The Consolations of Deep Time

Thinking about the age of the earth is – unexpectedly perhaps – among the more consoling and calming of all activities.

But it’s worth registering that for most of history, we humans had a poor sense indeed of how old the earth might be. Until the modern era, the leading minds of the Western world took their cue from the Bible and counted 76 generations between Adam and Christ (from Adam to Noah was 10, Noah to Abraham another 10, Abraham to David, 14 and so on) – which led to the confident notion that the earth must be around 4,000 years old.

Then, over the course of the late eighteenth and early nineteenth century, people started to look with new eyes at what had always lain before them – and had another think. They studied mountains, craters, cliffs and small creatures trapped in layers of rock and began to form very different conclusions. A vertiginous feeling descended. History might be far, far longer than anyone had assumed – and we humans hadn’t been around for most of it. There had been worlds before our world, long periods when there were seas where there are now suburbs and tropical forests where there are now frozen wastes. Unimaginably strange creatures had once walked the earth: the therizinosaurus, a towering theropod with enormous scythe-like talons from the Late Cretaceous period; the chalicotherium, a peculiar, knuckle-walking vegetarian mammal, which resembled a horse but had long, curved claws with which to pull down tree branches and the deinocheirus, a lumbering, humpbacked dinosaur with a pot-bellied frame, massive arms, and a duck-like beak.

The more scientists and geologists researched, the more ancient and weird everything seemed to get. In 1650, English Archbishop James Ussher had staked his professional reputation on the idea that the world had been created in precisely 4004 BC. By 1779, the naturalist Comte de Buffon, after researching cooling rates of molten rock, proposed that the planet was actually 75,000 years old. By 1830, the geologist Charles Lyell, influenced by his study of processes of erosion and sedimentation, argued for a then-astonishing 4 million years. By 1862, the physicist Lord Kelvin, using thermal calculations, came to 400 million years. By 1907, with the discovery of radiometric dating, scientists revised the estimate to at least 2 billion years. And by the mid-20th century, improved radiometric techniques led to a figure of 4.5 billion years old – which remains, for now, the settled number.

What had once seemed like an unchanging, juvenile world emerged as a place of incomprehensible antiquity. The realisation felt both profoundly humbling – and, in its way, deeply reassuring, for it served to shrink to far more manageable dimensions the significance of those most wretched and ephemeral of creatures: ourselves. Far from dominating history with our crises, arrogance and vanity, it seemed we were – in fact – just a very minor moment in a story of infinitely greater grandeur and significance. What matter our romantic failure in the context of that vast supercontinent Pangaea, which once held nearly all of Earth’s landmass and had begun breaking apart around 200 million years ago or that even older supercontinent, Rodinia, that existed over a billion years ago, and triggered an ice age so extreme that glaciers may have reached the equator. Why be quite so bitter over our professional disappointments when over a hundred million years ago, Antarctica was covered in conifer forests. Or why lose sleep over a rumour when more than 90% of the Earth’s history had passed before the first flower bloomed.

Religions had once urged us to remind ourselves of the non-human divine realm by placing images of the Virgin Mary or the Buddha around our homes. To follow the spirit of their example, we might place somewhere in the kitchen a fragment of banded ironstone, formed 2.5 billion years ago, when the first oxygen-producing bacteria rusted the seas and turned the oceans red. Or a picture of a piece of 4-billion-year-old Acasta Gneiss rock, forged in the planet’s infancy when its surface was still a hellscape of fire and impact craters.

When we are told by science that a bird is not simply a bird, but the lingering echo of a long-extinct dinosaur or that an eye took half a billion years of blind trial, we may feel all our certainties start to wobble. Our plans, daily urgencies and minor hopes seem newly absurd. Our finger nails are the ghosts of claws we no longer need; the clouds above are ancient molecules of water, carried here by asteroids – and nothing makes sense any more. How hard it is to stay outside the human frame for any length of time. Like astronauts on a spacewalk, we have only a few moments before we need to get back to more familiar settings.

And yet there is an enduring lesson here that we need to keep rediscovering: that nothing matters as much as we fear. Or, to echo a piece of religious wisdom whose relevance will never cease: that, blessedly, this too shall pass.