What's the evolutionary purpose of schizophrenia?

I was taught at school that only useful genes survive the test of time within an animal population. By that I mean only genes that lead to a selective advantage for the animal will get passed on to next generations. And animals that have genes which lead to a poor physical outcome in general get bred out of the population (because the effected animals have a small chance of mating and passing on the genes).

So what I ask is how come schizophrenia exists at all. I mean it is at about 1% of the population my understanding of biology says rates this consistently high means there must be a selective advantage of having these genes. What benefits does schizophrenia provide?

I have a number of thoughts. Firstly schizophrenia often appears in early adulthood: by this time the individual may have already had children so the genes have past on. But I don’t think this explains everything.

My other theory is that in the past people with psychosis may have appeared to be able to contact “the spirits”. Maybe because of this they were revered by the ancient cultures (rather than stigmatised). Also maybe paranoia can increase vigilance and suspicion - and perhaps these qualities were valuable in a feudal tribal context.

Either ways I find this fascinating and I would love to hear your thoughts.

(NB - I am not saying SZ is purely a genetic condition. Just that some genetics is involved).

J

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With identical twins, one can have schizophrenia and one not. So maybe it’s not genetic.

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It’s an interesting thing to think about. When I’m psychotic I have highly associative thinking, connecting all kinds of things sane people wouldn’t connect. Even if it is just by chance, some of these connections that others hadn’t thought about yet must make some sense, so there could be an advantage in that I suppose.

But evolution is a bit more nuanced. Not everything has a function (anymore). There are leftovers that used to be useful in one environment for a species, but are no longer so in the current environment. There’s also the possibility of useful genes mutating by chance into unuseful genes. The mutation by chance is a key element in explaining how adaptation to environments progresses, but I guess it can easily have negative outcomes as well. Now these ‘should’ be filtered out by the survival of the fittest principle, but maybe that’s not fully operative in modern societies anymore. I’m not sure for how long psychoses have been around to be honest, I’ve read some articles that say that it is a typically modern condition but then again others say the prophets were psychotic.

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Agreed. I know in my situation stress precipitated my illness. But at the same time there was a strong element of serious mental illness in my family tree.

Like your ideas that “bad” genes are more likely to pass on in modern society with all its supports. Had never thought of that.

It’s often a recessive trait that makes it into life without us even knowing it.

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There is a value for someone who can think outside the box and challenge pre-conceptions. Some sz’s can be creative. The fact that sz genes have remained in the gene pool means that they must have some utility.

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This is assuming it is genetic which it is not in all cases. there are so many causes of things that are considered SZ, so there are many, not just one.

Known statistics are around 1.1%, but that is probably based on what is reported. I have known plenty of people who exhibit symptoms of some form of SZ, maybe not strait SZ but at least SZA, Schizophreniform, Schizotypal, etc…
I’m not even going to try to count the number of friends or associations I knew as a teenager and into my 20s who had experienced seeing and hearing things apart from being under the influence of something. Various delusions. Inability to work jobs, depression, manic states…people who never went to doctors and never had a diagnosis…lost in the cracks, usually self medicating with drugs and/or alcohol…
there are people that would be considered high functioning that never get a DX, and are able to get by. If they had gone to a doctor and reported all the things they told me or i witnessed them doing they would most likely get some form of SZ type DX.

In some cases…not all but some, there have been several topics here about how people with Sz symptoms in non western cultures have been viewed as gifted, trained by shamans and prophets or other spiritual advisers to interpret and successfully deal with symptoms they exhibit. I would say insight, perception, the ability to see beyond the mundane, that there are realities beyond our 5 senses, and beyond what we see in 3D…

The element of surprise, random acts of unpredictability? If we fail to anticipate the unforeseen or expect the unexpected in a universe of infinite possibilities, we may find ourselves at the mercy of anyone or anything that cannot be programmed, categorized or easily referenced.

  • Fox Mulder, X Files

When you open your mind to the impossible, sometimes you find the truth.

  • Dr. Walter Bishop, Fringe

I’m not talking about debilitating symptoms…I’m talking about things that can be explored and are explored in some cultures, things that in the western world are considered purely delusion and hallucination. I have found one must learn to tell the difference between what is going on when our perception shows us things rather uncommon to most folks…

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A lot of my symptoms appear when I believe I am in danger so I wonder if it had some survival advantage in the past. It might help an animal backed into a corner to behave pretty unpredictably or make nonstandard associations.

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Well if it were in animals, I think the variation would be extinguished.

But humans can help those that are affected and so the gene can carry on.
Having less stressful livestyle can help prevent the gene from even expressing. (nuture vs. nature)
With newer meds, its possible to live a more normal life.
Animals don’t get that kind of help.

@Jimbob

Schizophrenia does not have to be advantageous. You have to realise that schizophrenia as a selection pressure is now only occurring in the past 10000 years. Our descendants were not governed by social norms regarding what age they procreated at. Schizophrenia in modern day starts from 16/17 on , so plenty of time for our descendants to spread vulnerable genetic information through out the wider genome. Also you must realise that language , complex social interactions , etc just happened a few minutes ago. In terms of our evolutionary past , and again there is very little time for filtering out vulnerable genes.

Now of course the above relates to evolution by natural selection. But who is to say that by virtue of the sheer complexity of the brain , the most complex structure known to man , in this universe , that this means that it is open to a whole host of problems , in its development and opperation?

Finally in the last 10000 years , if schiz , has indeed become a selection pressure , there is zero guarantee that sz will be eradicated due to its sufferers not having offspring. You have to realise that absolutely everyone is on a spectrum , so even if people with sz are not having offspring , there are an overwhelming majority that have varying degrees of mental challenges that are. If you like still propagating a set of vulnerable genes.

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Some really good points being made on this thread. Love it!

I saw a video of a professor once who talked about the evolutionary advantages that made sense. Can’t find it now of course. I think it may have opened my third eye here lately, a spiritual awaking or something. I’m not really studied in the third eye stuff at all. I’ve just told my family that it felt like I was growing one during a couple of episodes. I told my sis this the other day, and she said that I had said the same thing years ago and it gave her a sense of deja vu. Thanks for this thread. It’s interesting to think about.

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I’d say it’s more of a flaw of the genome rather than something that is positive.

For every good mutation there are probably hundreds of thousands of bad ones.

I think it’d be a rarity for some with Sz to wind up functioning beyond normal levels.

We can easily do it though it’s just a matter of extra effort and focus. These things can be learned. That said it is much more difficult than for people who haven’t developed this illness.

Not enough is really known and I think it probably has a myriad of causes.

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It’s a self-destructive mutant gene that doesn’t follow the rules. It is here. That’s a fact. So it’s NOT being bred out. Humans are animals but we’re on a higher order than other animals. We have survival instincts still but we are civilized. Yes, maybe in the animal kingdom weak genes get bred out but we are not living in Hitlers time when he tried to erase homosexuality, schizophrenia, and other races by killing them. We don’t erase faulty genes anymore. We treat the end results who are the people who suffer from them. Schizophrenia is part of the human race.

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