LIFE × EVOLUTION

The First Eyes

~515 million years ago

Phanerozoic · Paleozoic · Cambrian

One shale in South Australia has yielded two kinds of fossil eye. One pair, three centimetres across and carrying at least sixteen thousand hexagonal lenses, belonged to the largest predator of its time and resolved as sharply as any compound eye alive. The other, from a smaller arthropod, has three thousand lenses and a patch where they widen: a bright zone, the arrangement an animal uses to hunt in dim water.

Why it matters

Light-sensitive spots are far older, probably Precambrian. What appears here is the lens, and a lens is what turns the detection of light into an image. Once one animal could make out another at a distance, hiding, armour and speed all started to pay for themselves, which is why vision is a plausible engine of the Cambrian explosion.

Dating & uncertainty

The oldest well-preserved compound eyes are 515 Ma. Light-sensitive organs are certainly older, and probably Precambrian; what appears in the Cambrian is the lens, which is what turns light detection into an image.

Sources

1. Paterson et al. (2011), Nature · Acute vision in the giant Cambrian predator Anomalocaris and the origin of compound eyes
2. Lee et al. (2011), Nature · Modern optics in exceptionally preserved eyes of Early Cambrian arthropods from Australia
3. Schoenemann (2025), Arthropoda · Trilobite eyes and their evolution

Earth history as one day

21:16:392 h 43 min before midnight

if Earth’s 4.54 billion years were compressed into a single day