IRA FLATOW: This is Science Friday. I’m Ira Flatow.

Those of us of a certain age can remember the first showing of the movie Soylent Green. It premiered in 1973. The film drops us into a New York City that’s overcrowded, polluted, and is dealing with the effects of a climate catastrophe. Only the city’s elite can afford clean water and real food, like strawberry jam. The rest of the population relies on a communal food supply, called Soylent. There is Soylent Red, Soylent Yellow, and Soylent Green.

And spoiler alert– what is Soylent Green?

CHARLTON HESTON: You got to tell them– Soylent Green is people!

IRA FLATOW: Yes, people are eating people. And in what year is cannibalism the norm? 2022, of course.

Joining me today to talk about the importance of the film and parallels to our current time are my guests, Sonia Epstein, Curator of Science and Film at the Museum of the Moving Image, in New York City, and Jo Handelsman, Soil Scientist and Director of the Wisconsin Institute for Discovery, in Madison, Wisconsin.

Welcome back, both of you, to Science Friday.

SONIA EPSTEIN: Thank you.

JO HANDELSMAN: Great to be here.

IRA FLATOW: Great movie. Great movie, isn’t it?

SONIA EPSTEIN: Yeah, yeah.

JO HANDELSMAN: It is.

IRA FLATOW: All right, Sonia, tell us– give us a bit more of a rundown of the plot of this film.

SONIA EPSTEIN: Sure. So this is a Richard Fleischer film, which some people might know his other famous kind of science film, Fantastic Voyage, which he made in 1966. But the plot, it’s based on a book, called Make Room! Make Room! And as you say, it’s set in a very overpopulated New York City of 2022, and it follows a police detective, who is at work, trying to discover the roots of the Soylent Corporation that is basically one conglomerate that is in charge of all the food production in the city. And there’s a sort of pertinent quote for this conversation about, guards their farms like fortresses.

This detective, played by Charlton Heston, is trying to unravel a murder that is somehow related to the Soylent Corporation.

IRA FLATOW: Mmm, and film and art, right, Sonia, they’re often a reaction to what’s happening in the world. What was going on in the early ’70s that may have inspired Soylent Green?

SONIA EPSTEIN: Yes. So this film was released in 1973, actually on April 18th. So in just a few days from now. Silent Spring, the book that a lot of people credit with sort of the start of the environmental movement, by Rachel Carson, was published about a decade earlier. But in 1970 specifically, there was the Clean Air Act that was passed by the EPA, and also the first Earth Day.

So by 1973, certainly, the environment was a big part of people’s consciousness, connection between the population and its effects on the environment, and also the book, The Population Bomb, had come out a few years earlier, in 1968, I believe. And so, as I said, the effects of a growing population on the environment, and awareness of greenhouse gases– as you see in the film– that was all in the public consciousness very much at the time.

IRA FLATOW: Jo, in the film’s 2022, there’s almost no soil or agricultural land left. We are thankfully better off than in the film. But you write about the loss of soil. We are in sort of a state in our current world, heading in that direction.

JO HANDELSMAN: Absolutely. The film is so clairvoyant. It was so predictive of things to come, in terms of climate change and as well as loss of soil. We’re losing soil about 10 to 100 times faster than we’re producing soil. And so that puts us in a near crisis. And in some parts of the world, it already is a crisis, in terms of being able to grow crops and do all the things with soil that we normally do.

IRA FLATOW: And why is our soil eroding away?

JO HANDELSMAN: Well, we introduced the plow a few hundred years ago. And the plow does great damage to soil structure. So it breaks down clods and clumps and all that nice architecture that soil has naturally into single particles. And those are much more likely to blow away or wash away with wind and water than the clumps. That’s probably the biggest influence.

And then, the way that we farm is not increasing carbon in soil. It’s not increasing the health of soil. It’s just basically ripping the guts out of the soil and taking all the nutrients and leaving little behind. And that’s just a function of the kinds of plants we grow for human consumption and the way that we grow them.

IRA FLATOW: They don’t say in the movie that there is no soil left, but you can surmise that, if you have to eat people, that it’s you can’t make food without soil– certainly not enough to feed everybody.

JO HANDELSMAN: Absolutely. Yeah, they were absolutely right about that.

SONIA EPSTEIN: Yeah. If I may. There’s actually– just to anybody who may be inspired by this conversation to watch the film or rewatch the film if they’ve already seen it– there’s a really sort of interesting montage at the start of the film that kind of speaks to what you’re talking about, Jo, about the evolution of farming practices. It starts out sort of uplifting, and it’s about– has the Wright brothers, sort of about advances in human civilization, if you will, but then quickly sort of increases its pace and cuts to the advent of cars and industrial agriculture and things like that that kind of culminate in the opening sequence of an overpopulated world and no food.

And the only soil, I believe they say, that is left in the city is in Gramercy Park. And it’s protected by this like crazy fortress-looking tent. So just to add that.

IRA FLATOW: Great messaging, I mean, in this movie. They knew all the buttons to push on people at the time, because we had all this anxiety, I remember, about what we were putting in our bodies, weren’t we, Sonia?

SONIA EPSTEIN: Definitely. And interestingly– I mean, that also comes out of Silent Spring, and what Rachel Carson was pointing out about the use of pesticides. But this film had a science advisor, who was Dr. Frank Bowerman, who was prominently featured in the credits as the tech consultant. And he was an environmental engineer from USC, who was worried about population and pollution. And you see people wearing masks. So definitely a lot of concern at the time that this film I think engaged with purposefully.

IRA FLATOW: Jo, is it possible to produce food without soil?

JO HANDELSMAN: Yes, we can produce many plants and crops, like strawberries and tomatoes and lettuce– a lot of the vegetable crops and some fruits– in hydroponics or, in some cases, aeroponics. You may have heard of vertical farming, which is the idea of being able to stack up layers of agricultural activity in a hydroponic system, even in cities, so that you use very little of a footprint but you grow plants going up instead of out.

The problem is that we just don’t know how, and I think it’s unlikely that we’d ever figure out how, to make the staple crops of rice and corn and wheat, potatoes, some of the really high-nutrient crops that we use in very large quantities in the world, either to consume ourselves or to feed to our animals, at the level, in the quantities, that we would need without soil.

These plants are adapted to soil. They evolved in soil. And then we continued to breed them in soil. And so that’s what they need. And soil is– it’s more than just water, which hydroponics gives you water and some nutrients– but soil is worth–

IRA FLATOW: Yeah.

JO HANDELSMAN: It contains so much more than that.

IRA FLATOW: Sonia, I think the movie has aged very well. Some movies seem to go out of their time, but I think the anxieties that were in that film in 1973 are still around us today.

SONIA EPSTEIN: Definitely. I rewatched it recently. I think the only thing that looks a little kind of aged is the fact that I believe all of this was shot in a studio, so you can see some of the set dressings that to our CGI accustomed eyes look a little dated. But that’s also the appeal of the film, for anybody who appreciates set design and hand-painted things. But yeah, definitely the issues having to do with wealth disparity and equal equity and access, issues around climate change, that have only been exacerbated since this film was made 50 years ago– as I’m sure you’ve discussed on this show, that the recent IPCC report point out– so it is certainly one that is worth rewatching, particularly in this year.

IRA FLATOW: Yeah. One thing that did come true from the film is that there is a meal supplement drink called Soylent that you can buy now.

[CHUCKLING]

And supposedly it’s not made from people. I mean, what do you think, Sonia, would you give it a try?

SONIA EPSTEIN: I don’t know why they named it that.

[LAUGHTER]

JO HANDELSMAN: It seems like the death blow of the product before it’s even on the market.

IRA FLATOW: Well, but would you give it a try, Sonia?

SONIA EPSTEIN: Would I give it a try? I– as the film– there’s such beauty in cooking food and hearing the crunch and the textures, so I have never been one to look for meal supplements, luckily, because I enjoy cooking and shopping and all of those things.

IRA FLATOW: It struck me, Jo, that the word soylent has the word soil spelled differently in it. Do you think that was accidental or that was a hint about there’s no soil left?

JO HANDELSMAN: I think that was a hint. I think that these people were so acutely aware of the environmental issues that we were facing, and then would face even more acutely in 2022, that that had to have been deliberate. Otherwise, why would they have called it that?

IRA FLATOW: Yeah. And one thing you stress as a soil scientist and you talk about in your book, A World Without Soil, is that there is a solution to this issue. Can you walk us through what can be done to reverse our loss of soil?

JO HANDELSMAN: Sure. It’s actually one of the most soluble problems that we face today, which I find to be quite uplifting, because we face so many environmental problems that we don’t know how to solve. If we change our farming practices back to very straightforward practices of no-till farming, which means no plowing, where the seeds are drilled into the land instead of opening a plow with– open a furrow with a plow; if we used cover crops, which are crops that we plant at the end of the growing season, and they cover the soil and anchor the soil and feed the soil over the winter, until the next growing season; and then if we did intercropping, which is using multiple species to nurture the soil when we’re using particularly these plants like corn, which takes so much out of the soil and don’t put anything back in, we would probably stop erosion and begin building back our soil pretty quickly.

So those are the three basic ones. And then of course, adding more nutrients to the soil, adding compost, not throwing away all of our excess food that we do so readily in this world, but adding it back to the soil to be nutrition for the next round of crops would be very beneficial.

IRA FLATOW: And I want to thank both of you for going down memory lane with us today on Soylent Green.

SONIA EPSTEIN: Thanks, Ira.

JO HANDELSMAN: Thank you so much.

IRA FLATOW: You’re welcome.

Sonia Epstein, Curator of Science and Film at the Museum of the Moving Image, in New York, and Jo Handelsman, Soil Scientist, Director of the Wisconsin Institute for Discovery, in Madison, and author of A World Without Soil.

And if you can’t get enough of Soylent Green, the film will screen at the Museum of the Moving Image this fall as part of the ongoing series, Science on Screen: Extinction and Otherwise.

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