Despite overpopulation being a taboo topic these days, population pressure was a mainstream concern as recently as the latter half of the last century. Perhaps the earliest high-profile brand of population concern is Malthusianism: the results of a simple observation by Thomas Robert Malthus in 1798 that while unchecked population growth is exponential, the availability of resources (namely food) increases at a linear rate, leading to sporadic collapses in population due to war, famine, and pandemics (“Malthusian catastrophes”).
Equations like the Lotke-Volterra equations or the logistic map have been used to describe the chaotic growth and collapse of populations in nature, and for most of its existence Homo sapiens have been subject to similar natural checks on population size and accompanying booms and busts. Since shortly before the 1800s, however, it’s been nothing but up! up! up!, with the global population growing nearly eight-fold in little more than two centuries. Despite dire predictions of population collapse from classics like Paul Ehrlich’s The Population Bomb and the widespread consumption of algae and yeast by characters from the golden age of science fiction, the Green Revolution in agriculture largely allowed people to ignore the issue.
In recent decades the opposite of Matlhusianism, cornucopianism, has become increasingly popular. Cornucopians might point out that no one they know is starving right now, and believe that more people will naturally grow the carrying capacity for humans by being clever. This perspective is especially popular among people with substantial stock market holdings, as growing populations can buy more stuff. Many environmentalists decry the mention of a draw-down in human population as a way to affect environmental progress, pointing out the negative correlation in fertility and consumption disparities between richer and poorer nations. There are many other issues and accusations that typically pop up in any modern debate of human population and environmental concerns, but that’s not the topic of today’s post.
Regardless of where you fall on the spectrum from Malthusianism to cornucopianism, overpopulation vs. over-consumption, the fact remains: we don’t seem to know where to put all the poop.
In the spirit of optimism with a touch of cornucopianism and just in time for World Population Day 2020, here are three solutions for human population pressure from science fiction.
1. Explore The Possibilities of Soylent Green
I guess it’s a spoiler that in the movie Soylent Green, the eponymous food product is, indeed, made of people. Sorry if no one told you before. The movie has gone down as classic, campy, dystopian sci-fi, but it actually doesn’t have much in common with the book Make Room, Make Room by Harry Harrison it is based on. Both book and movie are set in a miserable New York City overpopulated to the tune of some 35 to 40 million people in the far-off future of 1999. The movie revolves around a murderous cover-up to hide the cannibalistic protein source in “Soylent Green,” while the book examines food shortages, climate catastrophe, inequality, and the challenges of an aging population.
Despite how well it works in the movie, cannibalism is not actually a great response to population pressure. Due to infectious prions , it’s actually a terrible idea to source a large proportion of your diet from the flesh of your own, or closely related species And before you get clever: cooking meat containing infectious mis-folded prions does not make it safe.
Instead of focusing on cannibalism, I’ll mention a few of the far-out ideas for producing sufficient food mentioned in the book. These include atomic whales scooping up vast quantities of plankton from the oceans, presumably artificially fertilized; draining swamps and wetlands and converting them to agricultural land; and irrigating deserts with desalinated seawater.
These suggestions are probably not even drastic enough to belong on this list. Draining wetlands for farmland and living space has historically been a common practice (polder much?), but it is often discouraged in modern times due to the environmental damage it can cause, dangers of building on floodplains, and recognition of ecosystem services provided by wetlands (e.g. CWA 404). Seeding the oceans by fertilizing them with iron or sand dust is sometimes discussed as a means to sequester carbon or provide more food for aquatic life. Family planning services are also mentioned as a way to help families while attenuating environmental catastrophe, but, as art imitates life, nobody in the book takes it seriously.
2. Make People 10X Smaller
If everyone was about 10 times shorter, they would weigh about 1000 times less and consume about that much fewer resources. The discrepancy in those numbers comes from the square-cube scaling law described by Galileo in 1638. To demonstrate with a simple example, a square has an area equal to the square of its side length, and a cube has a volume (and thus proportional weight) of the side length cubed. When applied to animal size this explains the increasing difficulty faced by larger animals to cool themselves and avoid collapsing under their own weight. So, if people were about 17 cm instead of about 170 cm they’d have a corresponding healthy body weight of about 0.63 kg instead of 63 kg (at a BMI of 21.75).
You can’t calculate the basal metabolic rate of a person that size using the Harris-Benedict equation without going into negative calories. If we follow the conclusion of (White and Seymour 2003) that mammalian basal metabolic rate scales proportional to body mass raised to 2/3, and assuming a normal basal metabolic rate of about 2000 kcal, miniaturization would decrease caloric needs by more than 20 times to about 92 calories a day. You could expect similar reductions in environmental footprints for transportation, housing, and waste outputs. Minsky estimated Earth’s carrying capacity could support about 100 billion humans if they were only a few inches tall, but this could be off by a factor of 10 in either direction. We should at least be able to assume the Earth could accommodate as many miniaturized humans as there are rats in the world currently, which is probably about as many as the ~16 billion humans at the upper end of UN estimates of world population by 2100.
Downsizing humans for environmental reasons was a major element in the 2017 film by the same name. But miniaturization comes with its own set of peculiarities to get used to. In Greg Egan’s 2002 novel Schild’s Ladder, Cass, one of the stories protagonists, is embodied in an avatar about 2 mm high after being transmitted to a deep-space research station with limited space. Cass experiences a number of differences in her everyday experience at her reduced size. She finds that she is essentially immune to damaging herself in collisions due to her decreased statue, and her vision is greatly altered due to the small apertures of her downsized eyes. The other scientists on the research station exist purely in software, taking up no room at all. But as long as people can live by computation on sophisticated computer hardware, why don’t we . . .
3. Upload Everyone
Greg Egan’s 1997 novel Diaspora has some of the most beautiful descriptions of existing in the universe as a thinking being ever committed to paper. That’s despite, or perhaps because of, the fact that most of the characters in the story exist as software incarnations running on communal hardware known as polises. Although simulated people (known as “citizens” in their polises) are the distant progeny of humans as we know them today, no particular weight is given to simulating their ancestral experience with any fidelity, making for a fun and diverse virtual world. Other valid lifestyle variations include physical embodiment as humanoid robots (called gleisners), and a wide variety of different modifications of biological humans. Without giving too much away, a group of biological humans are at some point given the offer of being uploaded in their entirety as software people. Whether bug or feature, the upload process is destructively facilitated by nanomachines collectively called Introdus. This seems like a great way to reduce existential risk while also reducing human environmental footprints. It’s a win-win!
Of course uploading predates 1997’s Diaspora by a long shot, and it’s practically a core staple of science-fiction besides. Uploading plays a prominent role in myriad works of science fiction including Greg Egan’s Permutation City from 1994, the Portal series of video games, the recent television/streaming series Upload, and many others. Perhaps the first story to prominently feature mind uploading is John Campbell’s The Infinite Brain published in Science Wonder Stories in 1930. The apparatus used to simulate a copy of the mind of the protagonist’s friend was a little different from our modern expectations of computers:
All of these were covered with a maze of little wheels and levers, slides and pulleys, all mounted on a series of long racks. At each end of the four tables a large electric motor, connected to a long shaft. A vast number of little belts rose up from this, and were connected with numberless cog wheels, which in their turn engaged others. There seemed to be some arrangement of little keys, resting on metal plates, and a sort of system of tiny slugs, like the matrices on a linotype; but everything was so mixed up with wires and coils and wheels that it was impossible to get any of the details.
I don’t know if any of the stories of mind uploading from fiction have environmental conservation as the main goal. There’s a lot of cool stuff you could do if you are computationally embodied in a simulated environment, and interstellar travel becomes a lot more tenable if you can basically transmit yourself (assuming receivers are available where you want to go) or push a few kgs of supercomputer around the galaxy with lasers and solar sails. Even if you choose the lifestyle mostly for fun, There should be substantial savings on your environmental footprint, eventually. Once we manage to match or exceed the power requirements of about 20 Watts for a meat-based human brain with a simulated mind, it should be reasonably easy to get that power from sustainable sources. Of course, current state-of-the-art models used in machine learning require substantially more energy to do substantially less than the human brain, so we’ll need to figure out a combination of shortcuts and fundamental breakthroughs in computing to make it work.
Timescales and Tenability
The various systems supporting life on Earth are complex enough to be essentially unpredictable at time scales relevant to human survival. We can make recently predictions about very long time scales: we can reasonably assert that several billion years from now when the sun will enter the next phases of its life cycle, making for a roasty situation a cold beverage is unlikely to rectify (it will boil away), and at short time scales: the sun is likely to come up tomorrow, mostly unchanged from what we see today. But any detailed estimate of the situation in a decade or two is likely to be wrong. Bridging those time scales with reasonable predictions takes deliberate, sustained effort, and we’re likely to need more of that to avoid existential threats.
Hopefully this list has given you ample food for thought to mull over as humans continue to multiply like so many bacteria. I’ll end with a fitting quote from Kurt Vonnegut’s Breakfast of Champions based on a story by fictional science fiction author Kilgore Trout:
“Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement.”