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I just read this from Wikipedia's Swarm Behavior article:

Despite the lack of centralized decision making, ant colonies exhibit complex behaviour and have even been able to demonstrate the ability to solve geometric problems. For example, colonies routinely find the maximum distance from all colony entrances to dispose of dead bodies.

There was no citation.

Is it true that ants dispose of their own dead? If so, how and why? I would've though it would be much better to just eat their own dead, which would be a "free" food source allowing the colony to reclaim some protein and nutrients. It would cost much more energy (and risk) to transport dead ant carcasses away from the hive.

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    $\begingroup$ If you want to watch something scary, google for "youtube cordyceps" for a clip from "Planet Earth". $\endgroup$ – Andrew Grimm Jul 29 '17 at 8:20
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Eating the dead makes far more likely you will catch whatever killed them. They transport and dispose of the dead for the same reasons we do, to reduce disease vectors. They dispose of their garbage for much the same reason, in fact they often dispose of both in the same place even if they separate the two in distinct piles. Hygiene is very important is colonial insects because you are constantly surrounded by other ants which makes disease transfer very easy. Fungal infections are particularly problematic. They also have specialized toilet sites for the same reason.

Note only some ants transport the dead outside, other put them is special chambers far from normal traffic and reserved for that purpose and refuse disposal. In either case they are moving them away from casual contact.

Source

Source 2

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    $\begingroup$ Humans do not transport their dead for the same reasons that ants do.. the theory of germ disease wasn't established until a little over 100 years ago, yet we've been making graveyards and burying our dead for thousands of years. Ants do not have emotions, or spend time remembering their dead. It's completely different. $\endgroup$ – Charles Jul 28 '17 at 21:07
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    $\begingroup$ Ants do of course have emotions, emotions are the basic way the brain functions, but no they do not "remember the dead". humans bury their dead because being around the dead make us uncomfortable, our brains evolved to make us feel uncomfortable around corpses because they are disease vectors. So yes it is ultimately for the same reason. $\endgroup$ – John Jul 29 '17 at 2:48
  • $\begingroup$ I would like to see supporting literature that addresses the neurological systems that are activated upon a person encountering a human corpse. In the case of the ants, they are specifically triggered by the detection of oleic acid. And you say for humans, it's most an emotional response that has an evolutionary advantage of circumventing the propagation of disease vectors? Again, literature please. $\endgroup$ – Charles Jul 29 '17 at 3:08
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    $\begingroup$ pleasure and aversion are the basic building blocks they underlie all learning, emotions exist in any creature capable of learning. as for the human corpse, I am unsure what you mean by "it's most an emotional" but corpse aversion it is the explanation for why the uncanny valley a well documented effect sciencedirect.com/science/article/pii/S0747563210001536 $\endgroup$ – John Jul 29 '17 at 5:23
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    $\begingroup$ You can also consider things like the disgust/revulsion reflex triggered by decaying corpses, which is as universal ncbi.nlm.nih.gov/pubmed/17630362 it is not hard to see how it would evolve as part of our behavioral immune system. Feel free to open a discussion to explore this further. $\endgroup$ – John Jul 29 '17 at 5:35
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Yes, ants do in fact relocate their dead away from the nest. This is because when an ant dies it releases oleic acid, a chemical that is strongly associated with death. Upon detection of the oleic acid, ants will move (carry away) their dead as to avoid contamination within the nest, just in the same way they do with their waste (ants are actually pretty "clean").

What's kind of funny is that, even if the ant is still alive, if a single drop (relative to the size of the ant) of oleic acid is applied to an ant, the colony will still move that ant to the graveyard/dumpsite (midden).

The common term that refers to these ritualistic behaviors is "necrophoric behavior".

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  • $\begingroup$ Good to see some cover the proximal reasons and mechanics of the behavior $\endgroup$ – John Jul 29 '17 at 3:04
  • $\begingroup$ "A single drop" sounds pretty huge compared to an ant... even bigger than the ant itself. If I had 100L of liquid smelling like a dead body dumped on me I'd want to go bury myself too. $\endgroup$ – Mehrdad Jul 29 '17 at 7:42
  • $\begingroup$ @Mehrdad The single drop is meant to be relative to the size of the ant. Thanks. $\endgroup$ – Charles Jul 30 '17 at 14:28
  • $\begingroup$ Interesting. What happens to that ant after it's dropped at the graveyard? Does it commit suicide? Does it wait a while then walk back to the nest? $\endgroup$ – DrZ214 Apr 5 '18 at 0:41

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