Approximately 66 million years in the past, a celestial body, identified as an asteroid, traversed Earth’s atmosphere and impacted the ocean floor. This cataclysmic event unleashed an explosion exceeding 6.5 billion times the magnitude of the atomic bomb detonated by the United States over Hiroshima.

The reverberations of this impact propelled vast quantities of particulate matter and sulfurous compounds into our planet’s atmosphere, effectively obscuring solar illumination and diminished thermal radiation for a span of about two years. Consequently, the fundamental process of photosynthesis ceased, halting all vegetal proliferation. The surviving dinosaur populations, deprived of their food sources, ultimately succumbed to extinction.

However, paleontological evidence indicates that fungi experienced a period of significant proliferation in the ensuing environmental conditions.

According to Bryan Walsh, a science journalist and editor at Vox, this ecological resilience positions mushrooms as instrumental to human perseverance should a comparable apocalyptic scenario materialize in the future.

Walsh’s 2019 publication, titled End Times, meticulously investigates the existential threats posed by both natural and anthropogenic catastrophic events. Within its pages, he highlights a shared characteristic among three primary categories of potential disasters – asteroid impacts, supervolcanic eruptions, and nuclear warfare – namely, their capacity to impede the sunlight essential for plant sustenance.

“Obscure the sun, and even the most adept survivor, a paragon of wilderness proficiency, will inevitably face starvation, along with the rest of humanity,” Walsh asserts in his work.

To ensure continued existence, he posits the necessity of adopting agricultural methodologies that do not rely on solar energy, specifically the cultivation of mushrooms, rodents, and insects.

Nuclear war, asteroids, or supervolcanoes could block the Sun

Scientific examinations suggest that the ramifications of supervolcano expulsions and nuclear detonations could mirror the aftermath of the asteroid impact that precipitated the demise of the dinosaurs.

For instance, an eruption of the Toba supervolcano approximately 74,000 years ago released substantial volumes of sulfur dioxide into the atmosphere, resulting in a reduction of solar irradiance by as much as 90 percent. This volcanic winter may have drastically contracted the global human population to a mere 3,000 individuals, according to one evaluation.

Should a multitude of nuclear detonations (in the thousands) occur, a similar nuclear winter scenario, dramatically diminishing sunlight levels by over 90 percent, could be induced. This projection, based on a seminal 1983 publication co-authored by Carl Sagan, indicates a potential global temperature decrease of up to 45 degrees Fahrenheit (25 degrees Celsius).

“Such swift and extreme climatic cooling would render agricultural practices infeasible, even in geographical areas unaffected by missile trajectories,” Walsh observes.

Essentially, the absence of sunlight would lead to the collapse of our established food supply chains.

The proposition of mushroom cultivation as a survival strategy, detailed in Walsh’s book, originates from David Denkenberger, a civil engineer. He introduced this concept in his 2014 book on post-apocalyptic sustenance, titled Feeding Everyone No Matter What.

“Perhaps upon humanity’s extinction, the dominion of fungi will be re-established,” Denkenberger conveyed to Walsh. “Why should we not embrace the consumption of mushrooms and avert our own extinction?”

Mushrooms do grow on trees, with or without the Sun

In the event of atmospheric obfuscation by particulate clouds or volcanic ash, leading to a rapid climatic downturn, colossal numbers of trees would perish. While humans would be incapable of processing this desiccated wood, fungi possess the ability to do so, independent of photosynthetic processes.

Walsh’s estimations suggest that a log measuring three feet in length (0.9 meters) and four inches in circumference should yield 2.2 pounds (1 kilogram) of mushrooms over a four-year period.

While this quantity might seem modest, Denkenberger postulates that with a reduced post-disaster population and optimized fungal propagation, this approach could prove viable.

Concurrently with mushroom cultivation utilizing lumber, the foliage from these deceased arboreal specimens could also be repurposed, he noted.

“The pulverized leaves could be brewed into a tonic to supply essential micronutrients such as vitamin C, or alternatively, fed to herbivorous animals like cattle or rodents,” Denkenberger informed Walsh.

Dead trees can feed other life forms, like rats and insects

Rodents, akin to fungi, exhibit the capacity to metabolize cellulose, the primary sugar constituent that comprises 50 percent of wood’s composition. Therefore, any residual organic matter left by fungal decomposition could potentially nourish these rodents, as suggested by Walsh. This pathway could furnish a protein source for human survivors.

Furthermore, rats possess a rapid reproductive rate and likely do not require sunlight for procreation, Walsh adds. A rat reaches sexual maturity within a mere six weeks, and subsequently, within 70 days, it can produce a litter of seven to nine offspring. Denkenberger’s calculations indicate that the entire human populace could subsist on rats within a two-year timeframe following a catastrophic event.

Invertebrates could also serve as a supplementary protein source, and a substantial proportion of insect species are anticipated to endure even the most pervasive, climate-altering existential catastrophes.

“The very attributes that contribute to the ubiquity and resilience of insects would enable numerous species to surmount even the most extensive, climate-altering existential calamities,” Walsh observes. “Beetles subsist on decaying wood, and humans, in turn, can subsist on beetles.”

Entomophagy is already an established dietary practice in various global regions and is concurrently gaining traction in other locales. Walsh recounts his experience at an insect food exposition in Richmond, Virginia, where he sampled a pasta dish featuring ground cricket meatballs, known as “Orthopteran Orzo,” and deep-fried mealworm larvae.

“Both offerings were palatable,” he states. “However, faced with starvation, I would certainly find them acceptable.”

Survivors would band together

Walsh’s book critically examines and refutes another prevalent notion regarding sustenance during an apocalypse: cannibalism.

He contends that such a practice would be counterproductive in the aftermath of a cataclysm that threatens human extinction, as fellow humans do not represent a sustainable food resource. Walsh references a 2017 study conducted by undergraduate students, which modeled the survival duration of the human species if reliance were solely placed on cannibalism. Their findings indicated that only a single individual would remain after 1,149 days, approximating a three-year period.

He further asserts, however, that the establishment of a new agricultural framework would necessitate collective endeavor. He anticipates that such cooperative efforts would likely emerge in a disaster scenario.

This article was originally published by Business Insider.

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