Amateur question: if we've retained these ostensibly dangerous or at least deleterious viral codes in our DNA, is there any reason why these virii don't serve a important evolutionary or remedial (maybe crisis) purpose?
Many important figures of history have had these traits. That isn’t to say that they are good in the whole, only that it is not obvious that they are something so maladaptive that they get trimmed from the evolutionary tree.
It’s only in the last 150 or so years that we expect all people to be Rational Economic Agents. If anything, I think /that/ is something that will get trimmed pretty quickly from the tree…
Ancient population suffers from massive viral load, causing such catastrophic damage that the whole surviving population carries some of the viral DNA fragments with it to this day.
Various illnesses are caused by promoter genes. These are genes that serve no purpose but they specialize in promoting themselves, so they spread through a population even though they serve no evolutionary fitness goal (often they bring illness). A good book on that topic:
Genes in Conflict: The Biology of Selfish Genetic Elements
However, referring to the original article of this thread, it is also possible that the same genes that give us depression also give us something positive, such as creativity.
There are perfectly plausible reasons why the conditions we regard as mental illness are adaptations that help evolutionary fitness:
- Depression puts one into a low-energy, contemplative state that enables reflection, healing and formulation of reformed ways of thinking and being ("dark night of the soul");
- Bipiolar is a pattern of swinging between high-energy bursts of inspiration and creation, and low-energy states of recuperation and reflection;
- Schizophrenia is a way of disassociating from real-world experiences that are too painful to experience with normal consciousness, and is a preferable alternative (from an evolutionary perspective) to suicide, buying time for processing and healing to take place, given the right kind of support.
Of course, that could be seen as a "just so" story too. Except that evolutionary theory says that only genes that promote evolutionary fitness should survive and spread through the genome, particularly given that replication of any given gene carries a significant cost. We can also easily observe that conditions like depression and schizophrenia normally develop in response to a trigger - i.e., a traumatic life event or extended period of abuse.
So, it's far less of a confected story to just accept that these conditions have been retained in the genome for the reason that makes most sense according to evolutionary theory: it's evolutionarily beneficial for them to be there.
First, I don’t know why you feel the need to include a hostile ad hom barb like “You seem to think evolutionary theory came to an end in 1882”.
I’ve done multiple Google searches and even done Google Books searches in the very book you linked, for the exact phrase “promoter gene”, and it really doesn’t seem to be a term that’s used, at all, really.
DNA promoters are well recognized, but not in the context you’re talking about.
I can very much understand the notion that genes may act to further their own propagation at the cost of the host’s fitness - sure.
It’s just that we first need to see evidence that it’s happening, by having a clear definition of what favours vs costs the host’s fitness.
The hypothesis you’ve cited (and from the book reviews it seems even the authors concede their hypotheses are highly speculative), seems to start with the assumption that these mental illness traits are opposed to the host’s fitness and confer no benefits whatsoever.
But all we have to do is point out the many cases in which these traits actually do benefit the host, which I did and you even conceded in the last line of your comment, and the hypothesis is void.
It reminds me of the “junk DNA” hypothesis, where researchers couldn’t find an obvious use for large sections of the genome so just assumed it to be useless and called it “junk”, only to be later found to have very important roles:
A common evolutionarily explanation for the existence of depression in the case of an illness is that it forces the individual to take rest, and being withdrawn lowers the risk of transmitting an infection. How depression and inflammation are related is quite well documented.
I read somewhere that hunters who hide in one place and need to stay focused for several hours of the day, have an advantage of being schizophrenic to a degree
Or hyper-focused with ADHD traits. Counter-intuitively hyper-focus on tasks "interesting" to the patient is an ADHD trait, it is not just being a "space cadet".
Men who were prone to alternative/extreme states of consciousness would have been better able to summon up the wild emotions necessary for savagery and violence, making them better fighters and hence giving them better mating prospects.
They would be constantly vigilant and unpredictable to someone unfamiliar with that particular trait. When wandering you might only have yourself as a reference so they would be a counter to that
If they've even lived long enough, no absolutely not. Unless you think someone who is routinely depressed is 'vigilant'.
[Hypo]mania is not the primary state of a bipolar patient. Can't speak to schizophrenia, but for those I've seen with that illness, functioning isn't their primary state, either.
Mania, maybe, but not depression. It clouds the mind and saps motivation in a way that would undermine efficacy in both hunting and surprise encounters.
Obviously I don't think it can be turned on-off, why would you even think that I was suggesting that? It's just easy for me to imagine these scenarios triggering mania in me whether I wanted it to or not, and I don't think I'm that unusual, that's all.
No, that's not how [hypo]mania works. You can 'imagine' all you want, but thinking that a specific scenario or time is when [hypo]mania 'lights up' is flat out incorrect.
And someone who experiences mania indicates an uncontrolled illness. Depression and mania prevent normal functioning. You seem to believe an unmedicated bipolar individual is a functional individual with some inkling of rational thought that could 'go into battle with no fear'.
If you don't know, don't post. And you don't know.
Your statements about what you know about me and my lived experiences, and my level of knowledge of those experiences, is bizarrely cruel. Please do not do this. Please don't try to silence me just because those things don't match up with your own experiences.
I don't know where you are getting the notion that I am saying that mania is rational or controllable. I was speculating based on personal experience around high stress situations. I do not understand why you are choosing to attack the notion that there could be evolutionarily advantageous benefits conferred upon the group.
Edit: we agree that I am speculating. I disagree with you that I have no right to speculate
I know both pretty well, indirectly or not. Given how much they can influence your energy and "will to live" I don't think they'd pair well with having to fight for your life.
