The scientific study of consciousness or subjective experiencing is a rapidly expanding research program engaging philosophers of mind, psychologists, cognitive scientists, neurobiologists, evolutionary biologists and biosemioticians. Here we outline an evolutionary approach that we have developed over the last two decades, focusing on the evolutionary transition from non-conscious to minimally conscious, subjectively experiencing organisms. We propose that the evolution of subjective experiencing was driven by the evolution of learning and we identify an open-ended, representational, generative and recursive form of associative (...) learning, which we call Unlimited Associative Learning (UAL), as an evolutionary transition marker of minimal consciousness. This evolutionary marker provides evidence that the evolutionary transition to consciousness has gone to completion and allows reverse-engineering from this learning capacity to the system that enables it – making possible the construction of a toy model of UAL. The model allows us to identify some of the key processes and structures that constitute minimal consciousness, points its taxonomic distribution and the ecological context in which it first emerged, highlights its function and suggests a framework for exploring developmental and evolutionary modifications of consciousness. We point to ways of experimentally testing the relationship between UAL and consciousness in human and in non-human animals and discuss the theoretical and ethical implications of our approach. The framework we offer allows the exploration of the evolutionary changes in agency, value systems, selective processes and goals that were involved in the transition to subjective experiencing from a perspective that resonates with the approaches of bio-semioticians. (shrink)

In our target article, “Learning and the evolution of conscious agents” we outlined an evolutionary approach to consciousness, arguing that the evolution of a form of open-ended, representational, and generative learning (unlimited associative learning, UAL) drove the evolution of consciousness. Our view highlights the dynamics and functions of consciousness, delineates its taxonomic distribution and suggests a framework for exploring its developmental and evolutionary modifications. The approach we offer resonates with biosemioticians’ views, but as the responses to our target article show, (...) our proposal also faces challenges and has led to suggestions that extend, develop and qualify it. Our response to the 14 varied and rich commentaries starts with the recurring and deep question raised by many of them – the relation between life and sentience. We explore this question by introducing and expanding on “vivaciousness”, a term we coined to describe the turbulent, flexible exploration-stabilization processes inherent in the living condition, as well as addressing the related concepts of Umwelt and selfhood. We then consider the question of the adequacy of unlimited associative learning (UAL) as an evolutionary transition marker (ETM) of minimal consciousness (rather than as a marker of a complex form of sentience), and the possible precursors of sentience. The engagement with these broad themes is entangled with a discussion of evolutionary transitions, constitutive emergence and the function/s of consciousness. The suggestions of our commentators, urging us to explore new concepts and new avenues of research within the framework of a richer view of evolution are then discussed. We end by briefly considering what we regard as a conceptual lacuna, which is leading to the indiscriminate use of the term “sentience” and which awaits further investigation. (shrink)