The mysterious Cambrian explosion: When light illuminated life
In the fascinating field of evolution, there is an important chapter that has long intrigued scientists: the Cambrian explosion.
543 million years ago, at the beginning of the Cambrian era, something extraordinary happened. At that time, only three major families of animals populated our planet. But in a blink of an eye on the geological scale, a blink of an eyelash in time, that number exploded to 38 distinct families, creating an unfathomable mystery.
At the heart of this conundrum is the meaning of vision. Researchers have long wondered how this sudden explosion of biological diversity could have occurred. Zoologist Andrew Parker puts forward an intriguing theory: that of “ light switching ”. According to him, it was the appearance of the vision which triggered this extraordinary phenomenon.
Before the Cambrian explosion, the sense of vision was in an embryonic stage. Some creatures had photosensitive cell organs capable of distinguishing darkness from light. The trilobite, a small, now extinct arthropod, was the first living being to possess a true eye, capable of perceiving images. And strangely, its appearance coincides perfectly with the start of the Cambrian explosion .
This newly acquired sense would have conferred such an important evolutionary advantage that it would have triggered a veritable "arms race" among the creatures of the time. This would have accelerated evolution in a way never seen before.
Charles Darwin , father of the theory of evolution, was long perplexed by this sudden acceleration. According to his theory of natural selection, gradual changes over long periods of time are the driving forces of evolution. The Cambrian explosion seemed to challenge this idea. Parker's "light switching" theory attempts to bridge Darwin's vision with the scientific facts observed during this tumultuous period.
It was only after the emergence of the sense of vision that plants and animals began to display varied colors. The appearance of color is intrinsically linked to that of the sense of vision, a magical alliance that has transformed our world and opened the door to dazzling biological diversity.
As we delve into the depths of evolution, the Cambrian Explosion remains a captivating chapter in our biological history. It is a reminder of the power of adaptation and innovation, a flash of light in the darkness of our understanding, inviting us to explore the mysteries of life on Earth.
Source: A. Martel “ The Power of Light ” Editions Trédaniel, 2016