Jan Zalasiewicz's "The Earth After Us"

Jan Zalasiewicz is a Lecturer in Geology at the University of Leicester, before that working at the British Geological Survey. A field geologist, palaeontologist and stratigrapher, he teaches various aspects of geology and Earth history to undergraduate and postgraduate students, and is a researcher into fossil ecosystems and environments across over half a billion years of geological time. He has published over a hundred papers in scientific journals.

He applied the “Page 99 Test” to his new book, The Earth After Us: What Legacy Will Humans Leave in the Rocks?, and reported the following:

For over a billion years, between roughly three billion and two billion years ago, rust precipitated on to the ocean floor, interbanded with layers of silica, to form the distinctive strata of the Banded Iron Formations, so ubiquitous in Precambrian terrain that they have their own acronym, the BIFs. We now exploit them for almost all the iron and steel we use, for they dwarf any other iron ore deposit on Earth. When our extraterrestrial explorers also need iron for their expanding colonies, it will be to the BIFs that they will turn; and they will no doubt soon form a conclusion as to how these deposits arose, as by-product and witness of the revolution that led to an oxygenated Earth.

--The Earth After Us, p. 99 (pars)

The sheer excess of it all! Human epics – those of the magnificent Ambersons, and of the urbane Forsytes, and of other such dynasties, may dance to the music of human timescales, measured in decades and centuries. But, in a biography of the Earth, one may casually skip across a billion years in a single paragraph. Encompass, too, the lives of trillions of generations of those organisms, the first photosynthetic microbes, that were, then, bringing about a revolution more profound than any before or since: the creation of that crazy, dangerous, unstable, cosmic rarity: a planet enveloped in free oxygen.

Narrated thus, it’s an absurdly abbreviated story, of course – an utterly minimalist cartoon. It hides, absolutely, a myriad complexities of biology and chemistry. It glosses, unpardonably, over the countless twists and turns and setbacks in turning what was, in effect, an alien planet, into one that that was to become familiar to us. This transformation did happen, though, and rendered possible that us who can then look back on (and, all too rarely, thank) those industrious microbes who first greened this planet.

We, too, are now transforming the Earth. We are not yet having the planet-changing effects of our unimaginably distant, single-celled ancestors. But we are executing our own distinctive changes to the Earth’ surface much, much more quickly. We are doing so, too, now, in full awareness of what we are doing, even if not in full control (some might argue, not in any significant control) of our collective actions.

The unconscious and amoral Precambrian microbes altered the planet for the better, almost unarguably (though with the sacrifice of myriad microbe species to whom oxygen was as poisonous as chlorine is to us). They opened the way for the beauty and complexity of multicellular life: of orchids and velvet worms and octopi and humming-birds. And of us. Now we are the pinnacle (in some interpretations) of that life, with manipulative intelligence and an avowed morality. It may be a brief ascendance, but if our legacy is to smash a good deal of the biosphere’s beauty and complexity, how will we compare, then, morally, with those microbes? Now there’s a point to tax the post-modern philosophers. While there’s still time for debate.

Learn more about The Earth After Us at the Oxford University Press website.

--Marshal Zeringue