#179 – Why evolution left us so vulnerable to depression and anxiety (Randy Nesser on the 80,000 Hours Podcast)

By 80000_Hours @ 2024-02-14T16:02 (+12)

We just published an interview: Randy Nesse on why evolution left us so vulnerable to depression and anxiety. Listen on Spotify or click through for other audio options, the transcript, and related links. Below are the episode summary and some key excerpts.

Episode summary

In what situation is anxiety useful? In situations where you’re in danger of losing something, it’s good to have a special mode of operation that alerts you to the possible loss, where you can take preventive action and avoid that situation in the future.

And is there only one kind of loss? No. You can lose your finger, you can lose your friend, you can lose your mate’s fidelity, you can lose your money, you can lose your health, you can fall off a building. And this helps to explain why there’s so many different kinds of anxiety. Natural selection has gradually and only partially differentiated kinds of anxiety to cope with those different kinds of possible losses.

- Randy Nesse

Mental health problems like depression and anxiety affect enormous numbers of people and severely interfere with their lives. By contrast, we don’t see similar levels of physical ill health in young people. At any point in time, something like 20% of young people are working through anxiety or depression that’s seriously interfering with their lives — but nowhere near 20% of people in their 20s have severe heart disease or cancer or a similar failure in a key organ of the body other than the brain.

From an evolutionary perspective, that’s to be expected, right? If your heart or lungs or legs or skin stop working properly while you’re a teenager, you’re less likely to reproduce, and the genes that cause that malfunction get weeded out of the gene pool.

So why is it that these evolutionary selective pressures seemingly fixed our bodies so that they work pretty smoothly for young people most of the time, but it feels like evolution fell asleep on the job when it comes to the brain? Why did evolution never get around to patching the most basic problems, like social anxiety, panic attacks, debilitating pessimism, or inappropriate mood swings? For that matter, why did evolution go out of its way to give us the capacity for low mood or chronic anxiety or extreme mood swings at all?

Today’s guest, Randy Nesse — a leader in the field of evolutionary psychiatry — wrote the book Good Reasons for Bad Feelings, in which he sets out to try to resolve this paradox.

In the interview, host Rob Wiblin and Randy discuss the key points of the book, as well as:

Producer and editor: Keiran Harris
Audio Engineering Lead: Ben Cordell
Technical editing: Dominic Armstrong
Transcriptions: Katy Moore

Highlights

What are emotions for?

Randy Nesse: I asked myself: anxiety is one emotion; there’s a bunch of emotions — why do they exist at all? And I went reading in my psychiatry textbook and the entire chapter on emotions was one and a half pages. That’s interesting. If you study heart disease and you look up in a medical textbook about heart disease, there’s 100 pages about how the heart works and what the different parts are for. So then I went looking at emotions research, and I spent a full year just reading about emotions.

And I pretty much gave up at the end of that. I thought, everybody’s arguing about how many emotions there are and what each emotion is for, and there’s no agreement. And I really was very frustrated. Then I went back and found what William James had to say about it — you know, William James, the great psychologist. He essentially said, “I’d as rather read the literature on emotions again as catalogue rocks on a New Hampshire farm. There’s no order, there’s no categories, there’s no way of making sense of it.” And I thought, well, if you can be frustrated, I can be frustrated too.

So I’d looked at evolutionary approaches, and most of them were saying, “What’s the function of anger? What’s the function of anxiety? What’s the function of depression?” And I asked myself, how do these emotions come to be? And the answer is that they’re suites of coordinated responses that change lots of things, physiologically and cognitively and behaviorally, to cope with a particular kind of situation that’s recurred over evolutionary time.

So people who felt the hot breath of a tiger on their shoulder and the lion salivating in front of them, who experienced the emotion of awe: those genes didn’t stick around at all; they became lion lunch. While people who had this coordinated response that we call a panic attack or a fight/flight reaction — where they start sweating, and they run really fast, and they breathe really fast, and their heart pounds, and their muscles get tight — those people were more likely to survive. So natural selection shaped a very specialised emergency response we call a panic attack.

And all of a sudden, with that insight, which I’d never quite had before, I realised that every emotion needs to be understood not in terms of its function — which was the prevailing evolutionary view and the still continuing evolutionary view by many people — but instead, in what situation is this emotion useful, or was it useful for our ancestors? This also solved one of the biggest conundrums about emotion research: are the emotions separate little entities, or are they all overlapping on dimensions? No, you think about this from an evolutionary viewpoint, and they’re like overlapping boughs on a tree, because they all evolved from each other. So this made sense of emotions.

So the question is: in what situation is anxiety useful? And the answer to that is: in situations where you’re in danger of losing something, it’s good to have a special mode of operation that alerts you to the possible loss, where you can take preventive action and avoid that situation in the future. And the next thing that happens is, hey, is there only one kind of loss? No. You can lose your finger, you can lose your friend, you can lose your mate’s fidelity, you can lose your money, you can lose your health, you can fall off a building. And this helps to explain why there’s so many different kinds of anxiety. Natural selection has gradually and only partially differentiated kinds of anxiety to cope with those different kinds of possible losses.

What's the point of sadness and depression?

Randy Nesse: So this takes us back to this distinction between sadness and depression. Anxiety is protecting us against losses, as possible, and keeping us from going back in situations that cause losses. If you have a loss that causes sadness, sadness doesn’t seem like it’s useful — because, hey, the loss has already happened, what are you going to do about it? But in fact, there’s a lot you can do about something if you’ve lost something.

If your child has just been washed out into the surf, you can swim out after your child, you can tell other kids to get off the beach, you can prevent any of your children from ever going in the ocean again, you can get sympathy and help from other relatives. There are all these things you can do to prevent further losses immediately and further losses in the future.

And if you lose your driver’s licence, you can get a different kind of wallet, so you’re not as likely to lose it in the future. It’s really good. If you say the wrong thing to your spouse and she won’t talk to you for a week, you can learn to stop saying things like that. It’s very good to feel sad and upset about making mistakes that cause losses.

Where this really becomes awful, though, is losses of a loved one. I spent three years of my life delving into a very detailed database where we looked at people who had experienced loss of a spouse. They were asked six months, 18 months, and 48 months later about all of the details, and we had a lot of information about them before they ever had the loss. And one of the questions was: is it true what we were all taught in psychiatry, that people who have ambivalent relationships need to get in touch with that ambivalence to get over their long-term grief? One of the profound findings from our research was that people who have ambivalent relationships before the loss don’t have as much grief as other people: it’s exactly the opposite of what we were all taught. Whoa.

Plus, the theory in psychiatry was always that delayed absent grief — people who don’t grieve — really have a problem and you need to get them in touch with their grief. Or specifically, based on Freudian theory, I spent many hours upon the direction of my well-meaning supervisors trying to help people who are having bad long-term grief get in touch with their anger towards the bereaved, because Freud’s idea was that suppressed anger was causing depression. I mean, everybody has anger towards everybody at some time, so you can always find something like that. But in our data, we found no hint that people who didn’t grieve immediately had more grief later; it was quite the opposite.

What we really did discover that was profound in our study is that a lot of people who experienced a lot of grief at six months didn’t remember anything about it at 48 months. They said, “No, grief never bothered me much.” Conversely, a lot of people who didn’t experience any grief initially later remembered themselves as having experienced it. For me, it taught me once again that we humans are subjective beings. And the idea that we can remember things accurately about our emotional lives? Not really; that’s just not how we’re designed.

But now you’re going to ask me, so why the hell is there grief, which causes so much awfulness? This is an unsolved problem, Rob. Some people say it’s an accident of our system for attachment. Other people say that actually it’s good to grieve the loss of a loved one — to help find them if in fact they’re not dead; they’re just lost in the savanna someplace, and to prevent other losses. This is a very profound question at the centre of bereavement research.

The distinction between something being good for a person vs. being good for someone's genes

Randy Nesse: Yeah, I find this a shocking thing, Rob, and a disturbing idea. I mean, I always thought that natural selection would shape us for health and happiness and cooperation and long, happy lives. And anything different from that meant there’s something wrong with the system. But once you start studying how evolution shapes behaviour-regulation mechanisms, you realise that it doesn’t give a damn about us, that doesn’t give a damn about anything: it’s a mindless process that any genes that make individuals do things that benefit transmitting more genes — which basically means having more children and taking good care of them and getting resources to do that — any genes that make that happen will become more frequent. Any tendencies genetically to do things that make your life end sooner, or have fewer offspring, or have fewer resources, those are going to go away — and the whole system doesn’t care at all.

I mean, a lot of our bad feelings are about things that have to do with reproduction. And we should pause just a moment and note that Freud was right about one thing for sure: he said that ultimately, it all comes down to sex. And it’s not sex — it’s reproduction. Sex is just one small part of having offspring, and taking good care of them, and raising them to a point where they can reproduce. But fundamentally, all of these systems are designed to maximise numbers of offspring and the benefits to relatives.

And a lot of times that makes us miserable. Bad things happen to our kids. Hey, that’s not us, but we’re wired — appropriately so — to feel really, really bad if our kids are not doing well, and we try to help them. So these are things that are built in. You don’t want to change them because they’ll be awful to lose that kind of feeling. For sex, it’s more of a different matter. When people can’t have sex, they really, really hate it. And that’s prewired, I think. It’d be nice to just tell yourself, “I shouldn’t care about that, because that’s about my genes and not me.” But actually, that doesn’t help a bit.

Striving for status, however: a lot of your work with 80,000 Hours, I think, has to do with people pursuing careers. And it’s always a challenge to figure out how grand a goal to set, and what to do when you’re not making progress towards a relatively grand goal.

How is it that severe depression can be really common?

Randy Nesse: This is, I think, the most important unanswered question in mood research. We need to try to understand severe depression in terms of how ordinary low mood is dysregulated. There is something called “kindling” at the foundation of a lot of depression research. It comes from epilepsy research, really: if you induce seizures in an animal by putting electrical probes in the brain, it makes it more easy for them to have seizures in the future with lower stimulus of a drug or electrodes.

And there’s an analogy here with depression: people who have episodes of depression go into depression more likely the next time, with fewer losses and lower stimuli, and that’s usually been interpreted as something in the depression harming the brain — and in fact, there are some brain changes that are associated with depression. But another evolutionary interpretation is that there’s a system that adjusts how easily depression goes off, depending on what experiences you’ve had. And if you’ve had repeated experiences of failure, then going into the mode that’s appropriate for failure more easily becomes easier.

And now we’re back into the same argument as we had for panic disorder: that is, it’s a positive feedback process where the more depressed you are, the more you get depressed. And guess what? In modern life, this is such a huge problem for people because you can go to your room and you can shut the door and turn off your cell phone and then lie in your bed crying, saying, “How come nobody ever calls me?” Because your cell phone is turned off. Or instead of calling somebody and going out and doing something, you could sit eating junk food and watching television, and that’s just like a recipe for becoming more and more depressed. And on top of that, you can not get any exercise, which is another recipe for being more depressed.

This is not an adequate explanation, I want to emphasise, Rob: the real explanation for why low mood escalates into depression needs a lot more work. But there’s a lot of work that’s been done that nobody pays attention to. A fellow named Eric Klinger, a psychologist in Minnesota, has been writing back in the 1970s about the normal sequence of events when you’re not making progress towards a goal. It’s quite profound work. He points out that the first thing you do is wait for a while, and the next thing you do is try a different strategy. The next thing you do is give up completely for a while. Next thing you do is try another strategy, and the next thing you do is completely change your goal and recognise that you’re never going to reach that goal.

There’s also other good research on this. Jutta Heckhausen — and again, I’m going to really simplify subtle social science research, and Carsten Wrosch is another researcher who’s worked on this — showing that people who keep pursuing unreachable goals spiral into worse and worse depression. [Heckhausen] was studying women who were approaching menopause, who wanted to have a child. That’s a bad situation because you’re doing more kinds of IVF and other kinds of things to try to have a child. It’s not working, and just spending a lot of effort and time and worry trying to make something happen that might not work. And then when many of these women reach menopause and give up on that, their depression goes away.

This whole line of research has made me change how I see patients. And it used to be that I would always encourage patients, “Keep trying, never give up. Your difficulty trying to do this is because of your depression. Don’t let the depression get the better of you.” And as I got older and I saw that not everybody can succeed in everything they’re doing in life, I started just listening more, and being more sympathetic and saying, “Can we talk more about why you feel you really have to apply to medical school for a fifth time?” Or to somebody else, “Can we talk more about why this is the only woman for you in the world, and you feel like you shouldn’t go on living unless this person will love you?”

So often people are pursuing something that’s very, very important and you sympathise with them. I think the key to good therapy in these situations is not just to tell them, “Don’t pay attention to your depression,” and it’s not to just tell them, “You’re never going to succeed at that. Give up.” The thing is to talk with them about, “Do you think that’s working? How much effort do you want to keep putting into this? Are there other things that would be better for you and your family than continuing to put in this effort towards getting that particular promotion or making that particular person respect you?”

On the other hand, it’s not simple, because we all spend our lives pursuing unreachable goals. And the people who succeed grandly very often are the people who do pursue giant goals, and fail over and over again and keep trying. So nothing is simple here.

Is mental health actually getting worse?

Rob Wiblin: I very frequently hear the claim that in countries like the US and the UK, mental health is getting worse, and more people have depression and anxiety than have ever had it before. I guess the data behind that has always seemed a little bit hazy to me, because it’s something that’s quite hard to figure out. Do you have a take on whether that is true or not?

Randy Nesse: Yeah, a lot of my work has been with epidemiologists, and I always ask them about that. It’s a great example of how information transmission is distorted, because everybody wants to hear something new and dramatic and horrible. The evidence is very poor for that. People went back in one study in Canada to visit the same people 30 years later, and ask the exact same people the exact same questions: no real evidence of increased anxiety or depression.

Furthermore, Ron Kessler, who’s probably the world’s leading epidemiologist for psychiatry, did a study during COVID — everybody was about “the COVID epidemic of mental health disorders” — and he did an actual proper study, randomly selected people asking all the right questions. And his conclusion was that there’s not really much evidence for increased rates of severe disorders; maybe a little bit of mild things. But that’s not to say this doesn’t deserve further study.

There’s also a study in the UK of young people who use social media a lot, and it looks like maybe they do have increased rates of problems. So we need to keep an eye on this kind of thing. It also looks like during the cocaine epidemic in the ’80s and early ’90s, there may have been increases, because so many people were wrecking their lives with cocaine and methamphetamine.

But the whole idea, I mean, people used to think that back in the good old days, these things weren’t problems. There’s so much more attention to them because of television advertisements for antidepressants, and outreach programmes to identify people with depression — many of them sponsored by drug companies. They can be helpful, but they also get people thinking and more comfortable revealing their symptoms in a way that makes the news media seem to find lots more depression and anxiety — when it’s very hard to actually do the studies and show that that’s actually increasing that much.

Which isn’t to say it isn’t a gigantic problem. Anxiety and depression, just by themselves, cause medical morbidity — that is, inability to go to work and early death and things like that — equal to almost all other disorders: not just mental disorders, but other disorders. These are gigantic world problems. And again, this takes us back to the core problem: Who the hell designed this thing? How come we’re all so vulnerable to so much useless suffering?

The origins of morality and the problem of simplistic selfish-gene thinking

Randy Nesse: So the reason I wrote those articles about psychoanalysis was because of talking with one of the wonderful biologists at the University of Michigan, Dick Alexander, and one of the wonderful biologists of our time, Robert Trivers. They had both written articles suggesting that the reason we have an unconscious is so that we can pursue our own selfish motives without knowing it, and better deceive other people and accomplish our goals. So you can tell somebody you love them passionately with a full heart, and then just have sex with them and leave the next day. That was kind of the simplistic version of the argument.

And I thought, well, that sounds awfully cynical. Not only that, but it doesn’t match what I’m seeing in my practice. I’m seeing people who lie awake nights wondering if they accidentally didn’t smile at somebody, or if they accidentally took a person’s parking spot. You know, people are very sensitive. How is it possible that we have these feelings of moral obligation and shame and guilt, even towards people we’re not related to? I mean, the great discovery by Bill Hamilton and George Williams of if you do things for your kin who share your genes, you can sacrifice a lot for them because they have the same genes, that’s called kin selection.

But I’ve become fascinated by the origins of morality and very distressed by the possibility that selfish-gene thinking can make people cynical. And I’ve seen it make people cynical. They say natural selection can only preserve genes that make us have more offspring, and therefore everything we do is basically selfish. Well, everything we do is basically in the interests of our genes in the long run, on the average. But that doesn’t mean that we’re all being selfish. And in fact, selfish people don’t do very well at all. The people who do best, we can tell from an evolutionary viewpoint, on average are those who have a moral sense and those who are loyal to their friends. We know this because most people are like that, and people who aren’t like that don’t do very well — except in large, great places where they can get away with stuff and move on to a different town another time.

So this led me to literally decades of trying to understand this. I first did what’s called commitment theory and did a whole book on evolution and commitment. But then gradually, I followed the work of Mary Jane West-Eberhard, an insect biologist who talks about what she calls “social selection.” And her point is so simple and so profound. She says that just as individuals pick out the best potential sexual partner, creating extreme traits like a peacock’s tail — and that’s why the peacock’s tail really drags the peacocks down, but it’s beneficial to the peacock’s genes, even though not to the peacock — she says that just as that happens for sexual selection, we also pick our social partners, and we’re trying to find some social partner who has things to offer, like resources and integrity and caring about us and the like.

And I took that idea and ran with it, and wrote several articles about partner choice as the way that natural selection shapes our capacities for morality and genuine relationships that are not just exchanging favours. Because real good relationships are not just exchanging favours. Or you care about somebody, and you don’t want a relationship with somebody who says, “You invited me over to dinner, so I’m going to invite you over to dinner.” No, that’s not how it works. The way it works for most people is, “I really like you. Let’s have some time together.” Isn’t it wonderful that we’re not like chimpanzees? We really have capacities for genuine morality and love and friendship. It’s astounding.

And nothing about selfish-gene theory makes that untrue. We need an explanation. I think the explanation is that we are constantly trying to be the kind of person other people want to be a partner with, and there’s big competition for that. There’s a lot of good psychological work about competitive altruism, where people compete to be more altruistic than others, and I think there’s a good reason for that.

I’m going to wrap this up by going back to social anxiety and guilt. Why do people have so much social anxiety? Because being very sensitive is generally a good thing for your genes, if not necessarily for you. And why do people have so much guilt and worry so much that they might have accidentally offended somebody? Because having that moral sense really is very important. People who don’t have that moral sense don’t have very many friends — or at least their friends are just friends who want to get something and trade favours, instead of friends who will actually care for them when they really need help.

But I think a big reason why evolutionary psychology hasn’t caught on more is because a lot of people have a simplistic version of selfish-gene theory: they think it implies cynicism and it implies everybody’s just out to have as much sex as they can. But taking a step back, and looking at how natural selection shapes our capacities for morality and loving relationships, I think is the antidote that can make all of this grow in a healthy way.