The Prevolution of Evolution: Life Marches In
There’s a new word preceding the E word evolution. Two Harvard scientists have made up a new word, prevolution, to describe a supposed stage before replication when natural selection was helping evolution evolve. What does prevolution act on? Simple, silly: prelife.
Martin Nowak and Hisashi Ohtsuki titled their paper in PNAS, “Prevolutionary dynamics and the origin of evolution.”1 By defining life in terms of evolution, they set the stage for a continuous process of evolution from chemicals to man, with information just appearing along the way. Their abstract makes it all sound very straightforward.
Life is that which replicates and evolves. The origin of life is also the origin of evolution. A fundamental question is when do chemical kinetics become evolutionary dynamics? Here, we formulate a general mathematical theory for the origin of evolution. All known life on earth is based on biological polymers, which act as information carriers and catalysts. Therefore, any theory for the origin of life must address the emergence of such a system. We describe prelife as an alphabet of active monomers that form random polymers. Prelife is a generative system that can produce information. Prevolutionary dynamics have selection and mutation, but no replication. Life marches in with the ability of replication: Polymers act as templates for their own reproduction. Prelife is a scaffold that builds life. Yet, there is competition between life and prelife. There is a phase transition: If the effective replication rate exceeds a critical value, then life outcompetes prelife. Replication is not a prerequisite for selection, but instead, there can be selection for replication. Mutation leads to an error threshold between life and prelife.
So life just marches in like the saints. It builds scaffolds. It crystallizes like ice out of water. What’s the problem? Their mathematics show it must be so.
It remains to be seen whether other scientists who have sweated over the origin of life will buy their definitions and descriptions. A look inside their paper shows the usual math and graphs. Mathematical derivations, however, often rely on initial conditions that are assumed. What are they assuming? Here’s where the word crops up:
- We assume, for simplicity, that all sequences grow in one direction.
- At first, we assume that the active monomers are in a steady state.
- For “supersymmetric” prelife, we assume that a0 = a1 = alpha/2, and ai = a for all other i.
- Let us now assume that some sequences can act as a templates for replication.
- Fig. 3 shows the competition between life (replication) and prelife. We assume a random prelife landscape where the ai values are taken from a uniform distribution between 0 and 1. All sequences of length n = 6 have the ability to replicate.
- All fundamental equations of evolutionary and ecological dynamics assume replication, but here, we have explored the dynamical properties of a system before replication and the emergence of replication.
Is the scheme rigged to achieve the result? “Traditionally, one thinks of natural selection as choosing between different replicators,” they said; indeed, replication has usually been understood as a prerequisite for natural selection. Nowak and Ohtsuki offer a different approach. “In the present theory, however, we encounter natural selection before replication.” How? Because they envision information carriers competing for resources in the chemical soup. By inventing a concept of prelife, they can have natural selection occurring “within prelife and between life and prelife.” In this way, natural selection “is not a consequence of replication, but instead natural selection leads to replication.” This inverted scenario requires some unpacking.
First of all, what do they mean by information? They defined “prelife” as “an alphabet of active monomers that form random polymers.” No information so far. But then they said, “Prelife is a generative system that can produce information.” Let’s follow their use of that word (information) in the paper. The paper began by admitting that “Evolution needs a generative system that can produce unlimited information. Evolution needs populations of information carriers.” But did they ever define what they mean by information? It appears they include too much in their picture: “we can define a prebiotic chemistry that can produce any binary string and thereby generate, in principle, unlimited information and diversity,” they said. “We call such a system prelife and the associated dynamics prevolution (Fig. 1).” It is doubtful that most theorists would consider the set of all possible random strings as information. By lowering the standard of information, they have helped themselves to “information carriers” that can compete on a stage of “prevolution” of “prelife.”
How plausible is this? It appears they have indiscriminately considered any polymer that “outcompetes” the others (by being more abundant) to be a contender leading to life. What if, however, the leading polymer – even if it can replicate – tends toward clumps that precipitate on the seafloor, till all available resources are used up? It would seem that one cannot assume that all sequences of building blocks are equally pregnant with life possibilities. Abundant replicators can lead to a dead end. At some point the leading polymer in the race for life has to contain functional information. The set of polymers capable of acting as templates of their own replication, furthermore, seems much smaller than the set of all polymers.
Their model is highly theoretical. They made no claims what the polymers are made of. Are the molecules made of RNA, DNA, PNA, or TNA? Are they one-handed? Math notwithstanding, models must at some point come to grips with real chemicals in a real solvent in a real environment. It is to be expected that real molecules will be much more intransigent than hypothetical ones. Their conclusion makes it clear that their scheme works only on a chalkboard:
We have proposed a mathematical theory for studying the origin of evolution. Our aim was to formulate the simplest possible population dynamics that can produce information and complexity. We began with a “binary soup” where activated monomers form random polymers (binary strings) of any length (Fig. 1). Selection emerges in prelife, if some sequences grow faster than others (Fig. 2). Replication marks the transition from prelife to life, from prevolution to evolution. Prelife allows a continuous origin of life. There is also competition between life and prelife. Life is selected over prelife only if the replication rate is greater than a certain threshold (Fig. 3). Mutation during replication leads to an error threshold between life and prelife. Life can emerge only if the mutation rate is less than a critical value that is proportional to the inverse of the sequence length (Fig. 4). All fundamental equations of evolutionary and ecological dynamics assume replication, but here, we have explored the dynamical properties of a system before replication and the emergence of replication.
1. Martin A. Nowak and Hisashi Ohtsuki, “Prevolutionary dynamics and the origin of evolution.” Proceedings of the National Academy of Sciences, Published online before print September 12, 2008, doi: 10.1073/pnas.0806714105.
Have you ever in your life come across a more bold, bald collection of highfalutin nonsense than this? You can’t just make up words and assume what needs to be proved in an argument. You can’t just help yourself to concepts foreign to your worldview and manipulate them mathematically to guarantee the outcome you want. If we were to follow their example, we could prove anything. Let’s demonstrate the evolution of gnomes, for example.
PreGnome Dynamics and the Origin of Garden Gnomes
Gnomes are beings that inhabit gardens and hide under toadstools. Here, we formulate a general mathematical theory for the origin of gnome. All known gnomes are made of terracotta and are found in gardens. Therefore, any theory for the origin of gnomes must address the emergence of such a system. We describe pregnome as an alphabet of terracotta ostracons that form random shapes. Pregnome is a generative system that can produce gnome parts. Pregnome dynamics have selection and mutation, but no replication. Gnomeness marches in with the ability of replication; Ostracons act as templates for their own replication. Pregnomeness is a scaffold that builds gnomes.
You get the idea. When you weren’t looking, they snuck in design concepts like information, competition, error, scaffolds, templates and information carriers. Well, of course! With a hole that big in the intransigent walls of chemistry, no wonder life just marches in (09/04/2008).
The flaws in this exercise are legion. They envisioned polymers as simple as binary digits (1’s and 0’s) that somehow can be “activated” and join up into chains. They claimed that any random string of binary digits carries information. They claimed that life is merely something that replicates and evolves. Well, fire does that. It replicates rapidly. It evolves, too. Feed it some different elements and it will turn all kinds of colors. It adapts to the environment. According to their definition, it must be alive. In this land of made-up words, we can call an oil spill prefire. They considered anything that outnumbers something else as having been “selected” without any consideration of whether it can do anything, like breathe or eat or move or write sonnets. According to their definition, natural selection selects bubbles in soapy water, and favors ice over dew on your windshield when the temperature drops.
Here is your tax money at work. This paper was partially funded by the National Institutes of Health and the National Science Foundation. Japanese people will be honored to know that funding also came from the Japan Society for the Promotion of Science. Those interested in the interaction between science and religion will also get a warm feeling in their hearts to learn that this bit of secularist, materialist, mechanistic propaganda was supported by the John Templeton Foundation. We hope the atheists at Nature will give the Foundation a pass this time (08/28/2008).