If aliens came to Earth millions of years in the future, what traces would they find of long-extinct humanity? In the post below Jan Zalasiewicz, a geologist from the University of Leicester and author of the forthcoming book The World After Us: What Legacy Will Humans Leave in the Rocks?, ponders what the potential symbols of our world might be for whomever, or whatever, is after us.
Harald V, King of Norway, seems a serious man, and he can certainly make a thoughtful speech. Hence to see him subsequently, with due ceremony, push the button to inflate a life-size model of the biggest pliosaur ever found – 15 metres long, for the record – makes for one of life’s more singular pleasures. It’s an event to be cherished and honed in the memory and passed on down to one’s grandchildren, imagined detail being added with each retelling. The occasion: the official opening of the Thirty-Third International Geological Congress a few weeks ago, when several thousand geologists descended upon the small town of Lillestrøm outside Oslo, to debate the Earth and its eventful past and uncertain future. The royal inflation of the pseudo-pliosaur was one of the organisers’ more fantastical touches, and for all I know the air-filled reptile is still there, lashed to the lawn in front of the conference centre, jaws agape, and painted so vividly as to look more roguish than terrifying.
The return of dinosaurs in some distant future was something that Charles Lyell imagined, nearly two centuries ago, when he contemplated the slow cycles of oceans and mountain chains and of life itself evolving through the immensity of deep time. Henry De La Beche chided him for this fancy, penning a satirical cartoon showing a Professor Ichthyosaurus, flipper pointing to a fossil human skull, teaching infant neo-dinosaurians about the curious life of the humanoid past.
Of course life and the Earth don’t work that way. What’s gone is gone. What will arise, moreover, can’t be predicted from contemplation of the gathering wreckage of a biological empire under siege. To suggest, an hour before the Yucatan meteorite tore into the Earth, that the small scurrying mammals would one day grow to fill the giant shoes of the dinosaurs, would have seemed, then, like the most outrageous of science fiction. Yet this happened. To predict, a few hundred million years ago, that the mighty sea scorpions would not go on forever, would have seemed unthinkable. Yet these armoured crustacean-like hoodlums vanished too, and so today we can venture safely to the beach for a stroll or a swim.
The future is uncertain, and the present is remarkable, not just historically and politically, but geologically too. When thousands of geologists get together to discuss their latest discoveries, then what is happening today seems ever more extraordinary, when viewed through the prism of the deep past. There was one throwaway remark, for instance, noting evidence that the Arctic Ocean has been ice-covered for 13 million years. Well, this is a state of affairs that looks set to end this century, perhaps within decades. And then there is the gathering evidence that the world’s climate, given a sufficient push, can turn on a sixpence, to suddenly refashion itself. How close are we to another such revolution, one wonders?
To have a Professor Ichthyosaurus of the far future musing on the fossilized evidence of our current predicament is, alas, an impossibility. But there may eventually arise a learned hyper-rodent, say, or arrive an inquisitive traveller from Betelgeuse 9. Perhaps these beings might organise scientific congresses too, at which inflatable models of creatures of the long-gone Human Era would be ceremonially inflated. What creature would they choose, then, for maximum dramatic impact? A blue whale, perhaps, for sheer size – or a narwhal, or a swordfish, or a giraffe?
Maybe the alien committee would go for the curiouser, rather than the merely large. They might select, say, that strange sabre-toothed beast, the walrus, gracing an artificial shoreline with an accompanying plastic humanoid for company (as replica of a carpenter, naturally). That might be a fitting symbol for a world – our world – that will still seem a cosmic Wonderland when viewed through that looking-glass of the far future. The shade of the Cheshire Cat might venture, then, one last rueful smile.