Bibliography

Annotated Bibliography

As part of my Anthrozoology program, I am developing a annotated bibliography on specific subjects related to my selected species:  Domestic (pet) dogs.  During the Spring 2018 semester I will be adding items.

Week 2: Get to know your species. What is a “day in the life” of an individual like? Describe your species and setting.

Charles, N., (August 2016), Post-Human Families?  Dog-Human Relations in the Domestic Sphere, Sociological Research Online, 21, (3) DOI: 10.5153/sro.3975

This article is an examination of the role of pet animals in human families and an attempt to answer questions as to whether changing attitudes towards pets are causing families to expand beyond species boundaries and become “post-human”.  Charles combined two data sources, one of which is a series of semi-structured interviews with 21 dog owners; the other source being secondary research from the Mass Observation Project (MO) conducted by Sussex University, which Charles incorrectly refers to as empirical data.

Charles poses three arguments for examination:  Whether close connections with companion animals disrupt human exceptionalism; whether the precarious nature of pets’ inclusion in families reinforces human exceptionalism; and whether extending the definition of “human” to include pets is compatible with the concept of human superiority.  He concludes that the inclusion of pets in families blurs the species boundary, but that the dependent nature of pets negates any alteration to the concept of human supremacy, and make it unclear as to whether the nature of families is changing.

I found the paper to be deeply flawed.  In the first place, the data collection was not randomized in any way, and the input of both the MO respondents and the interviewees was entirely subjective in nature.  Charles made no attempt to quantify his results in any way, and simply provided examples of individual responses as illustrating general attitudes of pet owners.

Bennett, P., McGreevy P., Payne E., (February 2015), Current perspectives on attachment and bonding in the dog-human dyad, Psychology Research and Behavior Management,  2015:8, 71-9, DOI: 10.2147/PRBM.S74972

This article is a review of recent literature regarding dog-human relationships and discusses methodologies for measuring them, concentrating on human personalities and individual characteristics of the human partners in these relationships.  The authors discuss the nature of the dog-human bond, and how this bond can be strengthened and optimized.

The bond between humans and dogs is described as a symbiosis, dating back more than 18,000 years, and is unique in among our species relationships with other animals in dogs’ ability to interpret our gestures and expressions.  It is also unique in the attachment bonds that dogs develop with their human companions, which is of benefit to both species.  The relationship is of particular benefit to dogs in that humans provide not only food and security, but emotional fulfillment and attachment.  Interestingly enough, the article describes human-dog bonds as “dyads”,  a grouping of two individuals, rather than as a family.  In fact, the article makes no mention of family bonds with pet dogs and simply refers to a relationship between the dog and one owner or handler.

The authors indicate that the dog view their relationships with owners differently than with other dogs and that their interactions with humans fills an emotional need that is distinct from interactions with members of their own species.  They postulate that dogs view humans as peers who can assist in interpreting their environment, providing a social reference point as well as an attachment bond.

The article discusses tools and methodologies for measuring the bonds between humans and dogs, addressing both their usage and limitations.  It provides recommendations for improving our understanding of the canines’ state of being and affect, in order to improve our interpretation of test results.

 

Week 3: What are the major health issues facing your species? Find at least two articles that discuss problems related to disease, injury, malnutrition, or artificial selection.

Larsen j., Villaverde C., (2011), Scope of the Problem and Perceptions by Owners and Veterinarians, Veterinary Clinics of North America: Small Animal Practice, 46 (5), 761-772, doi: 10.1016/j.cvsm.2016.04.001

The authors provide an analysis of sixteen studies of diagnosed canine and feline obesity, and provide conclusions on the issue of obesity in pet dogs and cats as a serious issue that affects more than half of some pet populations.  The causes for pet obesity were divided into animal factors (predispositions of some breeds, gender, neuter status, age and growth rate), and owner factors (diet and feeding method, exercise, owner age and physical fitness, income and owner perceptions of the pets’ fitness).

The owner factors are considered to the most significant, simply because the animal factors can be managed through diet and exercise.  Owners were found to have little understanding of the nutritional density and caloric content of the food being given to their pets.  They were also found to be unaware of the exercise that would be required to maintain their pets’ weights and overall condition at a healthy level.  Owner attitudes towards pets’ emotional states and preferences were also considered as contributing factors.  The article concludes with recommendations for consideration of energy needs as a determination of pet diets, and regular monitoring of body condition.

Asher, L., Diesel, G., Summers, J. F., McGreevy, P., Collins, L. M., (2009), Inherited defects in pedigree dogs.  Part 1:  Disorders related to breed standards, The Veterinary Journal, 182, 402-411, doi:10:1016/j.tvjl.2009.08.033

This article consists of a comprehensive literature review from multiple public and scientific resources for breed standards and inherited disorders for the fifty most popular British dog breeds.  Information related to inherited disorders was obtained from three online databases, to provide a comprehensive list of genetic disorders identified in those breeds.

The authors established a methodology for identifying disorders common to specific breeds, determining whether that disorder was related to breed standards, identifying the severity of that disorder, and establishing the overall susceptibility of dogs in those breeds to inherit the disorders.  The study also established the relative popularity of each breed, according to the number of kennel club registrations over ten year periods.

The study concluded that each of the fifty most popular breeds has at least one predisposition to a medical disorder relating to breed standards.  The authors were able to correlate breed-specific characteristics with genetic medical conditions, for example the specification of breed coloring and marking criteria for Dalmatians was statistically tied to deafness and urinary tract disorders.  The authors further noted that the descriptive nature of the breed standards led to breeders’ overemphasis of certain features, such as the pug’s twisted tail or bulldog’s stance, which directly relates to physical disabilities.  The study recommends an examination of conformation standards to preclude breeding to conformational extremes.

Week 4: What adaptations does your species have that are important to them? Find at least two articles that discuss natural behavior. Note: you may need to look at wild counterparts (but see Hosey et al., 2013 first) or the ancestors of your species to find answers. (Due 2/10/17)

Case, L. (2008), ASAS CENTENNIAL PAPER:  Perspectives on domestication: The history of our relationship with man’s best friend, Journal of Animal Science, 86 (11), doi: 10.2527/jas.2008-1147

In this article, Case examines the development of the relationship between humans and dogs from its prehistoric start to current western society.

Case cites mitochondrial DNA (mDNA) analysis of modern and ancient dogs as strong evidence of a single domestication event between humans and an extinct wolf species, rather than a competing theory of dispersed multiple domestications.  According to DNA analysis, dogs share 99.8 percent of their DNA with modern grey European and Asian wolves.  He hypothesizes that domestication occurred as ancient humans transitioned from hunter-gatherers to pastoral and agricultural societies, which attracted wolves as scavengers.  The group of wolves that lived in proximity to humans gradually diverged from their wilder cousins, and developed characteristics that allowed them to flourish in human communities in a process of “self domestication”.

He goes on to discuss the divergence in human treatment of wolves and dogs, giving wolves an evil aspect and reputation, even going so far as to discuss the werewolf legends of Europe as a factor in promoting generalized fear of wolves.  Whereas dogs association with humans progressed to the point that they are no longer considered domesticated, but “completely domestic”.   The articles goes on to discuss the progression of theories into dog behavior as a “domestic wolf”, and the now-discarded theory that humans should have “alpha” status in dog-human relationships, which have been discarded in favor of a social relationship in dog-human families.

I found the article to be missing a few key connections.  For example, Case contrasts dog and wolf behaviors, but fails to take into account that dogs are not descendants of modern grey wolves, they have a common ancestor.  It is very possible that modern wolves have diverged from the ancestral lineage just as much as dogs have.  Secondly, he fails to make the connection that domestication of dogs seems to have predated the first known permanent human settlements – which would indicate that dogs enabled human progression from hunter-gatherer in a sort of symbiotic relationship.  It is very possible that we succeeded as a species where archaic humans did not, simply because we formed an alliance with canines.

Udell, M. and Brubaker L, (2016), Are Dogs Social Generalists?  Canine Social Cognition, Attachment, and the Dog-Human Bond, Current Directions in Psychological Science, 25 (5), doi: 10.1177/0963721416662647

Udell and Brubakers’ article is a literature review, examining the factors involved in domestication and socialization of domestic dogs.  It begins with the observation that dogs have a general ability to adapt to different social situations – such as human family settings, feral dog groups, herding situations, etc., and are able to form social bonds in each of these situations.   The authors attribute this to a level of plasticity in dogs’ social abilities.

The authors identified one key attribute that contributes to dog’s tendency to be social generalists:  The delayed and extended developmental process that dogs have when compared to other canid species.  Dogs’ sensitive period for socialization occurs from 3 weeks of age, and continues for an additional 9 to 13 weeks, as compared to wolves’ which begins shortly after birth and ends much earlier.  This allows dogs to be exposed to other canines and humans for a lengthy period, and establish bonding behaviors.

One potential flaw in their research is that, like the Bennett, McGreevy and Payne article, they define relationships as one-to-one bonding of humans and dogs.  And they use attachment tests based on human-child-to-mother bonding studies, such as the Strange Situation Test.  This does not seem to match the reality of human family situations, or canines’ tendencies to naturally function in family groups.

 

 

Week 6-7: What are the leading causes of stress in your species? What’s the best way to measure physiological stress? Find 2 articles related to stress.

Coppola, C. L., Grandin, T., Enns, R. M. (2005). Human interaction and cortisol:  Can human contact reduce stress for shelter dogs?. Psychology & Behavior,  87 (2006), 537-541. doi: 10.1016/j.physbeh.2005.12.001

This article documents are study performed on dogs housed at a Humane Society shelter, investigating the effect that human contact had on the stress experienced by dogs in the shelter.   The experimenters collected saliva samples from two groups of dogs, one of which was a treatment group that had positive human contact at regular intervals starting shortly after intake to the shelter, and a control group that had only normal contact with shelter staff for feeding and caretaking.  The dogs in each group were randomized by age, sex and general breed type.

During the course of the experiment, saliva samples were collected from the dogs on days 2, 3, 4 and 9 of their stays in the shelter.  Samples were taken from dogs in the treatment group two hours following their contact sessions with humans, which consisted of playing, walking grooming, obedience training and general verbal and physical contact, lasting 45 minutes on average.   Cortisol levels in the saliva were measured to determine the overall level of stress in each dog.   The study indicated that the mean salivary cortisol levels of dogs in the control group were higher through day 4 with the highest levels found on day 3.   They also noted that the difference between the two groups leveled out afterwards with an overall lower level of salivary cortisol in each group.

This led the authors to conclude that socialization with humans shortly after entering a shelter environment tends to alleviate stress response.   The authors cited previous research indicating that social isolation is a high stress factor in shelter dogs, and that human contact is essential for their emotional wellbeing.

On potential flaw of the study, which may not have been avoidable, is that the dogs in both groups were selected on the basis of their lack of aggression and comfort level with being handled.  This would indicate that the dogs were previously socialized with humans and were accustomed to being in human company.  This factor would both raise the stress level of dogs that were isolated from humans as well as reduce the stress of dogs with regular positive contact.   It may very well be that feral dogs, or dogs that were unsocialized, would experience greater stress during human contact sessions than if they were left alone.

Shin, Y., Shin, N. (2017). Relationship between sociability toward humans and physiological stress in dogs. Journal of Veterinary Medical Science, 79 (7).  1279-1283. doi: 10.1292/jvms.16-0403

This study attempted to determine whether a relationship existed between the extent to which a dog is socialized with humans, and the physiological stress experienced by the dog.  Like the above study, the researchers elected to measure physiological stress reactions by means of salivary cortisol, reasoning that this provides a fast means of measuring changes in stress levels.

The dogs were selected from a mix of companion animals and shelter dogs and were subjected to behavioral testing to determine their level of sociability.  The sample size was small, consisting of 37 dogs, both purebred and mixed breeds; all of which were small dogs, the largest being 6.5 kg. Based on the test results the dogs were placed in two groups, dogs determined to be highly social and those with low sociability.  The dogs were then taken by their owner or a familiar handler to a testing facility.  Following a short relaxation period, the dogs’ saliva was collected before and after interaction with a friendly stranger.

Not surprisingly, the cortisol levels of the shelter dogs were found to be significantly higher than those of the companion dogs at all stages of testing, indicating that they have a high level of chronic stress and were more reactive to being placed in unfamiliar surroundings and interacting with strangers.   Similarly, the dogs that were determined to have low sociability had higher cortisol levels both upon being introduced to unfamiliar surroundings and upon interacting with a stranger.  The researchers concluded that socialized dogs are more adaptable to unfamiliar situations and people, and that poorly socialized animals were more likely to have unfavorable behavioral reactions in unfamiliar situations.

Although the study results are not surprising, I found it to have several fundamental flaws.  Besides the small sample size, there was no discussion of the behavior testing that was used to separate the animals into high and low sociability groups besides the statement that six factors were tested.  Also, there was no mention of any blinding process, which opens up the possibility that the evaluator could have been predisposed to having varying interactions with the dogs, based on their assessed socialization.

 

Week 8: What are the leading causes of negative affect and how is it identified in your species? Find 2 articles related behavioral (postures, vocalizations, behavioral tests) signs of negative affect or experiments testing affect. (Note: try to stay away from abnormal behaviors, such as stereotypies, since we’ll be tackling those next week and play, which we’ll cover under positive affect).. (Due 3/10/17)

Burman, O. (2014).  Do Dogs Show an Optimistic or Pessimistic Attitude to Life? A Review of Studies Using the ‘Cognitive Bias’ Paradigm to Assess Dog Welfare.  In Marshall-Pescini, S. & Kaminski, J. (Eds.), The Social Dog: Behavior and Cognition (pp 347-372) Amsterdam:  Academic Press.

In this book chapter, Burman examines the influence of dogs’ affective state on their decision processes and general behavior.  He begins with a general literature review on the subject, followed by an analysis of six studies in which dogs were assessed as having either a positive or negative affective valence due to levels of anxiety and stress, or the expectation of a positive or negative reward; and were observed performing trained tasks or making value decisions.

The review of individual tests revealed mixed results, with only two of them indicating that affective valence had an influence on cognitive function in dogs.  Burman identified a number of drawbacks to the methodologies used in testing, including his own experiment, and made recommendations to refine future testing on cognitive bias.  For example, he noted that food was the only positive reward used in testing, as opposed to social rewards.

He noted that animals’ affective state is a critical component of their welfare, and that the conventional behavioral and physiological assessments of affect can have misleading results.  Behaviors can have multiple causes and can be easily misinterpreted; and physiological changes, such as cortisol levels, can be caused by widely varying stimuli and affect.   He further noted that cognitive testing under controlled conditions can aid in determining the cause of a particular positive or negative affect, and should be added to the arsenal of persons performing welfare assessments.

Farago, T., Pongracz, P., Range, F., Viranyi, Z., Miklosi, A. (2010).  ‘This bone is mine’:  affective and referential aspects of dog growls.  Animal Behavior, 79 (4), 917-925.  Doi: 10.1016/j.anbehav.2010.01.005

This article explores the affective content of canine vocalization.  The authors conducted a blinded study in which dogs’ growls were recorded during three different affective states to determine whether this vocalization had content that was meaningful to other dogs.

The article begins with a review of literature in which various animals’ vocalizations were determined to have situational-specific meaning and was part of social interaction, such as dog barking or chimpanzee grunts.  This led to the purpose of the study, which attempted to determine whether dogs’ growls recorded when the dogs were in three different affective states, social play, resource guarding or offensive threatening, contained content that was understood by other dogs.  Afterwards, the dogs were placed in situations in which a resource (bone) was present, and one of the three categories of growls was played back.  The researchers found that the dogs had a higher incidence of leaving the bone alone when the resource guarding growl was played, over the aggressive or playing growls.

The researchers concluded that dog growls have varying affective content, and convey meaning about a dog’s emotional state, even when the dog emitting that vocalization is not present to provide context.   They concluded that the variations in affective content even extend to antagonistic growls  recorded under varying circumstances.

 

Week 9: What abnormal behaviors are typical for your species? Find 2 articles related to any abnormal behaviors or other psychopathology.

Tynes, V. V. & Sinn, S. (2014).  Abnormal Repetitive Behaviors in Dogs and Cats:  A Guide for Practitioners.  Veterinary Clinics of North America:  Small Animal Practice 44 (3).  pp 543-564.  Doi: 10.10.16/j.cvsm.2014.01.011

This article is review of work relating to abnormal repetitive behaviors (ARBs) in pets, including characteristics and possible causes, and providing recommendations for diagnosis and treatment.  The authors discuss the use of the terms “stereotypy” and “compulsive disorders”, concluding that the conditions are similar; but are different in the types of behaviors that are repeated and in the underlying causes.

The authors attempt to provide veterinary practitioners with a methodology for identifying abnormal repetitive behaviors, diagnosing possible causes and courses of treatment.   Various behaviors are discussed, including tail chasing/spinning, blanket sucking and lick dermatitis, with an emphasis on the possible pathological causes for the activity.  The guidance was to first eliminate any physical stimulus, such as gastric discomfort, allergies and pain, followed by determining if any neurological causes exist, before addressing possible mental or emotional distress as a cause.  The authors state that ARBs that are not caused by medical conditions are generally due to some form of conflict, anxiety or frustration, and provide recommendations for identifying and reducing environmental causes.

I found that this article provides rational and detailed methodology for isolating causes of ARB in pets.  The diagnostic process was empirical in nature and would aid in prevent veterinary or behavioral practitioners from arriving at any unfounded conclusions regarding the cause for repetitive behavior.

Bain, M. and Reich, M. (2014).  Tail chasing, leg licking – Can’t you stop? In  Horwitz, D. F. and Ciribassi J., Decoding Your Dog. pp: 281-295.  New York:  Mariner Books.

In this chapter, the authors define compulsive behavior as arising from normal activities, such as moving, grooming or eating, and continuing for extended periods at high levels.  The dogs often seem to have no control over beginning or ending the behavior, unless some external event happens to interrupt it.  They differentiate between types of compulsive/repetitive behavior, separating it into compulsive, attention-seeking, stereotypic, displacement and seizure behaviors.  The authors also distinguished between repetitive behaviors caused by medical causes, such as chewing and licking due to stomach disorders, and compulsive behaviors caused by external stressors.

The chapter provides examples of compulsive behaviors as illustrations and case studies of various type of compulsive behavior, the causes and possible treatments.  They stress the need to carefully examine the events leading up to the first times that the behaviors were observed, to identify the initial cause or causes.  An example was a dog that developed a lick granuloma on the site of an inoculation, coinciding with the dog’s owner starting a job with longer hours.  The separation anxiety contributed to the initial discomfort of the injection.  Therefore, it was necessary to treat both the granuloma and the underlying anxiety.  The authors stressed the need to treat all behavioral problems, since they are often overlapping and caused by the same stimulus.

A number of possible treatments were discussed, including avoiding or removing potential triggers, behavioral modifications and medications.  They concluded that when a compulsion manifests themselves, eliminating the compulsion must include behavior modification as well as treatment of the cause.

 

Week 12: Find 2 articles that examine positive welfare in your species. What do they want? What makes them happy?

Bradshaw, J. W. S., Pullen, A. J. & Rooney, N. J. (2014).  Why do adult dogs ‘play’?. Behavioral Processes 110 (2015). pp 82-87.  doi: 10.1016/j.beproc.2014.09.023

This article is a review of literature about the role of play in the lives of adult domestic dogs.  The authors examine the behaviors that dogs exhibit in solitary play, playing with other dogs and when playing with humans.  They found differences between social and solitary play, both in form and motivations for engaging in those behaviors.

In solitary play, dogs were seen to be engaging in a modified predatory behavior, in which dogs preferred to play with toys that moved or made noises over less active toys.  In solitary play, dogs were also observed to become bored with toys after they were “killed” and became interested in new toys almost immediately.

The act of playing with other dogs, and with humans, was found to be purely social interaction, and the play behaviors that dogs displayed were specific to the individuals being played with.  Dogs were found to engage in play as a one-to-one activity, with specific rules adopted for the type of playing.  For example, when tussling or “play-fighting” the dogs were seen to self-limit their behavior, and larger dogs often self-handicapped themselves when playing with smaller, weaker dogs or human children.  The objects used by dogs when playing also tended to be inert, such as frisbees or sticks, which do not incite any prey behavior.

When playing with humans, dogs also adopted play behaviors that were tailored to the person involved in the play.  Intense and frequent play was found to be more commonplace between dogs and owners in which coercive training was not used, and the dogs had a higher degree of obedience.  Frequent play behaviors were found to indicate a stronger and positive bond between dog and owner.

The authors concluded that play is indicative of positive affect, and part of social interaction that dogs require for their well-being.  It serves to develop and reinforce relationships both with other dogs and with their human partners.

Klinck, M. P. (2014). All dogs need a job.  In  Horwitz, D. F. and Ciribassi J., Decoding Your Dog. pp: 177-198.  New York:  Mariner Books.

In this article, Klinck discusses the mental stimulation and physical activity that dogs require for their emotional and psychological wellbeing.    She begins with a representative example of a pair of dog owners/apartment dwellers who are trying to cope with the destructiveness and activity level of their Weimaraner dog, and examines the emotional and mental needs that would drive the dog’s undesirable behavior.  This served as an example of a dog that required mental stimulus as well has physical exercise.

She continued with a discussion of dogs’ need for an enriched environment, in terms of mental exercise and to provide a stimulating environment in which the dog’s senses are engaged.  She also discusses how each environment must be tailored to the individual dog’s activity level and personality, including recognition of the instinctive behaviors that are inherent with particular dog breeds.  Examples were provided of how an overly rich environment, or one that provides the wrong kind of stimulation, can be stressful and frustrating for a dog and actually increase undesirable behaviors.

The article provides practical advice for dog owners on how to recognize their individual dog’s needs for stimulus and engagement, and how to provide the appropriate activities and enrichment that will meet their dog’s requirements for mental activity, social engagement and exercise.   Klinck also provided owners with methods of recognizing when their dogs were getting sufficient enrichment and how to periodically evaluate their dog’s affect and mood.

 

Week 13: What do “consumers” in your area want? How can welfare be a win-win? Find 2 articles relating to human attitudes or patterns of behavior that could be used to improve welfare for your species.

Power, E. (2008). Furry Families: making a human-dog family through home. Social & Cultural Geography 9 (5). 535-554. doi: 10.1080/14649360802217790

This article is based on the results of a survey of dog owners in Sydney, Australia, coupled with a literature review’ examining the role of companion dogs in families in the context of the home environment.  It examined the perceptions of the dogs and their relationships by family members and the human-perceived functions that the dogs performed as family members.

The survey results indicated that the family dogs were viewed as a variant of children, based on the relationship of care that the family extended to them in terms of feeding, exercising and general husbandry.  Interestingly, the respondents also viewed their families as a sort of pack with a hierarchical structure, with adults in the upper echelons and dogs and children in subordinate roles.  This enabled them to include dogs in the families, yet preserved the view of dogs as dogs, rather than anthropomorphizing them.  However, the family structure was rule-based with both children and dogs being expected to conform to training and avoid undesirable behaviors.  Although dogs were also allowed to enforce rules and schedules, and initiate activities such as play when the humans would have preferred to relax after work.  The study also noted that family dogs went beyond the roles of children in that they created outlets for social interaction outside of the family.

Power noted that more-than-human family structure was based on close interaction and cohabitation rather than on direct relationships.  Both the humans and dogs were able to define their relationships with a great degree of freedom, and the nature of the relationship between the dog and human family members had much to do with the overall aspect of the home in which they lived.

Bao, K. J. & Schreer, G. (2106). Pets and happiness: Examining the association between pet ownership and wellbeing. Anthrozoös 29 (2). 283-296. doi: 10.1080/08927936.2016.1152721

In this article, the authors report the findings of an on-line survey conducted of persons who identified as owners and non-owners of dogs and cats.  The survey population was 263 individuals, conducted by means of Amazon’s Mechanical Turk.  The purpose of the study was to determine if any differences existed in the subjective well being of pet owners and people who do not own pets, and whether any differences existed between dog and cat owners.

The individual responses were ranked on various scales to measure their general well being.  These included scales for subjective happiness, satisfaction with life, emotional state, and scales related to perceptions of pets.   The type and number of questions asked depended on whether the participants were pet owners.

Although the results indicated that pet owners and non-pet owners were generally equal in overall happiness and positive or negative emotions, pet owners were found to be generally more satisfied with their lives.  This apparent inconsistency was attributed to the fact that most respondents had owned their pets for more than 5 years, and the emotional effect of having a pet may have been incorporated into their natural baseline.  In comparing self-identified “cat people” with “dog people”, the survey results showed that both groups had the same overall satisfaction with life, however the dog owners were found to have somewhat higher overall happiness results.

The authors summarized their findings as being inconclusive in determining whether pets significantly contribute to human wellbeing and happiness, since the data represents only a snapshot of the participants’ emotional state at the time the survey was taken.  They indicated that the survey process should be conducted over an extended period of time as the relationships between pets and owners develop and change.