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Now, before you flag this question as blatantly off-topic, I claim to have a scientific basis for this(!): not some drug or remote control, but parasitic infection.

While reading about behavior altering parasites and parasitoids, I found this:

Parasites that induce behavioral changes in their hosts often exploit the regulation of social behavior in the brain...For example, Toxoplasma gondii attaches to the hypothalamus rather than target a specific cellular pathway; this broad targeting leads to a widespread increase in host dopamine levels, which may in turn account for the loss of aversion to cat odor...This rise in dopamine levels induces a loss of aversion to cat odor in the rats, increasing the risk of predation by cats, T. gondii’s definitive host.

Now, if a parasite can prevent mice from being afraid of cats, how hard would it be for another parasite to prevent humans from caring about each other's life(!)? Can a parasite develop some method by which it can alter behavior of humans in such a way that they just start killing each other for no reason? How easy/hard would it be for a parasite to do so?

Note: although it is just a curiosity question about whether it is possible or not, giving some description of neural pathways which stimulate social behavior in humans and how they are regulated would be much more appreciated.

marked as duplicate by ELL, kmm, WYSIWYG Jul 31 '16 at 19:48

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • interesting question, however you might still want to consider posting this question on skeptics.se – Ebbinghaus Jul 30 '16 at 17:11
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    @jordizambrino well I didn't wish to involve skepticism in the question, it is as general as was yours "can magnetoreception occur in humans?" Also, (if you've given close vote) can you please explain how the question is opinion based so that I can improve it? – another 'Homo sapien' Jul 30 '16 at 17:17
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    Okay let me clear this out ( as it seems to me that your opinion would be shared by many others) firstly, as I say in the question that its mere curiosity about whether its possible or not, second I've also cited a wikipedia paper that it occurs in mice, so can it occur in humans (just like you cite that cryptochromes are there in humans so can they attain magnetoreception). Anyways thanks that you didn't flag it, but an upvote won't hurt ;) – another 'Homo sapien' Jul 30 '16 at 17:27
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    Zombies are reanimated corpses, not just people who murder other people for no reason. There are many diseases and conditions that can possibly lead to people losing certain inhibitions and potentially unpremeditatedly killing other people. I suggest you reword the title to reflect the actual question. – Harry Vervet Jul 30 '16 at 21:11
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    Sorry guys but I just can't understand how the answer would involve opinion. Just some description of what neural mechanisms would need to be affected to bring this condition would be more than sufficient. – another 'Homo sapien' Jul 31 '16 at 8:23
up vote 6 down vote accepted

There are many examples of parasite manipulation in nature, if you want more examples you can look up the paper of Lefevre and Thomas (2008). I think the key is, in order for a parasite to develop such behaviour, that it should be giving them a fitness advantage. So I don't think it would ever happen for no reason. The paper discusses a few examples where the manipulation results in a higher transmission rate by the parasite.

I guess that because parasite manipulation is happening in many other organisms, it's probable that it happens to some extent in humans too. There are for example indications that when we are infected with malaria, the malaria parasites can change our odour profile to make us more attractive to mosquitoes, thus increasing it's transmission (Batista et al. 2014, De Moraes et al. 2014). There are also indications that our gut microbiota have an influence on our brain and behaviour, regulating anxiety, mood, cognition and pain, by communicating with our CNS (Cryan and Dinan 2012).

  • You've given a really nice answer, but I'm gonna wait for some time to see if I get some other response :) – another 'Homo sapien' Jul 31 '16 at 10:32

If there are drugs that can cause this kind of disorder you described, then it is possible to engineer a microbe, that can produce these drugs and maintain a chronic infection, which does not necessarily kills the host. Walking dead is not possible, human bodies cannot move with rotting muscles or without muscles, so you won't see real zombies, just insane ppl.

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