The evolutionary origin of depression

http://www.economist.com/sciencetechnology/displaystory.cfm?story_id=13899022

by tokenadult • 17 years ago

77 63 17 years ago

amichail2• 17 years ago

This will change in the future: everyone will know early on in life what their capabilities are based on analysis of their DNA.

Retric4• 17 years ago

Depression is not unique to humans. So I suspect it's a little more complex and fundamental than a failure to understand your limitations.

tokenadult9• 17 years ago

Depression is not unique to humans.

What animal model of depression do you have in mind?

tokenadult9• 17 years ago

Do you really think that people can set all of their personal goals just from knowing their genome?

amichail2• 17 years ago

Your genome will give you critical information about the sorts of things you would be good at.

For example, an analysis of your genome might tell you that you should pursue a startup that makes use of sophisticated mathematics.

The specifics of that startup are up to you.

colins_pride• 17 years ago

My environment shapes me far more than my genes. I know this because I'm not the same person who woke up this morning. Sure, my genes may predispose me to Alzheimers or Diabetes or cancer. They drive my physical characteristics, and maybe much more. But my essence is not pre-destined by my genes.

10ren• 17 years ago

It's an intriguing idea that seems to be associated with Soviet-era training and the mechanization of human beings, coerced into insect-like castes, as in Brave New World, and the lovely short-story Unaccompanied Sonata http://en.wikipedia.org/wiki/Unaccompanied_Sonata (or Ender's Game itself for that matter.)

I know you don't mean coercion, but simply informed choice; but I think the rebuttal is the same: our theories are not adequate to predict such things, even if we had all the information; especially when factors like 10,000 hours of practice and motivation seem so important. At best, they can suggest a probability distribution. Or: you don't know til you try.

I guess some specifics could be useful, like a probability distribution of expected height for a baby, for his/her potential as a basketball player. However, at the very young age where genome knowledge is most effective (by revealing as yet unexpressed traits). the baby is not able to make a choice. So it would effectively be Soviet-era training.

pie2• 17 years ago

This is one of those concepts that I always simply assumed to be true. Ordinary feelings of depression (i.e. specifically not chronic or "clinical" depression) are quite normal responses to situations that are, in fact, depressing. These feelings can help shake us out of situations we might otherwise suffer through.

Afton• 17 years ago

This is interesting. I wonder if it means anything more than "depressive people are those that are unable to let go of failure"? Seems like an apt description of many generally depressed people I know.

Side note: Anyone have thoughts on whether 'depression' is an umbrella term for distinct mental traits?

tokenadult9• 17 years ago

Anyone have thoughts on whether 'depression' is an umbrella term for distinct mental traits?

My sense of the evidence, as I read the masterwork on the subject

http://www.amazon.com/gp/product/0195135792/

just now for research I am doing, is that depression has multiple distinct causes, and a variety of particular manifestations.

jerf• 17 years ago

In addition to tokenadult's comment, which I would expect is probably correct, I would relate this from my abnormal psych class: A number of conditions given the same label are known to be distinct, in that we can tell there's definitely more than one distinct thing going on, but nobody quite knows where to draw the line. Part of the purpose of the label is to give psychologists simply a word with an agreed meaning so they can discuss it with each other. As they narrow down exactly what the variants are and figure out where to draw the line, psychologists will give the variants new, separate names.

This is closely analogous to the justification given in the Design Patterns book for programmers. And in both the design pattern and the DSM case, there is widespread misunderstanding about the fact that the most important thing for both is simply giving things names, since we can not talk clearly about what we do not have proper names for.

Schizophrenia is the classic example, which started out as all but a synonym for "idiopathic mental disorder" and has gradually been refined into various distinct pieces, but not without controversy [1]. It remains an over-broad distinction, but of course that's because nobody really knows how to cut it down better yet.

Depression definitely would seem to be very similar; just look at all the types listed here [2], which I'd hardly expect to be an exhaustive list. Certainly in the popular press, which rarely takes the time to really nail down what they are talking about, "depression" is a term so broad it has hardly any meaning beyond "I feel sad a lot".

There's a lot of slicing and dicing done by the real professionals, which the popular press is entirely oblivious to. (I only sampled at the beginning, but I can at least say that's a true statement with confidence.) And there's more defining yet to be done. If you're interested in the subject, it's definitely an interesting one for hackers, seeing how the most complicated computing device known to man can go wrong. It can be... scary, though. (I don't have specific book recommendations though. Perhaps others will chime in.)

1: http://en.wikipedia.org/wiki/Schizophrenia#Controversies_and...

2: http://en.wikipedia.org/wiki/Types_of_psychological_depressi...

wallflower2• 17 years ago

"The DSM-IV organizes each psychiatric diagnosis into five levels (axes) relating to different aspects of disorder or disability:

Axis I: clinical disorders, including major mental disorders, as well as developmental and learning disorders

Common Axis I disorders include depression, anxiety disorders, bipolar disorder, ADHD, Autism, phobias, and schizophrenia."

http://en.wikipedia.org/wiki/Diagnostic_and_Statistical_Manu...

miloshh• 17 years ago

Interesting hypothesis. However, isn't depression sometimes getting in the way of pursuing perfectly attainable goals? For example, finding more friends or losing a bit of weight are definitely not overly ambitious goals, but depressed people often despair that they will never be able to reach them.

tokenadult9• 17 years ago

isn't depression sometimes getting in the way of pursuing perfectly attainable goals?

It certainly plays out that way in actual medical cases, and cognitive therapy for depression is all about showing patients that they can still succeed in goal-directed behavior.

pie2• 17 years ago

Perhaps the hypothesis would apply more to the approach/situation rather than the goal.

If depressed people despair that they cannot find new friends or lose some weight, maybe the depression might direct them to try something new. That's how I see the idea presented here. (Unfortunately, you're right that many people are quick to give up and deem a goal impossible.)

darshan• 17 years ago

From the opening paragraph: [He] likens the relationship between mild and clinical depression to the one between normal and chronic pain. He sees both pain and low mood as warning mechanisms and thinks that, just as understanding chronic pain means first understanding normal pain, so understanding clinical depression means understanding mild depression.

In other words, yes, people with clinical depression find that it gets in the way of their daily life. His hypothesis is about why normal, healthy people suffer from low mood / mild depression from time-to-time, and what evolutionary advantage that might give us.

pwncat• 17 years ago

I disagree with this argument. I think another one's more salient. For a pack animal such as primal humans probably were, a certain type of moderate depression is a survival mechanism for dealing with low social status. Your appetite and libido decrease, you become inassertive, you accept mistreatment from others. Subjectively, this process and experience sucks, but lacking desire to mate with the alpha female keeps the omega male alive. Much more importantly (since nature doesn't care much about unsuccessful individuals) it's a survival mechanism for the pack; the depressive response ensures that, in extreme scarcity, the less successful individuals slink away and accept starvation, rather than challenging and potentially causing harm to the more important ones.

In modern society, this reaction is completely useless and utterly maladaptive. It also has a tendency to fire in people at all levels of social status, because modern society (with its dynamic, subtle, and multileveled play of social status) is confusing to the primal mind. So a depressive response can be rightly considered an illness.

Civilization expects everyone to assume the role most closely analogous to high beta/low alpha. People who have omega traits tend to be depressives; people who have too many alpha traits are sociopaths.

aswanson3• 17 years ago

Sounds reasonable, leading to the prime exception I take with this whole line of inquiry known as "evolutionary psychology": the lack of falsifiability of any plausible hypothesis. You can handwave pretty much any narrative that somewhat fits the data and publish.

ShardPhoenix2• 17 years ago

Not only is this particular hypothesis falsifiable, it has been more or less falsified (see http://en.wikipedia.org/wiki/Group_selection).

Also, it seems to me that in these kinds of discussions, a lot of these evolutionary-psychology stories are not meant to say "this is exactly why this thing evolved", but to demonstrate that there are reasons that such a thing could evolve. A lot of this kind of thinking is probably derived from arguing with anti-evolutionists who claim that such-and-such could never have evolved because it's apparently mal-adaptive.

lionhearted• 17 years ago

> Civilization expects everyone to assume the role most closely analogous to high beta/low alpha. People who have omega traits tend to be depressives; people who have too many alpha traits are sociopaths.

This is, far and away, one of the most intelligent and insightful comments I've read on Hacker News and explains a hell of a lot to me. I might quote you on this one later in an article I've got in the que to write: Is there any particular way you'd care for me to source you? I've got the permanent link and your screenname and can use that, but if you'd like it attributed differently I'd be happy to.

Thanks very much for the insight, and welcome to HN. I hope you stick around, this really got the gears turning in my head.

psranga• 17 years ago

Remember that modern civilization ENABLES many people to attain high positions. So I would not consider this expectation to be totally unrealistic. There are SO many ways in which to excel and influence society in the modern world that there is room for many many many (maybe all of us) to be near the top of something or other.

One example from the work world: all decent companies have a technical and management ladder so that people who are not completely aggressive can still influence strategy (e.g., Anders Hejlsberg?).

And with food/clothing/shelter becoming less and and scarce as time passes, being at the "top" is going to matter less and less.

pfedor• 17 years ago

Much more importantly (since nature doesn't care much about unsuccessful individuals) it's a survival mechanism for the pack

I am not a biologist, but according to (what I understood of) "The Selfish Gene" and the like, the natural selection takes place on the level of genes. Since the successful reproduction of a gene is usually (barring some exceptional situations mentioned in the book) tightly coupled with the fate of the individual carrying the gene, reasoning about natural selection that operates on individuals typically leads to correct conclusions. Reasoning about natural selection on packs is on the other hand typically incorrect, if it leads to conclusions different from the individuals-based selection.

In your example, if you imagine two genes, one that tells the low status carrier to accept starvation, and the other that tells its carrier to fight for dear life no matter what its social status, the second gene will win and the first one will go extinct, even if from the point of view of the whole pack the first gene could be better.

This is not to say that your hypothesis is invalid, as I'm sure it can be rephrased in terms of genes/individuals without losing the core message.

danteembermage• 17 years ago

IANAB either, but pack survival could have a role in gene transmission, it would just be more indirect. Suppose pack A is full of extreme non-depressives and B is depressive. Highlander style, only one male in A will survive while B can maintain a back-up stock in case accident befalls the alpha.

That said I don't see why the gene expression couldn't be:

if (alpha) { act like alpha } else { act depressed }

individually beneficial and pack beneficial simultaneously.

jibiki• 17 years ago

Yep. Here's a really good example from EY:

http://lesswrong.com/lw/kw/the_tragedy_of_group_selectionism...

"The mathematical conditions for group selection overcoming individual selection were too extreme to be found in Nature. Why not create them artificially, in the laboratory? Michael J. Wade proceeded to do just that, repeatedly selecting populations of insects for low numbers of adults per subpopulation. And what was the result? Did the insects restrain their breeding and live in quiet peace with enough food for all?

No; the adults adapted to cannibalize eggs and larvae, especially female larvae."

(Here's the actual paper:

http://www.pnas.org/cgi/reprint/73/12/4604.pdf

)

jballanc3• 17 years ago

Ok, well... I am a biologist and one of the first things you need to understand about "The Selfish Gene" is that much of what Dawkins presents as fact is very much under dispute in the biological research community. Be very cautious about accepting anything he presents as "the one true way" of understanding evolution. It is anything but!

One term you can Google for more information is "multi-level selection". I find the pack animal explanation actually rather interesting. It meshes well with some of the research that I'm doing on evolution as targeted at resource utilization efficiency. I think the real question is to what extent primitive man was a "pack" animal as opposed to a "group" or "tribe" animal. That is, I think there are many open ended questions regarding the social structure of early man (for one thing, if early man was a pack animal you'd have to explain the origin of monogamy, or at least limited polygamy, in place of the harem structure of most pack animals).

ShardPhoenix2• 17 years ago

Group selection has been proven not to work so you'd have to demonstrate a benefit for the depressed individual to justify it evolutionarily.

MaysonL• 17 years ago

The thing is, clinical [endogenous] depression strikes the successful and the unsuccessful alike - it's a biochemical imbalance, not a psychological reaction.

tokenadult9• 17 years ago

it's a biochemical imbalance, not a psychological reaction

To call depression a "chemical imbalance" is what physicians, compassionately, tell their patients to encourage them to take their medicines. But the doses of lithium, the best evidenced drug for depression, that are in the therapeutic range are many times higher than the natural level of lithium that occurs in any healthy untreated human being, and perilously close to the toxic dose.

The current view is that depression strikes people who have a genetic vulnerability (that much would be either biochemical or structural, perhaps a different vulnerability in different patients) who also experience certain kinds of environmental stress (perhaps not always the same kinds of stress for all patients with the same underlying vulnerability). That medicines relieve depression--as some plainly do for many patients--doesn't prove that what the patients had beforehand was a lack of those medicines, or even exactly an imbalance of the brain chemicals most influenced by those medicines. The most effective treatment for depression generally appears to be a both-and of prescribed medications and evidence-based cognitive therapy.

arketyp• 17 years ago

Arguing by group selection is far fetched as it is almost inherently wrong in concept, and demands further explanation in gene mechanics.

Even if accepting the group selection idea for the sake of argument, there are inconsistencies to what behavior one would expect to find. As the article elaborates on, depression is, crudely put, mental pain, and it comes with symptoms such as general lack of motivation. How does that fit with the over all good of the pack? Wouldn't the expected behavior be acceptance of the omega situation and great motivation to sacrifice itself for the pack (as in wolf packs where there is kinship involved)? How is an individual being gloomy and doing nothing - mental pain being inflicted - beneficial to the pack?

kingkongrevenge5• 17 years ago

> social status

Why does every arm chair discussion of evolutionary psychology veer to social hierarchy? The evidence is quite convincing that pre-agricultural humans were not so much hierarchical. Humans are not gorillas. It seems like various insecure nerds are very eager to project popularity issues.

I think depression is more about simple calorie preservation. People in situations where they feel they have no control get depressed. Imagine a famine. The cheerful go-getter says "By gum, there's food out there somewhere and I'm going to find it!" He tramps out of camp on a hunt, and drops dead of starvation two days later. Our depressive fellow says "We're fucked. I'm going to lie down and wait to die." He stays still and doesn't even think much, saving calories. Then by chance a deer wanders into camp eight days later and he's saved.

In this age of plentiful energy and food people seem to forget how central metabolism and energy scarcity is to evolution. The human body is mostly a machine set up to cope with highly variable energy intake. Energy efficiency and conservation should typically be the starting point when considering these issues.

As recently as 100 years ago huge numbers of people in northern climes would spend most of four months of the year lying in bed in a semi-depressive state to save energy.

aswanson3• 17 years ago

Why does every arm chair discussion of evolutionary psychology veer to social hierarchy?

Amen. What I have been trying to articulate in so many words but somehow fell short. Think that's my main gripe -- these explanations always veer into territory ripe with any number of convenient social stories.

tokenadult9• 17 years ago

Why does every arm chair discussion of evolutionary psychology veer to social hierarchy? The evidence is quite convincing that pre-agricultural humans were not so much hierarchical.

Yes, and also human beings were not as constrained geographically, but could leave one hunting band to wander off to an area previously unoccupied by human beings for most of human evolutionary history.

bored• 17 years ago

> alpha female keeps the omega male alive.

Sounds like group selection, common fallacy.

diN0bot• 17 years ago

seems more likely to me that depression doesn't get in the way of survival and reproduction.

rriepe• 17 years ago

My theory on it is something between "pack" benefit and "individual" benefit. I believe that depression is beneficial to pack hunters.

It goes like this: Operating in groups offers a great advantage. If a member of the group is lost, however, there follows a period of time where the group is more vulnerable. They haven't yet adapted (tactically) to a smaller group, so business as usual could end up getting them killed.

A period of mourning, however, with lowered dangerous activity, puts the group in less danger while they recoup from their loss. During this time they're more likely to gain new members, train young ones or simply adapt their tactics to fit their smaller numbers.

Think of it like this: Take Kobe off the team and the Lakers start to really suck. However, let them fill the fifth spot and rethink their strategies... and they start to look like a good team again.

TheSOB883• 17 years ago

Seems true, but I think we're talkin about a different kind of depression here than mourning over someone's death.

b-man• 17 years ago

I don't think the journalist did a good job when he took his conclusions as:

"Depression may turn out to be an inevitable price of living in a dynamic society."

That amounts to, Hey, we are doing something that hurt us as a society, but what the heck, lets all take the symptom of our mistake as a 'price' for our 'correct' path.

The blind leading the wounded.

tokenadult9• 17 years ago

Having thought about this article for a day, I'm wondering what the view of the cited scientist is of elevated human mood states, those that correspond to pathological states of hypomania and mania. One of the tricky issues in treating depression is to avoid inducing mania.

The evolutionary origin of depression

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