is the hypothetical end of the
scenarios have been discussed in science
, and religion
(see End time
The breadth of this article is on 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. This would
typically be during a mass
event, a precedent of which exists in the Permian–Triassic
among other examples.
In the near future, two anthropogenic
extinction scenarios exist: catastrophic climate change
; and two possible natural ones: bolide impact
and large-scale volcanism
. Both natural causes have occurred
repeatedly in the geologic past and there is no reason to consider
them unlikely in the future. As technology develops, there is a
possibility that humans may be deliberately destroyed by the
actions of a rogue state or individual in a form of global suicide attack
, but this is balanced by the
possibility that technological advancement may resolve or prevent
potential extinction scenarios. A more likely scenario is the
emergence of a pandemic of such virulence and infectiousness that
very few humans survive the disease. While not actually 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 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.
Severe forms of known or recorded disasters
Long-term habitat threats
- Within a million years, the hypergiant Eta
Carinae, which is 7500 light years from the Sun, may go
- In 1.4 million years Gliese 710 will
be only 1.1 light years from Earth and
might catastrophically perturb the Oort
cloud, possibly resulting in a comet shower.
- In about 3 billion years, our Milky
Way galaxy is expected to collide with the Andromeda
galaxy. Collisions of individual bodies will likely be scarce;
however, the consequences for orbits of stars and planets are
unclear, and impossible to predict for individual stellar
- In 5 billion years hence the Sun's stellar evolution will reach the red giant stage, in which it will expand and
engulf Earth. But before this happens it will already have changed
Earth's climate and its radiated spectrum may alter in ways
Earth-bound humans could not survive.
- In the far future the main certainty to human extinction will
be heat death and cooling with the
expansion of the
- Evolution of humanity into a posthuman life-form or existence by means of technology, leaving no trace of original humans.
The chances of a genetic change of humanity to replace its
ancestral predecessor is low, but possible in millions of years
- 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 will gradually transition into one or more new species.
This mechanism for the extinction of Homo
sapiens would, however, require that regional interbreeding
ceases for tens of thousands of years.
- Dysgenics among humanity resulting in
a less intelligent species. (See Idiocracy.)
- Evolution of another species that out-competes humans for food,
habitat or hunts as prey.
- Preference for fewer children; if developed world demographics are extrapolated they
mathematically lead to 'soft' extinction before 3000 AD.
Leslie estimates that if the reproduction rate drops to the
German level the extinction date will be 2400
- Political intervention in
reproduction has failed to raise the birth rate above the
level in the rich world, but has dramatically succeeded in
lowering it below the replacement level in China (see
One child policy). A
World government with a eugenic or small population policy could send
humanity into 'voluntary' extinction.
- Infertility: Caused by hormonal disruption from the chemical/pharmaceutical industries, or biological changes, such as the (controversial) findings of falling sperm cell count in human males. (See
The Children of Men
(novel) or Children of Men
(film).) This threat is taken very seriously by science, and there
are several chemical compounds with restricted usage for this
- A disruption, chemical, biological, or otherwise, in humans'
ability to reproduce properly or at all (see the Curse of Eve (novel) for more).
- Disease: The 'weak-gened' and birth-defected are kept alive by
medicines. This is the opposite of nature, where the weak are less
likely to survive and successfully reproduce, leaving the species
genetically 'strong'. Eventually everyone has weak/flawed genes,
and these defects become increasingly severe, until the human body
is unable to fight diseases, even with the help of advanced
medicine. In the end, disease ends the human species . Arguably
however if this point was reached natural selection would again
become a factor, potentially reversing this 'decline'.
extinction, a real-life political activist group exists, but
very small and marginal.
- 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
- Creation of a naked
singularity (such as 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
transition or strangelet incidents.
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.
- The world's food supply being threatened and extinguished as a
result of scientific tampering, due to genetic engineering
encouraging more prevalent plant diseases, or the interference of
pesticides contributing to the destruction of crops due to the
effect on bees (See colony
- Accidental contact of an alien
civilization by Earth's radio and TV signals, radar, Internet
tech dependent on radio, TV signals, other signals, resulting in
- Biotech disaster such as green goo.
(e.g. the warnings of Jeremy
Scenarios of extraterrestrial origin
- Major impact events.
- If a rogue black hole passed near the
Sun, it could disrupt Earth's orbit.
- 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
- Invasion by militarily superior aliens
(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.
- 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.
- In the event of contact with an alien species, radical
biological differences between human and extraterrestrial biologies
and immunities could, and probably would, end up killing each
other. Such an event was postulated in the story, War of the
- Solar flares may suddenly heat the
earth, or the light from the sun may be blocked by dust, slowly
freezing it (eg. the dust and vapour may come from a Kuiper belt disturbance).
- A vacuum phase transition could
destroy the universe.
- It is possible that the space of our universe, the Big Bang, and all its consequences are events
taking place within a computer or other device on another
cosmological plane, if this process were to end then everything
within the universe would summarily vanish (see Simulated Reality).
Attitudes to human extinction
Attitudes to human extinction vary widely depending on beliefs
concerning spiritual survival
(souls, heaven, reincarnation
, and so forth), the value of the
human species, whether the human species evolves individually or
collectively, and many other factors. Many religions prophesy
" to the universe
. Human extinction is therefore a part of
of many humans to the extent that
the end time means the absolute end of their physical humanity but
perhaps not an internal soul.
However not all faiths connect human extinction to the end times,
since some believe in cyclical regeneration, or that end times
actually means the beginning of a new kind of existence (see
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:
- There have been countless prophesies of extinction throughout
history; in all cases the predicted date of doom has passed without
much notice, 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” 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).
- 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.
- 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').
- 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).
- Some anthropologists believe that
risk perception is biased by social structure; in the "Cultural Theory of risk" typography
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).
- 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 , 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.
- The bias in popular culture is to relate extinction scenario
stories with non-extinction outcomes. (None of the 16 'most
scenarios in film are resolved by human extinction, for
- The threat of nuclear annihilation actually was a daily concern
in the lives of many people in the 1960s and 1970s. Since then the
principal fear has been of localized terrorist attack, rather than a global war of
extinction; contemplating human extinction may be out of
- Some people have philosophical reasons for doubting the
possibility of human extinction, for instance the final anthropic principle,
plenitude principle or intrinsic finality.
- Tversky and Kahneman have produced evidence that humans suffer
cognitive biases which would tend to
minimize the perception of this unprecedented event:
- 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.
- In cultures where human extinction is not expected the
proposition must overcome the "disconfirmation bias" against heterodox
- Another reliable psychological effect
relevant here is the "positive outcome
- 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 .
In general, humanity's sense of self
, and intelligence
are considered to offer
safe-guards against extinction. It is felt that people will find
ways to overcome potential
threats, and will take care of the precautionary principle
attempting dangerous innovations
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
A calculation by Hans
proved such a possibility theoretically impossible, but
the fear of the possibility remained among some until the test took
place. (See Ignition of the atmosphere with nuclear bombs
and Manhattan Project
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.
. "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.
Another characteristic of some humans that may be unique is their
religious belief, which in many situations encourages respect for
life. As a result, many great thinkers, such as Albert Einstein
, believed that "We shall
require a substantially new manner of thinking if mankind is to
Humans are very similar to other primates
their propensity towards intra-species violence
's The Third
(ISBN 0-09-980180-9) estimates that 64% of
hunter-gather societies engage in warfare every two years.
it has been argued (e.g. in the UNESCO Seville Statement) that warfare is a
cultural artifact, many anthropologists
dispute this, noting that small human tribes exhibit similar
patterns of violence to chimpanzee
groups, the most murderous of the primates, and our nearest living
' functions of reason and speech are more
developed in the brain of Homo
than other primates, but the relative size of the
is a constant in
; as human rational faculties have expanded, so
has the wetware
. The combination of inventiveness and urge
to violence in humans has been cited
evidence against its long term survival .
Omnicide is human extinction as a result of human action. Most
commonly it refers to extinction through nuclear warfare
, but it can also apply to
extinction through means such as global anthropogenic ecological catastrophe
Omnicide can be considered a subcategory of genocide
. Using the concept in this way, one can
argue, for example, that:
As this claim illustrates, the concept of omnicide raises issues of
and, hence, of moral responsibility
about large-scale social processes like the nuclear arms race
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,
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
the course of
action it is applied to.
Scenarios of the world without humans in media
The book The World Without
by Alan Weisman
a thought experiment
would happen to the planet and especially man-made infrastructures
if humans suddenly disappeared. Alan said that apes, with the
highest IQ amongst animals other than humans, may be the species
that succeeds humanity. The Discovery
film The Future Is
shows the possible future of evolution
on Earth without humans. The History Channel
Life After People
examines the possible future of life on Earth without humans. Life
After People is now a series on the History Channel. The National Geographic
ran a special called Aftermath: Population Zero
envisioning 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. It also implies that human extinction is due to
predation by some of these evolved species.
- Cawthorne, N. (2004). Doomsday. Arcturus Publishing
Limited. ISBN 1-84193-238-8
- Leslie, J. (1999). Risking Human Extinction
- Leslie, J. (1996). The End of the World: The Science and
Ethics of Human Extinction. Routledge. ISBN 0-415-18447-9
- Russell, J.D. (2008). Trojan Whores ~The Road to
Armageddon~ a Prophetic Retrospective, by Jahred Kammen, the Last
Liberal by (c)2008 Freedom Press International, 12115
Whitefish Avenue, Manhattan Beach, MN 56442; ISBN
- Global catastrophic risks and human extinction
Von Neumann said it was "absolutely certain (1) that there would be a nuclear war; and (2) that everyone would die in it" (underline added to quote from: The Nature of the Physical Universe – 1979, John Wiley & Sons, ISBN 0-471-03190-9, in H. Putnam’s essay The place of facts in a world of values - page 113). This example illustrates why respectable scientists are very reluctant to go on record with extinction predictions: they can never be proven right. (The quotation is repeated by Leslie (1996) on page 26, on the subject of nuclear war annihilation, which he still considered a significant risk – in the mid 1990s.)
Although existential risks are less manageable by individuals than health risks, according to Ken Olum, Joshua Knobe, and Alexander Vilenkin the possibility of human extinction does have practical implications. For instance, if the “universal” Doomsday argument is accepted it changes the most likely source of disasters, and hence the most efficient means of preventing them. They write: "...you should be more concerned that a large number of asteroids have not yet been detected than about the particular orbit of each one. You should not worry especially about the chance that some specific nearby star will become a supernova, but more about the chance that supernovas are more deadly to nearby life then we believe." Source: “Practical application” page 39 of the Princeton University paper: Philosophical Implications of Inflationary Cosmology
The 2000 review Armageddon at the Millennial Dawn from The Journal of Religion and Film finds that "While end of the world threats perhaps are not avoidable, the cinematic formulation of millennial doom promotes the notion that the end can be averted through employing human ingenuity, scientific advance, and heroism." Since this review was conducted, there had been a Hollywood production which postulates a (far future) outcome where humans are extinct (at least in the wild): A.I..
For research on this, see Psychological science volume 15 (2004): Decisions From Experience and the Effect of Rare Events in Risky Choice. The under-perception of rare events mentioned above is actually the opposite of the phenomenon originally described by Kahneman in "prospect theory" (in their original experiments the likelihood of rare events is over-estimated). However, further analysis of the bias has shown that both forms occur: When judging from description people tend to over-estimate the described probability, so this effect taken alone would indicate that reading the extinction scenarios described here should make the reader over-estimate the likelihood of any probabilities given. However, the effect that is more relevant to common consideration of human extinction is the bias that occurs with estimates from experience, and these are in the opposite direction: When judging from personal experience people who have never heard of or experienced their species become extinct would be expected to dramatically under-estimate its likelihood. Sociobiologist E. O. Wilson argued that: "The reason for this myopic fog, evolutionary biologists contend, is that it was actually advantageous during all but the last few millennia of the two million years of existence of the genus Homo... A premium was placed on close attention to the near future and early reproduction, and little else. Disasters of a magnitude that occur only once every few centuries were forgotten or transmuted into myth." (Is Humanity Suicidal? New York Times Magazine May 301993).
Abrupt.org 1996 editorial lists (and condemns) the arguments for human’s tendency to self-destruction. In this view, the history of humanity suggests that humans will be the cause of their own extinction. However, others have reached the opposite conclusion with the same data on violence and hypothesize that as societies develop armies and weapons with greater destructive power, they tend to be used less often. It is claimed that this implies a more secure future, despite the development of WMD technology. As such this argument may constitute a form of deterrence theory. Counter-arguments against such views include the following: (1) All weapons ever designed have ultimately been used. States with strong military forces tend to engage in military aggression, (2) Although modern states have so far generally shown restraint in unleashing their most potent weapons, whatever rational control was guaranteed by government monopoly over such weapons becomes increasingly irrelevant in a world where individuals have access to the technology of mass destruction (as proposed in Our Final Hour, for example).
ReligiousTolerance.org says that Aum Supreme Truth is the only religion known to have planned Armageddon for non-believers. Their intention to unleash deadly viruses is covered in Our Final Hour, and by Aum watcher, Akihiko Misawa. The Gaia Liberation Front advocates (but is not known to have active plans for) total human genocide, see: GLF, A Modest Proposal. Leslie, 1996 says that Aum’s collection of nuclear physicists presented a doomsday threat from nuclear destruction as well, especially as the cult included a rocket scientist.
Leslie (1996) discusses the survivorship bias (which he calls an "observational selection" effect on page 139) he says that the a priori certainty of observing an "undisasterous past" could make it difficult to argue that we must be safe because nothing terrible has yet occurred. He quotes Holger Bech Nielsen’s formulation: “We do not even know if there should exist some extremely dangerous decay of say the proton which caused eradication of the earth, because if it happens we would no longer be there to observe it and if it does not happen there is nothing to observe.” (From: Random dynamics and relations between the number of fermion generations and the fine structure constants, Acta Pysica Polonica B, May 1989).
For example, in the essay Why the future doesn't need us, computer scientist Bill Joy argued that human beings are likely to guarantee their own extinction through transhumanism. See: Wired archive, Why the future doesn't need us.
For the “West Germany” extrapolation see: Leslie, 1996 (The End of the World) in the “War, Pollution, and disease” chapter (page 74). In this section the author also mentions the success (in lowering the birth rate) of programs such as the sterilization-for-rupees programs in India, and surveys other infertility or falling birth-rate extinciton scenarios. He says that the voluntary small family behaviour may be counter-evolutionary, but that the meme for small, rich families appears to be spreading rapidly throughout the world. In 2150 the world population is expected to start falling.
See estimate of contact’s probability at galactic-guide. Former NASA consultant David Brin's lengthy rebuttal to SETI enthusiast's optimism about alien intentions concludes: "The worst mistake of first contact, made throughout history by individuals on both sides of every new encounter, has been the unfortunate habit of making assumptions. It often proved fatal." ( See full text at SETIleague.org.)