Journey of Life - Seas of Life 3
Steve travels back 3.8 billion years to when life began. Journeying round the oceans, he explores life's first laboratory and discovers how the incredible variety of sea creatures arose, from the first microbes to hagfish and dolphins.
The atmosphere was thin. There was no oxygen, and no protective ozone layer to shield the earth from the sun.
Unfiltered ultraviolet rays were beating down on the young planet in a strength that would be lethal to us.
Over time massive volcanic eruptions and meteor impacts destabilized the land.
Compared to this mayhem, the forming seas were a relative safe haven, so it must have been somewhere under the water that life first evolved. Exactly how life began remains a mystery, but there are some clues in this chemical soup. The seas were awash with organic molecules, the building blocks of all life. These were formed naturally in the primordial soup of the forming oceans.
Somewhere in this caldron, the recipe for our own DNA appeared. With this, the first sparks of life were ignited. Meet the ancestors. Simple cells like these were the first living things, the predecessors of all future life on earth. Over time, these cells diversified and spread around the world, but one group would have a devastating impact on the planet.
Here, off western Australia, these ancient microbes still exist today. Called stromatolite, they secrete strange pillars made of lime. It's like a scene from 3 billion years ago. They might look harmless now, but back then, these microbes almost snuffed out all life forever. By generating huge amounts of a new toxic gas, they triggered a global pollution crisis. That new gas's name was oxygen, and it utterly destroyed primitive cells, poisoning them by the billion. Extinctions swept the planet. But a few cells survived, and thrived on oxygen. They inherited the earth. From now on, oxygen would power all new life, from the tiniest cell to the biggest creature of all time. |
