title: An option space for early neural evolution.
abstract: The origin of nervous systems has traditionally been discussed within two conceptual frameworks. Input-output models stress the sensory-motor aspects of nervous systems, while internal coordination models emphasize the role of nervous systems in coordinating multicellular activity, especially muscle-based motility. Here we consider both frameworks and apply them to describe aspects of each of three main groups of phenomena that nervous systems control: behaviour, physiology and development. We argue that both frameworks and all three aspects of nervous system function need to be considered for a comprehensive discussion of nervous system origins. This broad mapping of the option space enables an overview of the many influences and constraints that may have played a role in the evolution of the first nervous systems.
authors.affiliation: Max Planck Institute for Developmental Biology, Spemannstrasse 35, Tübingen 72076, Germany gaspar.jekely@tuebingen.mpg.de.
authors.forename: Gáspár
authors.identifier: http://orcid.org/0000-0001-8496-9836
authors.initials: G
authors.lastname: Jékely
authors.affiliation: Department of Theoretical Philosophy, University of Groningen, Oude Boteringestraat 52, Groningen 9712 GL, The Netherlands.
authors.forename: Fred
authors.initials: F
authors.lastname: Keijzer
authors.affiliation: Philosophy Program, The Graduate Center, City University of New York, New York, NY 10016, USA History and Philosophy of Science Unit, University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Godfrey-Smith
mesh_terms: D000818:Animals; D005075:Biological Evolution; D009043:Motor Activity; D009420:Nervous System / Q000033:anatomy & histology*; D009424:Nervous System Physiological Phenomena
keywords: cnidarian; ctenophore; nervous system evolution; peristalsis; phototaxis; sponge