The idea of a stratified and open nature of the evolving universe implies that the hierarchy of nested structures is generated by some form of aggregation of underlying elements. This conceptual model requires a suitable description of how new layers emerge over time. Natural phenomena are not really ‘constructed’ by anybody but emerge naturally. The process of emergence to a new level or organisation is unique to each system and every level of organisation requires specific environmental conditions. In general, the emergence of new levels of organisation is associated with an increase in spatial and temporal scales. More suitable terms to describe how the world has become stratified are auto- or self-assembly which describe processes of aggregation of simpler elements into larger structures resulting in self-organised structures1.
The concept of multilayered systems becomes essential to understanding the world and involves the concept of the architecture of such systems. Under this perspective, although is accepted that the world is ‘just’ made of atoms and molecules, their arrangement (architecture) is what explains the unique properties of new assemblies. Interestingly, already Lucretius suggested that a ‘swerve’ of certain atoms was responsible for the obvious non-randomness of the universe2.
Macromolecules are formed by aggregations of atoms and of simpler molecules3. The new aggregates represent a very small proportion of what can be formed by all possible combinations and permutations of the elements but only some of these become sufficiently stable to exist over time. It is as if there is a kind of natural selection of what can exist in each physical environment4.
From: https://en.wikipedia.org/wiki/Macromolecular_assembly
A recent theory, called ‘Assembly Theory‘5, aims at explaining how complex molecular structures appeared in the universe. It provides a molecular mechanism for the origins of complexity. The authors propose a process of selection for entities that exist depending on their history following a recursive construction of objects along so-called ‘assembly paths’. The theory implies a temporal directionality that has nothing to do with thermodynamics but derives simply from combinations of self-assembly processes: there is a natural order in which objects can appear. This formation history is how Assembly Theory defines an object. Furthermore, the degree of selection among a set of objects can be measured if the molecular complexity, or ‘assembly index’, is known. These quantities combine to give a measure that determines the amount of selection that was necessary to produce an ensemble of objects. The authors’ key contention is that a transition from no selection to selection — such as happened when inanimate matter became animate — changes the pathways taken in assembly space, and that those changes can be expressed mathematically.
A similar mathematical approach is the Theory of Adjacent Possible, originally proposed by Stuart Kauffman6, which is the notion that the near-future outcomes of some developmental process are limited by objects that already exist. This idea has been developed further by Kauffman and his colleagues to explain environmental catastrophes.7 It is based on a logistic model8 which already shows well understood deterministic chaos.
Another approach, also based on recursive transformations, is the ‘Constructor Theory’9, “which considers how self-reproduction is compatible with the laws of physics, reformulating the laws as statements about which object transformations are possible or impossible, and why”. This view is well supported by Sharma et al10 when they suggest that “the smallest unit of matter is typically defined by the limits of observational measurements and may not itself be fundamental. A more universal concept is to treat objects as anything that can be broken and built. This allows us to naturally account for the emergent objects produced by evolution and selection”.
- See also: https://en.wikipedia.org/wiki/Biological_organisation ↩︎
- Lucretius: De rerum natura. Click here to read a verse translation by William Ellery Leonard (2008). ↩︎
- See: https://en.wikipedia.org/wiki/Macromolecular_assembly ↩︎
- This leads to the concept of a ‘fitness landscape’ in biological evolution, see: https://en.wikipedia.org/wiki/Fitness_landscape ↩︎
- Sharma, A. et al (2023): Assembly theory explains and quantifies selection and evolution. Nature 622, 321–328. ↩︎
- Stuart Kauffman (2008): Reinventing the Sacred. Basic Books. Click here to see Kauffman’s TEDtalk on this subject (April, 2023). ↩︎
- Cortes, M. et al (2023): The TAP equation: evaluating combinatorial innovation in Biocosmology. arXiv:2204:14115 ↩︎
- Robert M May (1976): Simple mathematical models with very complicated dynamics Nature 261, 459-467. ↩︎
- Chiara Marletto (2015): Constructor theory of life. Journal of the Royal Society – Interface 12, 20141226. Click here to see more about Constructor Theory. ↩︎
- Sharma, A. et al (2023): Assembly theory explains and quantifies selection and evolution. Nature 622, 321–328. ↩︎