Broadening the definition of a nervous system to better understand the evolution of plants and animals

Plant Signal Behav. 2021 Oct 3;16(10):1927562. doi: 10.1080/15592324.2021.1927562. Epub 2021 Jun 12.


Most textbook definitions recognize only animals as having nervous systems. However, for the past couple decades, botanists have been meticulously studying long-distance signaling systems in plants, and some researchers have stated that plants have a simple nervous system. Thus, an academic conflict has emerged between those who defend and those who deny the existence of a nervous system in plants. This article analyses that debate, and we propose an alternative to answering yes or no: broadening the definition of a nervous system to include plants. We claim that a definition broader than the current one, which is based only on a phylogenetic viewpoint, would be helpful in obtaining a deeper understanding of how evolution has driven the features of signal generation, transmission and processing in multicellular beings. Also, we propose two possible definitions and exemplify how broader a definition allows for new viewpoints on the evolution of plants, animals and the nervous system.

Keywords: Plants; animals; evolutionary convergence; nervous system.

Publication types

  • Review

MeSH terms

  • Animals
  • Biological Evolution*
  • Electrophysiological Phenomena
  • Nervous System Physiological Phenomena*
  • Plant Physiological Phenomena*
  • Signal Transduction
  • Terminology as Topic