Some of these species might have evolved some pre-brained memory, setting the foundational capabilities for interaction and adaptation within their environments. While far removed from the complex behaviors of their future descendants, these early organisms’ ability to respond to environmental cues marked the dawn of simple sentience in the animal kingdom. This pivotal moment laid the foundation for the intricate tapestry of life that would evolve, branching into the diverse forms of sentience observed in the animal world today.

Ediacaran biota (about 635 to 541 million years ago): By about 635 million years ago, clearly identified plant eaters evolved. Thriving in the oceans. Characterized by their unusual and diverse shapes, ranging from frond-like patterns to disk and tubular structures, the Ediacaran biota’s body plans defy easy comparison with modern life forms. The significance of the Ediacaran biota lies not just in their ancientness but in their representation of life’s experimental forays into multicellularity, offering clues to the evolutionary transition from simple microbial life to the complex organisms that would come to dominate the Earth. While we don’t know if this creature had a proto-nervous system, their existence set the stage for the Cambrian Explosion.