How life's forms modify and evolve the Earth II (Introduction)

by David Turell @, Friday, September 01, 2023, 20:15 (33 days ago) @ David Turell

This is the non-Darwin part:

"First off, the tilling processes that Darwin described are not limited to earthworms, with different burrowing animals having effects at different scales. Ants, for example, tend to bring up the finest grains of sand or soil. In Berlin, where I live, you often see small piles of fine sand heaped along the edges of cobblestones, and if you look closely, you will often see ants hard at work. Although the grains are typically brought up a few at a time, in places the ants are so abundant that they will shift many tonnes of soil per hectare per year. In one study that was directly inspired by Darwin’s work on earthworms – Geologic Work of Ants in Tropical America (1910) – the author, John Casper Branner, estimated that ants in Brazil were responsible for moving considerably more soil per hectare each year than earthworms in England. Meanwhile, larger burrowing animals such as badgers excavate huge mounds of earth, creating hillocks that can last for centuries, to say nothing of the earth-shifting activities of bandicoots, beavers, chipmunks, gophers, meerkats, mice and moles, or of burrowing birds and burying beetles.

"And it’s not just on land. As you walk to the sea across that part of a beach or mudflat that’s covered by waves when the tide is high, but exposed when the tide is low, you may see tiny crabs, no bigger than your fingernail, excavating burrows one armful of sand at a time. Don a mask and look beneath the waves, and you’ll find an incredible variety of animals digging burrows.

"Moreover, burrowing animals are not the only lifeforms to have a substantial planetary impact. Far from it. Before the evolution of the first trees, around 400 million years ago, rivers were far less likely to boast meanders and oxbows and other features that allow them to dawdle their way to the sea. Plants have also contributed a great increase in mud. Ancient reefs and banks of shells have not only left a legacy of enormous piles of limestones, they also have altered the shapes of mountains: as rocks go, limestones are relatively malleable, so when ancient reefs and banks of shells are crushed and cooked as mountain chains are upheaved, the presence of limestones will affect the way the mountains fold. The more limestones, the more folds. Limestones so treated will also, often, become crushed and cooked into marble. Many of the world’s greatest sculptures and monuments have been created from rock built by life and then transformed by Earth as it builds mountains. Next time you look at Michelangelo’s David, remember that it was built from marble formed from crushed life-rocks, as were many of the grandest buildings and structures of ancient Rome.


"First, certain species of archaea are responsible for the biological generation of methane, a greenhouse gas, which warms the climate. Second, no conversation about the impacts of lifeforms upon the planet would be complete without mention of the cyanobacteria. These lifeforms, formerly known as blue-green algae, are, in my view, the most important lifeforms in the history of the planet. At the time they evolved, more than 2.3 billion years ago, Earth had no oxygen molecules in the air to speak of. Instead, all the oxygen atoms were tied up in the water and the rocks. Cyanobacteria evolved to use the radiant energy of the Sun to split water molecules apart, a process that roughly halfway through the history of Earth would result in an atmosphere that contained oxygen molecules.

"Back then, the atmospheric oxygen would not have been adequate to support you or me. Yet its very appearance had several transformative effects. As oxygen is reactive stuff, its arrival led to a proliferation of new minerals. Indeed, Earth began to rust. At the same time, the advent of oxygen led to the creation of an ozone layer, which protects the planet’s surface from the most harmful rays of the Sun. The presence of this layer fundamentally changed the circumstances in which lifeforms on land subsequently evolved. And since the colour of the sky is a consequence of the composition of the atmosphere, lifeforms have also reached out and painted the heavens above.


"..the Never-Life Earth would not be the Earth of today, just without the green. It would be profoundly different: an alien planet. A human, or some other animal, magicked there would be killed in an instant, overcome by suffocating air and lethal levels of radiation.

"It would be a planet not merely lifeless, but deadly."

Comment: in the evolution of this planet a broad diversity of living organisms has played a major role. I view it as God guiding the formation of the Earth to be the perfect planet for life to appear. (See Privileged Planet thread) Then diverse life forms helped transform the Earth into its present state. A very emotional and well-written essay should be read in its entirety.

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