Behaviour: Normality / Pathology

Debate on the Applied-ethology network [].
Compilation by Dr Joël Dehasse (dvm) - Brussels - -
Clik here to look at the EMERGENCES of this discussion.

Wed, 12 Mar 1997 14:37:49 +0100
Dehasse Joel
Brussels - <> -
Hi everybody,
I would like to invite you to a discussion on NORMALITY and PATHOLOGY in animal behavior.
I sure have my definitions, but I'm curious to know yours.
I would like to load these definitions in my site as reference (please if you do not agree, specify it).
When we are able to agree on this basis, maybe we will be able to discuss on hyperactivity without being hypersensitive on the subject?
So who will open the show?

Nabil Brandl
The Danish Institute of Animal Science - Dept. of Animal Health and Welfare - Research Center Foulum - P.O. 39 DK-8830 Tjele - Denmark - HomePage:
Wed, 12 Mar 1997
Every animal population has a common pattern of behaviour. Any deviation
from this pattern is pathology.

Dr. Werner Haberl
Hamburgerstr. 11 - A-1050 Vienna, Austria - Email:
URL: (The Shrew (ist's) Site)
Wed Mar 12 1997
From: (The Shrew Site (W.H.))
1) I think the term 'pathological' is not the correct counterpart of the term 'normal'.
2) It is difficult and 'dangerous' enough to use the term 'normal' in human biology, about we ourselves should know most. Who sets the criteria for normality? In what frequency, percentage must a behaviour be performed to be regarded as so 'common', that any deviation would result as being not normal? Would a person with a disease or gene-combination that occurs with a high frequency in the population be not normal? What about diabetes? What about short-sightedness? OK, you may say, this is not behaviour, but what is the difference if we discuss the term 'normal'? (Although both examples result in a certain behaviour). Is a person smoking cigarettes normal or not? If someone speaks a language that is only spoken by a minority, would he be abnormal in your sense? Are people frequenting a nudist's beach normal? (or, maybe from an animal's point of view, is it normal to cover ones genitals by tiny pieces of cloth - which would mean that the majority of humans are pathological?). And so on...
3) So how can we ascertain 'normality' for 'animal'-behaviour? Wouldn't this be an anthropomorphism? Isn't our knowledge of animal behaviour too poor to judge over what is normal and what not (especially when the evaluation of the behaviour is dependent on the method we use)? Is the small percentage of a bird population that, due to given circumstances, would change to a different mating system pathological?
I am neither an etymologist nor psychologist, but it would be good to keep these thoughts in mind, when discussing the topic. What is referred to as not normal, I would probably carefully describe as 'strange or peculiar' or even more carefully as 'rare' behaviour'.
Also, if this discussion leads to ethics, the terms normal or pathological are not appropriate.
Some of you may say that all this is way off the topic because what we have in mind actually are 'dogs biting their keepers or pigs biting off their own tails etc.' But dogs did not have the opportunity to pick their keepers. *Think about the following sentence: It is 'normal' for pigs kept in hundreds on a few square meters to become 'weirdoes'. Those not becoming 'weirdoes' must truly be as 'pathological' as their owners? comes from the ethics-department. Does not evolution feed on the variety given by different frequencies of a behaviour, morphotype, gene-constitution? 'Mr. or Ms. Evolution' would probably regard any deviation as 'normal'.
All I am trying to say is that the subject is a dangerous one.
Somehow I have the impression that this discussion is not fit for an academic forum. We should all have discussed this already in school...
smoker, but neither short-sighted, hypersensitive, nudist nor diabetic. The Internet is used by a minority of people. I am one of them, so this may be pathological. Yes, and I must admit that I also drive a car, although I use public transport whenever possible. Hope my English is quite 'normal'

Jeff Rau
Jeffrey Rau <>
Wed, 12 Mar 1997
I believe Nabil's definition of normal behavior is weak, and I offer the following example to illustrate why: Populations of confined sows commonly show patterns of behaviour such as stereotypies, vacuum activity, and displacement activity, among a host of other behaviour. According to Nabil's definition, these should all be considered normal behaviour since they are common to the population. I beg to differ.
Nabil's definition of normal behaviour fails to account for the environmental effect on behaviour, specifically that there exists an environment which is required to accommodate patterns of normal behaviour specific to an animal's genotype.
It is erroneous to suggest that because it is common to observe a specific behaviour within a population, that behaviour should be considered normal.
I believe that normal behaviour is that which occurs when an animal's environment matches that for which it is genetically programmed. It follows that abnormal behaviour is any behaviour which falls outside of this definition.

Dr. Werner Haberl
Wed, 12 Mar 1997
We should be careful, when discussing 'dangerous' subjects. Behaviour is not only a matter of genetical programming.
Does the above definition mean, that a person walking barefoot in winter is not normal? Or does this definition include all behaviour, - ie every behaviour is normal?
Who genetically programmed my cat to eat potato-chips?

Jon Watts
University of Saskatchewan - Dept of Herd Medicine and Theriogenology - Western College of Vet. Med - 52 Campus Drive - Saskatoon - S7N 1B4 - Canada "The Holy Cow"
Wed, 12 Mar 1997
I'm sure that "normal" behaviour is that which is most likely to be seen in the environment in which the animal evolved, but I think defining it as such could invite some errors in interpreting the behaviour of animals in foreign or human-made environments.
For instance, suppose I take a lion, which has been programmed to behave appropriately as a predator, scrounger, layabout, opportunist in the Serengeti, and put it in a small cage. Should I interpret its escape attempts as pathological, or appropriate? When it lies down to sleep is this a dysfunction brought about by depression, or is it just sleepy?
If you can buy the idea that to attempt to escape may be "normal" behaviour for a lion in a cage (as I do), then you have to look for a different definition or decide that "normal" is an inappropriate adjective to describe behaviour.
Suppose the lion is pacing the cage in a repetitive, apparently purposeless manner for hours on end. Is it behaving abnormally? I say no.
Or rather I say that the question is meaningless. It is doing a variant of what many animals do when you put them in cramped, artificial, unstimulating environment (i.e. performing a stereotypy). From one angle you could argue that such behaviour is "normal" for an animal in these conditions. If you place the animal in a different (preferably better) environment, it will often respond with different behaviour or an expanded repertoire of behaviour. I prefer to say that what appears to be aberrant behaviour indicates much more about the "normality" of the environment from the animal's perspective, which may be a source of "stress", than it does necessarily about the psychopathological state of the animal itself.

Dr. Werner Haberl
Wed, 12 Mar 1997
Imagine having obtained some fish for your aquarium from two different shops. Those from shop #2 would show stereotype behavior by endlessly swimming up and down the edge of your aquarium. Those from shop #1 would not.
Now: according to the statement above, the #2 fish would behave 'normally' (given the stress in captivity). What about the #1 fish?
I agree with Jon Watts' statement that the question is 'meaningless', providing that 'meaningless' is simply understood as 'not being relevant to the current discussion'.
Another problem is the 'emotional value' and, regarding 'animals' the anthropomorphic interpretation, we attach to terms like 'normal' or 'pathological'. Is 'normal' behaviour positive or negative?
Who are we to judge?

Jeff - Jeffrey Rau <>
Wed, 12 Mar 1997
Hi Werner,
1. Please tell me what you find so "dangerous" about discussing what is or is not normal behaviour?
2. I agree, behaviour is not just a matter of genetic programming.
3. All behaviour is not normal, nor is it all abnormal (kind of a potpourri of normal/abnormal).
4. I would say that the person walking barefoot in the winter is probably normal, depending on your definition of what a normal person consists of. Is he/she displaying normal behaviour, well, that just depends on where this person happens to be (Florida, the Bahamas, the Arctic, indoors, outdoors, Sputnik, etc...). I'm sure many people will admit to walking barefoot in winter, I do every morning on my way to the shower!
5. I'm sure is not in your cats genetic program to eat potato chips specifically. However your cat is eating those potato chips because he/she/it is motivated to seek food and consume it, and that is what your cat is genetically programmed to do.

Jeff, answering to Jon Watts
Jeffrey Rau <>
Wed, 12 Mar 1997
Allow me to clarify. When I say 'environment' I understand it to mean stimuli in a general sense. For example; a sow will use straw, wood shavings, shredded paper, etc. to perform nest building behaviour under confinement conditions. She does not necessarily require a field of tall grass and/or bushes in order to perform this behaviour, perhaps just a reasonable facsimile thereof.
When you say "...environment in which the ANIMAL evolved..", do you mean ANIMAL or SPECIES? Either way the genetic program of the animal is firmly ingrained and determines, through its interaction with the
environment/stimuli, how the animal behaves.
Given a situation in 'the wild', where your lion finds itself in a similar situation of entrapment (i.e.: the cage simulates this very situation = the two 'environments'/'stimuli' are very similar), would you expect the lion to perform escape behaviour? Logically one would have to answer yes, as would I, and you I'm sure.
As for the sleep/depression situation, someone would have to spend some cash to investigate the notion of depression in lions.
I will do neither (because you are wrong, and I am comes name calling, and soon enough my mother will end up wearing a pair of army boots!). Normal is just the adjective which should be used here. I thoroughly agree; an animal performing escape behaviour in the presence of such entrapment stimulus is normal, whether it be a man/woman-made cage, or a mountain cave plugged by fallen rocks.
I think you are confusing the matter with your loose use of the word 'normal'. When you say such (stereotypy) behaviour is "normal" for an animal in these (cramped, unstimulating, etc..) conditions, I believe you should be
saying that it is "common" to observe animals performing stereotypies under these conditions. Yes, under those environmental conditions the stereotypy is common behaviour, but normal it is not! The way in which an animal does behave is not always the way it is programmed to behave according to its genetic makeup. This is apparent when its environment, or surrounding stimuli, does not match to that for which it is genetically programmed.
Yes, animals do perform normal behaviour under confinement conditions, however they also perform abnormal behaviour under those same conditions. Some stimuli are present, and some are not.
If you plan on throwing my "lion in a cave plugged by fallen rocks" analogy back in my face.......good luck. My lion will dig through the dirt and rocks and eventually escape, or starve to death trying. It is not confined by bars and concrete, without any hope of escape, nor is it fed daily to sustain such a hopeless existence, resorting to the performance of abnormal behaviour.
I agree that the aberrant behaviour can tell us much about the suitability of the environment (I will refrain from using the term 'normality' to avoid confusion) from the animal's perspective. Would you take one more step and say agree that it tells us how that environment is interacting with that animal's genetic program? (c'mon). Thus, it must also tell us something about the psychopathological status of the animal.

Tim Sutton <> to Jeffrey Rau <>
Wed, 12 Mar 1997
Tim asked me to forward this to the discussion group.
Here is my definition of normal behaviour:
Normal behaviour is behaviour which can be predicted with reasonable certainty within a given population. Pathological behaviour can often be the origin of normal behaviour.
Probably the best anecdote I can give to illustrate the point is in a troop of baboons. The baboons had a (predictable) habit of raiding rubbish bins in a nature reserve. When a 'baboon proof' lid was placed over the bin, this behaviour was prevented - until an adult baboon dipped a juvenile into the bin (pathological behaviour) - the latter was then retrieved with a handful of goodies from the bin. When this behaviour is consistantly / predictably repeated, it can be considered as normal behaviour for that troop of baboons.

Kelly Caithlin Kissane - Grad student - Central Michigan University - arachnology/animal behavior - <>
Wed, 12 Mar 1997
This topic surprises me! For as long as I have studied animal behavior, I was always told that any time an animal was removed from it's natural habitat, its behavior was suspected to be a lab artefact. Certainly when I describe any behavior my lab-reared spiders exhibit, the first call is "yes, but would it happen in nature?"

Dr. Werner Haberl, answering to Jeff Rau
Wed, 12 Mar 1997
>1. Please tell me what you find so "dangerous" about discussing what is or is not normal behaviour?
*Well, it seems to be a terminological (also philosophical, political) problem. Since you have introduced the term 'common' ('to avoid confusion') in your reply to Jon I feel a bit better. But to answer your question: It is 'dangerous', because the term has been/ is / and could be abused or misinterpreted by attaching a positive/negative value. If, in any case, I would use the term 'normal' I would make sure it is put in quotation-marks.
The term 'common' is a neutral one, that would also fit to Jon's lion-example.

>4. I would say that the person walking barefoot in the winter is probably normal, depending on your definition of what a normal person consists of. Is he/she displaying normal behaviour, well, that just depends on where this person happens to be (Florida, the Bahamas, the Arctic, indoors, outdoors, Sputnik, etc...). I'm sure many people will admit to walking barefoot in winter, I do every morning on my way to the shower!

*This was just an example. I really did not think about places like Florida or the shower. I know some people here in Vienna who walk barefoot in the snow (nice people and their kids wear shoes). They believe it is healthy. But enough for this. It does not lead us anywhere. It was just to answer your question.
The problem is, that everybody (?) knows what we are trying to talk about, but we have trouble formulating, without getting in conflict. Any philosopher or other humane-scientist would probably regard this discussion as 'kindergarten'.
To make a long story short: to state that something is 'normal' is quite different from the statement that something is 'common' although both statements would be expressed by the same number = percentage.
One principle of ethology is to be strictly descriptive in a paper's 'results-section' and put possible interpretations to the 'discussions-part'...
My intention is not to oppose Jeff's or Jon's statements, but merely to provide some (I think) important thoughts on this topic. But I am not the expert... If anybody thinks that I am wrong, please tell me, and so be it (and I will regard it as a precious addition to my way of thinking).
Also if this discussion turns out to be one between Jeff, Jon and me, it would be better not to bother the whole newsgroup. But maybe we can get back to what we 'think' Joel Dehasse actually meant in his initial query...

Jon Watts <>
Wed, 12 Mar 1997
Some people object to the concept of "stress", arguing that it is an ill-defined, woolly concept with many dimensions and within which there may be many categories or types of stress. I think "normal" is a like concept.
As far as my stereotypic animal is concerned, I think Tim Sutton should say it's normal because it is predictable that a captive animal might behave this way. Nabil Brandl might observe that a good number of captive animals do perform stereotypies, so by Nabil's definition it is a common, therefore normal, pattern of behaviour in a particular population of captive animals. Kelly Kissane notes that any captive animal behaviour could be artefactual, and therefore not representative of what the animal would have done in "the wild". While that is true I don't think it follows that all captive animal behaviour is "abnormal". Merely, as Kelly said, "suspect". Jeff Rau though appears to claim that only behaviour observed in a specific environmental context can ever be regarded as normal.
I am deliberately not saying whether the stereotyping animal's behaviour is normal or not. I think it is beside the point. The animal may well be bored, frustrated, suffering from dimished welfare or whatever, in ways we may never be able to understand. That is of great concern of course, but I think it is wrong to label the behaviour as abnormal as though it were some attribute of the animal which is at fault. The performance of a type of behaviour which is not usually seen in free-ranging animals indicates that some attributes of the environment are different from what the animal is "genetically programmed" to deal with. I say take it at face value. The animal is attempting to cope. It's attempts may be appropriate, inappropriate, successful or unsuccessful and the animal may suffer or become sick, have reduced reproductive potential or maybe it won't. The behaviour is in itself neither normal nor abnormal. It merely is....
I don't know that I would call this area "dangerous" but I agree with Werner Haberl that there is a lot of subjectivity and anthropomorphic baggage to carry along with concepts like "normality". Maybe we can function better without this one.

Jeff Rushen <rushenj@EM.AGR.CA>
Wed, 12 Mar 1997
In pigs, low energy intake as a result of restricted feeding (i.e. hunger) is a major cause of stereotyped behaviour. This stereotyped behaviour consists primarily of food searching behaviours. In a normal environment, the stimulation of food searching behaviours would probably be adaptive because it would most likely help the pigs find food, to reduce the underlying hunger. In gestating crates, the pigs cannot find more food. Furthermore, work of Cronin showed that performance of stereotypies uses up a substantial part of the sows' energy intake (presumably making the pigs even more hungry). Thus, in gestating crates, the performance of the behaviour makes the situation worse, rather than better. In this way the stereotypies can be considered as "pathological" or "abnormal", but only in this environment.

"Heather J. Billings" <billings@AESOP.RUTGERS.EDU>
Dept. of Animal Sciences - Cook College, Rutgers University - BILLINGS@AESOP.RUTGERS.EDU
Thu, 13 Mar 1997
As I've been reading the discussion of what is normal or abnormal behavior, I noticed a common theme. The difficulty in defining these terms arises because normal is not a term that applies to the behavior, per se, but to the context of the behavior. So, while a particular motor pattern may be within the typical behavioral repertoire of an animal, it may be appropriate or inappropriate to the context in which it is displayed. When an animal is introduced to an environment other than that in which the behavior evolved, such as in zoos, then this is difficult to determine without knowing whether the behavior has another function in the new environment than what was ascribed to it in the wild.

Marc Vandenheede <>
Universite de Liege - Faculte de Medecine Veterinaire - Bd de Colonster, Bat. B43, 4000 Liege - Belgium
Thu, 13 Mar 1997
It's maybe difficult to oppose normal and pathological.
I think that normality is the reverse of abnormality and the reverse of pathological is physiological.
The concept of normality/abnormality could be explain in terms of statistics, as already mentioned, or in ethical terms (good or wrong). The second possibility implies that we are judging things according to our scientific knowledge but also to our sensibility (cultural and personal).
A "physiological behaviour" could be defined as adapted to the present situation, representative of an approach of an hypothetical welfare state ("perfect harmony between an individual and its environment"). Some behaviours could be induced by a disrupted equilibrium between an individual and its environment, reflecting thus a reduction in welfare, but could be interpreted as "trying to cope" or "searching another equilibrium". If these behaviours are adapted to the modified situation, it would be called "physiological". But if it is not adapted and induce pathology or worsened welfare, it would be called "pathological".
For example, fear reactions can be adapted to the fear-eliciting situations and are physiological and essential behaviours but if the environment don't elicit the expression of these fear reactions (flight in a cage) or if the individual has a very high emotional reactivity (anxiety or phobia), it could be called pathological: the individual cannot find another equilibrium and the behaviour could elicit some pathologies (accidents, consequences of chronic stress) or even death.
Another example. One flee on a dog elicits scratching, it's a physiological behaviour: the welfare is good. But a lot of flees on a dog or some flees on an allergic dog elicit heightened scratching which causes woundings. In this case scratching could be called pathological because the situation gets worse.
P.S. Sorry for my poor English!

Peter Kabai - Ctr. for Zoology, Univ. Veterinary Medicine, Budapest, Hungary - <>
Thu, 13 Mar 1997
I agree that both normal and pathologic are anthropomorphic terms. Normality could be defined in at least two ways.
1) statistical approach: normal would be anything within a certain range (like 1SD) around the mean of a normal distribution. In most cases statistical normality equals predictability. (Lions kept in small cages spend much of their time with stereotypic behaviour, male lions in the wild would kill young offsprings of the previous dominant males. Both behaviours are predictable, and "normal" for the specific sub-sample) (Einstein's IQ score is not normal)
In enriched zoo environments we see less stereotypies, if Einstein's genome was cloned in a couple billion copies, statistical normality would be shifted to a new value.
2) social norm: a range of values accepted by society as "norm". stereotypies were accepted as normal in menageries, today they are not. There is a correlation between statistical and social norm of course (When you see animals only in Zoos, whatever they do looks "normal". If you base your acceptable range on other sources of information, Attenborough films, education, you shift your range.
Pathologic, I think is an entirely different way of thinking, though it might relate to the different definitions of normality.
1) pathologic in the statistical sense: anything BELLOW the range of statistical normality negatively affecting
the condition, reproduction etc of the individual. (Parasitic infection in wild population is "normal". Some animals might have much more parasites than average and die because of the "pathogenes".)
2) pathological in the social norm sense: anything bellow the social norm society wants to fix.
The social approach is ambiguous.
However, the statistical approach is not solid either. The ambiguity of the statistical approaches might be rooted in some cases in the changing environment which effects the distribution (from wild to zoo). Importantly, our concept of the normal range also depends on our knowledge about the distribution, and this also changes by time. (We know now, that infanticide, extra pair copulation, homosexuality, cannibalism and all those nasty things happen commonly in many species. They are predictable and "normal")
Traditionally, scientists have been interested in population "norms", and veterinarians in the sick individual. Seems it is all changing now: recent approaches to model the works of populations based on the individuals are very promising, and veterinarians are taking the population approach (pathogene infestation models etc) more seriously.
However, there is still a big gap between the two ways of thinking. For example, in my country, Hungary, like in many European countries the state sponsors a program to eradicate rabies from the wild, by
throwing vaccines from airplanes.
Rabies is a major control of population growth in foxes. Human death cases are less than one/year on average. Is this a good idea?
The number of "abnormal" stereotypies in zoo animals could probably be reduced infecting them with parasites. Antiparasitic behaviour is "normal" and has a social context in some species.
Is this a good idea?

Thu, 13 Mar 1997
Again we appear caught up in terminology. Good for debate, and one I personally am finding very interesting.
My stance on the issue is as follows (along similar lines to Jeff I think...)
The behavioural rules of response of an animal have developed through the process of natural selection, over thousands of years. These rules of response have shaped an animal to respond to the natural environment. However evolution is always one step behind, and the situation mankind puts animals in are six steps ahead! As I see it an animal uses naturally selected rules of response as a basis for its decisions (normal behaviour??????). However in situations far removed from the natural environment (e.g. lab) these rules of response may not allow an animal to cope with this environment. In this circumstance the behaviour patterns may be considered inappropriate (pathological?). They also may provide the basis for the development of behaviours such as stereotypies (develop from escape attempts?). The inability to fulfil behavioural rules of response may incur a measurable cost (can be statistically correlated with immunosuppression, incidence of organ pathology etc - quick plug for recent Barnard/Hurst/Nevison rodent papers).
The appropriateness of behaviour can be assessed in terms of an understanding of what evolution has designed an animal to do, and how current environments may impact on this design. Animals can be flexible in their responses, but only up to a point. Costs of inappropriate behaviour are measurable!
I would not use the term `Normal' and `pathological' in the context they have been used in this debate. They are too ambiguous, unless their meanings are defined by the person using them.

Ray Stricklin - (ws31)
Thu, 13 Mar 1997
I remember participating in a symposium on the housing and behavior of domestic animals in confinement - hosted by a regional section of the Animal Behavior Society. This was sometime during the early 1980's.
One European speaker, whose first language was not English, was asked "How do you know the behavior you have called abnormal behavior is abnormal?"
His response was, "Because the animals don't normally do it."
This answer drew some chuckles and smirks from those in the audience, but quite probably - if one chooses to use these terms - this may be the best answer one can give to the question!

Thu, 13 Mar 1997 21:19:19 +0100
Dehasse Joel <>
I am really happy with the debate on normality/pathology. I would like to give you the "emergences" of the discussion. I have added my proposals at the end of the list. (See list)
A normal behaviour is physiological, adaptive, and allows the system to come back to homeostasis. A pathological behaviour has lost its adaptive function, and is not able to lead the system to come back to homeostasis. The system may be seen as an individual animal, a family/pack/..., a species, ...