No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Spontaneous Emergence of Robust Cellular Replicators
Abstract
An experimental method is developed to evaluate the possibility of spontaneous emergence of self-reproducing patterns from
a quasi-random configuration. In order to achieve viability to the emerging patterns and to their components a robust transition
table is designed. Genetic reproduction is compared with self-inspection based reproduction in order to conclude that the
latter is better adapted to achieve the specified goal.
... Such non-degenerative reproduction is an immediate consequence of construction universality, an important result recently clarified and strengthened by Mc- Mullin[17]. Yet whereas such universality is computationally demanding and biologically implausible, a less stringent yet explicit encoding — one that enables a shift in heredity from limited towards indefinite — is in fact possible and indeed has already been implemented in a number of models[1, 10, 26, 30, 35]. Such a shift enables evolutionary complexity growth, described in the next section. ...
... Using such a network, it was found that larger, more complex loop structures emerged at the boundary between waves of superior and inferior species in a propagating hypercycle formation. Using a novel CA system incorporating both self-inspection and genetic reproduction strategies, Azpeitia and Ibáñez[1] investigated the spontaneous emergence of robust cellular replicators (self-replicating loops). Emergence in this system is notably achieved without explicit mechanisms (e.g. ...
... The diversity of multi-cellular life that has evolved in the biosphere is clear evidence that self-replication at concurrent multiple scales plays a critical role in the growth of complexity. Although the emergence of self-replication has been shown[1, 6, 10], self-replication of macro-scale replicators from simpler micro-scale ones has not 5 . The study ...
This paper reviews the history of embedded, evolvable self- replicating structures implemented as cellular automata systems. We relate recent advances in this field to the concept of the evolutionary growth of complexity, a term introduced by McMullin to describe the central idea contained in von Neumann's self-reproducing automata the- ory. We show that conditions for such growth are in principle satisfied by universal constructors, yet that in practice much simpler replicators may satisfy scaled-down — yet equally relevant — versions thereof. Examples of such evolvable self-replicators are described and discussed, and future challenges identified.
... One of them includes studies of self-replicating loops aimed at the verification of hypotheses related to the emergence of the biological life. These are studies of the conditions for spontaneous emergence of replicators from a random initial distribution of cell states in space (i.e., abiogenesis in the primordial soup), interactions of the replicators with one another, and their ability to mutate [8][9][10]. In addition, studies of self-replicating loops in the cellular space are of interest because they suggest a new paradigm for constructing parallel fine-grained algorithms and architectures. ...
... As in the case of 1D PSA, 2D PSA can be made more concise if we combine three pairs of the substitutions Θ 5 , Θ 6 ; Θ 9 , Θ 10 ; and Θ 11 , Θ 12 into three substitutions Θ (5,6) , Θ (9,10) , and Θ (11,12) , respectively. The substitutions Θ 3 and Θ 4 , which were combined in 1D PSA into one substitution, cannot now be combined since their union is obviously contradictory. ...
The parallel substitution algorithm, which is a spatial model for representing fine-grained parallel computations, is used for constructing self-replicating structures in a cellular space. The use of this model allows one to create more compact (in terms of the number of cell states and transition rules) and structured self-reproduction programs compared to the classical cellular automaton model. Two parallel substitution algorithms for modeling the self-reproduction of a cellular structure having the shape of a rectangular loop are presented. One of them models the self-reproduction of the original structures from left to right, and the other, from left to right and from bottom to top.
... Realizations of constructing machines in CA range in form from the intricate and functionally sophisticated architecture of von Neumann's Universal Constructor (UC)[49] (and variations thereof[9] [13] [26] [47]), to the underlying simplicity of Barricelli's numeric symbioorganisms[2]. Between these extremes exist a variety of other structures of marginal complexity, commonly taking the form of loops[1] [6] [7] [8] [15] [31] [40] [41] [44] [46] or worms[23] [42]. ...
... The evoloop is among a small subset 3 of CA systems[1] [7] [14] [42] [44] [48] within which occur evolutionary processes (viewed here as variation plus natural selection) that result exclusively from the local, structural interaction of embedded and explicit self-replicators. Such variation and selection processes are not defined a priori but rather emerge spontaneously from the low-level " physics " of the CA, a distinctly bottom-up feature, unique to such CA, that distinguishes them from other artificial evolutionary models such as, for example, those of evolutionary computer programs[17] [30] [50]. ...
In this paper we investigate population dynamics, genealogy and complexity-increase of locally interacting populations of cellular automata-based evolving self-replicating loops (evoloops). We outline experiments indicating that the evolutionary growth in complexity, known to be achievable in principle given the complete genetic accessibility granted by universal construction, may be achievable in practice using much simpler replicating structures. By introducing evoloop populations to hostile environments, we demonstrate that selection pressures toward smaller species can be mediated to enable evolutionary accessibility to larger species, which themselves roam a much more vast portion of genetic state-space. We show that this growth in size results from intrinsically biased genealogy inherent in the rules of the evoloop CA, normally suppressed by selection pressures from direct competition favouring the smallest species. This shows that, in populations of simple self-replicating structures, a limited form of complexity-increase may result from a process which is driven by biased genealogical connectivity--a purely emergent property arising out of bottom-up evolutionary dynamics--and not just by adaptation . Implications of this result are discussed and contrasted with other self-replication studies in Artificial Life and Biology.
Two fine-grained models of artificial biological cells are presented. They can be used as elements of computing devices that mimic properties of living organisms: growth, self-reproduction, and self-healing. The models are based on the parallel substitution algorithm that is a spatial model for representing fine-grained parallel algorithms and architectures. An artificial biological cell is constructed based on a genome fed to the input tape. The result is a model of artificial biological cell that contains the phenotype as a set of fixed data and the genotype as a set of mobile data.
Two models of an artificial biological cell are constructed in a fine-grained structure in the form of a self-reproducing loop. The models are developed on the basis of a parallel substitution algorithm, i.e., a system for modeling spatial fine-grained parallel algorithms and architectures. A model of a biological cell is constructed from a one-dimensional artificial genome written on the input tape. The proposed model contains a phenotype in the form of a set of fixed data and a genotype in the form of a set of mobile data. Such a cell can be an element of an artificial multicellular organism that simulates the following properties of living organisms: growth, self-reproduction, and self-repair.
A simple program for constructing a cellular self-reproducing rectangular loop of arbitrary size is developed based on the
parallel substitution algorithm (PSA), which provides a spatial model for representing fine-grained parallel computations.
In order to launch the self-reproduction of a loop of some specified size, one should enter its description into the input
tape. The program includes operators for preliminary cleaning the cellular array, which makes it possible to easily change
its internal functional structure. Two variants of the program are developed. The first variant constructs a chain of self-reproducing
loops of the given size, and the second variant constructs an array of such loops.
Dans les annees 40 et 50, J. von Neumann a developpe un modele d'automate autoreproducteur destine a l'elaboration de machines de construction ayant des capacites comparables a celles des organismes vivants, dans la mesure ou elles peuvent construire d'autres machines au moins aussi complexes qu'elles. Dans cet article, les As. comparent la strategie de modelisation de Neumann par rapport aux options choisies par des modeles d'autoreproduction developpes par la suite pour les automates cellulaires. Ils montrent que la nature de la description de soi et la necessaire universalite du mecanisme de construction, qui sont des traits fondamentaux de la proposition de Neumann, ont ete reconsideres dans les nouvelles strategies developpees pour modeliser le phenomene. Ces changements ont un grand interet pour le programme de recherche en biosemiotique dans la mesure ou ils revelent, d'une part, que la recherche sur les aspects semiotiques des systemes vivants est un effort important pour comprendre leur ontologie et leur epistemologie, et, d'autre part, qu'il est important de discuter les hypotheses informatiques sur lesquelles ils se basent
The vitalism/reductionism debate in the life sciences shows that the idea of emergence as something principally unexplainable
will often be falsified by the development of science. Nevertheless, the concept of emergence keeps reappearing in various
sciences, and cannot easily be dispensed with in an evolutionary world-view. We argue that what is needed is an ontological
non reductionist theory of levels of reality which includes a concept of emergence, and which can support an evolutionary
account of the origin of levels. Classical explication of emergence as “the creation of new properties” is discussed critically,
and specific distinctions between various kinds of emergence is introduced for the purpose of developing an ontology of levels,
framed in a materialistic and evolutionary perspective. A concept of the relation between levels as being inclusive is suggested,
permitting the “local” existence of different ontologies. We identify, as a working hypothesis, four primary levels and explicate
their nonhomomorphic interlevel relations. Explainability of emergence in relation to determinism and predictability is considered.
Recent research in self-organizing non-linear dynamical systems represents a revival of the scientific study of emergence,
and we argue that these recent developments can be seen as a step toward a final “devitalisation” of emergence.
Biological experience and intuition suggest that self-replication is an inherently complex phenomenon, and early cellular automata models support that conception. More recently, simpler computational models of self-directed replication called sheathed loops have been developed. It is shown here that "unsheathing" these structures and altering certain assumptions about the symmetry of their components leads to a family of nontrivial self-replicating structures, some substantially smaller and simpler than those previously reported. The dependence of replication time and transition function complexity on initial structure size, cell state symmetry, and neighborhood are examined. These results support the view that self-replication is not an inherently complex phenomenon but rather an emergent property arising from local interactions in systems that can be much simpler than is generally believed.
Self-reproduction in cellular automata is discussed with reference to Langton's criteria as to what constitutes genuine self-reproduction. It is found that it is possible to construct self-reproducing structures that are substantially less complex than that presented by Langton.
The von Neumann cellular automaton model is described and designs within this model are presented for objects that behave like tape and constructing units. An algorithm is developed for embedding in the cellular structure any automat on which effectively manipulates the tape and constructing units. The algorithm is based on a very simple language in which the behavior of such machines can be described. Finally, universality of construction and computation as well as automaton self-reproduction are disdussed relative to the von Neumann model. (Author)
A major impediment of cellular automata (CA) stems from the difficulty of utilizing their complex behavior to perform useful computations. Recent studies by Packard and Mitchell et al. have shown that CAs can be evolved to perform a computational task. In this paper non-uniform CAs are studied, where each cell may contain a different rule, in contrast to the original, uniform model. We describe experiments in which non-uniform CAs are evolved to perform the computational task using a local, co-evolutionary algorithm. For radius r = 3 we attain peak performance values of 0.92 comparable to those obtained for uniform CAs (0.93–0.95). This is notable considering the huge search spaces involved, much larger than the uniform case. Smaller radius CAs (previously unstudied in this context) attain performance values of 0.93–0.94. For r = 1 this is considerably higher than the maximal possible uniform CA performance of 0.83, suggesting that non-uniformity reduces connectivity requirements. We thus demonstrate that: (1) non-uniform CAs can attain high computational performance, and (2) such systems can be evolved rather than designed.
Self-reproduction in cellular automata is discussed with reference to the models of von Neumann and Codd. The conclusion is drawn that although the capacity for universal construction is a sufficient condition for self-reproduction, it is not a necessary condition. Slightly more “liberal” criteria for what constitutes genuine self-reproduction are introduced, and a simple self-reproducing structure is exhibited which satisfies these new criteria. This structure achieves its simplicity by storing its description in a dynamic “loop”, rather than on a static “tape”.
Self-reproducing, cellular automata-based systems developed to date broadly fall under two categories; the first consists of machines which are capable of performing elaborate tasks, yet are too complex to simulate, while the second consists of extremely simple machines which can be entirely implemented, yet lack any additional functionality aside from self-reproduction. In this paper we present a self-reproducing system which is completely realizable, while capable of executing any desired program, thereby exhibiting universal computation. Our starting point is a simple self-reproducing loop structure onto which we “attach” an executable program (Turing machine) along with its data. The three parts of our system (loop, program, data) are all reproduced, after which the program is run on the given data. The system reported in this paper has been simulated in its entirety; thus, we attain a viable, self-reproducing machine with programmable capabilities.
Self-replicating loops presented to date are essentially worlds unto themselves, inaccessible to the observer once the replication
process is launched. In this paper we present a self-replicating loop which allows for user interaction. Specifically, the
user can control the loop’s replication and induce its destruction. After presenting the design of this novel loop, we delineate
its physical implementation in our electronic wall for bio-inspired applications, the Bio Wall.
In this work we analyze different existing cellular automata capable of reproducing, and conclude that reproduction in those models is attained as a fixed point of the more general operation of construction, instead of being founded as a higher level specialized mechanism. Thus reproduction becomes a very unstable property and this fact is an obstacle in the aim of studying it together with other Alife characteristics, mainly because of destructive interactions. We propose a cellular reproduction model based on self-inspection as an attempt to overcome at least partially these drawbacks. We argue that our model attains a better founded an more robust reproduction scheme, and briefly explore the possibilities of using it to model the emergence of reproducing structures, to study the interplay between autonomy and reproduction, and to use it as a basis for evolutionary experimental scenarios.
Self-replicating structures in cellular automata have been ex- tensively studied in the past as models of Artificial Life. However, CAs, unlike the biological cellular model, are very brittle: any faulty cell usu- ally leads to the complete destruction of any emerging structures. In this paper, we propose a method, inspired by error-correcting-code the- ory, to develop fault-resistant rules at, almost, no extra cost. We then propose fault-tolerant substructures necessary to future fault-tolerant self-replicating structures.
Since von Neumann's seminal work around 1950, computer scientists and others have studied the algorithms needed to support self-replicating systems. Much of this work has focused on abstract logical machines (automata) embedded in two-dimensional cellular spaces. This research was motivated by a desire to understand the basic information-processing principles underlying self-replication, the potential long-term applications of programmable self-replicating machines, and the possibility of gaining insight into biological replication and the origins of life. We view past research as taking three main directions: early complex universal computer-constructors modeled after Turing machines, qualitatively simpler self-replicating loops, and efforts to view self-replication as an emergent phenomenon. We discuss our recent studies in the latter category showing that self-replicating structures can emerge from nonreplicating components, and that genetic algorithms can be applied to program automatically simple but arbitrary structures to replicate. We also describe recent work in which self-replicating structures are successfully programmed to do useful problem solving as they replicate. We conclude by identifying some implications and important research directions for the future.
We constructed a simple evolutionary system, "evoloop," on a deterministic nine-state five-neighbor cellular automata (CA) space by improving the structurally dissolvable self-reproducing loop we had previously contrived [14] after Langton's self-reproducing loop [7]. The principal role of this improvement is to enhance the adaptability (a degree of the variety of situations in which structures in the CA space can operate regularly) of the self-reproductive mechanism of loops. The experiment with evoloop met with the intriguing result that, though no mechanism was explicitly provided to promote evolution, the loops varied through direct interaction of their phenotypes, smaller individuals were naturally selected thanks to their quicker self-reproductive ability, and the whole population gradually evolved toward the smallest ones. This result gives a unique example of evolution of self-replicators where genotypical variation is caused by precedent phenotypical variation. Such interrelation of genotype and phenotype would be one of the important factors driving the evolutionary process of primitive life forms that might have actually occurred in ancient times.
We present a new self-reproducing cellular automaton capable of construction and computation beyond self-reproduction. Our automaton makes use of some of the concepts developed by Langton for his self-reproducing automaton, but provides the added advantage of being able to perform independent constructional and computational tasks alongside self-reproduction. Our automaton is capable, like Langton's automaton and with comparable complexity, of simple self-replication, but it also provides (at the cost, naturally, of increased complexity) the option of attaching to the automaton an executable program which will be duplicated and executed in each of the copies of the automaton. After describing in some detail the self-reproduction mechanism of our automaton, we provide a non-trivial example of its constructional capabilities. 1 Introduction The history of self-reproducing cellular automata basically begins with John von Neumann's research in the field of complex self-reproducing machi...
Self-replicating and self-repairing multicellular automata
- J A Reggia
- J D Lohn
- H.-H Chou
- J.A. Reggia