Human Environmental Engineering Goes Back a Long, Long Time

An alien species visiting Earth would find a planet clearly dominated by one species. It’s no secret that humanity has a major influence on all aspects of Earth processes – we’ve covered major portions of land surface in stone and asphalt; we’ve cleared natural landscapes and driven an ever-increasing number of species to extinction; we’ve filled the oceans with plastic and the atmosphere with greenhouse gases. This planet is very firmly in the grip of human activity.

But this legacy of environmental modification goes back further than we generally appreciate. Today’s issue of PNAS has a special section devoted to human evolution, and one paper outlines the modern understanding of the many ways our species has affected the physical world around us, and just how long we’ve been doing it. The fact is that our modern explorers – the intrepid adventurers of the past few centuries who discovered lands populated only by indigenous peoples or long-gone civilizations – were alien visitors to parts of the planet already dramatically transformed by human influence.

Here are some of the ways our species has been shaping natural environments since long before written history:

The Mystery of the Sunken City of Zakynthos

This scientific discovery reads like a science-fiction mystery novel.

It starts in 2014, when a group of tourists visiting the Greek island of Zakynthos decided to go snorkeling. While exploring the shallow ocean waters close to Alikanas Bay they stumbled upon what appeared to be the remnants of a sunken civilization: flat pavement stones and the circular bases of collapsed colonnades. Perhaps these were lost fragments of a city port submerged by the sea?

The divers took pictures and uploaded them online, where they reached the attention of Greece’s Ephorate of Underwater Antiquities, who sent in an archaeological investigation team. The team discovered something very odd: there was no pottery, no coins, no signs at all of any human life. If this had once been a city, who lived there? Who built it? And why didn’t they leave behind any artifacts?

Ghost World - Part III: Resurrection

De-extinction. It's an amazing and controversial idea, and it may even be impossible. It's also not what you think. 

In Part I of this series, I reviewed the ways in which our world is a poor impersonation of what it was thousands of years ago, haunted by the absence of the ancient giants that once provided stability to ecosystems. In Part II, I reviewed the ways in which modern researchers are hoping to fix those ecosystems, by transporting "replacement" species to fill the gaps left by extinction, and even "un-domesticate" certain species to recreate their wild ancestors. 

Isn't there another option though? Instead of trying to replace the dead, why not bring them back? Why not simply clone extinct species?

Ghost World - Part II: Revival

In my last post, I described how the modern-day world is a global version of a ghost town: the extinction of dozens of species of large animals at the end of the Pleistocene Epoch left ecosystems incomplete and unbalanced. Without mammoths, ground sloths, and the rest, some plants and animals have thrived, others have suffered or disappeared altogether, and even natural processes like fire and climate have been affected. The natural world is incomplete without them, and continues to degrade like an abandoned village.

Of course, the key to “fixing” a ghost town is quite simple: bring people back. They don’t even have to be the same people. Just about anyone can tend the overgrown gardens, drive the disused cars, and shoo away the rats and roaches. The same may be true of our ecosystems, which brings me to an ambitious – and controversial – conservation idea:

Pleistocene Rewilding.

Ghost World - Part I. Dearly Departed

Imagine walking into a ghost town, recently deserted. It wouldn’t take you long to realize what’s missing. Cars are still parked along the streets, batteries slowly failing; sprinkler systems still spring to life on schedule, watering lawns that are steadily growing out of control; untended gardens are gradually overtaken by weeds, while insects and rodents dart in and out of homes with nothing to stop them but cats turned feral now that no one is leaving food out for them. All of these things are meant to be there, but they aren’t doing what they’re meant to do. Without people to maintain the town, it has descended into disrepair and instability.

Our world is in a state of disrepair and instability for the same reason – something important is missing. We live in a ghost world.