Moving and sensing without input and output: early nervous systems and the origins of the animal sensorimotor organization

multicellular sensors and effectors are not given but derived from nervous systems;

activity within early nervous systems is primarily transverse to sensor-effector connections and spread out across sensor and effector surfaces;

soft animal bodies are instable platforms for sensors and effectors, sensing and motility are actively stabilized by relying on sensorimotor contingencies;

Given this point for point comparison, it becomes evident that the SBT and the ASMO provide a major conceptual reinterpretation of how early animals moved and sensed, compared to the input–output view. This reinterpretation also fits in with and contributes to current work in the cognitive sciences that stresses the importance of embodiment and sensorimotor relations for intelligence. The ASMO provides a new view on embodiment and sensorimotor organization, adding to ongoing work on the embodied aspects of cognition that will be important to pursue for more complex cases, such as recently proposed by Turvey and Fonseca (2014).8

The overall argumentative aim of the paper was to add to the available scenarios for early nervous system evolution by elaborating a particular coordination view on these events. Highlighting the differences with an input–output is not to criticize the latter but to clarify this coordination view. The major aim was to establish that the SBT significantly widens our conceptual options in dealing with early nervous systems: it provides new ideas, new questions and new suggestions for research. In a field as difficult as the evolution of early nervous systems, where so little is actually known and where conjecture still reigns, providing more clear and specific ideas on what could have happened must be considered progress.

I want to thank Allard Tamminga, Argyris Arnellos, Corijn van Mazijk, Isabella Sarto-Jackson, Jan Degenaar, Marc van Duijn, Ot de Wiljes, Pamela Lyon, Peter Godfrey-Smith, Ronald van Elburg, Tanny Dobbelaar, Werner Callebaut and two anonymous reviewers for the helpful discussions or comments on previous versions of this paper. The KLI, Institute for Evolution and Cognition Research in Klosterneuburg, Austria, is gratefully acknowledged for the hospitality given when working on this paper.