The evolutionary origin of depression | Hacker News Reader

The evolutionary origin of depression

economist.com

77 pointstokenadult63 comments

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.

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.

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.

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.)

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.

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?

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.

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...

"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...

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.

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

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.

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

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.

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

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.

I think it would be much more effective to evaluate whether you're actually good at sophisticated mathematics.

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

Are there any participants here who can point to some genetic research on how likely it is that genome analysis will ever be that specific on the individual level?

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.

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

Depression is not unique to humans.

What animal model of depression do you have in mind?

Parrots and dogs will tear apart their environments (and sometimes their bodies) under certain circumstances, such as extended loneliness. Seems similar to human depression.

Yes, my housemate's dog has separation anxiety which is not good (but he was adopted from a shelter).

We hypothesize he gets all anxious because when we are leaving and locking him in his (reinforced) cage - he doesn't know if we'll ever return. Which is different from humans - as in we know that it is only a matter of time.

This review, and its references, are a little dated, so I presume that the animal models are much more sophisticated by now:

http://dx.doi.org/10.1111/j.1440-1819.1990.tb00461.x

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.

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

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.

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.

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).

Evolution is essentially an algorithm. That's why we can use logic to predict that genes that regulate behavior for "less successful individuals to slink away and accept starvation" are unlikely to arise, since not a single one of the ancestors of that individual were less successful and slunk away to accept starvation.

There's a mister Hardy and a mister Weinberg that would like to have a word with you about that logic...

http://en.wikipedia.org/wiki/Hardy-Weinberg

The other thing to keep in mind is that evolution works as a movement through nucleotide space over a fitness landscape. The fundamental flaw in much of Dawkins work is his reliance on a biologically unrealistic definition of a "gene". Sure, if you go with his definition of genes then logic can tell you all sorts of things about evolution that aren't necessarily true.

I think depression helps people "keep their head down" in oppressive situations. An aggressive alpha male can kill you so slink away and stay alive. If your younger than the alpha you can just wait him out. This might explain why it's so much more prevalent in teenagers where staying alive might gives you time to become the alpha.

Slavery is a more recent example of this, if you are aggressive you will be killed, but keep your head down at the chance exists to reproduce. And most people alive today have some slaves/peasants ancestors.

Today we end up with some suicides, but that's rare enough it might not outweigh the benefit when that feedback loop stays on track so you avoid jail etc.

Any mention of "alpha male" costs you your entrance ticket to the discussion. There is no such thing in humans.

> An aggressive alpha male can kill you

What advantage does an "agressive alpha" have over you? Any human can kill any other human very easily. Rock to the head, game over. We're not talking about walruses.

Social power structures of any complexity are a post-agricultural development, and therefore of limited importance to human genes. The social structure in a hunter-gather band of 20 is simple and flat.

As trite and cliche as mentions of "alpha male" have become, there is good reason to believe that early human social structure might have involved just such a character. Namely, some of our closest relatives in the great ape family have this sort of "alpha-male-with-harem" approach.

Now, there is also good reason to believe that the evolutionary adaptation that pole-vaulted early humans ahead of the other apes was a change in their social structure. However, even if that is true, you also have to remember that humans have spent a much larger portion of their evolutionary lineage as great apes than as modern (or nearly-modern) humans. That is, even if early humans had distinct social structures from their ape cousins, we are bound to have many remnants of the ape social structure left in our genomes.

In other words, depression doesn't necessarily have to have been an adaptation of early humans, it could just as easily have been an adaptation of early primates that humans just haven't had time to get rid of yet!

If you accept the popular premise that man is a pleistocene animal designed to live in hunter-gatherer bands then you don't really have to wonder much about the innate social tendencies of humans. We have dozens of detailed ethnographies of hunter-gatherer bands. They are socially flat. Some people are highly esteemed, but nobody has any sort of disproportionate power.

> the ape social structure left in our genomes

The apes and the gibbons vary dramatically so it seems a bit silly to expect useful common denominator social behaviors applicable to humans. Bonobos and gorillas and orangutans are all very different. And none of the apes are at all comparable to humans in how they make their living. None of them are primarily team hunters.

Evolution has a long history and vestigial adaptations don't instantly disappear if they are part of complex systems. Rat brains also use dopamine and there seems to be a link between dopamine and depression so it's roots might be vary ancient.

Looking modern males at the average American high school, biker gang, or hunting party and you will notice social stratification. Humans don't do the Alpha with harem, but young men often fight for levels of dominance. In scripted environments they might fight over academic prowess but simple fist fighting is not that uncommon. And when males fight you get into some basic game theory as to how much energy to expend and damage to risk.

If the systems that cause depression where useful thought human history then removing the possibility of depression may have had serious costs.

PS: Just because the human brain works extremely well does not mean it's elegant.

Edit: Modern hunter gathers have just as much history as we do. Extrapolating how humans lived 500,000 years ago from what we have seen modern bands do is a mistake.

There were no humans 500,000 years ago. Fully modern humans are more like 60,000 years old. And truly cognitively modern humans are more recent than that.

> Looking modern males at the average American high school, biker gang, or hunting party

Well, I say you watch too many B movies. Struggling for social dominance in a hunting party? Really? Nobody fought for "dominance" at any social institution I've been involved with. However, people do all kinds of weird things, much like zoo animals, when caged in unnatural environments like public schools, housing projects, corporate cube farms, and prisons.

There were no humans 500,000 years ago. "The term "human", in the context of human evolution, refers to the genus Homo," "The Homo genus diverged from the Australopithecines about 2 million years ago in Africa."

http://en.wikipedia.org/wiki/Human_evolution granted Homo sapiens are younger than that.

Nobody fought for "dominance" at any social institution I've been involved with. I recall doing this on several occasions in unscripted environments. I don't know if you are male, or if you spent much time unsupervised with groups of 8 - 20 other young men, but it's seemed really common.

This might also be more obvious to those who win these games. And there are edge cases. I recall having 12 people watching me play video games and when my mother asked me to share I offered and got a “we just want to watch” response. This seemed more like a completion to find the best followed by watching the master situation. But it was still odd and even though the observer never saw the dominance play it still happened and if I was less talented we would have kept sharing for longer.

I also recall being a member of a crowd watching the master at an arcade even if nobody watches game play videos. It's also customary to have the person who wins keep the table in pool or fighting games. This is normally less obvious than simply beatings ones chest, but watch how people walk around a body builder some time.

Considering the biologist in this thread disagrees with you, you may want to tone down your arrogance.

Also, I do not think you could kill me with a rock, unless I were sleeping and you were dropping it from excessive height.

I see no disagreement.

I could kill you with a coffee mug or a bic pen if you were unarmed. In the unlikely event you're unusually strong and alert I'd get my brother to help. Power in a band of humans has way more to do with how many relatives you happen to have than any silly conception of "alpha".

So, maybe the 'alpha' is automatically the person with the most allies in a time of conflict.

Most criticism I've seen has been from marxist biologists? (Like intelligence being largely inherited, it seems to contradict some dogma in Marxism.)

This sums up the old debate: http://cogweb.ucla.edu/Debate/CEP_Gould.html

(As a non-biologist, even I know the stature of Maynard Smith, Mayr etc.)

Is there some new development with support for e.g. species-selection, etc?

Characterizations of Gould as a Marxist biologist are roughly as ad hominem as that article accuses Gould of being.

As another non biologist, I understand that Gould's main contribution was punctuated equilibrium. he thought that the primary driver in evolutionary change was rare and relatively quick changes across a population - the external environment would change, or a new advantageous trait would develop which would transmit rapidly. It also clashes with attempts to determine more gradual models of genetic propagation throughout populations.

Characterizations of Gould as a Marxist biologist are roughly as ad hominem as that article accuses Gould of being.

As I have asked people to do before,

http://news.ycombinator.com/item?id=555734

I'd love to hear from people who disagree with [insert name of controversial figure here] just why they disagree with that person, not just their party label for that person. It is perfectly possible for a person who has wrong ideas to have other, correct ideas.

>>It is perfectly possible for a person who has wrong ideas to have other, correct ideas.

Agreed. But here we have an author that researchers in two fields argue are intellectually dishonest in his public writing.

Only experts in the field (or maybe amateurs which read the discussion carefully) can have an opinion.

So do you really want to use your time by reading books about subject X which you know might be have 5-50 percent slanted content to agree with e.g. the Mormon church?

It is not just that you get real information, it is that some of the information you get will be twisted...

Edit: And since it is relevant to your comment, note that someone voted me down but lacked counter arguments... :-)

Well, I already mentioned that you should check who the critics were. Maynard Smith, Wilson and Mayr. AFAIK, they each have more than double the cred in the field as Gould and Dawkins have -- together.

Marxist... Lewontin, Steven Rose Kamin et al can hardly be described as liberal or right wing... :-)

Can you mention three non-leftwing well known biologists in that camp? One?

The fun part about Gould is the criticism from intelligence researchers. They more or less accuse Gould of misrepresenting the contents of their field -- very similar to how Gould is described by evolutionary biologists...

Edit: I might also add that there were lots of discussion about how new "punctuated equilibrium" really where.

Edit II: First post by a user 460 days old? I am honored! :-)

Not to completely throw up a smokescreen to hide the fact that I think you're better read on this debate than I am, but your challenge is pretty reminiscent of what bugs me about this debate: It's often framed as a debate between politically motivated hacks vs their more sensible, less biased opponents, when there was real scientific disagreement at stake, and a disagreement that has at least some practical political implication. Admittedly, this defense works better when talking about controversy between Gould and Dawkins (who is not at all apolitical himself) than between Gould and Wilson.

That, and I thought that the best place I could find on the internet to defend Gould would be in the middle of a thread full of amateur evolutionary psychologists making up stories about why depression came into being. :-)

re your edit II: There was some stuff about this on Pharyngula recently that put it on my mind, and plus the combination of screeching flamewar and biological debate in this makes it pretty interesting reading.

Evolutionary biology interests me and to have a clue, I had to understand the controversy. Time wasted, which I want back. :-(

As I wrote, the easiest way to understand is to note that the heavy people of both evolutionary biology and intelligence research agree on Gould's intellectual dishonesty.

(Almost all positive reviews on Gould's book on intelligence came from the extreme left or from non-psychologists.)

The top levels of the intelligence researchers and the evolutionary biologists were incompetent idiots and/or in a conspiracy? (More or less what the creationists argue about evolutionary biologists, by the way!)

It is just not believable.

> when there was real scientific disagreement at stake

It was mainly Gould's public writing that was criticized, not the research.

Note that my previous comments were downvoted by someone that obviously disagrees, but lacks arguments... True believers are sad.

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

)

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.

> 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.

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.

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.

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.

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

That wikipedia link has absolutely nothing to do with the falsification of the narrative he proposed.

I have no problems with narratives and possible explanations but if you scour the literature you will not find, on average, the qualifiers of uncertainty. I _do_ have a problem with people who take a casual glance at said literature and present their arguments with no degree of uncertainty. Just-so stories strike me as the epitome of intellectual laziness.

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.

I have no idea how this type of thinking came about and have no problem admitting it.

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

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?

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

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.

> alpha female keeps the omega male alive.

Sounds like group selection, common fallacy.

> 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.

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.

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.

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