Suicide
Classification and external resources
The Suicide by Édouard Manet 1877–1881
ICD-10	X60–X84
ICD-9	E950
MedlinePlus	001554
eMedicine	article/288598
MeSH	F01.145.126.980.875

Suicide (Latin suicidium, from sui caedere, "to kill oneself") is the act of intentionally causing one's own death. Suicide is often committed out of despair, the cause of which can attributed to a mental disorder such as depression, bipolar disorder, schizophrenia, autism spectrum disorders, alcoholism, or drug abuse.^[1] Stress factors such as financial difficulties or troubles with interpersonal relationships often play a significant role.^[2]

Over one million people die by suicide every year. The World Health Organization (WHO) estimates that it is the 13th leading cause of death worldwide^[3] and the National Safety Council rates it sixth in the United States.^[4] It is a leading cause of death among teenagers and adults under 35.^[5][6] The rate of suicide is far higher in men than in women, with males worldwide three to four times more likely to kill themselves than females.^[7][8] There are an estimated 10 to 20 million non-fatal attempted suicides every year worldwide.^[9]

Views on suicide have been influenced by broader cultural views on existential themes such as religion, honor, and the meaning of life. The Abrahamic religions traditionally consider suicide an offense towards God due to the belief in the sanctity of life. It was often regarded as a serious crime and that view remains commonplace in modern Western thought. However, before the rise of Christianity, suicide was not seen as automatically immoral in ancient Greek and Roman culture. Conversely, during the samurai era in Japan, seppuku was respected as a means of atonement for failure or as a form of protest. Sati is a Hindu funeral practice, now outlawed, in which the widow was expected to immolate herself on her husband's funeral pyre, either willingly or under pressure from the family and society.^[10] In the 20th and 21st centuries, suicide in the form of self-immolation has been used as a medium of protest, and the form of kamikaze and suicide bombings as a military or terrorist tactic.

Medically assisted suicide (euthanasia, or the right to die) is a controversial issue in modern ethics. The defining characteristic is the focus on people who are terminally ill, in extreme pain, or possessing (actual or perceived) minimal quality of life resulting from an injury or illness.

Self-sacrifice on behalf of another is not necessarily considered suicide; the subjective goal is not to end one's own life, but rather to save the life of another. However, in Émile Durkheim's theory, such acts are termed "altruistic suicide."^[11]

Classification[link]

Risk factors[link]

A representative listing of circumstances for suicide in 16 states in the United States. This chart does not include all possible circumstances.^[21]

Clinical studies have shown that underlying mental disorders are present in 87% to 98% of suicides, however, there are a number of other factors are correlated with suicide risk, including drug addiction, availability of means, family history of suicide, or previous head injury.^[22][23]

Socio-economic factors such as unemployment, poverty, homelessness, and discrimination may trigger suicidal thoughts.^[24] Poverty may not be a direct cause, but it can increase the risk of suicide, as impoverished individuals are a major risk group for depression.^[25] A history of childhood physical or sexual abuse^[26] or time spent in foster care.^[27][28][29]

Hopelessness, the feeling that there is no prospect of improvement in one's situation, is a strong indicator of suicide. One study found that among a group of people previously hospitalized for suicidal tendencies, 91% of those who scored a 10 or higher on the Beck Hopelessness Scale would eventually commit suicide.^[30] Perceived burdensomeness^[31] a feeling that one's existence is a burden to others such as family members is often coupled with hopelessness as are the feelings of loneliness,^[32] either subjectively (i.e., the feeling), or objectively (i.e., living alone or being without friends and lacking social support^[33]) and the feeling of not belonging^[34] as strong mediators of suicidal ideation.

Advocacy of suicide has been cited as a contributing factor. Intelligence may also be a factor. Initially proposed as a part of an evolutionary psychology explanation, which posited a minimum intelligence required for one to commit suicide, the positive correlation between IQ and suicide has been replicated in a number of studies.^{[35][36][37][38][39]} Some scientists doubt, however, that intelligence can be a cause of suicide,^[40] and intelligence is no longer a predictor of suicide when regressed with national religiousness and perceptions of personal health.^[41] According to the American Psychiatric Association, "religiously unaffiliated subjects had significantly more lifetime suicide attempts and more first-degree relatives who committed suicide than subjects who endorsed a religious affiliation."^[42] Moreover, individuals with no religious affiliation had fewer moral objections to suicide than believers.^[42]

One study found that a lack of social support, a deficit in feelings of belongingness and living alone were crucial predictors of a suicide attempt.^[43] One study found that among prison inmates, suicide was more likely among inmates who had committed a violent crime.^[44]

Medical conditions[link]

In various studies a significant association was found between suicidality and underlying medical conditions including chronic pain,^[45] mild brain injury, (MBI) or traumatic brain injury (TBI).^[46][47] The prevalence of increased suicidality persisted after adjusting for depressive illness and alcohol abuse. In patients with more than one medical condition the risk was particulaly high, suggesting a need for increased screening for suicidality in general medical settings.^[48][49]

Sleep disturbances such as insomnia^[50] and sleep apnea have been cited in various studies as risk indicators for depression and suicide. In some instances the sleep disturbance itself may be the risk factor independent of depression.^[51]

A careful medical evaluation is recommended for all people presenting with psychiatric symptoms as many medical conditions present with psychiatric symptomatology. The major medical conditions presenting with psychiatric symptoms in order of frequency were infectious, pulmonary, thyroid, diabetic, hematopoietic, hepatic and CNS diseases.^[52] Conservative estimates are that 10% of all psychological symptoms may be due to undiagnosed medical conditions,^[53] with the results of one study suggesting that about 50% of individuals with a serious mental illness "have general medical conditions that are largely undiagnosed and untreated and may cause or exacerbate psychiatric symptoms".^[54][55]

Mental disorders[link]

Certain mental disorders are often present at the time of suicide. It is estimated that from 87% to 98% of suicides are committed by people with some type of mental disorder.^[56] Broken down by type: mood disorders are present in 30%, substance abuse in 18%, schizophrenia in 14%, and personality disorders in 13% of suicides.^[57] About 5% of people with schizophrenia die of suicide.^[58] Major depression and alcoholism are the specific disorders most strongly correlated with suicide risk. Risk is greatest during the early stages of illness among people with mood disorders, such as major depression or bipolar disorder.^[59]

Depression is among the most commonly diagnosed psychiatric disorders;^[60][61] increasingly diagnosed across various segments of the worldwide population.^[62][63] 17.6 million Americans are affected each year; approximately 1 in 6 people. Within the next twenty years, depression is expected to become the leading cause of disability in developed nations and the second leading cause of disability worldwide.^[64] While the psychological and medical communities no longer classify acts of self-harm as suicide attempts, recent research has indicated that the presence of self-injurious behavior may be correlated to increased suicide risk.^[65] While there is a correlation between self-harm and suicide, it is not believed to be causal; both are most likely a joint effect of depression.^[66] This may also be classified as deliberate self-harm and is most common in younger people, but has been increasing in recent years in people of all ages.^[67]

Most people who attempt suicide do not complete the act on their first attempt. However, a history of suicide attempts is correlated with increased risk of eventual completion of a suicide.^[68]

Biology[link]

Some mental disorders identified as risk factors for suicide often may have an underlying biological basis.^[69][70] Serotonin is a vital brain neurotransmitter; in those who have attempted suicide it has been found that they have lower serotonin levels, and individuals who have completed suicide have the lowest levels.^[71][72] This dysregulation in the serotonin pathway has been identified, in the ventromedial prefrontal cortex. This alteration in the brain has been found to be a risk factor for suicide independent of a history of a major depression "indicating that it is involved in the predisposition to suicide in many psychiatric disorders."^[73][74][75]

There is evidence that there may be an underlying neurobiological basis for suicide risk independent of the inheritable genetic factors responsible for the major psychiatric disorders associated with suicide.^[76] Genetic inheritance accounts for roughly 30–50% of the variance in suicide risk between individuals.^[77][78][78] Having a parent who has committed suicide is a strong predictor of suicide attempts.^[79][80][81]

Epigenetics, the study of changes in genetic expression in response to environmental factors which do not alter the underlying DNA, may also play a role in determining suicide risk.^[82][83][84]

Perceived burdensomeness to others[link]

Several studies have found perceived burdensomeness to others to be a particularly strong risk factor. It also differentiates between attempted vs. completed suicide and predicts lethality of suicide method unlike feelings of hopelessness and emotional pain. Likely related to this, completed suicides are characterized by altruistic feelings while non-lethal self-injuries are characterized by feelings of anger or self-punishment.^[85]

An evolutionary psychology explanation for this is that suicide may under some circumstances improve inclusive fitness. This may occur if the person committing suicide will not have more children (even if not committing suicide) and takes away resources from relatives by staying alive. An objection is that some suicides, such as healthy adolescents committing suicide, likely do not increase inclusive fitness. One response is that adaptations to the very different ancestral environment may be maladaptive in the current one."^[85][86]

Substance abuse[link]

Substance abuse is the second most common risk factor for suicide after major depression and bipolar disorder.^[87] Both chronic substance misuse as well as acute substance abuse are associated with suicide.^[88] This is attributed to the intoxicating, disinhibiting, and dissociative effects of many psychoactive substances. When combined with personal grief, such as bereavement, the risk of suicide is greatly increased.^[89] More than 50% of suicides have some relation to alcohol or drug use and up to 25% of suicides are committed by drug addicts and alcoholics. This figure is even higher with alcohol or drug use among adolescents, playing a role in up to 70% of suicides. It has been recommended that all drug addicts or alcoholics undergo investigation for suicidal thoughts due to their high risk of suicide.^[90] An investigation in the New York Prison Service found that 90% of inmates who committed suicide had a history of substance abuse.^[91]

Problem gambling[link]

Problem gambling is often associated with increased suicidal ideation and attempts compared to the general population.^{[112][113][114]}

Early onset of problem gambling increases the lifetime risk of suicide.^[115] However, gambling-related suicide attempts are usually made by older people with problem gambling.^[116] Both comorbid substance use^[117][118] and comorbid mental disorders increase the risk of suicide in people with problem gambling.^[116]

A 2010 Australian hospital study found that 17% of suicidal patients admitted to the Alfred Hospital's emergency department were problem gamblers.^[119]

Media coverage[link]

Various studies have suggested that how the media presents depictions of suicide may have a negative effect^[120] and trigger the possibility of suicide contagion also known as the Werther effect, named after the protagonist in Goethe's The Sorrows of Young Werther who committed suicide.^[121][122] This risk is greater in adoloescents who may romantacize death.^{[123][124][125]} It appears that while news media has a significant effect, that of entertainment media is equivocal.^[126]

The opposite of the Werther effect is the Papageno effect in which coverage of effective coping mechanisms, coping in adverse circumstances, as covered in the media about suicidal ideation, may have protective effects. The term is based upon a character in Mozart’s opera The Magic Flute named Papageno who fearing the loss of a loved one was going to commit suicide until three boys showed him different ways to cope.^[127]

Methods[link]

The most common methods of suicide in the United States.

The leading method of suicide varies dramatically between countries. The leading methods in different regions include hanging, pesticide poisoning, and firearms.^[128] A 2008 review of 56 countries based on WHO mortality data found that hanging was the most common method in most of the countries,^[129] accounting for 53% of the male suicides and 39% of the female suicides.^[130] Worldwide 30% of suicides are from pesticides. The use of this method however varies markedly from 4% in Europe to more than 50% in the Pacific region.^[131] In the United States 52% of suicides involve the use of firearms.^[132] Asphyxiation (such as with a suicide bag) and poisoning are fairly common as well. Together they comprised about 40% of U.S. suicides. Other methods of suicide include blunt force trauma (jumping from a building or bridge, self-defenestrating, stepping in front of a train, or car collision, for example). Exsanguination or bloodletting (slitting one's wrist or throat), intentional drowning, self-immolation, electrocution, and intentional starvation are other suicide methods. Individuals may also intentionally provoke another person into administering lethal action against them, as in suicide by cop.

Whether or not exposure to suicide is a risk factor for suicide is controversial.^[133] A 1996 study was unable to find a relationship between suicides among friends,^[134] while a 1986 study found increased rates of suicide following the television of news stories regarding suicide.^[135]

Prevention[link]

A United States Army suicide prevention poster

Suicide prevention is a term used for the collective efforts to reduce the incidence of suicide through preventive measures. Various strategies restrict access to the most common methods of suicide, such as firearms or toxic substances like pesticides, and have proved to be effective in reducing suicide rates. Studies supported by empirical data have indicated that adequate prevention, diagnosis and treatment of depression and alcohol and substance abuse can reduce suicide rates, as does follow-up contact with those who have made a suicide attempt.^[136] Although crisis hotlines are common there is little evidence to support or refute their effectiveness.^[137][138]

The Best Practices Registry (BPR) For Suicide Prevention is a registry of various suicide intervention programs maintained by the American Association of Suicide Prevention. The programs are divided, with those in Section I listing evidence-based programs: interventions which have been subjected to indepth review and for which evidence has demonstrated positive outcomes. Section III programs have been subjected to review.^[139][140]

In various countries, individuals who are at imminent risk of harming themselves or others may voluntarily check themselves into a hospital emergency department; this may also be done on an involuntary basis on the referral of various individuals acting in an official capacity such as the police. This is referred to by various names such as being "committed" or "sectioned". They will be placed on suicide watch until an emergency physician or mental health professional determines whether inpatient care at a mental health care facility is warranted and may hold the individual for a period of usually three days duration. A court hearing may be held to determine the individual's competence. In most states, a psychiatrist may hold the person for a specific time period without a judicial order. If the psychiatrist determines the person to be a threat to himself or others, the person may be admitted involuntarily to a psychiatric treatment facility. After this time the person must be discharged or appear in front of a judge.^[141]

Screening[link]

The U.S. Surgeon General has suggested that screening to detect those at risk of suicide may be one of the most effective means of preventing suicide in children and adolescents.^[142] There are various screening tools in the form of self-report questionnaires to help identify those at risk such as the Beck Hopelessness Scale and Is Path Warm? A number of these self-report questionnaires have been tested and found to be valid for use among adolescents and young adults.^[143] There is, however, a high rate of false-positive identification and those deemed to be at risk should ideally have a follow-up clinical interview.^[144] The predictive quality of these screening questionnaires has not been conclusively validated, so it is not possible to determine if those identified at risk of suicide will actually commit suicide.^[145] Asking about or screening for suicide does not appear to increase the risk.^[146]

In approximately 75% of completed suicides the individuals had seen a physician within the year before their death, including 45% to 66% within the prior month. Approximately 33% to 41% of those who completed suicide had contact with mental health services in the prior year, including 20% within the prior month. These studies suggest an increased need for effective screening.^{[147][148][149][150][151]}

Treatment[link]

There are various treatment modalities to reduce the risk of suicide by addressing the underlying conditions causing suicidal ideation, including, depending on case history, medical,^[152] pharmacological,^[153] and psychotherapeutic talk therapies.^[154]

The conservative estimate is that 10% of individuals with psychiatric disorders may have an undiagnosed medical condition causing their symptoms,^[155] upwards of 50% may have an undiagnosed medical condition which if not causing is exacerbating their psychiatric symptoms.^[156][157] Illegal drugs and prescribed medications may also produce psychiatric symptoms.^[158] Effective diagnosis and if necessary medical testing which may include neuroimaging^[159] to diagnose and treat any such medical conditions or medication side effects may reduce the risk of suicidal ideation as a result of psychiatric symptoms, most often including depression, which are present in up to 90-95% of cases.^[160]

Recent research has shown that treatment with lithium has been effective with lowering the risk of suicide in those with bipolar disorder to the same levels as the general population.^[161] Low doses of Lithium with minimal side effects has also proven effective in lowering the suicide risk in those with unipolar depression as well.^[162]

There are multiple evidence-based psychotherapeutic talk therapies available to reduce suicidal ideation such as dialectical behaviour therapy (DBT) for which multiple studies have reported varying degrees of clinical effectiveness in reducing suicidality. Benefits include a reduction in self-harm behaviours and suicidal ideations.^[163][164] Cognitive Behavior Therapy for Suicide Prevention (CBT-SP) is a form of DBT adapted for adolescents at high risk for repeated suicide attempts.^[165]

Epidemiology[link]

Deaths for self inflicted injuries per 100,000 inhabitants in 2004.^[166]

unknown   <3   3–6   6–9   9–12   12–15   15–18

18–21   21–24   24–27   27–30   30–33   >33

Worldwide suicide rates have increased by 60% in the past 45 years, mainly in the developing countries and is currently the tenth leading cause of death^[1] with about a million people dying by suicide annually, a global mortality rate of 16 suicides per 100,000 people, or a suicide every 40 seconds.^[167] According to 2007 data, suicides in the U.S. outnumber homicides by nearly 2 to 1. Suicide ranks as the 11th leading cause of death in the country, ahead of liver disease and Parkinson's.^[168]

Gender[link]

Suicide rate per 100,000 males (left) and female (right) (data from 1978–2008).   no data   < 1   1–5   5–5.8   5.8–8.5   8.5–12   12–19   19–22.5   22.5–26   26–29.5   29.5–33   33–36.5   >36.5

In the Western world, males die much more often by means of suicide than do females, although females attempt suicide more often. Some medical professionals believe this stems from the fact that males are more likely to end their lives through effective violent means, while women primarily use less severe methods such as overdosing on medications. In most countries, drug overdoses account for about two-thirds of suicides among women and one-third among men.^[67]

Alcohol and drug use[link]

In the United States 16.5% of suicides are related to alcohol.^[169] Alcoholics are 5 to 20 times more likely to kill themselves, while the misuse of other drugs increases the risk 10 to 20 times. About 15% of alcoholics commit suicide, and about 33% of suicides in the under 35 age group have a primary diagnosis of alcohol or other substance misuse; over 50% of all suicides are related to alcohol or drug dependence. In adolescents alcohol or drug misuse plays a role in up to 70% of suicides.^[90][170]

Ethnicity[link]

National suicide rates differ significantly between countries and amongst ethnic groups within countries.^[171] For example, in the U.S., non-Hispanic Caucasians are nearly 2.5 times more likely to kill themselves than African Americans or Hispanics.^[172]

Social aspects[link]

Legislation[link]

A tantō knife prepared for seppuku.

In some jurisdictions, an act or incomplete act of suicide is considered to be a crime. More commonly, a surviving party member who assisted in the suicide attempt will face criminal charges.

In Brazil, if the help is directed to a minor, the penalty is applied in its double and not considered as homicide. In Italy and Canada, instigating another to suicide is also a criminal offense. In Singapore, assisting in the suicide of a mentally handicapped person is a capital offense. In India, abetting suicide of a minor or a mentally challenged person can result in a maximum 1 year prison term with a possible fine.^[173]

In Germany, the following laws apply to cases of suicide:^[174]

• Active euthanasia (killing on request) is prohibited by article 216 of the StGB (Strafgesetzbuch, German Criminal Code), punishable with six months to five years in jail
• German law interprets suicide as an accident and anyone present during suicide may be prosecuted for failure to render aid in an emergency. A suicide legally becomes an emergency when a suicidal person loses consciousness. Failure to render aid is punishable under article 323c of the StGB, with a maximum one year jail sentence.

Switzerland has recently taken steps to legalize assisted suicide for the chronically mentally ill. The high court in Lausanne, in a 2006 ruling, granted an anonymous individual with longstanding psychiatric difficulties the right to end his own life. At least one leading American bioethicist, Jacob Appel of Brown University, has argued that the American medical community ought to condone suicide in certain individuals with mental illness.^[175]

Religious views[link]

In most forms of Christianity, suicide is considered a sin, based mainly on the writings of influential Christian thinkers of the Middle Ages, such as St. Augustine and St. Thomas Aquinas; suicide was not considered a sin under the Byzantine Christian code of Justinian, for instance.^[176][177] In Catholic doctrine, the argument is based on the commandment "Thou shalt not kill" (made applicable under the New Covenant by Jesus in Matthew 19:18), as well as the idea that life is a gift given by God which should not be spurned, and that suicide is against the "natural order" and thus interferes with God's master plan for the world.^[178] However, it is believed that mental illness or grave fear of suffering diminishes the responsibility of the one completing suicide.^[179] Counter-arguments include the following: that the sixth commandment is more accurately translated as "thou shalt not murder", not necessarily applying to the self; that God has given free will to humans; that taking one's own life no more violates God's Law than does curing a disease; and that a number of suicides by followers of God are recorded in the Bible with no dire condemnation.^[180]

A Hindu widow burning herself with the corpse of her husband, 1820s.

Judaism focuses on the importance of valuing this life, and as such, suicide is tantamount to denying God's goodness in the world. Despite this, under extreme circumstances when there has seemed no choice but to either be killed or forced to betray their religion, Jews have committed individual suicide or mass suicide (see Masada, First French persecution of the Jews, and York Castle for examples) and as a grim reminder there is even a prayer in the Jewish liturgy for "when the knife is at the throat", for those dying "to sanctify God's Name" (see Martyrdom). These acts have received mixed responses by Jewish authorities, regarded both as examples of heroic martyrdom, whilst others state that it was wrong for them to take their own lives in anticipation of martyrdom.^[181]

Suicide is not allowed in Islam.^{[182][dubious – discuss]}

In Hinduism, suicide is generally frowned upon and is considered equally sinful as murdering another in contemporary Hindu society. Hindu Scriptures state that one who commits suicide will become part of the spirit world, wandering earth until the time one would have otherwise died, had one not committed suicide.^[183] However, Hinduism accept a man's right to end one's life through the non-violent practice of fasting to death, termed Prayopavesa.^[184] But Prayopavesa is strictly restricted to people who have no desire or ambition left, and no responsibilities remaining in this life.^[184] Jainism has a similar practice named Santhara. Sati, or self-immolation by widows was prevalent in Hindu society during the Middle Ages.

Philosophy[link]

The Way Out, or Suicidal Ideation: George Grie, 2007.

Some see suicide as a legitimate matter of personal choice and a human right (colloquially known as the right to die movement). Supporters of this position maintain that no one should be forced to suffer against their will, particularly from conditions such as incurable disease, mental illness, and old age that have no possibility of improvement. Proponents of this view reject the belief that suicide is always irrational, arguing instead that it can be a valid last resort for those enduring major pain or trauma.^[185] This perspective is most popular and has a good deal of support in continental Europe, where euthanasia and other such topics are commonly discussed in parliament.^[186]

A narrower segment of this group considers suicide something between a grave but condonable choice in some circumstances and a sacrosanct right for anyone (even a young and healthy person) who believes they have rationally and conscientiously come to the decision to end their own lives. Notable supporters of this school of thought include Friedrich Nietzsche, and Scottish empiricist David Hume.^[187] Bioethicist Jacob Appel has become the leading advocate for this position in the United States.^[188][189] Adherents of this view often advocate the abrogation of statutes that restrict the liberties of people known to be suicidal, such as laws permitting their involuntary commitment to mental hospitals.

Locations[link]

Some landmarks have become known for high levels of suicide attempts. The four most popular locations in the world are reportedly San Francisco's Golden Gate Bridge, Toronto's Bloor Street Viaduct (before the construction of the Luminous Veil),^[190] Japan's Aokigahara Forest and England's Beachy Head.^[191] In 2005 the Golden Gate Bridge had a count exceeding 1,200 jumpers since its construction in 1937.^[192] In 1997 the Bloor Street Viaduct had one suicide every 22 days,^[193] and in 2002 Aokigahara had a record of 78 bodies found within the forest, replacing the previous record of 73 in 1998.^[194] The suicide rate of these places is so high that numerous signs, urging potential victims of suicide to seek help, have been posted.^[195]

Advocacy[link]

Advocacy of suicide has occurred in many cultures and subcultures. The Japanese military during World War II encouraged and glorified kamikaze attacks, and Japanese society as a whole has been described as suicide 'tolerant' (see Suicide in Japan).

William Francis Melchert-Dinkel, 47 years old in May 2010, from Faribault, Minnesota, a licensed nurse from 1991 until February 2009, stands accused of encouraging people to commit suicide while he watched on a webcam.^{[196][197][198][199]}

A study by the British Medical Journal found that Web searches for information on suicide are likely to return sites that encourage, and even facilitate, suicide attempts.^[200] There is some concern that such sites may push the suicidal over the edge.^[201] Some people form suicide pacts with people they meet online.^[202] Becker writes, "Suicidal adolescent visitors risk losing their doubts and fears about committing suicide. Risk factors include peer pressure to commit suicide and appointments for joint suicides. Furthermore, some chat rooms celebrate chatters who committed suicide."^[203]

Language[link]

Because suicide was a crime in various countries, including in England and Wales which decriminalized it in 1961, the word 'commit' has traditionally been used in reference to it. Organisations such as the BBC and the Samaritans have stopped using this word because of its negative connotation. 'Attempt' suicide or other phrases are preferred.^[204] The Guardian and The Observer also avoid the phrase, preferring the use of "killed him or herself".^[205]

Other species[link]

"Suicide" has been observed in salmonella seeking to overcome competing bacteria by triggering an immune system response against them.^[206] Suicidal defences by workers are also noted in a Brazilian ant Forelius pusillus where a small group of ants leaves the security of the nest after sealing the entrance from the outside each evening.^[207]

Pea aphids, when threatened by a ladybug, can explode themselves, scattering and protecting their brethren and sometimes even killing the lady bug.^[208] Some species of termites have soldiers that explode, covering their enemies with sticky goo.^[209][210]

Asian black bears being used as "bile bears" are known to frequently try to kill themselves as a result of the severe pain caused by the permanent holes in their abdomen and gall bladder.^[211][212]

There have been anecdotal reports of dogs, horses, and dolphins committing suicide, but with little conclusive evidence.^[213] There has been little scientific study of animal suicide.^[214]

See also[link]

Footnotes[link]