Autopoiesis - life maintaining and reproducing itself

Autopoiesis diagram
Diagram based on a figure by Pier Luigi Luisi (see below).

The word autopoiesis is a psuedo-Greek combination of 'auto-' meaning 'self' and 'poiesis', meaning 'creation'. This is good because it measns the ability of a system to construct its own component parts and self-organise these into itself and maintain itself without help from another system (though the precise requrirements of this autonomy restriction is debatable). A vortex, such as a whirlpool is self-organising and contrstructs itself, in a sense, but does not qualify as autopoietic because its component parts are really just particles in fluid phase and the vortex does nothing to make them that way. We might one day produce an 'autonomous' robot that can construct itself by assembling basic components and if it were to exist, then it would arguably be autopoeitic. To achieve the task, though, it would need to somehow exist in some very simple form to begin with and boot-strap itself into full form, otherwise it would not be making itself. This is very hard to conceive. If we relax the reqirements a little, we might imagine that it is only required to make copies of itself from assembling basic components. In this case, it would have to percieve the components available and have the information necessary for assembling them in the right way. So far, the only systems physically capable of this are living systems: every time a cell divides, in a sense a robot creates a copy of itself. We do not know of anything other than living systems that can do this, though we still don't understand how they appeared (presumably by boot-strap self creation) in the first place (see our Origins Theme).

A system may be considered autopoietic if the parts to the organization interact with each other in such a manner that they are continuously producing and maintaining the pattern and elementary parts that constitute the system. An autopoietic system is one that is organized to continuously reproduce its own parts and structure.
The term autopoiesis was introduced to systems theory by Citing Maturana and Varela, who defined an autopoietic system as “a closed topological space that ‘continuously generates and specifies its own organization through its operation as a system of production of its components, and does this in an endless turnover of components.” Classical examples of autopoietic systems are biological organisms. The human body, for example, is believed to replenish every cell within itself over the course of a seven to ten year period. Likewise, the entire set of macromolecular elements within a given cell is regenerated approximately 100,000 times during its lifetime. During this extraordinary turnover of matter, the cell maintains its overall structure, coherence, and relative autonomy.2

Autocatalytic Chemistry

The ability of a system (any arrangement of matter) to remake itself is termed autopoiesis and this has been identified as one of the two necessary capabilities of anything living (Maturana, 1980). The other is cognition, more precisely, the detection and selection of particular elements from an environment, which is a random mix of different elements (e.g. molecules). Such selection is a kind of information processing that results in a decrease of entropy for the system doing the selection, relative to its environment (that is because the probability of finding any particular molecule inside the system is different from the random expectation of finding it, based on the random mix outside). To be truly autopoietic, a system must be able to gather resources from the natural environment so as to utilise (make useful) these for the purpose of self-making (either repair or reproduction). Intriguingly, some quite simple chemical systems have been shown to exhibit this capability. For example, Zepik et al. (2001) experimented with fatty-acid ‘vesicles’ (self-contained droplets) and was able to demonstrate their  reproduction and self-maintenance by autonomous homeostatic processes.

Maturana and Varela      Pier Luisi
Leaders of the autopoiesis concept, first formulated by Maturana and Varela, further developed by Luisi.

Bitbol and Luisi (2004) showed that autopoiesis and cognition are separately necessary conditions for life, not inseparably linked as apparently first thought by Maturana and Varela. They illustrated their point with reference to the the autopoietic fatty acid cells. From this work, it became clear that for a system to live, it must have at least the following three properties: autopoiesis, cognition (as described above) and an unbroken boundary to define its limits; this stops the ingredients of life from diffusing apart, rendering life's chemical reactions too thinly spread to work as a whole. This last element is a clear case of information embodied as living structure: the tegument or boundary ‘closes’ the living system in a thermodynamic sense, enabling a difference in the mixture of chemicals and their energies to persist either side of it. In practice, all known living systems are cellular (though some biologists may include viruses). Indeed, the cell tegument has never been broken since the beginning of life---it has only been divided by repeated fission. Indeed, every cell in your body is not only a distant relative of the first cells that ever existed, it is a fission product; the most recent living instantiation of those first cells (though none of the original material need remain). Multicellular organisms like plants and rabbits are really just colonies of specialising cells that cooperate by communicating information and sharing materials. In this way, the division among organisms (such as you and I) is just an elaboration of division among cells.
As a result, all life from its beginning to the presently living, is unified as a set of cells, related through replication from a common ancestor. What has been replicated is material in only a rather trivial sense: cells continually replace their material contents. What has been maintained and replicated throughout the whole history of life is the information content that organises this material into a structure that lives, by which we now mean it is information embodied in biochemistry and biological structure that maintains itself, using cognition and the information processing of self-control (homeostasis) and reproduction (information replication, which is a kind of communication).

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