of its components. It is something of a “God-in-the-gaps” idea, except contrived for scientific materialists, that serves to explain why we can’t explain complex systems. Human consciousness is the classic case of emergence. Scientists admit that there is no way to predict from studying the brain’s biochemistry, or from even just understanding so far as is possible the workings of the neuron–the brain’s most basic unit–that conscious awareness would arise so profound until even the very existence of the human from whose brain it arose could question his own existence. Philosophers and theologians, ancient and near, use this mysterious awareness to posit that it reflects an immaterial soul inhabiting the body, that is perhaps immortal. Consciousness, i.e., the soul, is the aspect of humanity with which God or the gods was most concerned. But science will have nothing of it. Consciousness arises from natural physical processes. Since science can’t explain consciousness using the reductionist method that had otherwise proved so profitable in explaining the natural world, the theory of emergence developed; that the interactions among particulate matter and energy were too numerous and complex to allow prediction of what might be their aggregate result, with a little hint that indeed, emerging complexity might be synergistic.
In so far as emergence acknowledges the limits of reductionism , particularly in biological phenomenon, it robustly describes a bit of scientific reality. Science can’t even predict, nor create, even knowing as much as it does about the quantum mechanics of atoms and molecules, how protein molecules fold themselves in a particular way such that they can usefully be employed by a cell to do work. An improperly folded protein is useless to a cell, but science has yet to resolve the mystery of how protein molecules fold themselves properly. The folding of the protein molecule is an emergent, i.e., mysterious, quality of the atoms comprising the molecule that science can’t decipher. Of course, the transition from non-life to life, a wee more complicated than mere protein folding, is apt to be an unpredictable “emergent” quality of interactions amongst ordinary organic chemicals that yield to no explanation or human duplication.
When Craig Ventnor announced in May of 2010 that his lab had created the world’s first synthetic cell, some might have imagined that we had finally solved the emergence paradox. Ventnor, being something of a cross between an Optimist Club scientist and a carny con-artist, probably wished for people to believe that such was the case. But it wasn’t. He didn’t start from simplicity and engineer complexity until a living cell arose. He simply copied the genetic code of an already-living cell (the simple bacterium, Mycoplasm mycoides) into a computer that he then used to manufacture, a few snippets at a time, his new cell’s genetic code, though altered just a bit so that it was distinguishable from the original. The newly-manufactured code was inserted in the cell and the cell began replicating. Except for manufacturing the code by computer-guided chemistry, nothing Ventnor did was new, and it’s debatable whether any of it was even remarkable or useful. The secret to modifying and duplicating genetic codes was long ago discovered in the agriculture industry. Ventnor no more created a synthetic cell from scratch than the Miller-Urey experiment proved how life arose.
A major part of the problem of ascertaining how life arose is determining from where it arose. There are the usual suspects: Darwin’s warm little pond; silica mud; deep sea vents; the surface interfaces of deeply-interred rocks, etc. Since the discovery of extremophiles, i.e., bacteria than can survive the harshest of conditions, and the discovery of bacteria thriving in places where no sunlight penetrates, the list of possible contenders is enormous. Since we now know life can survive most anywhere, it can logically be reckoned that it could have arisen anywhere.
But there is a great irony pregnant with trying to spark life into existence by recreating the conditions under which it is believed to have arisen. Even if we stumble upon a life-creating habitat such that life organizes itself from scratch, we still won’t know whether we have discovered the way life originally arose. As life exists nearly everywhere on earth we look for it, it could have arisen anywhere, and under any number of conditions. But if we are able to figure out at least one set of environmental conditions that precipitates life, at least it would put to rest the idea that life’s appearance had to have supernatural origins.
Robert M Hazen’s Genesis is a good primer for getting a handle on the developments in the origin-of-life field. But don’t be disappointed if you find things are not quite as advanced as perhaps the general public believes.