A degenerative process underlying hierarchic transitions in evolution

Physical limits of natural computation as the biological constraints of morphogenesis, evolution, and consciousness: On the 100th anniversary of Efim Liberman (1925-2011)

Efim Liberman (1925-2011) introduced in 1972 the idea of natural computation realized internally by living systems. He considered the physical principles employed by living systems as essential constraints that limit the computational process occurring in the course of adaptation, morphogenesis, and neural activity. The most general limits determined by the physical fundamental constants are universal for all nature. However, the more specific constraints are intrinsic to each biological system and can be overcome in the course of the evolutionary process. We discuss the roles of biological macromolecules, particularly the cytoskeleton, in shaping the actualization patterns formed in the internal measurement process occurring in living systems. Cytoskeletal rearrangements determine cellular, morphogenetic, and perceptive transformations in living systems and participate in the combinatorial genetic events that lead to evolutionary transformations. The operation of neurons is based on the transmission of signals via the cytoskeleton, where the digital output is generated that can be decoded through a reflexive action of the perceiving agent. It is concluded that the principles of natural computation formulated by Liberman represent the most fundamental feature of living beings and form the basis for the general theory of biological systems, with essential consequences for understanding metabolic closure, morphogenesis, evolution, and consciousness.

Toward a Bio-Organon: A model of interdependence between energy, information and knowledge in living systems

What is an organism? In the absence of a fundamental biological definition, what constitutes a living organism, whether it is a unicellular microbe, a multicellular being or a multi-organismal society, remains an open question. New models of living systems are needed to address the scale of this question, with implications for the relationship between humanity and planetary ecology. Here we develop a generic model of an organism that can be applied across multiple scales and through major evolutionary transitions to form a toolkit, or bio-organon, for theoretical studies of planetary-wide physiology. The tool identifies the following core organismic principles that cut across spatial scale: (1) evolvability through self-knowledge, (2) entanglement between energy and information, and (3) extrasomatic "technology" to scaffold increases in spatial scale. Living systems are generally defined by their ability to self-sustain against entropic forces of degradation. Life "knows" how to survive from the inside, not from its genetic code alone, but by utilizing this code through dynamically embodied and functionally specialized flows of information and energy. That is, entangled metabolic and communication networks bring encoded knowledge to life in order to sustain life. However, knowledge is itself evolved and is evolving. The functional coupling between knowledge, energy and information has ancient origins, enabling the original, cellular "biotechnology," and cumulative evolutionary creativity in biochemical products and forms. Cellular biotechnology also enabled the nesting of specialized cells into multicellular organisms. This nested organismal hierarchy can be extended further, suggesting that an organism of organisms, or a human "superorganism," is not only possible, but in keeping with evolutionary trends.

The reversibility of cellular determination: An evolutive pattern of epigenetic plasticity

Until the middle of the 20th century, embryogenesis patterns were considered as based on a rigid, unidirectional ontogenetic development, whose nuclear programming yields an irreversibility feature for cellular determination. Further empirical pieces of evidence have provided new insights about a certain reversibility to cellular determination, finding new biomolecular mechanisms (nuclear reprogramming, dedifferentiation, transdifferentiation) which have clearly shown that such a reversibility exists, warranting a certain cellular plasticity inside cell cycle; moreover, they seem mainly ruled by epigenetic factors. In this framework, evolution can be viewed as a systemic transformation of the spatiotemporal epigenetic organization, and the maintenance of the stable final adult stage includes a possibility of dedifferentiation at the particular points of ontogenetic development leading to the achievement of the final stage though the alternate sets of epigenetic trajectories. This paper is aimed to briefly outline historically the main aspects which have led to define the mechanisms of cellular plasticity, highlighting the chief empirical facts supporting it and the related still unresolved problematic issues.