THE "FATAL FLAWS" WITH RICHARD CARRIER'S DOGMATIC DEFINITION OF LIFE
The "Fatal Flaws" with Richard Carrier's
Dogmatic Definition of Life
First, there is no consensus definition of life. Dozens of sources could be cited, but here are just a few examples:
JV Chamary (2019) notes in "A Biologist Explains: What is Life?" :
"Although biology is the study of life, even biologists don't agree on what 'life' actually is. While scientists have proposed hundreds of ways to define it, none have been widely accepted. And for the general public, a dictionary won't help because definitions will use terms like organisms or animals and plants -- synonyms or examples of life -- which sends you round in circles."
Benner et al. (2011) give examples of the divergence of thought that exists on the subject (See, also, Benner (2010). Defining Life):
"Accordingly, we are attempting to meet the ‘‘put-a man-on-the-moon’’ goal of obtaining a synthetic genetic system that can sustain to a greater degree its own access to Darwinian evolution. Even should this be done, however, the community would not be unanimous in its view that a synthetic biology had been created. Various theories of biology constructively held by many in the community add criteria for a definition-theory of life. For example, those who subscribe to the Cell Theory of life will no doubt wait until the synthetic chemical system capable of Darwinian evolution is encapsulated in a cell. Those who subscribe to a metabolism theory of life might wait until the artificial synthetic genetic system also encodes enzymes that catalyze the transformation of organic compounds. Even those who subscribe to a Darwinian theory of life might insist that before a synthetic biology is announced, the artificial system must evolve to a natural change in environment, not to one engineered in the laboratory. Where one draws the line is, again, a matter of culture." (p. 14)
Some OoL investigators argue that we shouldn't even try to define life. See, for example, Szostak (2012). Attempts to define life do not help to understand the origin of life. Journal of Biomolecular Structure and Dynamics, 29(4), 599-600); wherein he writes:
"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."
Bains (2020), “Getting Beyond the Toy Domain. Meditations on David Deamer’s ‘Assembling Life'” argues just the opposite that a consensus definition of life is needed in the OoL field; while further noting the inconsistent usage of other terms, including "evolution," "replication," and "protocell":
“But there is an even bigger problem. We do not even know what life is…if we are to decide how life originated then we must have some idea of what the minimum requirements are for us to call a system “alive”…Are “experiences wet/dry cycles” and “requires genetic information” qualities of the same class? Fish do not experience wet-dry cycles, are they not alive? Weather is a wet-dry cycle, does this mean, as Lineweaver has argued, that hurricanes cannot objectively be distinguished from life?"
"This is not pointless sophistry. There is a reason to be more specific in characterizing life (let us not say “defining”), the need for precision in language. Along with most other writers on OOL, Deamer uses “evolve” to mean “change” and to mean “the result of selection for fitter genotypes”, with the implication that one is related to the other. This is seriously misleading. Similarly “replication” can mean production of a new organism from a genetic blueprint (as in “viruses replicate”) or kinetically-determined self-catalysis (as in “crystal defects replicate”). In my (metaphorical) book these are fundamentally different processes; using common language implies they are not, but does not elucidate their similarities or differences. Again, the term ‘Protocell’ is used to mean any liposome-like membrane encapsulating other molecules. In my opinion, a vesicle encapsulating random organic molecules is almost as far from life as the bulk “prebiotic soup” from which it was made. To draw “Protocells → Progenote” in a diagram skips over everything about how that transition happens, i.e., how life originates!…"
"When we make similes, analogies and metaphors between things that we do not understand, we risk equating real world properties with rhetorical turns of phrase. At best this is unhelpful, at worst (and this happens often) downright misleading, suggesting that round blobs of chemicals are “like” cells and so in some way are cells…"
"When we say “replicate” we need to know exactly what we mean by that. For what it is worth I think the key difference between life and non-life lies in coded information. But these are words. What precisely do they mean? My (and others’) inability to define this in chemically testable terms is one on the major roadblocks in our understanding of the emergence of life that AL hardly mentions; how translation arises (and the capacity for evolution as a necessary consequence of translation."
"There is also a lot of excitement about “systems chemistry” and “autocatalytic” systems, catalyzed mainly by Stuart Kauffman. Kaufmann postulates that a sufficiently diverse collection of reactive and catalytic molecules would undergo a phase transition and become self-propagating, autocatalytic, i.e., life-like. But what does “diverse” mean? Atmospheric photochemical networks have nearly as many components and more reactions than central metabolism. Does this mean the atmosphere is alive? Specificity and accuracy need to be included; what biochemicals do not do is at least
as important we what they do.”
Kitadai & Maruyama (2018). Origins of building blocks of life: A review. Geoscience Frontiers, 9(4), 1117-1153:
Life is generally characterized by the following three functions: (1) compartmentalization: the ability to keep its components together and distinguish itself from the environment, (2) replication: the ability to process and transmit heritable information to progeny, and (3) metabolism: the ability to capture energy and material resources, staying away from thermodynamic equilibrium (Fig. 2; Nakashima et al., 2001, Ruiz-Mirazo et al., 2004, Ruiz-Mirazo et al., 2014).
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| Figure 2 Kitadai & Maruyama (2018) |
2. Richard's "Lee peptide" does not meet his own definition:
Second, Richard's "Lee peptide" self-replicator does not even meet his 'own' definition of life (aka NASA's definition of life). Although, Richard does not expressly say so, it seems he subscribes to NASA's working definition of life, which states that: “Life is a self-sustaining chemical system capable of Darwinian evolution.” Indeed this is a popular working definition for life (See, e.g., Higgs, P. G., & Lehman, N. (2015). The RNA World: molecular cooperation at the origins of life. Nature Reviews Genetics, 16(1), 7-17.: “In this Review, we adopt the view that if a replicating RNA system were present in the RNA World, then this would count as ‘life’, as it would satisfy the frequently used definition that life is a self-sustaining chemical system that is capable of evolution.”). But the simple fact is that not everyone agrees with this definition, because, for one, it is not all encompassing. For example, a population of mules is not alive by this definition since mules are sterile and therefore incapable of Darwinian evolution. But even if we accept the NASA definition of life, Richard's "Lee peptide" self-replicator still does not meet this definition for at least two reasons:
(1) Richard's "Lee peptide" is not a "self-sustaining chemical system." As explained by Benner (2010). Defining Life): "They [i.e., the architects of the NASA definition] used the phrase 'self-sustaining' to imply that a living system should not need continuous intervention by a higher entity (a graduate student or a god, for example) to continue as 'life.'” Not only does the "Lee peptide" require investigators to maintain a steady supply of building blocks to keep the self-replication reaction going (i.e., the 'two-halves' discussed above that a "Lee peptide" connects together to make more copies of itself), but as explained further in "Q's Open Challenge to Richard Carrier", Lee et al. 1996 reports the "Lee peptide" exhibits parabolic rate kinetics—not exponential—due to product inhibition. Specifically, when the "Lee peptide" makes a copy of itself, the resulting "Lee peptide" copy (i.e., product) fails to dissociate from the template strand (i.e., it tends to ‘stick’ or stay bound to the original "Lee peptide"). This means that with each successive round of self-replication, fewer and fewer "Lee peptide" copies are created. It is a case of diminishing returns (even in "a suitable environ") with progressively dwindling results until the autocatalytic cycle is effectively arrested. As such, the "Lee peptide" does not meet the NASA definition of life, since it is not "a self-sustaining chemical system." (For a further detailed discussion of this problem, see, "Why the 'Lee Peptide' Cannot Sustain Exponential Growth Even with a Continuous Supply of Substrates").
(2) Richard's "Lee peptide" is not "capable of Darwinian evolution." Even if the "Lee peptide" was a "self-sustaining chemical system" it still does not meet the NASA definition of life, because it is not enough for the "Lee peptide" to double exponentially, or even to acquire mutations. The "Lee peptide" must be able to make copies of those mutations so they are 'inherited'. But the mutated "Lee peptides" tested by Lee et al. 1996 "crippled" the "Lee peptide" so that it could no longer self-replicate. As explained by Benner (2010). Defining Life): "They [i.e., the architects of the NASA definition] exploited the phrase 'Darwinian evolution' as a shorthand for a process, elaborated over the past 150 years, that involves a molecular genetic system (DNA in terran life) that can be replicated imperfectly, where mistakes arising from imperfect replication can themselves be replicated, and where various replicates have different 'fitnesses.'" Put another way, implicit in "capable of Darwinian evolution" is "The requirement for reproduction with errors, where the errors are themselves reproducible." (emphasis added). Benner et al. (2011) elaborate:
"[R]eplication alone is not sufficient for a genetic molecule to support Darwinian evolution. A Darwinian system must generate inexact replicates, descendants whose chemical structures are different from those of their parents. Further, these differences must then be replicable themselves. It does no good if the mutant has changed its biophysical properties so dramatically that the mutant genetic molecule precipitates, folds, or otherwise loses the ability to encode selectable information. While self-replicating systems are well known in chemistry, those that generate inexact replicas with the inexactness itself being replicable are not." (emphasis added)
An Autopoietic Theory Based Definition of Life:
Finally, to be transparent about my own biases, I subscribe to the following autopoietic theory based operational definition of life, where: "a system can be said to be living if it is able to transform external matter/energy into an internal process of self-maintenance and production of its own components." (Luisi, Pier Luigi. The Emergence of Life (p. 122). Cambridge University Press.). To me, this makes the most sense, and seems the most all encompassing, while capturing the essence of "life" and what distinguishes it from nonlife. To elaborate:
“‘A living system is a system capable of self-production and self-maintenance through a regenerative network of processes which takes place within a boundary of its own making and regenerates itself through cognitive or adaptive interactions with the medium’. In doing so, we propose a definition of the living based on the theory of autopoiesis.” (Damiano, L., & Luisi, P.L. (2010). Towards an autopoietic redefinition of life. Origins of Life and Evolution of Biosphere, 40(2), 145-149).
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