The Story of Earth: The First 4.5 Billion Years, From Stardust to Living Planet
The Story of Earth: The First 4.5 Billion Years, From Stardust to Living Planet
by Robert M. Hazen
Viking
This gentle book by Robert Hazen, a professor of earth science who specialises in minerals, answers almost all of life's big questions. How the universe was formed, how the earth came into existence, how plant and animal life arose, and how the moon got there are all explained in a highly readable manner.
Hazen has a rare knack of being able to explain chemistry, a root science of existence, in a way that makes it accessible and engaging. His skills at elucidating complex scientific ideas stretch to geology and physics, the two other major parts of this story.
Those with an interest in how we got here need only keep this small volume on their bookshelves to have the entire story of existence readily available at their fingertips.
The Story of Earth is a biography of our planet. Scientists will note that its novel theme is to look at how the mineral content of the planet influenced life and vice versa. Others will use the book as a primer on earth science.
Hazen begins with a thumbnail sketch of the Big Bang (13.7 billion years ago), and explains how this one-time event brought matter into existence. He tells of the role that gravity had in bringing together the gases released by the Big Bang to form stars. These then exploded into supernovas and flung the gases of life - carbon, oxygen, nitrogen - out into space. Dust and gas from the supernovas, again pulled together by gravity, coalesced 4.5 billion years ago to form the planets in our solar system , including the earth.
Hazen deals with this basic science swiftly before getting into what really interests him - the earth's geological and chemical evolution. The earth, he points out, has been through a lot: it's been very hot, it's been very cold, it's been battered by storms, and completely shrouded in water. It's been hit by big asteroids at least twice, and one of them knocked enough stuff off its surface to coalesce in space and form our moon. The earth was a watery swirl 200 to 500 million years ago. Then huge bits of granite began to float on a layer of basalt that had formed over the water, and land was formed.
All this is fascinating but Hazen's explanation of how life arose is even more so. Life, to most of us, is a magical, intangible quality. But to scientists, it's a matter of systems organisation driven by the law of evolution. 'Life is a self-sustaining chemical system capable of undergoing Darwinian evolution,' Hazen quotes scientist Gerald Joyce.
Put very simply, molecules follow the law of evolution and try to survive their environment like everything else does. The fittest molecules are those which organise themselves in a certain way. If they succeed in surviving, they reproduce the successful pattern and pass on information about how they did it. (Joyce showed this happening in a test tube with specially engineered RNA molecules in 2009). When that first happened on the earth, between 4.4 billion years and 3.5 billion years ago, life had begun.
Hazen also indulges in the dangerous game of predicting the future. But he offers one certainty: one day, a large asteroid will slam into the earth again and wreak destruction on a mass scale. It might be next year, or it might be in a million years. But it's going to happen. Living things probably won't survive, he says, but the earth will. Then life will start all over again.
