This article is from the In-Depth Report Humankind's Enduring Fascination with the Apocalypse
Science Talk

The World Without Us: Suppose Humans Just Vanished--Then What?

In this episode, journalist Alan Weisman, Laureate Associate Professor in Journalism and Latin American Studies at the University of Arizona, discusses his new book "The World Without Us," a massive thought experiment about the aftermath of humanity's sudden disappearance. Plus we'll test your knowledge of some recent science in the news. For info on and articles by Alan Weisman, go to

Science Talk June 27, 2007 -- The World Without Us: Suppose Humans Just Vanished—Then What?

Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting June 27th. I am Steve Mirsky. This week on the podcast, journalist Alan Weisman conducts a gigantic thought experiment [on] what would the Earth be like if human beings suddenly disappeared a week from now, a year from now, a century from now, and thousands of years down the road. Plus, we will test your knowledge about some recent science in the news. First up, Alan Weisman. He is a veteran journalist and a senior producer at Homelands Productions—that's a journalism collective that produces independent public radio documentaries. He is a professor of journalism at the University of Arizona and the author of a new book about this idea of the events that would unfold if humanity just vanished. I called him at his office in Tucson.

Steve: Alan, good to talk to you today.

Weisman: It's my pleasure.

Steve: Your book is called The World without Us. It's a fairly self-explanatory title, but why don't you give us the nickel tour of the idea of this book?

Weisman: Well, it started about the summer of 2003. I got a call from an editor at Discover magazine, who asked me to do a piece for the magazine on what would the world be like without human beings in it, and I said, "You mean what's going to be left here after we eat ourselves into extinction and drag down many other species with us?" and she said, "No", and she said, "I read about [that] all the time. What I want to know is what if we just disappear tomorrow, what would be left, how would nature respond in our absence?" And I replied that that was rather unlikely; and then we started to talk about a few scenarios, you know, space aliens [taking us](unclear 1:51) away to some zoo across the galaxy or [a] homo sapiens-specific virus picks us all off. Once that was established thought that it could happen, however slim the chances were, it began to dawn on me that this was a very interesting way of looking at the world. What if we just theoretically take human beings off it? And this gives us a much clearer idea of what else is here, and if we can see how it would respond without all of our daily pressures, it would in turn make us look at our impact.;that's sort of from the other direction. And [I said] I think, you know, this is a very interesting idea, where did you get [it?] And she said, "Well, I got it from you," and I said "I am completely lost here"; and she explained to me that she had seen in 1994 a piece I did for Harper's magazine about [Chernobyl]her Nobel. I went there seven years after the explosion and among other things I reported how in the absence of human beings in villages around the reactor that had been abandoned, how the rest of nature was rushing in to fill the void, how neatly trimmed hedges and landscaping were now growing wild. They were virtually hiding houses, tree roots were breaking up pavement, and it was rather remarkable to go to—its the scenes of one of humanit[y's]ies greatest devastation and see that nature was, kind of, having filled it. And she said at that time she thought that was such an alarming article; that over years of editing stories on environmental destruction it began to be one of the most hopeful articles that she could recall. So, she said what would happen if this deploys everywhere, if suddenly human beings were gone. I began my research by going to a couple of abandoned places, places where human beings had left for very different reasons. One of them is the last fragment of primeval forest in Europe. It's that one that you kind of see in your mind's eyes when you are a kid and someone is reading Grimms' fairy tales to you. The dark, brooding forest with many metric tons of moss hanging off these trees and wolves howling; and there is such a place. It still exists on the Poland/Belarussian border. It was a game preserve that had been satisfied in the 1300s by a Lithuanian duke who later became king of Poland and then a series of Polish kings and then Russian Czars kept it as their own private little hunting ground—very little human impact [for] about half a million acres—and you go in there and you see these enormous trees. It's a temperate forest like many of us have grown ups around, certainly here in the United States where any of us who, you know, apart from growing up in a desert or down in these southern forests or say Florida—this place is familiar; and yet it's a much bigger version, and yet it does not feel strange to us; it almost feels right, like something feels complete in there, and there are some surprises that we wouldn't even think of. There are bison in there for example. The bison is directly related to the American bison—in fact our American bison came from Europe originally—and there are still a herd of 600 of them in there. So, that was rather remarkable to see what Europe might have been like had not human beings become so populous therein and overrun it and sort of civilized and turned what used to be wilderness into a park-like environment. I went to the Korean DMZ, and if you get to this little scratch of land—it's about 180 miles long and two-and-a-half miles wide—that has two of the world's biggest armies faced off against each other across it and in between it's become an inadvertent wildlife preserve. It's remarkable to be standing there and you see species that might be extinct if it weren't for this one little piece of land that has held in this incredible tension. You sometimes will hear each side screaming at each other through loudspeakers or flashing their propaganda back and forth and in the middle of this thing will float flocks of cranes, which are some of the most beautiful and some of the most endangered species on Earth that went through this; and were [it] not for the state of war that has existed since 1953—it's actually before—between the two Koreas that has been this interminable truth—if peace were declared these species might not have a home anymore. So, from those examples I started to get an idea of what the world might look like without us. But then it occurred to me to really understand, I would also have to get a baseline for: What was the world like before us? What was it like before there were any human beings at all? So, I went back to Africa, to the place where humans originally evolved—and this is the continent where there are still huge animals roaming around—and it turns out that weve used to have huge animals in all the other continents as well and then many of the islands; [it] seems that one after another were discovered by human beings and the great populations of large animals were extirpated rather quickly after human arrival.

Steve: When I talked just briefly about what happens to the actual structures—you spent part of the book just talking about what happens to the buildings when we disappear.

Weisman: Well, I found a couple of things really interested people when I started talking to them about what I was writing. One was their initial reaction to a world without people? I was surprised that about 90 percent of the people would say, "Oh! That just sounds so nice," and (laughs) it was like this refreshing concept.

Steve: What was it that Sartre said, "Hell is other people".

Weisman: Well, I guess there is something to that, and I think that they were rating on [a] lot of levels, but I think one of them was sort of this primal nostalgia for something that we know we have lost even though most of us have never seen it. It was sort of like my feeling when I went into this forest in Poland. I had never seen a forest this complete, but it didn't feel strange to me. It felt recognizable. So, that was a very strong reaction, but another one that people would put to me immediately was, well, what would happen to all of our stuff if we weren't here anymore and, you know, could nature wipe out all of our traces? Are there some things that we have done that are indestructible or indelible? If nature could for example take New York City and take it back to the forest that was there when Henry Hudson first saw in 1609, I mean how would it actually happen? So, I had a fascinating time. I started it in New York, and I went to several other places too. I had a fascinating time talking to city engineers, talking to city maintenance people, for example the people that you know keep subways going, about what it takes to hold off nature; and I discovered that our huge imposing overwhelming infrastructures that seem so monumental and indestructible are actually these fairly fragile concepts that continued to function and to exist day by day thanks to [a] few human beings out there upon whom the infrastructure and all of us really depend, but guys who keep the subways clear in New York. New York City—the name Manhattan actually comes from an Indian term referring to its hills. It used to be a very hilly island and of course the city was flattened eventually to have a grid of the streets imposed on it. Around all those hills used to flow lots of streams. There were about 40 different streams and numerous springs all over Manhattan Island. Well, what happened to that water? That water was runoff water from rainfall and from the water table. Well, there is still this [just as] much rainfall as ever on Manhattan; that water has now been suppressed—its underground. Some of it runs through the sewage system; that sewage system is never as efficient as nature a[t]nd leaking away water—the capacity isn't as flexible as nature's capacity. So, there is a lot of ground water rushing around underneath and it's trying to get out; and even on a clear sunny day, the subway guys have to pump 13 million gallons of water away. Otherwise, the subway tunnels will start to flood.

Steve: I have lived here all my life; I never heard that before.

Weisman: Well, I walked around underneath the subways. We went to see some pumping stations in Brooklyn, and I was told about places in Manhattan where they are constantly fighting rising underground rivers that are corroding away the tracks; but you stand in these pump rooms and you see an enormous amount of water gushing in. It's really impressive and down there in a little box are these pumps that are pumping it away and the[n] pumping that uphill, of course, because this stuff is underground. So, when, say, if human beings disappear tomorrow, one of the first things that would happen is that the power would go off. A lot of our power comes out of nuclear plants or coal fire plants that have automatic switches. They are fail-safe switches to make sure that in the event of no humans monitoring the system that plants don't go out of control, and I have a whole chapter in nuclear plant describing what would happen if there were no humans. You know minding the system there. Once the power goes off, the subway starts filling. Within 48 hours, you are going to have lot of flooding in New York City. Now, some of this would be visible on the surface. You might have some sewers overflowing. The sewers themselves would very quickly become clogged with debris. In the beginning, we will be talking about plastic bags. There are innumerable plastic bags that are blowing around the city, and later, as nobody is trimming the hedges in the park, it would going to start to get leaflet[s] or things like that that is[are] going to be clogging up the sewers, but what would be happening underground would be corrosion. You know, just think of the 4, 5 and 6 lines down Lexington Avenue. You stand under there and are waiting for the trains—there is[are] always steel columns that are holding up the roof—which is really the street—and as these things start to corrode, they will eventually start to collapse. According to the city engineers and some people at universities like [at]a Cooper Union in[and] Columbia who I talked to, that after a while, the streets are going to start cratering; and this could happen within just a couple of decades and pretty soon some of the streets were going to revert to the surface rivers that we used to have in Manhattan before we built all of this stuff. Many of the buildings in Manhattan Island like many cities in the world are anchored to bedrock, but they were not—these foundations even, if they are still being foundations—they were not designed to be waterlogged all the time. So, a professor from Cooper Union described to me—and this is someone who deals with structural integrity of building seal[s], now consults all over the world to how to make a building terrorist proof. His vision is of buildings that would eventually start to topple and fall, some water rock foundations that give the way for it, hurricane winds—and we are bound to have some more hurricanes in the East Coast as climate change gives us more extreme weather—and so a building will fall down and will take down a couple of others as it goes, very much the same way when a tall tree falls in the forest it takes down a few others and it creates a clearing; and into those clearings will be blowing seeds from plants and those seeds will establish themselves in cracks. They will already be brooding in leaf litter anyhow, but the addition of lime from powdered concrete from broken buildings will create less of an acidic environment for various species, where—you sort of get the idea—a city will start to create its own little ecosystem and plants will be growing in leaf litter on top of pavement. Plants will be going through cracks in pavement. Every spring when the temperature hovers on one side or other, freezing, cracks will be appearing, water will dip down into them. The water will freeze. It will widen the crack and leave the seed to blow in there. It happens very quickly.

Steve: It's fascinating stuff. I am curious you are a professor of journalism as well as of Latin American studies. I have walked down the Avenue of the Dead in Teotihuacán in Mexico and I am assuming you have too.

Weisman: Yes, I did walk on [it], yes.

Steve: Right! And you have also seen the Mayan ruins that are [so] completely overgrown you can't even find them without help from NASA sometimes, and I am just curious if those experiences informed either your curiosity or your outlook in any way.

Weisman: No question. The first time that I went into the Mayan ruins of western Guatemala, I had to hike half a day into an archaeological dig; and the archaeologists who were accompanying me explained to me that the hills and the ridges that we were going over were actually buried cities. The hills were pyramids, the ridges were walls, and yet there was a mature mahogany forest growing out of them. And I said "Wow! Why don't you guys excavate all these?" And they said, "We would love to—there is not enough money in the world to excavate all of the archaeology that is sitting beneath our feet and all over the world. There are civilizations that have been silted over, buried and life springs anew from their very rooftop." It's a fairly common experience you having mentioned—Teotihuacán in Mexico—you know, the Pyramid of the Sun is one of the largest structures on Earth and much of that was completely hidden until it was, you know, really cleared away in the 19th century.

Steve: Yeah! So your book is looking at a situation that, you know, on the surface it sounds pretty far fetched, but we have seen it in microcosm played out over and over again throughout history.

Weisman: Well, I am not suggesting that we have to worry about human beings suddenly disappearing tomorrow, you know, some alien (unclear 19:00) comes and takes us away; in fact on the contrary, what I am finding is that this way of looking at our planet by theoretically just removing us for a minute turns out to be such a fascinating way of looking at it that it kind of disarms people's fears; or the terrible way that depression that can engulf you when we read directly about the environmental problems that we have created and the challenges that we are facing and possible disasters that we may be facing in the future. Because frankly whenever we read about those things—because we are organisms [and] like any other organisms are survivalists hardwired—and our concern is “Oh my god! Are we going to die?", you know, "Is this going to be the end?" My book just eliminates that one right in the beginning by saying, you know, the end has already taken place. For whatever reason human beings are gone and yet we get to know sit back and look to see what happens in our absence. And it's just sort of a delicious little way of reducing all the fear and anxiety and being able to look at an enormous number of different approaches to, you know, "what would happen in our absence", which is another way of looking at, "well, what goes on in our presence"; and I raised an opportunity towards the end of the book of human beings continuing to be part of this ecosystem, but yet doing it in much more balance with the rest of the planet. It's something that I approach by first looking at not just the horrible things that we have created that, that are so frightening, such as our radioactivity, such as our pollutants—some which maybe around until the end of the planet—but also some of the beautiful things that we have done. And I raised the question, you know, wouldn't it be a sad loss if humanity was extirpated from the planet? What about our greatest acts of art and expression? Our most beautiful sculpture, our finest architecture, will there be any signs of us at all that would indicate that we were here at one point? And this is a sort of a second reaction that I always get from people. At first, they are thinking how this would be beautiful without us, but then, "Wouldn't it be sad not to have us here?" And I don't think it's necessary for us to all disappear in order for the Earth to come back to a healthier state before our industrialization began to tinker with it.

Steve: And maybe your book can be a blueprint for a part of that process. It's a terrific book.

Weisman: Well, I appreciate that.

Steve: Alan Weisman, thank you very much for speaking with us today. And I hope everybody will go out and read it.

Weisman: Well, thanks a lot Steve. The World without Us has been an enormously gratifying experience for me, hardly enough; you can't write about "the world without us" without the help of [an] enormous number of human beings, and therein lies the clues the way to a healthy world may come through human beings.

Steve: This was an edited version of my interview with Weisman; another edited version of the entire interview—including material not included in what you just heard—is published in the July issue of Scientific American magazine. It's also available free on our Web site, We will be right back.

Male voice: Wandering around? Visit Scientific American: Mobile Edition on your Web-enabled mobile device; go to for the latest science news and analysis plus daily trivia questions. That's on your mobile's browser.

Steve: Now it's time to play TOTALL.......Y BOGUS. Here are four science stories, but only three are true. See if you know which story is TOTALL.......Y BOGUS.

Story number 1: Geologists say that new housing in Galveston, Texas would destroy a ridge that protects the barrier island from storms.

Story number 2: A British light welterweight boxer was tested and found to pack a punch about ten times harder than a non-pugilist.

Story number 3: Also from the world of sports, sort of—Takeru Kobayashi may not be able to defend his Nathan's Famous 4th of July Hot Dog Eating Contest championship because of a medical condition.

And story number 4: Also from the world of food, sort of—red wine may have some good cardiovascular benefits, but a new study shows that red wine may contribute to tooth decay.

Time is up.

Story number 1 is true. The L.A. Times reports that Galveston city leaders are going to re[ap]prove the construction of four thousand new homes and two hotels, even though geologists they commissioned warned them that they will destroy the [city’s]cities natural storm protection. So, everybody in Galveston, you might want to pick up a copy of The World Without Us.

Story number 2 is true. Light welterweight champ, Ricky "The Hitman" Hatton, could punch with a force of some 400 kilograms—about 900 pounds; a civilian tested with the same equipment topped out at 38 kilograms of force. For more, check out the June 25th edition of the daily Sciam podcast 60-Second Science. On Saturday, Hatton beat Jose Luis Castillo with a fourth round knockout on a body blow to retain his light welterweight championship—that's the 136- to-140-pound weight class.

Story number 3 is true. Takeru Kobayashi may be sidelined from the Hot Dog Eating Championship because of an arthritic jaw. The 165-pound Kobayashi has won the Coney Island Hot Dog Cramming Contest six years in a row. Last year, he ate 53 and three-quarter hot dogs in 12 minutes, but it looks like this year he won't be able to cut the mustard.

All of which means that story number 4 about red wine promoting tooth decay is TOTALL.......Y BOGUS. Because a study coming out in the July 11th issue of the Journal of Agricultural and Food Chemistry found that both red and white wine appear to be agents against tooth decay because they control the growth of several strands of Streptococci bacteria involved in tooth decay and even some cases of sore throats. So, if you drink, don't drive to the dentist.

Well that's it for this edition of the weekly Scientific American podcast. You can write to us at; check out news articles at our Web site,; the daily Sciam podcast 60-Second Science is at the Web site and at iTunes. For Science Talk, the weekly podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.

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