From Newsgroup: talk.origins

A particularly good assessment of Lee Cronin's Assembly Theory:

https://youtu.be/nMJ-_pTykog?si=fO1eCFGG3hd-41h1&t=693

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From Newsgroup: talk.origins

On 29/01/2026 10:15 am, MarkE wrote:

A particularly good assessment of Lee Cronin's Assembly Theory:

https://youtu.be/nMJ-_pTykog?si=fO1eCFGG3hd-41h1&t=693

Spoiler:

AT's "copies + index" correlates with rCLspecified complexityrCY.

AI summary:

*What Assembly Theory is*

Assembly Theory, as described in the commentary, is a general, substrate-independent measure of compositional complexity. It defines complexity via an assembly index: the minimum number of recursive steps required to build an object from basic building blocks, allowing reuse
of intermediate parts. This applies equally to molecules, proteins,
texts, or Lego sets. The assembly index provides a probabilistic lower
bound on how unlikely an object is to arise from undirected processes.
When combined with copy number (how many identical copies are observed), Assembly Theory functions as a form of specified complexity: high
assembly index plus multiple copies indicates the action of a directed process, which CroninrCOs group interprets as selection. Practically, this
has been used as a model-free biosignature detector, operationalised via
mass spectrometry, where fragmentation patterns are calibrated to
estimate assembly index and distinguish life-associated samples from
non-life.

*What Assembly Theory is not*

Assembly Theory is not a chemical mechanism, a reaction pathway, or a
recipe for how molecules are physically assembled; its assembly pathways
are explicitly idealised and non-physical. It does not provide a
concrete model for prebiotic evolution or selection, nor does it explain
how a material selection process capable of storing, copying, varying,
and filtering information could arise before biology. Despite rhetoric
about rCLnew physics,rCY the commentary argues it does not deliver a new causal framework, only a way to diagnose that selection has occurred,
not how it occurred. Nor is it fundamentally novel relative to existing
ideas: at its core, it amounts to specified complexity implemented via a compression-like measure plus copy number, which can detect life-related structure but does not move the origin-of-life problem forward in a mechanistic or explanatory sense.

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From Newsgroup: talk.origins

On 1/28/2026 5:15 PM, MarkE wrote:

A particularly good assessment of Lee Cronin's Assembly Theory:

https://youtu.be/nMJ-_pTykog?si=fO1eCFGG3hd-41h1&t=693

https://pmc.ncbi.nlm.nih.gov/articles/PMC10978598/

This is a paper that discusses what Assembly theory is "What it does and
does not do."

It really is impractical to apply it to current biomes and evolution of existing lifeforms. It isn't even applicable past evolution of life.
It requires that you be able to determine what existed at the time and
then determine the possible historical assembly path. Since the
possible materials available for assembly is changing over time you
can't determine the assembly path except over very short periods of time
for which you have some idea of what existed at that time. This just
means that you can't use it to determine the probability of the assembly
path for something like a polypeptide enzyme (simple chain of amino
acids) and you definitely can't use it to assess something like the F0
ATPase complex of multiple polypeptide proteins. You have no idea of
what the original polypeptide sequence was that evolved to have that
enzyme activity. It isn't as simple as trying to figure out what the
sequence is and what the concentrations of each amino acid might have
been in order to create that particular sequence of amino acids. For
extant proteins you have the genetic code to consider, but it isn't just
that. The vast majority of existing proteins have evolved from
preexisting proteins by gene duplication. So you have to figure out
what the original protein sequences were that eventually evolved to have
that enzymatic activity. No one can do this at this time except for
closely related protein families, but these identifiable protein
families likely started from some other protein sequence.

What it seems to be useful for is to determine if some complex molecules
like amino acids and the purines and pyrimidines involved in nucleic
acid are found in higher amounts than expected by random chance. You
may expect these molecules to be present at some low level in a cosmic
dust cloud or planetary atmosphere, but lifeforms assemble these
molecules, so they can be present in the mix of possible molecules at
higher concentrations than the existing concentration of carbon, oxygen, nitrogen and hydrogen might be responsible for. The assembly paths for
amino acids from the constituent atoms can be determined and the
probability of random chemical activity can be determined if you know
the concentration of component parts, so you may be able to tell if the concentration of these complex molecules are in a higher abundance than expected.

It works for simple molecules too. If you found an 20% molecular oxygen atmosphere around some exoplanet you might conclude that it had aerobic photosynthetic life. That seems to be the only means to maintain such a
high concentration of molecular oxygen in an atmosphere.

It doesn't seem to be very useful to use to evaluate the evolution of
life on earth. It might be useful to assess the evolution of the first
self replicating molecules if we ever figure out what they were.

Ron Okimoto

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