Depression as a concept doesn’t make sense to me. Why on earth would it be fitness enhancing to have a state of withdrawal, retreat, collapse where a lack of energy prevents you from trying new things? I’ve brainstormed a number of explanations:
depression as chemical imbalance: a hardware level failure has occurred, maybe randomly maybe because of an “overload” of sensation
depression as signaling: withdrawal and retreat from the world indicates a credible signal that I need help
depression as retreat: the environment has become dangerous and bad and I should withdraw from it until it changes.
I’m partial to the explanation offered by the Predictive Processing Model, that depression is an extreme form of low confidence. As SSC write:
imagine the world’s most unsuccessful entrepreneur. Every company they make flounders and dies. Every stock they pick crashes the next day. Their vacations always get rained-out, their dates always end up with the other person leaving halfway through and sticking them with the bill.
What if your job is advising this guy? If they’re thinking of starting a new company, your advice is “Be really careful – you should know it’ll probably go badly”.
if sadness were a way of saying “Things are going pretty badly, maybe be less confidence and don’t start any new projects”, that would be useful...
Depression isn’t normal sadness. But if normal sadness lowers neural confidence a little, maybe depression is the pathological result of biological processes that lower neural confidence.
But I still don’t understand why the behaviors we often see with depression—isolation, lack of energy—are ‘longterm adaptive’. If a particular policy isn’t working, I’d expect to see more energy going into experimentation.
[TK. Unfinished because I accidentally clicked submit and haven’t finished editing the full comment]
I think you’re asking too much of evolutionary theory here. Human bodies do lots of things that aren’t longterm adaptive—for example, if you stab them hard enough, all the blood falls out and they die. One could interpret the subsequent shock, anemia, etc. as having some fitness-enhancing purpose, but really the whole thing is a hard-to-fix bug in body design: if there were mutant humans whose blood more reliably stayed inside them, their mutation would quickly reach fixation in the early ancestral environment.
We understand blood and wound healing well enough to know that no such mutation can exist: there aren’t any small, incrementally-beneficial changes which can produce that result. In the same way, it shouldn’t be confusing that depression is maladaptive; you should only be confused if it’s both maladaptive and easy to improve on. Intuitively it feels like it should be—just pick different policies—but that intuition isn’t rooted in fine-grained understanding of the brain and you shouldn’t let it affect your beliefs.
My views come more from listening to experts and not from looking at specifics. When studying bioinformatics that’s basically what they told us about the result of researching genetics with computer models. Afterwards when talking to experts, I also heard the same sentiments that most claims of group selection shouldn’t be trusted.
I too have heard that group selection is not well believed it just seems so out of sync with my understanding of systems theory that I’m skeptical about taking people’s word on it.
Since we can sequence genomes we know how many changes need to happen for the difference between organisms. We know that gene drift destroys features for which there isn’t selection pressure to keep them like our ability to make our own Vitamin C.
It seems to me like the moving pieces that are needed for computer models are there, so I would trust experts opinions of people on the topic more strongly then would be warranted 30 years ago where opinions were mostly based on intellectual arguments.
Depression as a concept doesn’t make sense to me. Why on earth would it be fitness enhancing to have a state of withdrawal, retreat, collapse where a lack of energy prevents you from trying new things? I’ve brainstormed a number of explanations:
depression as chemical imbalance: a hardware level failure has occurred, maybe randomly maybe because of an “overload” of sensation
depression as signaling: withdrawal and retreat from the world indicates a credible signal that I need help
depression as retreat: the environment has become dangerous and bad and I should withdraw from it until it changes.
I’m partial to the explanation offered by the Predictive Processing Model, that depression is an extreme form of low confidence. As SSC write:
But I still don’t understand why the behaviors we often see with depression—isolation, lack of energy—are ‘longterm adaptive’. If a particular policy isn’t working, I’d expect to see more energy going into experimentation.
[TK. Unfinished because I accidentally clicked submit and haven’t finished editing the full comment]
I think you’re asking too much of evolutionary theory here. Human bodies do lots of things that aren’t longterm adaptive—for example, if you stab them hard enough, all the blood falls out and they die. One could interpret the subsequent shock, anemia, etc. as having some fitness-enhancing purpose, but really the whole thing is a hard-to-fix bug in body design: if there were mutant humans whose blood more reliably stayed inside them, their mutation would quickly reach fixation in the early ancestral environment.
We understand blood and wound healing well enough to know that no such mutation can exist: there aren’t any small, incrementally-beneficial changes which can produce that result. In the same way, it shouldn’t be confusing that depression is maladaptive; you should only be confused if it’s both maladaptive and easy to improve on. Intuitively it feels like it should be—just pick different policies—but that intuition isn’t rooted in fine-grained understanding of the brain and you shouldn’t let it affect your beliefs.
On a group selection level it might make lots more sense to have certain people get into states where they’re very unlikely to procreate.
On of the finding of data-driven models of evolution of the last decades, is that group selection mostly isn’t strong enough to create effects.
Hmm, which models?
My views come more from listening to experts and not from looking at specifics. When studying bioinformatics that’s basically what they told us about the result of researching genetics with computer models. Afterwards when talking to experts, I also heard the same sentiments that most claims of group selection shouldn’t be trusted.
I too have heard that group selection is not well believed it just seems so out of sync with my understanding of systems theory that I’m skeptical about taking people’s word on it.
Since we can sequence genomes we know how many changes need to happen for the difference between organisms. We know that gene drift destroys features for which there isn’t selection pressure to keep them like our ability to make our own Vitamin C.
It seems to me like the moving pieces that are needed for computer models are there, so I would trust experts opinions of people on the topic more strongly then would be warranted 30 years ago where opinions were mostly based on intellectual arguments.