Assembly theory of evolution explained | Lee Cronin and Lex Fridman

Assembly Theory principles appear applicable to economic systems because capitalism efficiently finds shortest-path solutions to production problems, suggesting similar optimization principles govern both biological and economic assembly.

“I'm always leaping out of um my competence but in economics I'm just wondering if you could apply this in economic process it seems like capitalism is very good at finding shortest path M you know every time but there are ludicrous things that happen because actually the cost function has been minimized”

Assembly Theory is often misunderstood as measuring data compression (like in computer science), but it measures something different: the amount of information required on a causal chain of events to construct an object, where you only gain access to previous information after doing work.

“not just compression what we do right now in computer science and data one big kind of um uh um kind of misunderstanding as assembly theory is telling you about how compressed the object is that's not right it say how much information is required on a chain of events because the nice thing is if you when you do compression in computer science we're wandering a bit here but it's kind of worth wandering I think in you you um assume you have instantaneous access to all the information in the memory yeah assembly Theory you say no you don't get access to that memory until you've done the work and then you access that memory you can have access but not to the next one”

In the assembly possible universe, objects can access all possible motifs instantaneously with zero effort, allowing any object to be made, because only physical laws constrain possibility.

“in the assembly possible you have to apply the laws of physics but you can get access to all the motifs instantaneously with no effort so that means you could make anything then”

The assembly index can be measured empirically for molecules using Mass Spectrometry (MS), infrared spectroscopy, and Nuclear Magnetic Resonance (NMR), where each technique independently gives convergent measurements of the same assembly index value.

“before this paper came out we've with published papers explain how you can measure the assembly index of molecules okay so that's not so trivial to figure out”

A selecting mechanism or 'factory' (like a Von Neumann constructor, ribosome, or Tesla assembly plant) is not magical or mystical; it is an actual causal process encoded in physical reality that constrains and directs the construction of objects.

“you could think about in terms of of a Von noyman Constructor first selection a ribosome a Tesla plant assembling Teslas you know the the difference between the assembly Universe in Tesla land and the Tesla Factory is everyone says no Teslas are just easy they just spring out you know how to make them all the Tesla Factory you have to put things in sequence and out comes a Tesla”

Individual objects may deviate from the shortest path if they are part of a multi-object cooperative assembly space where two or more objects (A and B) must be made efficiently together, rather than each in isolation; this creates compromises where one object takes slightly longer to enable overall system efficiency.

“but but you can find instances where the shortest path isn't taken for an individual object an individual function MH um and people go ah that means the shortest path isn't right and then I say well I don't know I think it's right still because so of course because there are other driving forces it's not just one molecule now when you start to now you start to consider two objects you have a joint assembly space and it's not now it's a compromise between not just making A and B in the shortest path you want to make a and b in the shortest path which might mean that a is slightly longer”

The factory and the selection mechanism emerge from the interplay between the environment and the objects being constructed—neither pre-exists; they co-evolve through interaction.

“the factory emerges in the envir the interplay between the environment and the object objects that are being built”

Objects must be finite, decomposable into subunits, distinguishable, persist over time, and be breakable such that the set of constraints to construct them from elementary building blocks is quantifiable; an object's history is encoded within it.

“objects need to be finite um and they need to be decomposable into subunits”

The shortest assembly path is important because in an environment with limited resources and molecule decay, molecules that can self-replicate using the fewest steps will outcompete and supersede those requiring more steps, making shortest-path construction a conservation law for propagated motifs.

“imagine you've got uh an envir a given environment that um that you have a budget of atoms you're just flinging together yep and the the objective of those atoms that being flung together in say molecule a um have to make that they have they decompose so molecules decompose over time so the molecules um in this environment in this magic environment have to not die but they do die there's a there's they have a half life so the only way the molecules can get through that environment out the other side let pretend the environment is a box you go in and out without dying and there's a there's just an infinite supply of atoms coming or well a large Supply the molecule gets built but the molecule that is able to template itself being built um and survives in the environment will will basically re Supreme”

Assembly Theory can be applied to non-chemical domains: the speaker's lab is applying it to emoji pixels, where each emoji at a given resolution is treated as an object, and the shortest pixel assembly path from a 'base emoji' can be computed.

“I've started assembly theory of emoticons with my lab believe it or not so we take emojis yeah pixelate them and work out the assembly index for emoji yeah and then work out how many emojis you can make on the path of emoji so there's the Uber emoji from which all other emoj em emojis emerge”

Calculating the assembly index computationally becomes exponentially harder as objects become larger and more complex, but there are physical shortcuts to measurement without computational calculation.

“it's a hard problem but actually if you look at it so the best way to look at it for let's take a molecule so if the molecule has um 13 bonds first of all take 13 copies of the molecule and just cut all the bonds so take cut 12 bonds and then you just put them in order yeah and then that's how it works so and you keep looking for Symmetry and re or or copies so you can then shorten it as you go down and that becomes commentor quite hard um for some natural product molecules um it comes very hard it's not impossible but we're looking at the bounds on that at the moment but as the object gets bigger it becomes really hard”

Determining whether applying Assembly Theory to visual/pixel-based data requires choosing a fundamental scale (resolution) makes the results sensitive to that choice, with implications changing dramatically as resolution assumptions change.

“in the same way in chemistry we assume the bond is fundamental what we do and there here is we assume the resolution at the scale of which we do it is fundamental and we're just working that out and that you're right that will change right because as you take your lens out a bit you it will change dramatically”

A molecule with 13 bonds can have its assembly index calculated by taking 13 copies, cutting all bonds, arranging them in order, and then looking for symmetries and repeated patterns to shorten the construction path.

“if the molecule has um 13 bonds first of all take 13 copies of the molecule and just cut all the bonds so take cut 12 bonds and then you just put them in order yeah”

Complex nested systems (cities, cells, factories) readjust and find new shortest paths when given sufficient time and heterogeneity, suggesting a universal principle that shortest paths are not fixed but evolve as systems adapt.

“I keep seeing parallels everywhere where there are complex nested systems where if you give it enough time and you introduce a bit of heterogeneity the system readjusts and finds a new shorts path but the shortest path isn't fixed on just one molecule now it's in the actual existence of the object over time and that object could be a city it could be a cell it could be a factory”

Chemical bonds are the fundamental constraints in assembly possible within chemistry, serving as the only base-level constraints beyond the laws of physics.

“assembly possible laws of physics come in in this case in chemistry bonds MH in assembly so that means those are extra constraints I guess yes and they're the only straints”

Before the Nature paper publication, the speaker and collaborators published papers explaining how to physically measure the assembly index of molecules—demonstrating that assembly index is not merely theoretical but empirically accessible.

“almost before this paper came out we've with published papers explain how you can measure the assembly index of molecules okay so that's not so trivial to figure out”