The view he expressed was given respectful coverage by Carl Zimmer in his widely publicised article "Can Science Define Life in Three Words", the only blemish from the usually perceptive Zimmer in an otherwise interesting and balanced article.
Not only is Szostak’s view wrong, but he compounded the error with the opening sentence;
“Attempts to define life are irrelevant to scientific efforts to understand the origin of life.” So, not just unhelpful, but irrelevant as well!
Let’s see. Let’s put reputation to one side for a moment and put him to the test.
His article is quite short, so we can examine it in detail. First, the title; '"Attempts to Define Life Do Not Help to Understand the Origin of Life." That view is not logical. How can we understand the origin of something that is undefined? In fairness to Szostak, we do recognise what life is, by its principal features of growth, metabolism, reproduction and homeostasis, but he has completely overlooked the rather obvious fact that any conclusions that are reached about the origins of life (that being his particular project, his job, his profession) will look extremely questionable, almost laughable, if those conclusions fail to explain the point at which life began. So a definition of life is not only helpful, but relevant as well.
He continued; “Simply put, the study of the ‘origin of life’ is an effort to understand the transition from chemistry to biology. This fundamental transition was the result of a lengthy pathway consisting of many stages, each of which is the subject of numerous scientific questions. Simple chemistry in diverse environments on the early earth led to the emergence of ever more complex chemistry and ultimately to the synthesis of the critical biological building blocks. At some point, the assembly of these materials into primitive cells enabled the emergence of Darwinian evolutionary behavior, followed by the gradual evolution of more complex life forms leading to modern life.
Somewhere in this grand process, this series of transitions from the clearly physical and chemical to the clearly biological, it is tempting to draw a line that divides the non-living from the living. But the location of any such dividing line is arbitrary, and there is no agreement on where it should be drawn. An inordinate amount of effort has been spent over the decades in futile attempts to define ‘life’ – often and indeed usually biased by the research focus of the person doing the defining.
As a result, people who study different aspects of physics, chemistry and biology will draw the line between life and non-life at different positions. Some will say there is no life until a well defined set of metabolic reactions are in place. Others will focus on spatial compartmentalization, on the various requirements for Darwinian evolution, or on the specific molecules of inheritance. None of this matters, however, in terms of the fundamental scientific questions concerning the transitions leading from chemistry to biology – the true unknowns and subject of origin-of-life studies.”
“None of this matters in terms of the fundamental scientific questions...” What could be more fundamental to a biologist than defining life? And as for “the true unknowns...” that’s just snobbery.
Szostak should immediately ditch all his current work and focus on the question of life, because what he has articulated is a disgrace to biology. The problems he outlined illustrate just why biologists cannot agree as to what life is. The competing views that he described have one thing in common; they are all focused on the functions and physical features of entities that are living, not on the underlying essence of the functions and features.
He continued; “Beyond the arbitrary nature of efforts to define the boundary between non-life and life, this effort is illusory for a deeper reason. As one focuses experimentally on any of the ‘defining’ properties of ‘life’, the sharp boundary seems to blur, splitting into finer and finer sub-divisions. As an example, let us look at the emergence of Darwinian evolution, which is often cited as a key aspect of the definition of life (with good reason, as Darwinian evolution is indeed the unifying characteristic of all of biology).”
Now he’s indulging his own bias. The unifying feature of biology is not evolution, it is life. (Generalisation can be useful, but not in this instance.) However, Darwinian evolution is the best he can come up with to describe life, which is possibly why he is not keen on discussing a definition, the deficiencies of his position being rather obvious.
But that does not prevent him using it to hijack the topic as he continued; “Certainly once cells with genetically encoded advantageous functions existed, classically defined Darwinian evolution had begun, and most people would define such cells as alive. But what about the previous steps? Such cells would likely have been preceded by protocells, with replicating genetic information, but lacking coded functions that provided a cellular advantage. At this stage, replication with heritable variation would have existed, and whatever process drove replication would most likely have had biases that led to changes in the genetic structure of the population over time.
Would that minimalist form of evolution qualify such protocells as being alive? Going back even further, consider genetic molecules replicating in solution or on particulate surfaces – again, biases in replication would lead to selection for sequences that are better templates, i.e., easier to replicate. Even the assembly of the first genetic polymers would have had biases, leading to non-random population structures. Darwinian evolution itself emerged in a series of stages, step-by-step, gradually leading to the almost infinite potential for organismal variation seen in modern biology. And yet, to define a single point along the progression as the point at which Darwinian evolution first emerged would be difficult. More importantly, such a definition would not further our understanding of the transitions involved or the nature of the physical and chemical forces driving those transitions.”
Basically, what he has said there is that it’s just too difficult.
But, by presenting this as THE argument, he’s also being tricky. By switching from discussing the boundary between non-life and life, to a discussion about the point that evolution began, he has muddied the waters, because they are not the same questions as he would like us to assume, they are very different. The point at which Darwinian evolution first emerged is not the point at which life began. That is so wrong. You first have to have life, then you have to have variation, then natural selection can take effect, then evolution can begin. He is two or three steps behind the game.
He concluded with; “What is important in the origin of life field is understanding the transitions that led from chemistry to biology. So far, I have not seen that efforts to define life have contributed at all to that understanding.”
Let’s help him out. The transition from chemistry to biology must have been a relatively simple process, because you cannot have stages of life. Either you have life or you do not. But Szostak cannot see that simplicity.
You’ll note from his article that complexity is something of a mental hurdle, a fixation that intrudes on his thinking to such an extent that he can’t see the forest for the trees. (And he’s not alone in this. This inability to forget the complexity of modern life forms is a major stumbling block in getting people to think logically about life. Life forms might be complex, but life is not.) But because life forms CAN be complex, Szostak has made the mistake of thinking that life must be complex.
This intrusion by complexity into Szostak’s thinking can be seen in his regular references to “lengthy pathways” “many stages” “ever more complex chemistry” “grand process” “series of transitions” “series of stages” “single point along the progression...” Those transitions and stages that he refers to are clearly transitions to more complex life forms, as he would concede.
So he has made the same error as Edward Trifonov, who defined life as “reproduction with variation”.
While they both see life correctly as a process, they both make the mistake of focusing on the outcome of the process, instead of the driver of the process. The driver of the process is molecular cooperation, Szostak’s field of expertise. The field in which he’s worked for twenty years, so the irony of this is beyond belief.
Cooperation sparked the first life forms, so cooperation IS life. The transition from chemistry to biology was brought about in one step by cooperation. Chemistry – spark – biology.
That's how simple it is.
It’s all about forests and trees.
The argument above shows that the definition or theory of life, and the origin of life are not only linked; they are complementary – each assists an understanding of the other, which, when you think about it, is how it should be.
I must thank the Journal of Biomolecular Structure and Dynamics for making articles available online.