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CONTINUATION. "Reggia et al., presented several small self-replicating loops, essentially based on Langton's work." https://lnkd.in/dn83zJW View in LinkedIn

FREE ENERGY. "All processes are driven by changes in free energy, which in turn is made up of two parts, enthalpy and entropy. Since all systems try to go to their highest states of randomness (increase in entropy), naturally occurring ordered states must arise through enthalpic compensation." https://lnkd.in/dEpJBda View in LinkedIn

FUNCTIONAL AND STRUCTURAL DEATH. "The concept of death in cellular automata is just as important as self-reproduction. Death is important to realize for natural selection, which is based on the survival of fitter organisms. Realization of death can be functional or structural." https://lnkd.in/dSdcD2A View in LinkedIn

DIVERSITY OF STRUCTURES. "This paper will delve more deeply into the origin of natural products with an emphasis on the fundamental problem of just how such an extraordinary and bewildering array of structure types has arisen through evolutionary processes." https://lnkd.in/dEpJBda View in LinkedIn

SIZE REDUCTION AT A COST. "Langton observed that the capability of computational universality found in the self-reproducing automata of von Neumann is not known to be present in any self-replicating molecules or in the biological structure of any known living entity. Consequently, Langton achieved a substantial reduction in size by abandoning computation universality." https://lnkd.in/dSdcD2A View in LinkedIn

REPLICONS ALONE. "Langton and his successors Byl, Reggia et al., developed self-replicating automata which are much simpler than the universal constructor. These machines, however, lack any computing and constructing capabilities, their sole functionality being that of self-replication." https://lnkd.in/dvjjarA View in LinkedIn

INSUFFICIENT. "Langton observed that although the capacity for universal construction, as studied by von Neumann and Codd, is a sufficient condition for self-replication, it is not a necessary one. Furthermore, natural systems are probably not capable of universal construction." https://lnkd.in/dvjjarA View in LinkedIn

CELLULAR AUTOMATA. "Langton’s self-reproducing loop is one of the most famous models of self-reproduction using cellular automata." https://lnkd.in/dSdcD2A View in LinkedIn

"LANGTON LOOPS are a particular "species" of artificial life in a cellular automaton created in 1984 by Christopher Langton. They consist of a loop of cells containing genetic information, which flows continuously around the loop and out along an "arm" (or pseudopod), which will become the daughter loop. The "genes" instruct it to make three left turns, completing the loop, which then disconnects from its parent." https://lnkd.in/dX4P4qb View in LinkedIn

SO ENDS this first of two weekends contemplating the evolution of metabolism. Bewildering in its complexity, it has a small number of simple motifs. And many of these complexities have been repurposed over time, contributing to the complexity. In some cases by wholesale acquisition of pathways by horizontal gene transfers; in others, by huge macro events such as the Great Oxygenation which required a complete retooling. No wonder the wiring systems are not logical or simple. View in LinkedIn