Human extinction

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Human extinction is the end of the human species. Various scenarios have been discussed in science, popular culture and religion (see End time). The scope of this article is existential risks. Humans are very widespread on the Earth, and live in communities which (whilst interconnected) are capable of some kind of basic survival in isolation. Therefore, pandemic and deliberate killing aside, to achieve human extinction, the entire planet would have to be rendered uninhabitable, with no opportunity provided or possible for humans to establish a foothold beyond Earth. This would typically be during a mass extinction event, a precedent of which exists in the Permian–Triassic extinction event among other examples.
In the near future, anthropogenic extinction scenarios exist: global nuclear annihilation, total global war, overpopulation^[1] or global accidental pandemic; besides natural ones: Meteor impact and large scale volcanism; and anthropogenic-natural hybrid events like global warming and catastrophic climate change. Naturally caused extinction scenarios have occurred multiple times in the geologic past although the probability of reoccurrence within the human timescale of the near future is infinitesimally small. As technology develops, there is a theoretical possibility that humans may be deliberately destroyed by the actions of a nation state, corporation or individual in a form of global suicide attack. There is also a theoretical possibility that technological advancement may resolve or prevent potential extinction scenarios. The emergence of a pandemic of such virulence and infectiousness that very few humans survive the disease is a credible scenario. While not necessarily a human extinction event, this may leave only very small, very scattered human populations that would then evolve in isolation. It is important to differentiate between human extinction and the extinction of all life on Earth. Of possible extinction events, only a pandemic is selective enough to eliminate humanity while leaving the rest of complex life on earth relatively unscathed.

Contents

• 1 Possible scenarios
  • 1.1 Severe forms of known or recorded disasters
  • 1.2 Environmental collapses
  • 1.3 Long-term habitat threats
  • 1.4 Population decline
  • 1.5 Scientific accidents
  • 1.6 Scenarios of extraterrestrial origin
  • 1.7 Other
• 2 Perception of human extinction risk
• 3 Observations about human extinction
  • 3.1 Omnicide
• 4 In popular culture
• 5 See also
• 6 Notes
• 7 References
• 8 Further reading

Possible scenarios

See also: Risks to civilization, humans and planet Earth

It has been suggested that this article be merged with Risks to civilization, humans and planet Earth. (Discuss) Proposed since July 2010.

Severe forms of known or recorded disasters

• Nuclear or biological warfare;^[2] see World War III.
• Pandemic^[2] involving an antibiotic-resistant bacterium, antifungal-resistant fungus, prion, or antiviral-resistant virus. Past examples include the Spanish flu outbreak in 1918 and the 2009 flu pandemic.

Environmental collapses

• Dramatic temperature fluctuations or changes, such as catastrophic global warming^{[citation needed]}
• Occurrence of a large-scale volcanism,^{[citation needed]} possibly a supervolcano (250 million years ago, after the Permian–Triassic extinction event life on land took 30 million years to recover).^[3]

Long-term habitat threats

• In about 1 billion years from now, the Earth's oceans will disappear, due to the Sun brightening. However, well before this, the level of carbon dioxide in the atmosphere will be too low to support plant life, destroying the foundation of the food chains.^[4] See Future of the Earth.
• In about 5-6 billion years from now, the Sun will start to become a red giant. The oceans and the much of the atmosphere will boil away and the Earth's temperature will rise well above the boiling point of water. About 7-8 billion years from now, the Earth will probably be engulfed by an expanding Sun and destroyed.^[5][6]

Population decline

Further information: Population decline

• Preference for fewer children; if developed world demographics are extrapolated they mathematically lead to 'soft' extinction before 3000 CE. (John A. Leslie estimates that if the reproduction rate drops to the German level the extinction date will be 2400.^[1])
• A World government with a eugenic or small population policy could send humanity into 'voluntary' extinction.^{[citation needed]}
  • Political intervention in reproduction has failed to raise the birth rate above the replacement level in the rich world, but has dramatically succeeded in lowering it below the replacement level in China.^{[citation needed]} (See One child policy.)

Scientific accidents

• The creators of the first "superintelligent" entity could make a mistake and inadvertently give it goals that lead it to immediately "annihilate" the human race.^[2][7]
• In his book Our Final Hour, Sir Martin Rees claims that without the appropriate regulation, scientific advancement increases the risk of human extinction as a result of the effects or use of new technology. Some examples are provided below.
  • Uncontrolled nanotechnology (grey goo) incidents resulting in the destruction of the Earth's ecosystem (ecophagy).
  • Creation of a "micro black hole" on Earth during the course of a scientific experiment, or other foreseeable scientific accidents in high-energy physics research, such as vacuum phase transition or strangelet incidents. There were worries concerning the Large Hadron Collider at CERN as it is feared that collision of protons at a speed near the speed of light will result in the creation of a black hole, but it has been pointed out that much more energetic collisions take place currently in Earth's atmosphere.

Scenarios of extraterrestrial origin

• Major impact events.
• If a rogue black hole passed near the Sun, it could disrupt Earth's orbit. (See "A Pail of Air".)
• Gamma-ray burst in our part of the Milky Way. (Bursts observable in other galaxies are calculated to act as a "sterilizer", and have been used by some astronomers to explain the Fermi paradox.) The lack of fossil record interruptions, and relative distance of the nearest Hypernova candidate make this a long term (rather than imminent) threat.
  • Wolf-Rayet star WR 104, which is 8000 light years from the Sun, may produce a gamma ray burst aimed at the Sun when it goes supernova.
• Invasion by militarily superior extraterrestrials (see alien invasion) — often considered to be a scenario purely from the realms of science fiction, professional SETI researchers have given serious consideration to this possibility, but conclude that it is unlikely.^[2]
  • Gerard O'Neill has cautioned that first contact with alien intelligence may follow the precedent set by historical examples of contact between human civilizations, where the less technologically-advanced civilization has inevitably succumbed to the other civilization, regardless of its intentions.
• A vacuum phase transition could destroy the universe.
• Biological contamination upon contact with extraterrestrial life.^{[citation needed]}

Other

• Modification of humans into a new species
  • Technological transition into a posthuman life-form or existence.
    • Commentators such as Kevin Warwick point to the possibility of humans evolving by linking with technology;^[8] while others have argued that humanity will inevitably experience a technological singularity, and furthermore that this outcome is desirable (see singularitarianism).
  • Natural Evolution of humanity into another hominid species. Humans will continue to evolve via traditional natural selection over a period of millions of years, and homo sapiens may gradually transition into one or more new species.
• Evolution of another species that out-competes humans for food, habitat or hunts as prey.^{[citation needed]}

Perception of human extinction risk

The general level of fear about human extinction, in the near term, is very low, despite the pronouncements of some fringe groups. It is not an outcome considered by many as a credible risk. Suggested reasons for human extinction's low public visibility:

1. There have been countless prophecies of extinction throughout history; in all cases the predicted date of doom has passed without much notice, such as 2012, making future warnings less frightening. However, a survivor bias would undercut the credibility of accurate extinction warnings. John von Neumann was probably wrong in having “a certainty”^[3] that nuclear war would occur; but our survival is not proof that the chance of a fatal nuclear exchange was low (or indeed that such an event could not occur in the future).
2. Extinction scenarios (see below) are speculative, and hard to quantify. A frequentist approach to probability cannot be used to assess the danger of an event that has never been observed by humans.
3. Nick Bostrom, head of the James Martin 21st Century School Future of Humanity Institute, has suggested that extinction risk-analysis may be an overlooked field because it is both too psychologically troublesome a subject area to be attractive to potential researchers and because the lack of previous human species extinction events leads a depressed view of the likelihood of it happening under changing future circumstances (an 'inverse survivorship bias').
4. There are thousands of public safety jobs dedicated to analyzing and reducing the risks of individual death. There are no full-time existential safety commissioners partly because there is no way to tell if they are doing a good job, and no way to punish them for failure. The inability to judge performance might also explain the comparative governmental apathy on preventing human extinction (as compared to panda extinction, say).
5. Some anthropologists believe that risk perception is biased by social structure; in the "Cultural Theory of risk" typography "individualist" societies predispose members to the belief that nature operates as a self-correcting system, which will return to its stable state after a disturbance. People in such cultures feel comfortable with a "trial-and-error" approach to risk, even to unsuitably rare dangers (such as extinction events).
6. It is possible to do something about dietary or motor-vehicle health threats. Since it is much harder to know how existential threats should be minimized^[4], they tend to be ignored. High technology societies tend to become "hierarchist" or "fatalist" in their attitudes to the ever-multiplying risks threatening them. In either case, the average member of society adopts a passive attitude to risk minimization, culturally, and psychologically.
7. The bias in popular culture is to relate extinction scenario stories with non-extinction outcomes. (None of the 16 'most notable' WW3 scenarios in film are resolved by human extinction, for example.^[5])
8. The threat of nuclear annihilation actually was a daily concern in the lives of many people from the 1950s through the 1980s. Since then the principal fear has been of localized terrorist attack, rather than a global war of extinction.
9. Some people have philosophical reasons for doubting the possibility of human extinction, for instance the final anthropic principle, plenitude principle or intrinsic finality.
10. Tversky and Kahneman have produced evidence that humans suffer cognitive biases which would tend to minimize the perception of this unprecedented event:
    1. Denial is a negative "availability heuristic" shown to occur when an outcome is so upsetting that the very act of thinking about it leads to an increased refusal to believe it might occur. In this case, imagining human extinction probably makes it seem less likely.
    2. In cultures where human extinction is not expected the proposition must overcome the "disconfirmation bias" against heterodox theories.
    3. Another reliable psychological effect relevant here is the "positive outcome bias".
    4. Behavioural finance has strong evidence that recent evidence is given undue significance in risk analysis. Roughly speaking, "100 year storms" tend to occur every twenty years in the stock market as traders become convinced that the current good times will last forever. Doomsayers who hypothesize rare crisis-scenarios are dismissed even when they have statistical evidence behind them. An extreme form of this bias can diminish the subjective probability of the unprecedented.^[6]

In general, humanity's sense of self preservation, and intelligence are considered to offer safe-guards against extinction. It is felt that people will find creative ways to overcome potential threats, and will take care of the precautionary principle in attempting dangerous innovations. The arguments against this are; firstly, that the management of destructive technology is becoming difficult, and secondly, that the precautionary principle is often abandoned whenever the reward appears to outweigh the risk. At least one instance where the principle may have been overruled was when prior to the Trinity nuclear test, one of the project's scientists (Teller) speculated that the fission explosion might destroy New Mexico and possibly the world, by causing a reaction in the nitrogen of the atmosphere. A calculation by Hans Bethe proved such a possibility theoretically impossible, but the fear of the possibility remained among some until the test took place.

Observations about human extinction

The fact that the vast majority of the species that have existed on Earth have become extinct, has led to the suggestion that all species have a finite lifespan and thus human extinction would be inevitable. Dave Raup and Jack Sepkoski found for example a twenty-six-million-year periodicity in elevated extinction rates, caused by factors unknown (See David M. Raup. "Extinction: Bad Genes or Bad Luck" (1992, Norton). Based upon evidence of past extinction rates Raup and others have suggested that the average longevity of an invertebrate species is between 4-6 million years, while that of vertebrates seems to be 2-4 million years. The shorter period of survival for mammals lies in their position further up the food chain than many invertebrates, and therefore an increased liability to suffer the effects of environmental change. A counter-argument to this is that humans are unique in their adaptive and technological capabilities, so it is not possible to draw reliable inferences about the probability of human extinction based on the past extinctions of other species. Certainly, the evidence collected by Raup and others suggested that generalist, geographically dispersed species, like humans, generally have a lower rate of extinction than those species that require a particular habitat. In addition, the human species is probably the only species with a conscious prior knowledge of their own demise, and therefore would be likely to take steps to avoid it.
Humans are very similar to other primates in their propensity towards intra-species violence; Jared Diamond's The Third Chimpanzee (ISBN 0-09-980180-9) estimates that 64% of hunter-gather societies engage in warfare every two years. Although it has been argued (e.g. in the UNESCO Seville Statement) that warfare is a cultural artifact, many anthropologists^{[citation needed]} dispute this, noting that small human tribes exhibit similar patterns of violence to chimpanzee groups, the most murderous of the primates, and one of two of our nearest living genetic relatives. The "higher" functions of reason and speech are more developed in the brain of Homo sapiens than other primates, but the relative size of the limbic system is a constant in apes, monkeys and humans. The combination of inventiveness and urge to violence in humans has been cited as evidence against its long term survival.^[7]

Omnicide

Omnicide is human extinction as a result of human action. Most commonly it refers to extinction through nuclear warfare or biological warfare,^[9][10][11] but it can also apply to extinction through means such as global anthropogenic ecological catastrophe.^[12]
Omnicide can be considered a subcategory of genocide.^[13] Using the concept in this way, one can argue, for example, that:

“

The arms race is genocidal in intent given the fact that the United States and the Soviet Union are knowingly preparing to destroy each other as viable national and political groups.[14]

”

As this claim illustrates, the concept of omnicide raises issues of human agency and, hence, of moral responsibility in discussions about large-scale social processes like the nuclear arms race or ecologically destructive industrial production. That is, part of the point of describing a human extinction scenario as 'omnicidal' is to note that, if it were to happen, it would result not just from natural, uncontrollable evolutionary forces, or from some random catastrophe like an asteroid impact, but from deliberate choices made by human beings. This implies that such scenarios are preventable, and that the people whose choices make them more likely to happen should be held morally accountable for such choices. In this context, the label 'omnicide' also works to de-normalize the course of action it is applied to.

In popular culture

The book The World Without Us by Alan Weisman deals with a thought experiment on what would happen to the planet and especially human-made infrastructures if humans suddenly disappeared. The Discovery Channel documentary miniseries The Future Is Wild shows the possible future of evolution on Earth without humans. The History Channel's special Life After People examines the possible future of life on Earth without humans, and was made into a series of the same name. The National Geographic Channel's special Aftermath: Population Zero envisions what the world be like if all humans suddenly disappeared. The British science-fiction drama Primeval also puts forward an alternative view of Earth after the extinction of humans: how other species of animals, such as rodents and insects will evolve to fill niches left by humans. The video-game franchise, Pikmin depicts the main character, Captain Olimar, arriving on a planet hugely resembling Earth, yet no humans are seen. Pikmin 2 depicts Olimar and his new partner, Louie, returning to the Pikmin Planet to collect "treasures". These treasures are usually man-made items like bottle caps and batteries. The threat of human extinction and its effect on society is present in many science fiction stories including Warhammer 40,000, Mass Effect, and Titan A.E..

See also

• 10 Ways to End the World
• 2012 phenomenon (Numerologically derived eschatology, with arbitrary extinction mechanism.)
• Death from the Skies
• Extinction
• Extinction event
• Holocene extinction event
• Mutual assured destruction
• Risks to civilization, humans and planet Earth
• Space and survival
• Toba catastrophe theory
• Voluntary Human Extinction Movement