Resonance of Structural Evolution and Chemical Evolution in the Origins of Life
I am conducting personal research on the origins of life. Not specifically from the perspective of the creation of chemical substances or cellular functions, but I approach the subject of life as a self-organizing system, interpreting it from the standpoint of a systems engineer.
In my previous articles, I have proposed a hypothesis that, in the process of chemical evolution where chemicals become more complex and advanced, life approached by utilizing or substituting the structure and mechanisms of the Earth’s environment for chemical substances.
In this hypothesis, I focus not only on pure chemical reactions but also on physical structures and phenomena. To organize this effectively, I began to think that it is better to separate and sort the discussion of physical structures from that of chemical substances and chemical reactions.
In this article, I introduce the concept of structural evolution, focusing on physical structures. The idea is that my hypothesis will be clearer by considering structural evolution and chemical evolution as two wheels of a cart in the origins of life. Additionally, by organizing from the perspective of structural evolution, it becomes visible that life skillfully utilizes not only chemical reactions but also the mechanisms of natural phenomena.
Utilizing Physical Structure
Life phenomena are established by absorbing energy and chemical substances from the outside world and conducting chemical reactions. Naturally, in the origins of life, it is natural to consider the process of chemical evolution, focusing on chemical substances and chemical reactions when thinking about how life was born from non-living things.
On the other hand, I believe that explanation becomes easier when combining another perspective with chemical evolution. That is the perspective of structural evolution.
Simply put, during the process of the birth of life, a lipid membrane like a cell membrane must have been formed at some point. This membrane drastically changed the structure surrounding the chemical substances. In this sense, the emergence of the membrane is a significant evolution, but it is a matter of physical structure, not a story of chemical substances or chemical reactions. It should be easier to explain by providing a framework that focuses on the change in structure. This is why I think it is better to add the perspective of structural evolution in the origins of life.
Of course, physical structures do not create new physical structures by themselves. It is impossible to consider chemical evolution and structural evolution separately. Structural evolution occurs in the process of chemical evolution, and it has a complementary relationship where structural evolution positively affects chemical evolution.
Perspective of Structural Evolution
In the structural evolution of the origins of life, I think it is better to consider both static and dynamic structures. Dynamic structure means considering it as a system.
Regarding structures involved in life phenomena that I recognize, the following concepts exist:
a) Partition
A physical partition that accumulates chemical substances. The partition has a function to prevent internal chemical substances from freely moving and dissipating, and also to avoid sudden mixing with a large variety of chemical substances. Additionally, it also plays a role in retaining water inside and maintaining temperature and pH.
In a word, the function of such a partition is to maintain the internal chemical environment for a certain period.
On Earth, in the origins of life, there are two clear partitions. One is a pond or puddle, and that was the initial partition. Then, the membrane, the second partition, emerged through structural evolution.
b) Aggregate
Similar to a partition, there is also an aggregate that structurally gathers the same type of chemical substances. Unlike partitions, aggregates have a structure where chemical substances gather to something central, without a boundary with the outside.
c) Pathway and Carrier
For chemical evolution to proceed, it is necessary for the chemical substances produced by chemical reactions to move to other places where other chemical reactions occur. This movement of generated chemical substances is a necessary event, and here also, concepts of structure and structural evolution are needed.
In the early Earth, rivers were pathways, and the flow of water was considered a carrier for moving chemical substances. Additionally, I think that the upward airflow created by the evaporation of water, clouds, and rain circulating by being blown by the wind and raining on the land are also pathways and carriers.
The fact that pathways and carriers circulate holds significant meaning in chemical evolution. This is because chains of chemical reactions can form feedback loops if pathways and carriers circulate. Life has a significant feature of self-regulation function, and there is a feedback loop of chemical reactions in it. It is noteworthy that a structure that could form a feedback loop of chemical reactions existed on the early Earth.
Afterwards, through structural evolution, pathways and carriers for the movement of chemical substances became those generated by the chemical substances themselves. It is considered that the fibrous structure that also appeared in the structure of aggregates became the pathway. This is the same fibrous thing as the cell skeleton. A mechanism that moves chemical substances on this fibrous pathway is believed to have emerged as a carrier. At first, it might have used the flow of water between fibers, but eventually, a cart-like carrier that moves on the fibers was created, and chemical substances moved by sticking to this cart.
Utilization of Natural Phenomena in Structure Generation
In structural evolution, it is necessary to generate various structures, but it is difficult to assemble structures only by chemical reactions caused by chemical substances. Therefore, it is thought that the forces of natural phenomena other than chemical reactions are also utilized in structure generation.
For example, it is known that the formation of a lipid membrane, if you can produce a fatty acid with one end hydrophobic and the other end hydrophilic, the fatty acids will naturally stick together in water to form a single or double lipid membrane. By utilizing this phenomenon, you do not need the ability to shape it into a sphere if you can cause a chemical reaction to produce a fatty acid that meets the conditions.
Similarly, substances that form a medium with viscosity should stick together to form a mass, which can be utilized.
Furthermore, it is easy to form substances with fibrous structures from loops of chemical reactions that repeat the same process. This is a chemical reaction loop that adds substances to the ends of substances generated in the previous chemical reaction. By repeating this mechanism, it is possible to generate substances with fibrous structures.
In addition, crystallization phenomena and synchronization phenomena are considered to be usable for the formation of substances with the same structure and the occurrence of chemical reactions at the same timing. Crystallization corresponds to a static structure, while synchronization phenomena correspond to a dynamic structure.
Synchronization phenomena refer to phenomena such as synchronization of things like pendulums, synchronization in distributed systems doing periodic processing, and simultaneous chemical reactions occurring when conditions are met in homogeneous water with changes in temperature or pH.
Even before the appearance of DNA, which is key to the proliferation of living organisms, questions arise about how static chemical substances with the same structure and dynamic structures for complex processing to proceed with timing were realized. Although it is not yet clearly organized, it seems that there are hints in the crystallization and synchronization phenomena.
Effects of Structural Evolution
Various types of structural evolution make chemical evolution easier. The reasons are mainly the following three points.
The first point is internalization of structure. Initially, divisions like ponds and puddles, and paths like rivers and airflow, along with the circulating water carrier, were used. However, with the cell membrane acting as a division and the cellular skeleton as the path and carrier, it switched to internalization.
The second point is miniaturization. Changing from a geographical scale pond or puddle division size to a cell membrane level division signifies miniaturization.
The third point is portability. Although it is due to internalization and miniaturization, if various chemical substances are incorporated into a viscous aggregate or enveloped by a membrane, there is a possibility of realizing a chain of complex chemical reactions in that unit.
By utilizing such small aggregates or membrane-enclosed capsules, it is possible to tour ponds and puddles along the circulation of water on Earth. This allows a collection of chemical substances capable of complex and advanced chemical reaction chains, maintaining that structure, to enter ponds and puddles where there were only simple chemical substances before, thus increasing the possibility of new encounters between organic substances, or groups of organic substances with structures, promoting chemical evolution.
In Conclusion
Speaking of housing, appliances, electrical products, and daily necessities that make the functional aspects of life convenient are similar to chemical substances. We can live efficiently and comfortably by mastering these items.
On the other hand, various structures are essential in a house: the pillars and beams that support the house, walls and roofs that divide the outside and rooms, doors and windows that allow people, light, and air to pass through, corridors and ducts for moving within the house, and electrical wiring, gas pipes, and plumbing for bringing in and out energy and water. Additionally, it’s essential to consider designing dynamic structures for entering, exiting, and moving.
Viewing the origin of life through the dual wheels of chemical and structural evolution is similar to the evolution of human life and housing.
When utilizing large trees or natural caves to shield from the rain and wind, it might have been challenging to incorporate tools that would become unusable when wet or small tools easily blown by the wind into life. By building our own houses, we could more effectively shield from the rain and wind, enriching the tools used in daily life. And as housing becomes more advanced, with room partitions, insulation performance, opening and closing of doors and windows, and the introduction of lifelines, the tools used in life also become more advanced.
This approach of analyzing evolution from the perspectives of structure and processing is not just applicable to the origins of life or housing, but can be applied to various fields. Of course, this framework is inspired by the relationship between system architecture and applications in information and communication systems.
By applying this framework to many fields, it may be possible to gain useful discoveries and insights in each field.
