"Say a Homo sapiens-specific virus – natural or diabolically nano-engineered – picks us off but leaves everything else intact. How would the rest of nature respond if it were suddenly relieved of the relentless pressures we heap on it and our fellow organisms?" – The World Without Us, Alan Weisman.
Alan Weisman's grand thought experiment, The World Without Us, challenges us to imagine a world in which humans are no longer the dominant force. Fittingly, the elaborate scenarios and extensively researched extrapolations that Weisman posits in his 2007 book served as a conceptual reference point for the world depicted in The Last of Us.
Here, through a combination of Weisman's research, some creative thinking and the The Last of Us Remastered's photo-mode, we can build a picture of how nature might go about tearing down our grandest structures and reclaiming the land on which even our biggest cities are built. The results illustrate that even as the few remaining survivors of The Last of Us struggle to stay alive, nature thrives.
More than that, though, Weisman's book gives hints of the dangers that any remaining survivors would have to face in the longer term. In doing so, it allows us to conjure up wild imaginings of the kinds of hazards that we might expect to negotiate in any possible sequel to Naughty Dog's post-pandemic classic.
"Back when they told you what your house would cost, nobody mentioned that you'd also be paying so that nature wouldn't repossess it long before the bank."
As anyone who has ever tended a garden, pulled a weed or cleaned out a gutter knows, vegetation grows wherever it can and as vociferously as it's allowed to. With people long since fled to fenced-off quarantine zones to guard against the infected, the buildings without are left to stand silent watch over the encroaching flora as nature moves in unimpeded.
Inside once beloved homes, outbreaks of mould slowly eat away at timber frames and degrade seals. Leaks occur around chimney breasts and rain finds its way in through roofs fallen into disrepair. Before too long, the elements have found a way inside walls built to withstand them and nature is making a mockery of the interior design we once agonised over.
Once exposed, the yearly cycle of fluctuating temperatures first cracks and then shatters windows, which allows still more flora and fauna inside as the whole process slowly accelerates. Soon, nature is eating structures from inside and out, reclaiming wooden frames, wheedling into hairline cracks in exposed brick work and spreading tiny tendrils through hardy building materials like a network of expanding veins.
Alongside this assault come colonies of insects and a menagerie of rodents, birds and small mammals that take up residence after years of being kept out in the cold. They exacerbate structural weaknesses as they chew through internal studwork walls and ceiling joists until external walls have little to support them and so begin to collapse.
Perhaps fittingly, the most effective catalyst for the change once we are gone comes from something that we currently cannot live without. Just as seedlings and insects are busy weakening that which is built above ground, another more primal force is wreaking havoc on what lurks below.
"Most of all, though, you are beset by what in other contexts is the veritable stuff of life: water. It always wants in."
"After we're gone, nature's revenge for our smug, mechanized superiority arrives waterborne."
Cast a cursory glance at almost any road or pavement and you'll see the effects of water's power. Every year, the seasonal cycle sees surface water freeze and thaw, which in turn causes cracks in cement, asphalt and stone alike.
Add to this the bursting of frozen pipes and remove the people necessary to make repairs and within a few years large pools have formed that support an abundance of plant life in what was once a busy suburban street. Soon after, without people to clear drains and maintain the underground network of sewer systems, this surface water has nowhere to go even if it wanted to.
The ground floors of buildings flood as water finds its way into every structure, either from the top or the bottom. As it collects on the surface, streets are gradually submerged until they more closely resemble rivers - but it's the drama unfolding below ground that causes the most dramatic changes to our once great cities.
Human ingenuity has enabled us to build transport systems underground, but they require diligent monitoring and maintenance. Every single day, millions of gallons of water are expelled from New York's subway system by a network of mechanical pumps; even if it doesn't rain, water gushes in from the bedrock.
Similarly, London's tube network, portions of which sit far enough below ground to be used as bomb shelters during the Second World War, requires that same all-important human intervention to ensure its pumps keep up the ceaseless fight against a daily deluge. Without people maintaining this vital system, breakdowns occur and the power eventually runs dry.
Within days, water from the submerged tunnels finds its way into the foundations of monuments built of steel, concrete and glass.
In US cities frequently battered by hurricanes, the assault taking place above and below ground eventually proves too much for edifices once celebrated as modern wonders of architecture. They collapse against one another like drunken strangers as foundations give way and Mother Nature sets about implacably toppling these towers of human hubris. As the years roll by, her hold tightens and an inescapable truth is writ large across the face of a landscape reclaimed; she is not the invader here. We are.
"If everyone on Earth disappeared, 441 nuclear plants, several with multiple reactors, would briefly run on autopilot until, one by one, they overheated."
With the human population so drastically reduced and the world outside our barbed-wire walls abandoned to the infected and to nature, large swathes of critical human infrastructure collapse. Alongside the benign and relatively harmless fall of roads, homes and office blocks comes a much greater threat from unattended nuclear power plants.
The threat of the infected would be compounded by radiation poisoning that would seep into the air and water from decaying power plants. Even if emergency procedures have been initiated before abandoning the plants, thus terminating fission in the core and ceasing the production of electricity, there are still the hundreds of thousands of tons of nuclear scrap that require storage and constant cooling.
Once the water in the cooling systems evaporates or they become otherwise ineffective, all bets are off. Large areas surrounding the plants become wastelands, while airborne pollution and irradiated water would be carried many miles from the source. The resulting radiation poisoning could further decimate a human population already on the brink of extinction, making survival still more desperate.
At this point, the last vestiges of the human race either band together or turn increasingly savage as they fight over scarce clean water supplies and safe havens. Perhaps at that moment humanity would shine but it seems unlikely. As Bill drily observes of the infected, "Y'know, as bad as those things are, at least they're predictable. It's the normal people that scare me."
Who knows what effect gradual radiation poisoning might have on those infected. Maybe we'd get lucky and it would kill them off, giving us one less thing to worry about. Or maybe they'd evolve, mutating into something more deadly still.
The world that Joel and Ellie inhabit in The Last of Us is one beset on all sides. Just as they fight to survive the threat of the infected, so too does nature fight to reclaim its once unspoiled domain. The surprising thing is that this is a battle that's taking place every day, all around us, and one that we are all a part of to a larger or smaller degree. The Last of Us gives us a glimpse of what might come to pass should we become too preoccupied or too few in numbers to continue to keep nature at bay.
It might be a bleak picture for the human race but thanks to Naughty Dog's environmental artists and Alan Weisman's provocative thought experiment, it is not without its moments of beauty. Unruly and wild as it may be, nature likes to remind us that it was here first, and will be here long after the last of us are gone.
"Look around you, at today's world. Your house, your city, the surrounding land, the pavement underneath, and the soil below that. Leave it all in place, but extract the human beings. Wipe us out, and see what's left."