The emergence of the first brains were likely in the earliest known hunters. By about 520 million years ago, hunters roamed the seas. In the Cambrian explosion, a period of rapid evolutionary development that began around 541 million years ago, the earliest known animals with structures recognizable as brains made their debut in the Earth’s oceans. They possessed rudimentary beginnings central nervous systems, including a brain. This allowed for advanced sensory processing, decision-making, and coordinated movement.

Anomalocaris (518 to 500 Million Years Ago): Among these early pioneers, creatures like Anomalocaris canadensis stand out. During the Cambrian Period, the Anomalocaris was a formidable predator of the seas. It reached lengths of up to three feet. With its large, compound eyes, flexible, segmented body, and a pair of grasping appendages in front of its mouth, it was perfectly adapted to detect and capture prey. Anomalocaris swam the ancient oceans with undulating movements, using its circular mouth lined with serrated plates to consume trilobites and other early marine animals.