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Cronin et al. (2006): The imitation game - A computational chemical approach to recognizing life
The authors of this article "propose an approach to the recognition of 'living' artificial chemical systems based on chemical cells (chells) as a Gedankenexperiment that exploits a cellular imitation game. The conceptual implications of this Turing test like method are discussed as a procedure for deciding whether an artificially constructed chemical system is or is not alive".
The Turing test had the effect that "the question 'Can machines think?' was replaced by 'Are there imaginable digital computers that would do well in the imitation game?'" and "has proven a remarkably effective concept that has continued since 1950 to provoke discussion in the fields of computer science, philosophy of the mind and cognitive science".
A researcher named Harel "proposed that a kind of Turing test could be used to assess the quality of computer models for systems biology" and the authors of this paper "believe that just such a touchstone is needed also in the field of artificial cellularity in particular and the recognition of life in general"; therefore they "propose to use a similar approach here, that of an 'imitation game' that could help answer the analogous question 'Are there artificial chemical systems that would do well in the cellular imitation game'".
[W]e are interested in the fact that the chell in question should be able to communicate with natural cells (directly or via a relay) in such a way that, as in the spirit of the original imitation game, it can be interrogated by the latter. In such a case, it is not necessary that the language used for interrogating the chell is universal, as was the case for human languages in the original Turing test. On the contrary, the language by which a chell is interrogated by the natural cell should be sufficiently sophisticated so as to appropriately distinguish between alternative outputs from realizable experiments. We envision that as our knowledge of both chells and natural cells increases, better and better experiments will be possible that will distinguish ever more detailed and finegrained hypothetical properties and features of living matter. In turn, this will give rise to richer and richer communication languages between the artificial and natural entities. [...]
[I]nterrogation could take place following any of a series of increasingly more complex and sophisticated mechanisms, starting perhaps with a relatively simple quorum-sensing type of language based on, for example, low molecular weight signaling molecules, and moving toward mechanical transduction, bio-film formation and swarming patterns of behavior. Even as simple a mechanism as quorum sensing offers enough flexibility by virtue of it being 'Turing complete' (that is, it offers the potential of generating any recursively enumerable language).
Regarding the question whether such a test can be implemented, the authors write:
Current technology would seem to severely limit the chances of implementing such an idealized cellular imitation test in the foreseeable future. It might, however, still be possible to define, with the help of the synthetic biology/artificial life, origins of life and astro/exobiology research communities, a practical realization that, although not following the details of a Turing test, would share its philosophy. We propose that such a practical realization might draw some inspiration from the highly successful critical assessment of protein structure prediction (CASP) program.
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