A scene from the last phase of Ragnarök, after Surtr has engulfed the world with fire, painted by Emil Doepler c. 1905. Image: Haukurth/Wikimedia Commons.
With COVID-19 afflicting the world, and a climate crisis looming, humanity’s future seems uncertain. While the novel coronavirus does not itself pose a threat to the continuation of the species, it has undoubtedly stirred anxiety in many of us and has even sparked discussion about human extinction. Less and less does the end of the species seem an area of lurid fantasy or remote speculation.
Indeed, the opening decades of the 21st century have seen investigation into so-called ‘existential risks’ establish itself as a growing field of rigorous scientific inquiry. Whether designer pathogen or malicious AI, we now recognise many ways to die.
But when did people first start actually thinking about human extinction?
The answer is: surprisingly recently. As ideas go, the idea of the extinction of the human species is a new one. It did not, and could not, exist until a few centuries ago.
Of course, we humans have probably been prophesying the end of the world since we began talking and telling stories. However, the modern idea of human extinction distinguishes itself from the tradition of apocalypse as it is found across cultures and throughout history.
In the ancient mythologies you will not find the idea of a physical universe continuing, in its independent vastness, after the annihilation of humans. Neither will you find the idea of the end of the world as a totally meaningless event. It is invariably imbued with some moral significance or revelatory lesson. Meaning and value lives on in a spiritual afterlife, in anthropomorphic gods, or an eventual rebirth of creation.
Only very recently in human history did people realise that Homo sapiens, and everything it finds meaningful, might permanently disappear. Only recently did people realise the physical universe could continue — aimlessly — without us. However, this was one of the most important discoveries humans have ever made. It is perhaps one of our crowning achievements. Why? Because we can only become truly responsible for ourselves when we fully realize what is at stake. And, in realizing that the entire fate of human value within the physical universe may rest upon us, we could finally begin to face up to what is at stake in our actions and decisions upon this planet. This is a discovery that humanity is still learning the lessons of — no matter how fallibly and falteringly.
Such a momentous understanding only came after centuries of laborious inquiry within science and philosophy. The timeline below revisits some of the most important milestones in this great, and ongoing, drama.
c.75,000 BP: Toba supervolcanic eruption rocks the planet. Some evidence implies Homo sapiens nearly goes extinct (though scientists disagree on the details). Around the same time, advanced human behavior and language emerge: This kickstarts cumulative culture, as recipes for technology begin to accumulate across generations. An immense journey begins…
Phase 1 (Prehistory to 1600): Indestructible value
No clear distinction between ethics and physics, so no true threat to the existence of ethics in the physical universe. Indestructibility of value. No ability to think of a possible world without minds.
c.400 BC: Even though they talk of great catastrophes and destroyed worlds, ancient philosophers all believe that nature does not leave eternally wasted opportunities where things, or values, could be but never are again. Whatever is lost in nature will eventually return in time — indestructibility of species, humanity, and value.
c.360 BC: Plato speaks of cataclysms wiping away prior humanities, but this is only part of eternal cycling return. Permanent extinction is unthinkable.
c.350 BC: Aristotle claims that everything valuable and useful has already been discovered. Everything knowable and useful can be found in the ‘wisdom of the ages.’ Precludes thinking on perils and risks that have not previously been recorded. Material conditions of mankind cannot radically change, or fail.
c.50 BC: Lucretius speaks of humankind ‘perishing,’ but also asserts that nothing is ever truly destroyed in nature, and that time eventually replenishes all losses. Our world may die, but it will eventually be remade.
c.1100 AD: Persian theologian Al-Ghazâlî develops ways of talking about possibilities in terms of their logical coherence rather than availability to prior experience — crucial to all later thinking on risks previously never experienced.
c.1200: Hindu-Arabic numeral system introduced to Europe, later allowing computation of large timespans that will be instrumental in discovery of the depth (rather than eternity) of past and future time.
c.1300: Islamic and Christian philosophers invent logical possibility as a way of thinking about the ways God could have created the world differently than it actually is. Theologians like William of Ockham conduct first thought experiments on a possible world without any human minds. Still, God would never manifest such a world, they believe.
1350: Black death kills up to 200 million people in Europe and North Africa. Around 60 percent of Europe’s population perishes.
1564: Using new logical conceptions of possibility, Gerolamo Cardano inaugurates the science of probability by thinking of each dice throw as the expression of a wider, abstract space of possibilities.
Phase 2 (1600-1800): Cosmic nonchalance
Modern physics implies that ours is one planet among many, but it is generally presumed that the universe is habitable and filled with humanoids. For every populated planet destroyed, another grows. Species cannot die. Indestructibility of value continues. Inability to recognise existential stakes.
1600s: Copernican Revolution gains momentum. Growing acceptance, following supernova sightings, that planets and suns can be destroyed. But from stars to species, nothing can be lost: It will regrow again elsewhere.
1680s: Breaking with orthodoxy, Robert Hooke and Edmond Halley controversially endorse the idea of prehistoric extinctions caused by massive geological cataclysms. Such conjectures remain fringe, however.
1705: Following Leibniz and Newton’s invention of calculus, long-term prediction of nature becomes feasible. Halley predicts the return of his comet.
1721: Population science takes hold: People start thinking of Homo sapiens as a global aggregate. Baron de Montesquieu writes of humanity expiring due to infertility.
1740s: Reports of behemoth fossil remains found in Siberia and America begin to interest, and confuse, naturalists. Could these be extinct beasts?
1750s: Speculations on human extinction, as a naturalistic possibility, begin to emerge. Yet many remain confident that humans would simply re-evolve on Earth.
1755: Lisbon earthquake shocks Europe. Influential geologist Georges Buffon accepts prehistoric species extinctions, ponders on which animals will inherit the Earth after we are gone.
1758: Linnaeus adds genus Homo to his taxonomy. Halley’s comet returns, confirming his prediction.
1763: Thomas Bayes’s revolutionary work on probability is published, providing rules for thinking about probabilities of events prior to any trials. Proves essential to later thinking on risks beyond precedent.
1770s: First declarations that Homo sapiens may be specific and unique to the Earth, and thus contingent upon the planet’s particular conditions. Baron d’Holbach writes that, if Earth were destroyed, our species would irreversibly disappear with it.
1773: Probability theory applied to issues of global catastrophic risk: Joseph Lalande computes likelihood of Earth being hit by a comet intersecting our orbit.
1778: Georges Buffon provides first experimental calculations of the window of planetary habitability, argues that eventually Earth will become irreversibly uninhabitable.
1781: Enlightenment philosophy culminates in Kant’s critique of the way we bias and distort our objective theories with our moral prejudices. We may like the idea that the amount of value is constant in the universe, and that valuable things cannot irreversibly be destroyed, but that doesn’t mean it is true.
1790s: Deep time and prehistoric extinctions accepted as scientific consensus. Modern palaeontology and geology are born. They unveil a radically nonhuman past. Georges Cuvier theorises our planet has been wracked by many catastrophes throughout its past, wiping out scores of creatures.
1796: First notions of long-term human potential — to alter material conditions and alleviate suffering — begin to come together in the work of (e.g.) Condorcet. Meanwhile, Marquis de Sade becomes the first proponent of voluntary human extinction. Pierre-Simon Laplace says that the probability of a cometary collision is low but will ‘accumulate’ over long periods of time. He remains confident that civilisation would re-emerge and be replayed, however.
1800: By the century’s close, George Cuvier has identified 23 extinct prehistoric species.
Phase 3 (1800-1950): Cosmic loneliness
Growing recognition that the entire universe may not be maximally habitable nor inhabited. Cosmic default is hostility to life and value. Many accept human extinction as irreversible and plausible — but not yet a pressing probability.
1805: Jean-Baptiste François Xavier Cousin De Grainville writes first fiction on The Last Man. He then kills himself.
1810s: Human extinction first becomes a topic in popular culture and popular fiction. People start more clearly regarding it as a moral tragedy. Value begins to seem insecure in the universe, not indestructible.
1812: Scientists claim the Mars-Jupiter asteroid belt is the ruins of a shattered planet. Joseph-Louis Lagrange attempts to precisely compute the exact explosive force required.
1815: Eruption of Mount Tambora causes famine in China and Europe and triggers cholera outbreak in Bengal. Volcanic dust in the atmosphere nearly blots out the sun; the perturbation provokes visions of biosphere collapse.
1826: Mary Shelley’s The Last Man, depicting humanity perishing due to a global pandemic. First proper depiction of an existential catastrophe where nonhuman ecosystems continue after demise of humanity: Our end is not the end of the world.
1830s: Proposing catastrophes as explanations in astrophysics and geophysics falls into disrepute, the argument that the cosmos is a stable and steady system wins the day, this obstructs inquiry into large-scale cataclysms for over a century.
1844: Reacting to Thomas Malthus’s theories of overpopulation, Prince Vladimir Odoevsky provides first speculation on omnicide (i.e. human extinction caused by human action). He imagines our species explosively committing suicide after resource exhaustion and population explosion cause civilisation’s collapse. Odoevsky also provides first visions of human economy going off-world in order to stave off such outcomes.
c.1850: Large reflecting telescopes reveal deep space as mostly empty and utterly alien. Artistic depictions of Earth from space begin to evince a sense of cosmic loneliness.
1859: Darwin’s “The Origin of Species” published. Progressivist tendencies in early evolutionary theory fuel confidence in human adaptiveness and inexorable improvement. Fears of extinction are eclipsed by fears of degeneration.
1863: William King hypothesises that fossil remains found in Neander valley represent an extinct species of the genus Homo. The ‘Neanderthal man’ becomes first extinct hominin species to be recognised. 1865: Rudolf Clausius names ‘entropy’ and theorises the universe’s heat death. Despite provoking gloomy visions from writers like Henry Adams and Oswald Spengler, it seems far off enough to not be pressing.
1890s: Russian Cosmism launched with the first writings of Fedorov and Tsiolkovsky, making clear the stakes of extinction: They both realise that the only route to long-term survival is leaving Earth. First calls to escape X-risk by securing humanity’s foothold in the wider cosmos.
1895: Tsiolkovsky provides first vision of a Dyson sphere: a sun-girdling sphere that allows full harnessing of solar energy. Suggests mega-scale restructuring of the Solar System in order to further secure human civilisation and ensure its long-term future.
1918: Great War provokes many intellectuals (including Winston Churchill) to ponder omnicide, but still a remote possibility. Physicists begin to realise how stringent and rare the conditions of habitability may be. Yet belief in humanoids inevitably re-evolving remains high.
c.1930: J.B.S. Haldane and J.D. Bernal provide first coherent synthesis of ideas regarding long-term potential, existential risk, space colonisation, astroengineering, transhumanism, bioenhancement, and civilisational pitfalls. Haldane notes that if civilisation collapses, yet humanity survives, there is no guarantee advanced civilisation would re-evolve.
1937: Olaf Stapledon further synthesises these ideas into a comparative study of omnicide in his awe-inspiring Star Maker.
Phase 4 (~1950 to present): Astronomical value
Nuclear weapons, for the first time, make extinction a policy issue. It shifts from speculative possibility to pressing plausibility. Anthropogenic risks come to fore. Birth of internet gives critical mass to previously disparate communities. Finally, a rigorous framework for thinking analytically about X-risk is developed around the millennium.
1942: Edward Teller fears that a nuclear fission bomb could plausibly ignite the atmosphere of the Earth and destroy all life. Development of the bomb goes ahead regardless, even though scientists later concluded more research was needed to ascertain that this biosphere-annihilating event would definitely not occur.
1945: Hiroshima and Nagasaki. Atom bomb changes how we relate to intelligence’s place in the cosmos. Faith in inevitable progress takes a battering. Rather than recurrent and omniprevalent owing to its adaptiveness, technological intelligence comes to be considered as potentially rare and even maladaptive.
1950: Leó Szilárd suggests the feasibility of a planet-killing ‘cobalt bomb.’ Enrico Fermi articulates the most significant riddle of modern science, the Fermi Paradox. Catastrophism begins to reassert itself, with scientists asking whether supernovas caused past mass extinctions.
1950s: The modern field of AI research begins in earnest.
1960s: Initial SETI projects return only ominous silence. Biologists begin to insist that humanoids would not necessarily evolve on other planets. Dolphin research suggests alternative models of intelligence. Technological civilisation appears increasingly contingent, heightening the perceived severity of X-risk.
1962: Rachel Carson’s book Silent Spring raises the alarm on climate catastrophe.
1965: I.J. Good speculates that an AI could recursively improve itself and thus trigger a runaway ‘intelligence explosion,’ leaving us far behind. It will be our ‘last invention,’ he muses.
Late 1960s: Fears of overpopulation reassert themselves in neo-Malthusianism. Growing discussion that space colonisation is the only long-term guarantee for human flourishing and survival. In line with this, scientists like Freeman Dyson propose large-scale astroengineering as a method to further entrench and fortify the foothold of intelligence within the universe.
1969: First crewed mission lands on the moon.
1973: Brandon Carter articulates the Anthropic principle. Goes on to derive the Doomsday Argument from it, which uses Bayesian probability to estimate how many generations of humans are likely to yet be born.
1980s: Bayesian methods vindicated in statistics. Luis and Walter Alvarez report findings that lead to consensus that an asteroid or comet killed the dinosaurs. Through this, catastrophism is vindicated: astronomical disasters can significantly affect (and threaten) terrestrial life.
1982: Jonathan Schell pens The Fate of the Earth, stressing nuclear threat and the moral significance of the foreclosure of humanity’s entire future.
1984: Derek Parfit publishes Reasons and Persons. Population ethics clarifies the unique moral severity of total human extinction.
1986: A year after a hole in the ozone layer is discovered in Antarctica, Eric Drexler publishes Engines of Creation, hinting to X-risks from nanotech.
1989: Stephen Jay Gould publishes Wonderful Life, insisting that humanoid intelligence is not the inevitable result of evolution. In his Imperative of Responsibility, Hans Jonas demands a ‘new ethics of responsibility for the distant future.’
1990s: NASA tasked with tracking threats from asteroids and near-Earth objects. Internet allows convergence of disparate communities concerned about transhumanism, extropianism, longtermism, etc.
1996: John Leslie publishes The End of the World: The Science and Ethics of Human Extinction. Landmark text meticulously studying Carter’s Doomsday Argument.
2000: Marvin Minsky suggests that an AI tasked with solving the Riemann hypothesis might unwittingly exterminate humanity by converting us, and all available matter in the Solar System, into ‘computronium’ so that it has the resources for the task.
2002: Nick Bostrom introduces the term ‘existential risk.’
2010s: Deep learning takes off, triggering another boom in AI research and development.
2012: Researchers engineer artificial strains of H5N1 virus that are both highly lethal and highly virulent.
2013: CRISPR-Cas9 first utilised for genome editing.
2018: IPCC special report on the catastrophic impact of global warming of 1.5ºC published.
2020: Toby Ord publishes The Precipice. COVID-19 pandemic sweeps the globe, demonstrating systemic weakness and unpreparedness for global risks.
Thomas Moynihan is a writer from the UK, currently working with Oxford University’s Future of Humanity Institute. His work explores the history of ideas about human extinction and existential risk. His most recent book is X-Risk: How Humanity Discovered Its Own Extinction, from which this article is adapted. It was first published by the MIT Press Reader, and has been republished here with permission.