We find stories of people coming back from the dead in fiction as well as legends, myths, and religions. Coming back from the dead tends to mean becoming alive again, after being dead long enough to remove doubt about being dead. At the more real end of the spectrum, common sense suggests it’s not a safe bet if we’re talking about being dead for a long time, at least outside of religious contexts. Fiction, on the other hand, has no problem with having people walking and talking again after being dead for years or even decades or centuries. How possible is it for someone to come back from being dead for years, without preparation like cryogenics? In fact, for answering this question, let’s rule out the use of all technology as well as supernatural contexts listed above. The idea is to examine the question from a scientific point of view, resorting only to nature.
It is of course possible for someone to only appear to be dead. Maybe the closest we can get to a person seeming dead for such a long time is a coma, though a person in a coma simply appears to be in a deep sleep.[1] More controversial are so-called zombies, human corpses that are supposedly reanimated. There are theories that Haitian zombies at least are normal living people who have merely been drugged and then tricked into believing they are dead.[2] Salt is rumored to be a remedy, which further supports the trickery theories.
As for actually being dead, there are numerous reports of people who were temporarily without independent breath and heartbeat for a short time until resuscitated, maybe due to severe physical injury or risky surgery. There’s also the Lazarus syndrome, where a person fails to respond to resuscitation efforts and then spontaneously gets a pulse a short time later, after resuscitation efforts were already given up.[3] The people in both of these situations can be considered temporarily “dead.” though not for a very long time.
Actually Coming back from the dead after some number of years, doesn’t really seem like something we humans are designed to do. To begin with, it took a lot to come up with a person with a good brain. Gestation in the human womb basically follows through the course of our evolution, starting with a single cell, becoming multicellular, giving us gills and a tail at some point, getting rid of the gills and noticeable tail, and finally yielding (hopefully) a healthy human baby. This is a delicate process that has been developing for millions of years. Even slight interference in that process can lead to birth defects or worse. Also we are related by evolution to other animals, and yet I don’t think we’ve found much evidence that other primates – or even other mammals – can come back from the dead after a long time either.
Sure enough, it does seem to be absent from our everyday experience. It’s common knowledge that someone can suffer brain damage if they stop breathing for just minutes. A lack of fresh blood supply can lead to problems as well, as it can cause gangrene, which is tissue death.[4] Human organs themselves may need refrigerated when donated, to preserve them until they can be transplanted into the recipient. Suffice it to say, coming back to life after lying dead in a coffin for years, just does not seem like a part of being human.
What does the rest of life on Earth have to offer in that area? Other organisms as well seem to have their share of what resembles coming back from the dead. Though many of us have seen plants die from not enough water, seeds from at least some of those plants can produce living plants after months or even years without a good supply of water or nutrients. Brine shrimp – sold for decades as “sea monkeys” – can be revived from a dry powder mixed with water.[5] More impressive are tardigrades, also known as water bears, which are tiny animals that can not only survive dehydration but also can survive harsh temperatures and pressures, vacuum-like conditions, high radiation levels, and a lack of food.[6] But like humans, I don’t think other forms of life can truly come back to life after years either.
Yet coming back to life seems to be a significant part of culture. Could the problem be with having a definition of death that says the organism can no longer be alive? That’s basically what the Merriam-Webster web site says death is, the “permanent cessation of all vital functions” and “the end of life.”[7] I see nothing wrong with that definition. And if we find humans coming back to life through only natural means, then there may be something wrong with our definition of death specifically for humans. Suppose we do find a corpse from a cemetery, walking and talking after being dead for 10 years, without any unnatural interference. If we truly consider it to have come back to life, then we must either accept it has been altered from its natural state of post-life deterioration and desiccation or else redefine what life for that reanimated corpse is.
For our hypothetical walking corpse, we have basically ruled out the possibility of it being a normal healthy human, assuming we are excluding things like miracle healing or reversing the effects of time for a given organism. Then our reasoning suggests we find a new definition of life for the corpse, as in something that is at least partly nonhuman. Finding a natural but nonhuman way of restoring a significant amount of functionality to a dead human corpse, including some intelligence, sounds very much like fiction. The chance of success is slim to none. Nature can of course surprise us.
First, what can reproduce some brain function? There is a fungus capable of hijacking an ant’s brain and telling it to find a good spot for the fungus to grow.[8] This fungus uses chemicals after infecting the ant with a spore, but the fact that it can manipulate a brain in such a specific way hints at some awareness of brain tissue. Maybe – just maybe – the fungus species might eventually adapt to focus on neurons to the exclusion of other tissue. With a huge amount of luck, it may even adapt to reproduce some of the human brain’s structure and connections.
What good is a brain without a way to move? That problem could possibly be solved by Dictyostelid, a group of a slime molds, amoeba that can form complex structures. These particular slime molds can deal with pending starvation by having their individual cells join to form something like a slug that can crawl to a suitable place and create a stalk for launching spores.[9] To be useful for moving a corpse, the cells would need to cooperate in such a way to imitate human muscles. Impossible? I don’t know.
But how would our walking corpse see? This problem could potentially be solved by a single-celled organism as well. This time it’s a group of single-celled algae called warnowiids. A warnowiid – in spite of being just a single cell – actually contains a structure like an eye, having the same basic parts as our eyes.[10] Each can probably only see a dot, but maybe enough of them together could lead to vision, especially if they have some kind of nerve-like cells in between.
Are we any closer to answering the question of whether nature would allow a dead human to return to life after being dead for years? Maybe a little. Solving any of these three problems in a corpse is a bit farfetched, and solving all three in this context is quite a long shot. These organisms would probably have to be present before or shortly after the death of the person being reanimated, which in itself is unlikely. And then the ant-zombie fungus only affects certain species of ants that way, slime molds only crawl when desperate enough to find a new source of food, and warnowiids are kind of rare and probably prefer a pond to a human corpse anyhow.
Yet the solutions here offer at least some promise, considering nature has probably done some stranger things. All the organisms just described – from brine shrimp to warnowiids – are definitely unusual, and yet we’ve only scratched the surface in terms of weirdness that can be found in nature. I’m sure someone with more time and biological expertise than me could make a more convincing case for why we should expect to see dead people up and walking around. Nevertheless, here’s one potential way for that to happen, resorting only to science. Maybe I’ll revisit this topic again in the future, applying supernatural concepts instead. Until then, this topic might haunt me.
References
[1] https://en.wikipedia.org/wiki/Coma
[2] https://en.wikipedia.org/wiki/Zombie
[3] https://en.wikipedia.org/wiki/Lazarus_syndrome
[4] https://www.mayoclinic.org/diseases-conditions/gangrene/symptoms-causes/syc-20352567
[5] https://en.wikipedia.org/wiki/Sea-Monkeys
[6] https://en.wikipedia.org/wiki/Tardigrade
[7] https://www.merriam-webster.com/dictionary/death
[8] https://www.livescience.com/47751-zombie-fungus-picky-about-ant-brains.html
[9] https://en.wikipedia.org/wiki/Dictyostelid
(c) Copyright 2018 by Mike Ferrell
Odd STEM 