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I've done some Googling and only found case stories without any scientific backup. Most of the case reports about animal suicide online can by easily debunked by logical reasoning. For example there is a story about some dozen of cows throwing themselves off a cliff, but this event took place at the same moment a thunderstorm was growling, which could have easily spooked the poor animals to render them imprudently enough to make them less aware of the danger of the cliff(s) in the surrounding area.

Is there real scientific evidence about this phenomenon aside from a few case stories? Are there even scientific studies out there describing it or at least confirm that the reason for animal suicide in some of the case reports is inconclusive?

IMPORTANT EDIT: (in a response to Oddthinking♦'s remark about a lack of definition of suicide) Yes, definitions are a great problem here, I agree. What does count as suicide? A parent saving his or her child by taking a deadly bullet... is that suicide? It's all a matter of definitions. However, what I meant by suicide here is not (and this is a bit difficult to word correct for me, because I'm not fluent in English) the act of a direct response to a stimuli, either internal (need to reproduce) or external (seeing that child is in danger and sacrifice in an attempt to prevent the child's death), but rather the act of self destruction after analyzing and abstracting the stimuli and putting these ideas of ideas (e.g. if the idea is: I'm in pain because I get beaten every time, then an idea of that idea could be: this pain lowers my quality of life and in the absence of any hope that this regular beating will quit, committing suicide and facing the fear of death seems like a better option than continuing life). Note that this requires the animal to have concept of abstract concepts (in my wording ideas of ideas), like life, death, time, fear, etc. I originally wanted to ask this question because I was wondering about the fundamental difference between animals and humans (if any), and suicide seemed like a good candidate to presume investigating.

I hope I didn't confuse to much people :-)

Jori
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    Related: http://skeptics.stackexchange.com/questions/2304/do-lemmings-commit-suicide-by-jumping-off-cliffs – nico Jul 19 '14 at 12:09
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    I would argue that [semelparity](http://en.wikipedia.org/wiki/Semelparity_and_iteroparity) counted as suicide, but it is more an argument of definitions not facts, so I can't bring myself to make it an answer. – Oddthinking Jul 19 '14 at 18:10
  • @Oddthinking I tried to respond to your comment about the lack of a definition of suicide from my side, but the reply became too large, so I had to put it in the question itself. – Jori Jul 19 '14 at 20:16
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    I dislike this question. It requires anthropomorphising animals thought-processes, and pretty much starts with a need for consciousness, which is already an area impossible to supply definitive answers to. Your bounty request for "additional opinions" is telling; opinions are generally off-topic (with exceptions). – Oddthinking Jul 22 '14 at 06:21
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    @Oddthinking Opinions is maybe a bit misworded here, I meant more scientific articles or references to EXPERT opinions. It doesn't require animals to have anything. I gave only a bit of context about what I meant by "animal suicide". This context is useful if you want to understand to question better (e.g. you can deduct from it that semelparity doesn't count as animal suicide here). I don't see the need for a downvote here, but if you honestly feel the question is bad, it's okay, but I would rather hear suggestion for improvement :-). Thank-you for commenting. – Jori Jul 22 '14 at 08:09
  • I guess a bee stinging a fleshy creature doesn't count, because it is for the good of the hive? – Kip Jul 25 '14 at 20:59
  • @Kip Yes, doesn't count. It still is a direct response to a stimuli (the idea of fleshy creatures damaging the hive when seeing it and associating it with a rudimentary instinct, the urge to protect the species). But thanks for the suggestion. They are more than welcome. (OFF-TOPIC, is it: "more then welcome" or "more than welcome"?) – Jori Jul 25 '14 at 21:07
  • "more than welcome" :) – Kip Jul 26 '14 at 00:46

2 Answers2

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There is not enough scientific data to prove suicidal behavior in non-human animals.

Naturalists have not identified suicide in nonhuman species in field situations, despite intensive study of thousands of animal species. ... Few empirical investigations have been carried out on this topic [1].

Modern naturalistic studies have found little evidence of self-harming conduct among nonhuman species [2].

A recent study (but of the same author) supports this:

No convincing animal model of suicide has been produced to date, and despite the intensive study of thousands of animal species naturalists have not identified suicide in nonhuman species in field situations. When modeling suicidal behavior in the animal, the greatest challenge is reproducing the role of will and intention in suicide mechanics [3].

Animals response to stimuli can lead to accidents and self-destruction:

Lacking the capacity to visualise and enact their own deaths, animals are seen to be driven by an instinct of self-preservation. ... animal acts of self-destruction were not intentional, but accidental and instinctual responses to stimuli [4].

References:

  1. Preti A. Suicide among animals: a review of evidence. Psychol Rep. 2007 Dec;101(3 Pt 1):831-48. PubMed PMID: 18232440.
  2. Preti A. Suicide among animals: clues from folklore that may prevent suicidal behaviour in human beings. Psychol Rep. 2005 Oct;97(2):547-58. PubMed PMID: 16342583.
  3. Preti A. Animal model and neurobiology of suicide. Prog. Neuropsychopharmacol. Biol. Psychiatry. 2011 Jun 1;35(4):818-30. doi: 10.1016/j.pnpbp.2010.10.027. PubMed PMID: 21354241.
  4. Ramsden E, Wilson D. The nature of suicide: science and the self-destructive animal. Endeavour. 2010 Mar;34(1):21-4. doi: 10.1016/j.endeavour.2010.01.005. PubMed PMID: 20144484.
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Cornelius
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  • I'm pretty sure there are also cases of animal self-sacrifice, such as to preserve their offspring. Although the stories that come to mind are all second-hand anecdotes, so not suitable evidence here without a solid case study. And also not a true "suicide," so it wouldn't fundamentally change the nature of the answer anyway. – Flimzy Jul 19 '14 at 17:20
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http://en.wikipedia.org/wiki/Bile_bear

The Chinese media reported an incident in which a mother bear, having escaped her cage, strangled her own cub and then killed herself by intentionally running into a wall.[14]

Certainly an anecdote rather than a scientifically validated study, but animals are clearly capable of committing suicide. Or at least bears are.

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