The role of the eye in evolution

Could the development of the first eyes be the secret behind the Cambrian explosion?

The first signs of life on Earth date back some 3500 million years - 3.5 billion that is, and around 1 billion years after Earth became - well - Earth. This was the end of the Hadean Eon (as in: like Hades - all fire and brimstone stuff) and the start of the Archean Eon.

But things just toddled along with slow development of the precursors to plants (with the ability to photosynthesise), multicellular animals, and eventually about 570 millions years ago arthropods came along. But still all animals remained "soft bodied" -  a situation that existed for some 300 million years all up. Not much of an achievement for almost 3 billion years...

But then everything changed at around 530 million years ago. In less than five million years, "nearly all the major animal groups on Earth today independently evolved hard body parts."

Andrew Parker summises that this early stage of what became known as the Cambrian Explosion came about because Trilobytes developed the first eyes - probably not much more than simple light receptors. With eyes, they could now see their prey. As Parker describes: "Before long it had also evolved swimming capabilities and strong, grasping limbs and mouthparts: it had become an active predator – in fact, the first active predator – with visual search capabilities."

Naturally any prey species that also developed "sight" were in a better position to see and therefore avoid becoming lunch. Those that could avoid being eaten had the evolutionary leg up as opposed to those that didn't see it coming.

And so began the Cambrian Explosion and the "evolutionary arms race" that rages on even today.

Makes sense...