Seafloor Footprints Point to Earliest Evidence of Sight

The creatures left no eyes in the record. They were soft-bodied, mostly gone. But they left footprints, and those footprints suggest they may have already been able to see.

A paper in PNAS upended one of the most durable stories in evolutionary biology. Researchers analyzed 231 fossilized movement trails from the Ediacaran-Cambrian transition, spanning roughly 546 to 526 million years ago. The Ediacaran preceded the Cambrian Explosion by millions of years. It was not supposed to be the era of vision. The Cambrian was. The study suggests that picture is wrong.

The method is direct in its simplicity. Animals that can't sense anything at a distance wander randomly. Their tracks meander, cross and backtrack. Animals that can detect something from afar change course toward it. Their trails curve. They loop. They have direction.

By reading 231 sets of ancient trails, researchers Zekun Wang and Tianyun Shi traced how sensing capacity changed across 20 million years. The earliest tracks: random. Later tracks: purposeful. Just before the Cambrian began, around 539 million years ago, some of these animals were navigating toward resources from an estimated 10 centimeters away, a range that suggests basic vision was already in play.

The Cambrian Explosion didn't flip a switch. It inherited a nervous system that had been building for millions of years in the dark.

Read the full story at Phys.org, June 2, 2026

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