Is the Emergence of Life an Expected Phase Transition in the Evolving Universe? (2401.09514v2)

Abstract: We propose a novel definition of life in terms of which its emergence in the universe is expected, and its ever-creative open-ended evolution is entailed by no law. Living organisms are Kantian Wholes that achieve Catalytic Closure, Constraint Closure, and Spatial Closure. We here unite for the first time two established mathematical theories, namely Collectively Autocatalytic Sets and the Theory of the Adjacent Possible. The former establishes that a first-order phase transition to molecular reproduction is expected in the chemical evolution of the universe where the diversity and complexity of molecules increases; the latter posits that, under loose hypotheses, if the system starts with a small number of beginning molecules, each of which can combine with copies of itself or other molecules to make new molecules, over time the number of kinds of molecules increases slowly but then explodes upward hyperbolically. Together these theories imply that life is expected as a phase transition in the evolving universe. The familiar distinction between software and hardware loses its meaning in living cells. We propose new ways to study the phylogeny of metabolisms, new astronomical ways to search for life on exoplanets, new experiments to seek the emergence of the most rudimentary life, and the hint of a coherent testable pathway to prokaryotes with template replication and coding.

• The paper presents a theoretical framework uniting collectively autocatalytic sets and the adjacent possible to explain life’s emergence as a first-order phase transition.
• It demonstrates that molecular reproduction arises when chemical diversity reaches a critical threshold, challenging traditional models of life's origin.
• The study proposes experimental setups to detect small molecule autocatalytic networks in exoplanetary and ancient Earth-like environments.

Analyzing the Paper: "Is the Emergence of Life an Expected Phase Transition in the Evolving Universe?"

The paper by Stuart Kauffman and Andrea Roli presents a comprehensive theoretical framework for understanding the emergence of life as an expected phenomenon in the universe. The authors propose a novel definition of life, highlighting its emergence through a first-order phase transition via collectively autocatalytic sets (CAS) and the theory of the adjacent possible (TAP).

Key Contributions and Theoretical Insights

The cornerstone of this work is the unification of two mathematical theories: Collectively Autocatalytic Sets (CAS) and the Theory of the Adjacent Possible (TAP). CAS suggests that molecular reproduction emerges as a phase transition when chemical networks reach sufficient diversity. TAP posits how molecular diversity increases over time, resulting in rapid expansion beyond initial slow growth. The synergy between these theories supports the paper's central claim that life is a natural phase transition in chemical evolution.

Definitions and Concepts

The paper introduces critical concepts such as Kantian Wholes and different forms of closure essential to the definition and understanding of life. A Kantian Whole is a system where parts and the whole coexist in mutual dependency, observable in living organisms. The paper delineates three forms of closures achieved by living systems:

• Catalytic Closure: Ensures that every reaction is catalyzed by a system component.
• Constraint Closure: Involves systems doing thermodynamic work to construct and maintain constraints essential for their operations.
• Spatial Closure: Relates to the physical containment of the system, akin to a cell membrane.

These closures characterize life as emergent phenomena not inherently directed by traditional Newtonian laws.

Implications and Experimental Outlook

With the identification of small molecule collectively autocatalytic networks in all 6700 prokaryotes, the paper raises significant implications for understanding life's origin. This finding challenges the prevailing assumption that template-replicating polynucleotides are necessary for the origin of life. Such small molecule networks provide a potential minimalistic model of life for experimental endeavors seeking life's emergence.

The authors propose novel experimental setups to test these ideas in astrobiology, notably on exoplanets and within ancient earth-like environments. The suggestion to seek small molecule autocatalytic sets presents a promising avenue for life-detection experiments beyond Earth.

Theoretical and Practical Impacts

The work challenges strong reductionism and classical physics paradigms by asserting that life's evolution and biosphere cannot be deduced from initial conditions and known laws. It introduces notions of open-ended evolution and the creative nature of biological processes that escape complete mathematical description via set theory, emphasizing evolutionary biology's distinctive requirement for function-based explanations.

Future Developments

The paper opens multiple pathways for future research, including investigating the transition from minimal autocatalytic systems to complex life forms like prokaryotes and eukaryotes. Further research could include the evolution of metabolic pathways and the integration of these pathways within multicellular life forms. There is potential for further exploration of how such systems might have facilitated the development of genetic coding and template replication mechanisms.

This theoretical framework potentially revolutionizes our approach to studying life's origins and evolution. As research progresses, we may gain deeper insights into the interconnectedness of life, the universe, and the fundamental principles facilitating the continuous emergence of complexity within evolving systems.