Depression reduces capacity to learn to actively avoid aversive events
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Re: Depression reduces capacity to learn to actively avoid aversive events
#2This is exactly what you'd expect if the hypothesis that depression is an evolved adaptation for surviving no-win scenarios that can only be waited out holds.
In a scenario where a disaster has negatively affected the primary productivity of the local food web (e.g. volcano, forest fire, bolide, plague or tsunami), the groups of social species that exist in an environment are likely to engage in internal strife until the food web productivity the group subsists on has returned to normality. Phenotypes which reduce activity across the board without making any changes to their distribution of activities, just hoping for things to get better on their own, are likely the phenotypes that are most successful at surviving to reproduce within conditions of intragroup strife when these infrequent disasters occur.
If this line of reasoning bears out to correctly describe the actual selection pressures that have led to the genes for depression evolving, it follows that what we call major depressive disorder is in fact the genome seeing and carrying out false positives for needing the famine-survival strategy.
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Incidentally, I first came across the theory I'm repeating here on Steven Byrne's neuroscience blog, if you want an avenue for finding sources.
Re: Depression reduces capacity to learn to actively avoid aversive events
#3"These findings suggest that in young adults, depressive symptoms are associated with difficulty in overriding prepotent responses to actively avoid aversive outcomes in the absence of reward."
My word... Could they have phrased that any less clearly?
As I understand it: the more depressive symptoms the subjects showed, the less likely they were to actively avoid bad outcomes (unless there was some other associated reward).
Re: Depression reduces capacity to learn to actively avoid aversive events
#4This is exactly what you'd expect if the hypothesis that depression is an evolved adaptation for surviving no-win scenarios that can only be waited out holds. In a scenario where a disaster has negatively affected the primary productivity of the local food web (e.g. volcano, forest fire, bolide, plague or tsunami), the groups of social species that exist in an environment are likely to engage in internal strife until…
Context: I dabbled in evolutionary biology at the university level, not enough for even a minor in the subject.
My understanding is the existence of selection does not necessarily mean every trait that exists right now has an evolutionary benefit. It is more coarse grained that anything that doesn’t prevent you from breeding is acceptable. Depressed people are not made infertile by their depression, so there will be a subset of depressed people (assuming depression even has a hereditary component). This doesn’t mean the trait of depression has an advantage in order to exist, it just isn’t so much of a disadvantage that it doesn’t exist.
Re: Depression reduces capacity to learn to actively avoid aversive events
#5This is exactly what you'd expect if the hypothesis that depression is an evolved adaptation for surviving no-win scenarios that can only be waited out holds. In a scenario where a disaster has negatively affected the primary productivity of the local food web (e.g. volcano, forest fire, bolide, plague or tsunami), the groups of social species that exist in an environment are likely to engage in internal strife until…
There is nothing about evolutionary theory that posits that all current biological structures/functions must have a evolutionary purpose.
Only the system as a whole must carry superior fitness, not each of its individual components. Given a sufficiently complex system, its rather expected that there will be negative, or even outright destructive functions that arise. You can certainly try to find a positive reason for why cancer, disease, death during conception, etc exist, but there is a much simpler explanation.
Depression in this view, isn't something outright that was adaptively constructed, but merely a side effect of how the mind works.
Re: Depression reduces capacity to learn to actively avoid aversive events
#6This is exactly what you'd expect if the hypothesis that depression is an evolved adaptation for surviving no-win scenarios that can only be waited out holds. In a scenario where a disaster has negatively affected the primary productivity of the local food web (e.g. volcano, forest fire, bolide, plague or tsunami), the groups of social species that exist in an environment are likely to engage in internal strife until…
"Depression stops ant whorls" is my favorite quick and snappy summary.
Re: Depression reduces capacity to learn to actively avoid aversive events
#7This is exactly what you'd expect if the hypothesis that depression is an evolved adaptation for surviving no-win scenarios that can only be waited out holds. In a scenario where a disaster has negatively affected the primary productivity of the local food web (e.g. volcano, forest fire, bolide, plague or tsunami), the groups of social species that exist in an environment are likely to engage in internal strife until…
There is nothing about evolutionary theory that posits that all current biological structures/functions must have a evolutionary purpose. Only the system as a whole must carry superior fitness, not each of its individual components. Given a sufficiently complex system, its rather expected that there will be negative, or even outright destructive functions that arise. You can certainly try to find a positive reason fo…
I've often wondered if depression is exactly that, a system level optimization. Sometimes depression just happens, but sometimes it is triggered by low social status, realizing you've hurt someone in an unjustified or accidental way, having other mental illness, being seriously injured, or some other way that threatens the fitness of the overall group. Depression might be a (albeit flawed) system level way of reducing the amount of physical and social resources those people consume so that the non-depressed strata of society can better take them.
Note: this is a speculation, not assertions of fact
Re: Depression reduces capacity to learn to actively avoid aversive events
#8Earlier quoted context omitted.
There is nothing about evolutionary theory that posits that all current biological structures/functions must have a evolutionary purpose. Only the system as a whole must carry superior fitness, not each of its individual components. Given a sufficiently complex system, its rather expected that there will be negative, or even outright destructive functions that arise. You can certainly try to find a positive reason fo…
I've often wondered if depression is exactly that, a system level optimization. Sometimes depression just happens, but sometimes it is triggered by low social status, realizing you've hurt someone in an unjustified or accidental way, having other mental illness, being seriously injured, or some other way that threatens the fitness of the overall group. Depression might be a (albeit flawed) system level way of reducin…
You’re proposing group selection, which always never happens.
Evolution functions not at the level of groups, or even individuals, but genes inside of individuals.
Most of the time thinking of it as group selection at the genetic level (=individuals) does work, fortunately.
Re: Depression reduces capacity to learn to actively avoid aversive events
#9This is exactly what you'd expect if the hypothesis that depression is an evolved adaptation for surviving no-win scenarios that can only be waited out holds. In a scenario where a disaster has negatively affected the primary productivity of the local food web (e.g. volcano, forest fire, bolide, plague or tsunami), the groups of social species that exist in an environment are likely to engage in internal strife until…
There is nothing about evolutionary theory that posits that all current biological structures/functions must have a evolutionary purpose. Only the system as a whole must carry superior fitness, not each of its individual components. Given a sufficiently complex system, its rather expected that there will be negative, or even outright destructive functions that arise. You can certainly try to find a positive reason fo…
My understanding of the "modern" point of view is that selection acting at the level of the gene (not the organism or group) is sufficient as a theory. The Selfish Gene and The Extended Phenotype go into this stuff in a lot of detail.
Totally agree with your first sentence though. And even if there is a plausible adaptive function it may have only been adaptive in the past, or might be a side effect of some other adaptive function (see sickle cell anemia), or a host of other possibilities.
Re: Depression reduces capacity to learn to actively avoid aversive events
#10Earlier quoted context omitted.
There is nothing about evolutionary theory that posits that all current biological structures/functions must have a evolutionary purpose. Only the system as a whole must carry superior fitness, not each of its individual components. Given a sufficiently complex system, its rather expected that there will be negative, or even outright destructive functions that arise. You can certainly try to find a positive reason fo…
I've often wondered if depression is exactly that, a system level optimization. Sometimes depression just happens, but sometimes it is triggered by low social status, realizing you've hurt someone in an unjustified or accidental way, having other mental illness, being seriously injured, or some other way that threatens the fitness of the overall group. Depression might be a (albeit flawed) system level way of reducin…
I think its just a natural consequence of our mind working on a positive-negative reward system, which I think its critical to any intelligence. Being manically positive is just as detrimental as being chronically depressed.
Its entirely normal to be negative, or to ignore stimuli, or decide not to do things. In some situations, say if you were trapped in a cage your whole life, you'd agree it'd be entirely normal to be depressed. It would make no sense to waste energy running around hitting iron bars that won't break.
In this sense, depression is somewhat of a social construct. We determine someone is depressed because we believe their reaction to the environment to not be normal.