This is my position, too. It’s hard enough to diagnose – or in many cases even to define – mental illness in humans, which is why we have diagnostic tools like the DSM (Diagnostic and Statistical Manual of Mental Disorders). It would be far more difficult to make such a diagnosis in an animal.
Still, just based on my experience with dogs, I’ll make a pertinent observation. Animals like dogs with advanced cognitive function clearly have personalities – they may be playful or aloof, inquisitive or fearful, obedient or naughty, placid or aggressive, etc. As with humans, some of this is genetic and some the result of upbringing and learned experiences, good and bad. And where there are personalities, there is the possibility of some personality traits becoming extreme or unusual, or what we would call aberrant.
For example, I had a dog who right from puppyhood displayed an unusual degree of fear-aggression, manifested mostly in a tendency to nip if you tried to take something away from him, especially if he was fearful because he knew it was something he wasn’t supposed to have, like a book he had stolen and was gnawing on. It took a great deal of time and patience and much love and much expensive training to wean him out of it, and probably the mellowness of maturity helped, too.
So my answer, based only on limited experience, is that to the extent that mental illness can be defined as an aberrant behavioural trait, yes, animals with advanced cognition can have such traits. Are they the same mental illnesses that humans are subject to? My guess is “no”; that though there’s obvious overlap in some very basic aberrant traits like paranoia, even those common traits will elicit different behaviours, and many mental illnesses are probably unique to humans.
We know even less about bird psychology than we do about mammals, but we do know that their brains work very differently from ours. The most recent common ancestor of birds and mammals would have been something reptile-like, and so entirely lacking in most of what we’d call “higher brain functions”. Now, if birds end up with similar minds to ours despite their different brains, that would be quite interesting, and probably tell us a lot about how minds work.
All of that applies even more so to octopuses (we know even less about their psychology, and they’re far more distantly related, and there’s probably even more interesting insights to be discovered from them).
One of our dogs did that when his sister died (think Little Ann). He’d sit all day in the backyard where she would and just stare. He died a couple of weeks later.
I’ve lived with birds (parrots) for a couple of decades now. My late spouse once described them as emotions wrapped in feathers. They aren’t us, and they aren’t mammals, but they have similar emotions of fear, anger, lust, contentment, curiosity, affection, and grief/sadness. They also have significant problem-solving skills (some species having more of this than others). Unlike other animals, like dogs and dolphins, many parrots CAN be taught to speak human language on some level (very, very simple) and it’s clear at this point that they have some ability to use human words and phrases to communicate with the featherless bipeds they interact with. My current bird is no Alex Pepperberg but he has a collection of about twenty words and phrases, several of which he uses to communicate with me. Among other things, he can inform me when his food and water bowls need attention which is handy. (Almost amusing when he’s upset about something, reacts by throwing things around including the food and water, then demands they be refilled). I’m not saying he has language as we normally mean it in humans, I’m saying he can communicate with me.
Parrots are also notorious for displaying “maladaptive behaviors”, up to and including self-harm. Us non-scientific types will use words like “depression” and “insanity” because these behaviors resemble those conditions in humans. Birds kept in solitary confinement without interactions with anything else, isolated, in the dark, will develop screaming and self-harm just as can happen with humans kept in similar conditions. Birds who lose a mate or an companion (either bird or human) can display reduced affect, eat and drink less, sit hunched over in a corner, and so forth much as humans might when grieving.
My current bird, Griffin, is a well-adjusted, well-socialized parrot who is normally, calm, never showed a sign of being self-destructive, and a charmer but in September 2023 when I was unexpectedly re-hospitalized after major surgery he went into a melt-down. His human - who had clearly been in a bad way (I was weak and in pain) was taken away in the middle of the night. Dawn came and went and it wasn’t until late in the afternoon a friend was able to look in on him for me. She reported that he was SCREAMING, she could hear him from outside my apartment, and tearing his feathers out, literally ripping his feathers out of his body, and wouldn’t stop. That looks to me like full-blown panic. Over the years he’d lost one human (my spouse) and two other bird flockmates and I suspect he was terrified he’d lost me as well, and sitting there, alone in the apartment with none of the expected breakfast he was probably also wondering what the hell was going to happen to him. Turns out that hearing my voice over the phone calmed him down, although he was looking around as if he was trying to figure out where my voice was coming from. We recorded some voice mails of me talking to him that she could play for him until I was able to return home.
Now, my bird lives with me, I can observe him closely. Wild birds? If a wild bird is grieving a lost mate and goes hides in a hole we humans don’t see it. That doesn’t mean it doesn’t happen, just that it’s unobserved. You can claim that sort of panic/melt-down is due to the unnatural conditions of being kept in captivity, but if we don’t look for this sort of thing in wild birds we don’t see and some will maintain it doesn’t happen… when really we just don’t know.
Except… there have been observations in the wild that some bird species do exhibit behaviors. Crows, ravens and magpies will gather around a dead flockmate for a period of time. Wild barns owls under observation will sometimes stop eating after a mate dies. Some counter with examples of birds losing a mate gaining another or forming new relationships within a flock as evidence they don’t feel such loss while completely ignoring that seeking new relationships or even re-marrying is quite common among humans that have lost a mate, yet we don’t declare that people feel no grief.
Some behaviors analogous to human disorders - such as pulling out so many feathers as to cause bald patches just as some humans pull out their own hair or pick at their skin - have also been observed in wild birds as well as captives.
Of course, maladaptive behaviors in the wild can result in animals becoming a predator’s lunch. An animal with a mental illness that is incapacitating is not likely to survive. And humans with mental illness who nonetheless manage to hold down a job, keep a roof over their heads, and otherwise function in society raise the possibility that animals with mild versions of OCD, depression, or other things we call mental illness in humans might be able to survive for a normal lifespan even if they may not be as happy/content/whatever as their flockmates, and we may not be able to spot such problems in wild animals who have zero incentive to open up to us about their problems.
People who keep tamed birds can observe oddities, which are often dismissed as artifacts of being captive. But why was only one bird out of the dozen or so we’ve kept over the years inclined to stay in his cage and had to be coaxed out, then didn’t want to leave the small bedroom the cage was in, wanted to hide under a towel if we ever had to transport him outside the home, what might be called agoraphobic in humans and not all the birds kept in the same home and conditions?
Yes, we have to be cautious about anthropomorphizing animals. Especially outside the mammals because birds are very different from humans in all sorts of ways. But I think it’s an error to go to the opposite extreme of thinking they’re not at all like us, in any way. If it looks like a duck, walks like a duck, and quacks like a duck it’s almost certainly a duck. Likewise, if it looks like grief or depression or a phobia it might actually be that. If similar behaviors are observed in a similar context then it’s not unreasonable to propose it really is a similar emotion or, in the case of mental illness, similar dysfunction.
The notion of treating mental illness in animals is complicated by many species having a different baseline of normal. Parrots are arguably even more social than humans are, a bird wanting to avoid other birds is much more abnormal than a human who prefers solitude to a lot of social interaction. On the other hand, predators like hawks live solitary lives outside of the short intervals when they mate with another of their species - they have no need of social interactions and living in near-complete solitude is very normal for them whereas it would be quite odd for a human and deeply abnormal for a parrot.
To be clear, what I said was that birds’ brains are very different from ours, that is to say, the physical, material structures. What goes on inside of those brains, the mind, might be more similar than we’d expect. And getting similar minds (to the extent that they are similar) from such different brain structures is very interesting.
A few of you are talking about dementia, but it’s important to note that dementia is not a mental illness, it’s a neurological illness. It’s the brain losing its ability to function well and suffering deficits as a result. You could maybe say that has some conceptual overlap with certain types of mental illness, but generally no one in the medical or mental health professions considers dementia to be a mental illness.
Some are, some aren’t. Some are maladaptive thoughts and behavioral patterns, some are simply normal drives that are over or under-tuned due to personal biology, some are due to a conflict between cultural/environmental issues and beliefs about the self – there are all sorts of reasons that a mental illness can develop and only a fraction of them are considered to be primarily driven by physiology.
The diathesis-stress model is often used when trying to understand the origin of mental illness. Due to various biological, environmental, and social factors, some people are more vulnerable than others to certain types of stresses and certain reactions to those stresses. Not everyone who experiences the same sorts of stress and trauma will develop mental illness as a result of them, and not every instance of a particular mental illness is caused by the same sort of stress or even caused by a stress at all.
This is reductive to absurdity. “Insane” is a high bar to set and the vast majority of people who experience mental illness are not insane. Reducing it to a binary like you suggest would be profoundly unhelpful. The etiology of mental illness can be complex, but we’re far better at understanding it than you suggest.
As to whether animals can be affected by mental illness – it’s really hard to tell because of a lack of communication. I personally suspect that animals can experience something close enough to certain types of mental illness that you could reasonably say it’s equivalent – with depression probably being the most obvious one. But there are a lot of disorders that require a complexity of mind that they probably don’t even have. For instance, could a dog be narcissistic? Or delusional? Probably not. Even something like paranoia is beyond them as it requires assumptions about other agents that they probably do not make – they may react unreasonably fearfully but that’s probably high vigilance or simply having an abnormally low threshold for the threat detection part of their brain to activate. They probably can’t form the sort of idea that a paranoid human would do by ascribing some sort of sinister conspiracy against them.
Without the ability to communicate with them more fully, we’re just guessing at the reasons for their behaviors. Sometimes it can be obvious enough to be a good guess (animals in a terrible environment showing depression) but for anything more complex than that we’re taking a bigger and bigger leap to interpret it.
I have known, and anyone who has raised a good many animals has known, individuals who were born ‘with a wire loose’. They may be untrainable, unable to be socialized, or subject to unpredictable, non-rational rages or fear episodes. Often these animals are euthanized as unmanageable. So I think that other animals than ourselves are subject to genetic defects that create bizarre behaviors.
In nature, erratic and irrational individuals would also not survive to reproduce, by and large.
Domestic animals also suffer from environmentally-inflicted mental disorders. Many horses, for example, which are kept alone in dimly-lit boxes for almost all their waking hours (an extremely common way to keep them) may develop a spectrum of stereotypical practices such as shifting from foot to foot without let up, chewing on themselves, ‘cribbing’ which is grabbing on to something and sucking air into their lungs … Many social or herd animals if raised and kept alone show social dysfunction when put with others of their kind, and animals kept by humans who fail to understand them (the large majority of modern humans know almost nothing about animals) may develop all kinds of induced pathological behaviors, some of which will be permanent even if the environment changes.
Sure. There are probably many ways to get to the same result. Just as different species have different means of sex determination with the end result of (at least) two sexes for reproduction and varying degrees of sexual dimorphism, there are probably different ways of building brains that can do various tasks like remember, learn, navigate, communicate, etc. Actually, we know that to be a fact given how diverse creatures like mammals, birds, and cephalapods (octopus, squid, cuttlefish, etc.) all engage in these tasks with vastly different brain structures.
The major structural differences between the brains of mammals and that of Aves is in the mammalian neocortex and the equivalent evolutionarily newer structures in birds. It was once believed that the human “limbic system” was part of the newer development (and that archaic term and mentality is still in use in psychology), and therefore emotions were a uniquely human (or at least primate) experience. However, it has become clear that both mammals and birds display behavioral responses that are characteristic of the same qualities of affect, and that emotions are almost certainly a very primitive and likely even pre-cognitive evolutionary development to provide innate feedback to sensory information and not some separate function of ‘higher’ animals.
It isn’t especially surprising that the development of cognition in Aves (to the extent that we can be confident that it exists) is parallel to that of Mammalia because despite the fact that most birds fly and (except for bats) mammals do not, we have evolved after diverging in the same terrestrial environment where the ‘visible’ electromagnetic spectrum and the acoustic signals that transfer in air are primary long range senses. Most birds practice nesting and raising of their young even though they are exclusively oviparous (egg-laying) and demonstrate group and kin behaviors similar to many mammalian species, and many birds definitely ‘play’ even above and beyond learning hunting and survival skills as do most mammals, so it is not at all surprising that they are found to have analogous brain structures and functions despite evolutionary divergence.
Cephalopods are very different, not only having diverged much further back even before the development of chordate structures but also having a distributed neurophysical structure, and of course a completely different environment that they have evolved to live in. We cannot even begin to guess at what the emotional experience of an octopus might be, although they have certainly been observed in play-like behaviors and demonstrating attachment to human handlers as well as their well-known mechanical problem solving abilities. Since they do not raise their young (most female octopus and squid species die shortly after their spawn hatch, although they do spend their last portion of life guarding the unhatched eggs) they clearly don’t have maternal instincts or kin behaviors, and thus they are presumed to be the closest thing to truly alien cognitive intelligences we have interacted with.
Ah! Those things we have to do. There’s a thread about holding in a sneeze. Like a sneeze, when some thoughts emerge in our heads, if we hold them in we face the risk that our head will explode. No apology necessary.
Actually, although you may have intended that to be a joke, the acetabula (‘suckers’) are extremely versatile units, capable of both fine manipulation and containing receptors for the cephalopod equivalent of taste and smell as well as tactical feedback. While the arms of an octopus (technically not tentacles because they have acetabulum) are controlled by the central brain, there is a lot of neurological processing that goes on in the arms themselves, to the extent that most experts in octopus anatomical and neuroscience believe that they have significant local autonomy that is nothing like any vertebrate central nervous system. So (it is speculated) that their sentience is probably far more distributed than our experience. What this would do in terms of cognitive function and qualia is unknown but is suspected to have something to do with why octopuses are so good at figuring out mechanical puzzles.
Psychiatric and neuropsychiatric illness is abnormal behavior and function in various emotional experiential and neurocognitive domains. What is “normal” is going to be different for different species but any species that achieves its normal range of emotions and neurocognition with complex brains is going to have a certain fraction of the time that individual brains are out of normal range. To believe otherwise is untenable to me.
It would be anthropocentric though to define normal and abnormal only relative to human standards. We would have to understand and define normal for the species first. Of course there may be some that are very analogous: reactive depression; anxiety … but we may be myopic. They may have disorders specific to their normal that don’t translate to us?
At the end of her life our wonderful Golden had a brain tumor which manifested itself as dementia. She ran in the school field across the street from us her entire life, and at the end she lost the ability to find her way out of it. I had to leash her and guide her home.
We had a golden whom we were convinced had ADHD or some neuroses. A beautiful and very loving dog, but she would chase after the shadows of leaves cast upon interior walls. When we took her and our other pup to a dog park, she would run back and forth along the fence - ostensibly chasing the cars driving along a road. VERY high energy and VERY different from the several other goldens we’ve had. We gave her to a family with 3 young children who would give her the stimulation see seemed to need.
A dog with very high energy unusual for the breed is not mentally ill, just maladapted to the environment it finds itself in. Someone looking for a gun dog might find her just perfect.
