Events in Early Nervous System Evolution

Abstract

We propose that neurons and nervous systems evolved among thin, motile, microbe‐eating animals during the Ediacaran period (635–543 million years ago). Spiking neurons evolved from epithelial cells around the margins of Ediacaran microbial mat grazers that initially specialized to detect weak bioelectric fields of nearby animals and to trigger rapid withdrawal movements. According to this scenario, nervous systems are a consequence of two preceding animal innovations, external digestion and motility, which have co‐evolved in concert with nervous systems ever since. We suggest that fundamental characteristics of modern nervous systems can be explained by studying how nervous systems originated during the Ediacaran period, as natural computers for predictive statistical inference given event‐based sense data.

Evolutionary puzzle: discussing the evolution of sentience in Metazoa through a phylogenetic perspective

“…However, the view of a unique nervous system originating in the common ancestor of Eumetazoa is against recent genomic data that positioned Ctenophora as the sister-group of all the other Metazoa (Giribet 2016; Giribet and Edgecombe 2020), which would lead to at least two independent origin of nerve cells. The scenario proposed here supports previously reported assumptions, where the evolution of nervous systems has been considered to be codependent to other characteristics such as external digestion (Evans et al 2019;Mángano and Buatois 2020) and motility (Paulin and Cahill-Lane 2019). These two characteristics together, according Paulin and Cahill-Lane (2019), created the possibility of meetings between different species in the environments, accompanied by the emergence of ecological relationships, such as predation.…”

“…The scenario proposed here supports previously reported assumptions, where the evolution of nervous systems has been considered to be codependent to other characteristics such as external digestion (Evans et al 2019;Mángano and Buatois 2020) and motility (Paulin and Cahill-Lane 2019). These two characteristics together, according Paulin and Cahill-Lane (2019), created the possibility of meetings between different species in the environments, accompanied by the emergence of ecological relationships, such as predation. In this context some attributes may have been selected for more efficient escape from predation, and one of these characteristics that remains in almost all living animals, is the ability of flexible escape behaviours opportune by nervous systems.…”

“…The scenario proposed here supports previously reported assumptions, where the evolution of nervous systems has been considered to be codependent to other characteristics such as external digestion(Evans et al 2019;Mángano and Buatois 2020) and motility(Paulin and Cahill-Lane 2019). These two characteristics together, accordingPaulin and Cahill-Lane (2019), created the possibility of meetings between different species in the environments,…”

Event‐Predictive Cognition: A Root for Conceptual Human Thought

“…This volume starts with a novel perspective on the phylogenetic development of event processing units, that is, neurons themselves. Paulin and Cahill‐Lane (2021) argue that in a particular environmental niche 560 million years ago—just a few million years before the Cambrian explosion—some of the motile animals that fed on microbial mat‐grounds started to feed on each other, resulting in a dynamic predator–prey situation. The authors corroborate evidence that the evolution of event‐predictive neurons allowed animals to feed as long as possible while avoiding to be eaten since they were now able to flee just in time, that is, when the “being eaten” event onset was imminent.…”

Events, Event Prediction, and Predictive Processing

“…More is needed to fully characterize events and event coding, in addition to some notion of coherence, as indeed discussed by the papers in this issue: evolution of event inference, learning of events, context‐dependent inference of events, involvement of action and the self‐model, continuous versus discrete processing, recombinability, semantics, and linguistic properties (see Cooper, 2021; Paulin and Cahill‐Lane, 2021; Ünal and Papafragou, 2021). And things are, as always, more complicated when it gets to implementation and cognitive functions, with topics including temporal as well as hierarchical segmentation, involvement of the default network, relation to future thinking, overlaps (involving hippocampus) with episodic memory and spatial representation (see Bilkey and Jensen, 2019; Knott and Takac, 2021; Stawarczyk et al, 2021).…”