Figure 1.

(A) Comparison of Turing tests for intelligence and life, taken from Cronin et al. (2006). (B) Graphical summary of the method used by Lentini et al. (2017) to quantify life-likeness of SCs capable of bidirectional chemical communication with V. fischeri. (Top) The biological communication between when V. fischeri cells is taken as benchmark against which the synthetic/natural communication is contrasted. (Middle) When V. fischeri cells send a signal to SCs that are not able to reply, a change in the expression levels of 175 V. fischeri genes is observed. (Bottom) When V. fischeri cells send a signal to SCs that are able to reply with a response signal, a change in the expression levels of 107 V. fischeri genes is observed. Therefore, SCs behavior is capable of offsetting 68 (= 175 − 107) differences in V. fischeri gene expression levels, recovering the 39% (= 68/175) of the biological behavior. (C) Three examples of SCs capable of establishing the kind of molecular communication with V. fischeri of the same type as described by Lentini et al. (2017). (Left) The actual experimental system made in the laboratory: TX-TL machinery produces two proteins capable of sensing the primary signal (sent by the bacteria), and, as response, produces a secondary signal (sent to the bacteria); this SC is based on the expression of two genes. (Center) A hypothetical SC—simpler than the one shown on the left, where the receptor is not produced by the TX-TL machinery, but it is added from the beginning as ready-to-work protein; this SC is based on the expression of one gene. (Right) A hypothetical SC—very complex and currently out-of-reach—where TX-TL components (>100) are all produced by the TX-TL machinery itself, together with the two proteins needed for communication (this SCs is based on the expression of >100 genes). The three SCs clearly have different complexity ([3] >> [1] > [2]) and different life-likeness, but they would result in the same 39% value when evaluated by a behavioral assay (as in B). (D) A possible workflow diagram—inspired from Damiano et al. (2011)—for the evaluation of SC life-likeness based on the measure of “organizational relevance.” The organizational relevance is evaluated after a first screening for the “imitative relevance.” The question is how to devise a method to map the dynamical processes occurring within the artificial system (i.e., the synthetic mechanisms that generate the behavior under investigation) with a benchmark organization, stemming from a reference theory. This study suggests that systemic theories of life, such as autopoiesis, (M,R)-systems and relational biology, or chemoton are best candidate for it, but it left to future investigation the screening and the selection of the best criteria for their application.