Gaia's One Billion Years Task: Colonizing the Land

 

Gaia as the sea Goddess Grammamare according to Hayao Miyazaki's interpretation in the film "Ponyo"

Imagine a time machine that brings you back to the Earth of one billion years ago, right in the middle of the eon called the "Proterozoic." First of all, you need an oxygen respirator, otherwise you'll die of suffocation in a few minutes. You also need a wide-brimmed hat and an outfit that covers your limbs in such a way as to protect your skin from the ultraviolet radiation. It is your planet, but in this period it is not especially friendly to a metazoan as you are.

You walk a few cautious steps onward. In front of you, the blue sea. You turn around: an expanse of dry rocks that continues all the way to the horizon. No traces of anything green that you can see: no plants, no insects, no birds, nothing like that. Above you, the sun is bright in the blue sky. You notice that it is a little less bright than you are used to seeing it, in your time. No traces of clouds: it is what you expected: no trees means no evapotranspiration of water vapor, no volatile organic compounds to function as nucleation sites for the water droplets that form clouds. 

You walk toward the sea. There are mainly rocks, but also some sandy places: small patches of beach. If there is a beach, there has to be a river, somewhere, that created it. You see it, not far away. It is completely dry, its bed going straight through the rocky landscape from the hills in the distance. Rains, when they arrive, must be torrential downpours that come and go quickly. 

You kneel on the beach, in front of the sea, lifting some water with your cupped hands. You know that it should be less salty than the seawater you are used to in your time, and you are tempted to taste it to confirm. But that is not a good idea. That water is brimming with microorganisms, most of them unlike anything your immune system is used to. You drop the water on the surface of a rock, where it forms a dark spot that rapidly evaporates and disappears. 

Standing up in front of that alien sea, you look at the gentle waves coming and going. You know that there are no fish in there. No crabs, no seashells, no seaweed, nothing like that. But there are enormous numbers of microorganisms. They are photosynthesizing, eating each other, reproducing by splitting themselves in two. They can live only in water. Is there life on the dry rocks on the shore? Maybe some of those microscopic creatures survive there, maybe even thrive, perhaps algae or even ancestors of modern lichens. But they are just eking out a precarious existence. They are invisible to the naked eye, and their time has not come yet.

On the horizon, an enormous orange moon rises as the sun slowly fades on the opposite side. You keep looking at the dark waters in front of you. Just under the surface, you glimpse something that looks like a pair of large eyes. You think you see her just for a moment, Gaia in her form of sea goddess, languidly swimming in the calm sea. 

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Back to your time machine. You dial 350 million years before your time, the start of the Carboniferous Period. You press the button. 

You emerge out of the machine, breathing the fresh air, smelling something you had never smelled before. Whatever it is, the air is humid, rich in oxygen. You are in a small clearing, in front of you, there is a pond surrounded by a lush forest. Trees, tall trees, forming a full canopy under the low clouds, swept by a gentle wind. The place is eerily silent: no birds, no insects, nothing like that. Yet, you recognize the place: this is your planet, Earth, not yet the way it will be in the future that is your time, but a familiar world. 

As you stand, a noise comes to you: a buzz. You see something flying away, an insect of some kind. It starts raining. It is a warm, gentle downpour that wets you rapidly, but ends quickly. It has been enough to disturb the creatures living under the low bushes. You have a glimpse of them scuttling away: tetrapods, early amphibians. They jump into the water of the pond and then disappear. They are your ancestors, the ancestors of all the metazoans that will move on land in the future that's your time. 

As you walk, splashing your boots on the mud, you wonder how Gaia pulled this incredible trick: transforming the bare rock of entire continents into lush forests. While you think that, you have a glimpse of a pair of bright eyes staring at you from the canopy. You look up, and they disappear, leaving only a Cheshire-cat smile of the Goddess of the Forests, then she vanishes among the branches.

Images of the Goddess courtesy of "Mon Seul Desir"