Vision evolved as early as 540 million years ago during the Cambrian explosion. The ability to see, alongside the development of hearing, provided organisms with the evolutionary advantage of sensing their environment from a distance. This sensory evolution necessitated the development of larger brains for the complex processing of visual data, marking a pivotal moment in the cognitive evolution of life.

Pikaia Gracilens (520 to 505 Mya): In the ancient seas of the Middle Cambrian, starting around 520 million years ago, Pikaia gracilens swam into the annals of evolutionary history as one of the earliest known chordates, a group that would eventually give rise to vertebrates, including fish and, much later, humans. Measuring up to 6 centimeters in length, Pikaia boasted a series of notable features for its time, including a notochord—a flexible rod running along its back, which would become the backbone in its vertebrate descendants—and rudimentary structures suggesting the early development of a circulatory and nervous system. While Pikaia itself lacked well-defined eyes, its place in the evolutionary lineage hints at the beginnings of the complex sensory organs that would become eyes in later vertebrates.

These early scales provided a vital protective layer, acting like underwater armor against predators, abrasions, and environmental threats. The keratin genes that led to scales are an interesting part of our story. When amphibians evolved onto land, scales near the tips of their evolving toes transformed into thicker protection and traction, eventually giving rise to claws, nails, and hooves. Meanwhile, cold temperatures and sun exposure led to the development of warming and protective traits like feathers, fur, and hair. Specialized “scales” evolved into horns in various species, such as triceratops and rhinos, despite their unrelated lineage. Additionally, keratin genes influenced the formation of beaks in birds. All these diverse traits originated from the same keratin genes.

Long-Term Memory: By about 375 million years ago, the foundations for long-term memory were likely established among the more complex vertebrates, facilitating survival in increasingly varied and challenging environments.

Tiktaalik is a prime example of this evolutionary milestone. It is an extraordinary creature that bridged the gap between aquatic fish and amphibians. With its forward-facing eyes—an adaptation indicative of its predatory lifestyle, it  navigated both the waters and the emerging land habitats. This semi-aquatic way of life, combining elements of both aquatic and terrestrial existence, would have necessitated the use of long-term memory for tasks such as remembering the locations of feeding sites, water bodies, and safe paths between them. Its adaptations, including limbs capable of supporting its weight on land, suggest a complex lifestyle that likely benefited from the development of long-term memory, enabling it to exploit the resources of both realms effectively.

• Kingdom: Animalia > Phylum: Chordata > Class: Sarcopterygii (lobe-finned fishes)