A New Theory for the Assembly of Life in the Universe

The introduction to one of the linked papers is far more informative and frankly readable than the article:

> Biological systems have access to a lot of information—genetically, epigenetically, morphologically, and metabolically—and the acquisition of that information occurs via evolutionary selection over successive cycles of replication and propagation [7]. One way to look at such systems is by comparing the self-dissimilarity between different classes of a complex system, allowing a model-free comparison [8]. However, it has also been suggested that much of this information is effectively encrypted, with the heritable information being encoded with random keys from the environment [9]. As such, these random keys are recorded as frozen accidents and increase the operative information content, as well as help direct the system during the process of evolution, producing objects that can construct other objects [10].

https://www.mdpi.com/1099-4300/24/7/884

We don't know whether the universe is infinite in space. The universe reachable to us is actually quite finite. The age of the universe is ~ 10^60 Planck time, and the size of the observable universe is also 10^60 Planck length. log2(10^60) ~ 200, so with all the universe time and space, you could only brute force a 800 bits string, or 400 DNA base pairs. That's not a lot at all. You can't just shrug complex systems as "random".

The actual number of bits the universe could've brute forced regarding life is probably less than 100 bits. That's not a lot at all. Think about bootstrapping a compiler in a hostile assembly with just 100 bits to boot.

Darwin's natural selection only gets you going once you have self replicating molecules and a way to inherit properties.

If it takes even 100 pairs of RNA to bootstrap life, that's already too much.

Another funny way to look at it, is that if there's truly no randomness in the universe (if everything was predetermined in the big bang), literally everything you know has kolmogorov complexity of less than 1000 bits+number of bits required to represent laws of physics + number of bits to describe the initial condition in the big bang. The program that decompress it just simulates the whole universe and fetches the information from the given coordinates.

Here me out: Earth life first put a surface around the seawater it was in. Each cell is really a bag of saline (unless you're a plant and then you have rigid walls) plus other stuff. That was encapsulated. Anyone who has kept saltwater fish knows that they only do well in a narrow range of temperatures, salinity, and so forth.

Then creatures thermoregulated, carrying the necessary temperatures for life within themselves. Slow down at night. Basking in the sun: an innovation. Feathers, then fur. Brown fat cells. All this to keep our interior seawater just so.

But what if what kickstarted life wasn't just chemistry, but the cycles applied to the chemistry? A warm little pond, a soup all of its own. New unreacted chemicals (nutrients) rain in. A bit of tide washes out the chemicals at the bottom of the entropy chain (waste). Rain in, wash out, over and over, allowing for a concentration. Dump chemicals in an unmoving tank of water, they head toward equilibrium, but have them surging in and out, you can get interesting stuff. Rain in, wash out; inhale, exhale; eat, excrete; heartbeat. All cycles. Urea cycle, Krebs cycle, glyoxylate cycle. Once you step back to see that life works as repeated cycles of chemistry, well, we probably needed cycles to get started, just as we needed chemistry and other conditions to get started. We incorporated those cycles because life is not static, it persists because it repeats.

So perhaps -- and this is just a perhaps -- not only does life need one "set" of chemistry or another to begin (maybe arsenic instead of phosphorus, hydrogen sulfide instead of water), it needs cycles, interlocking cycles. So not just a year with seasons, but day and night (tidally locked planets need not apply), and even tides (hope you have a moon) would be needed. The more cycles to piggyback upon, the more opportunities for chemistry to capture, repeat, and encapsulate those cycles, to self-perpetuate.

Just something I wonder about.

Wagner also talks about the "probability space" of organic molecules being too high for life to emerge through true randomness.

For even the simplest components of life, like the citric acid cycle, to come into existence is something like everybody in the world hitting the lottery number every day for a billion years. or something.

I don't remember how he brings his theory down to earth because I didn't finish the book, but a cool thing to think about.

Not surprisingly, such an ambitious project has aroused skepticism. Its proponents have not yet made clear how it might be tested in the lab. And some scientists wonder whether assembly theory can even deliver on its more modest promises to distinguish life from nonlife, and to think about complexity in a new way.

At least the article failed to dig deeper into this:

>> by narrowing down relatively complex molecules to a small subset. Ordinary chemical reactions already “select” certain products out of all the possible permutations because they have faster reaction rates.

Since the theory is about assembly all the way down the the bottom, does it seem the theory needs to account for the next level down (and below that from quantum foam to atoms), relative to this chemical selection process? Why is it, or what is it about the universe that causes this, or makes it inevitable?

"What they have proposed is a limited special case of an RLE-Huffman coding algorithm, which means their paper introduces a simpler version of what was already considered one of the simplest coding algorithms in computer science."

The 8 Fallacies of Assembly Theory https://hectorzenil.medium.com/test-8f0be54817c4

And https://arxiv.org/abs/2210.00901

It is laughable that people think it is irrational to believe in the virgin birth of Jesus Christ but then blithely believe that life itself was birthed from nothing for no reason.

Natural Selection cannot even begin until life exists, which is like saying that you can't even start counting to one million until you're already at nine hundred and ninety-nine thousand nine hundred and ninety-nine.

The existence of life is the only interesting question in the Universe because without life no other question can even arise.

> "Our central thesis is that molecules with high MA [Molecular Assambly Index] are very unlikely to form abiotically, and the probability of abiotic formation goes down as MA increases, and hence experimental determination of MA is a good candidate for a life detection system. If our hypothesis is correct, then life detection experiments based on MA can indicate the presence of living systems, irrespective of their elemental composition, assuming those living systems are based on molecules."

You could get a false positive from a pre-biotic but molecularly complex planet, such as Earth in the 100 million years before the origin of the first self-replicating genetic-information-containing entity. Such an environment would contain many complex molecules, whose sites of formation/sources could include metal-rich hydrothermal vents, metal-rich clays, meteorite inputs, ocean surface photochemistry, etc.

In a planet with established life, particularly one with oxygenic photosynthesis , these processes don't allow organic molecules, amino acids etc., to accumulate in high amounts because every system is full of microbial scavengers that take up almost every complex molecule they come across, with a few exceptions (the 'persistent organic fraction' derived from tree lignin etc.). Also, free molecular oxygen is a kind of bleach that eventually degrades many organic molecules.

However, in an abiotic system these complex molecules could persist for hundreds or thousands of years, particulary in the absence of free oxygen. Such a complex molecular soup would then provide many opportunities for the generation of simple living systems.

Incidentally, the most plausible current theory of the origin of life puts the protein-producing rRNA-based ribosome at the center, and the concept is that abiotically produced amino and nucleic acids formed conglomerates, and these bodies developed the ability to replicate themselves by pairing up with free abiotically produced amino and nucleic monomers and catalyzing bond formation (May 2022):

https://www.nature.com/articles/d41586-022-01303-z

> "Structure that links amino acids suggests that early organisms could have been based on an RNA–protein mix."

Potentially has big practical applications as it allows for construction of chemical computers that compute through chemical reactions.