Interspecies hormonal interactions between man and the domestic dog (Canis familiaris)

To date, hormonal influence in interspecies interaction has not been examined. In a study of a dog agility competition among human/dog teams, men's pre-competition basal testosterone (T) levels were positively related to changes in dogs' cortisol levels from pre- to post-competition, but only among losing teams. Furthermore, pre-competition basal T in men on losing teams predicted more than half of the variance in dogs' cortisol change. This relationship was mediated through men's punitive and affiliative behaviors towards their dogs immediately after competition. Men's T change was also a significant predictor of dogs' change in cortisol such that men who experienced greater decreases in T after a loss were associated with dogs that experienced greater increases in cortisol. In winning teams, men's pre-competition T and T changes were unrelated to dogs' cortisol changes. These results are discussed in light of T as a proxy for dominance motivation as well as T's relation to stress across the species boundary.     

Gender Differences in Owners Interacting with Pet Dogs: An Observational Study

Many studies show that people form strong affectional bonds with their dogs, treating them like family members or children. The present study investigates differences between women and men owners during interactions with their dogs, in a situation designed to investigate attachment and, thus, to promote emotional and affective responses: the Ainsworth's Strange Situation. Twenty‐five dog owners, 10 men and 15 women, were observed during free interactions with their pets in an adapted version of the ‘strange situation procedure’. Their behaviour towards their pets was videorecorded. Talking to the dog was evaluated together with the occurrence of affiliative and play behaviours. The owner's level of attachment to the dog was assessed using a questionnaire. Women and men differed in the use of verbal communication. Women talked more than men and had a shorter latency in starting talking. Their utterances resembled more closely infant‐directed speech or ‘motherese’. In contrast, there were no clear gender differences in affiliative and play behaviours. Both women and men engaged in play with their dogs and provided physical comfort. No differences emerged in the level of attachment reported by women and men owners in the questionnaire. These data support the hypothesis that the behaviour of modern pet owners towards their dogs is an interspecific parental behaviour, and suggest that behaviours evolved to provide care and comfort to human infants have been co‐opted for interacting with other social partners. The difference in verbal communication between women and men is in agreement with an evolutionary scenario suggesting a greater pre‐disposition in women to use language as a relational tool.     

Manipulating the affiliative interactions of group-housed rhesus macaques using positive reinforcement training techniques.

Social housing, whether continuous, intermittent, or partial contact, typically provides many captive primates with opportunities to express affiliative behaviors, important components of the species-typical behavioral repertoire. Positive reinforcement training techniques have been successfully employed to shape many behaviors important for achieving primate husbandry goals. The present study was conducted to determine whether positive reinforcement training techniques could also be employed to alter levels of affiliative interactions among group-housed rhesus macaques. Twenty-eight female rhesus were divided into high (n = 14) and low (n = 14) affiliators based on a median split of the amount of time they spent affiliating during the baseline phase of the study. During the subsequent training phase, half of the low affiliators (n = 7) were trained to increase their time spent affiliating, and half of the high affiliators (n = 7) were trained to decrease their time spent affiliating. Trained subjects were observed both during and outside of training sessions. Low affiliators significantly increased the amount of time they spent affiliating, but only during nontraining sessions. High affiliators on the other hand, significantly decreased the amount of time they spent affiliating, but only during training sessions. These data suggest that positive reinforcement techniques can be used to alter the affiliative behavior patterns of group-housed, female rhesus monkeys, although the two subgroups of subjects responded differently to the training process. Low affiliators changed their overall behavioral repertoire, while high affiliators responded to the reinforcement contingencies of training, altering their proximity patterns but not their overall behavior patterns. Thus, positive reinforcement training can be used not only as a means to promote species-typical or beneficial behavior patterns, but also as an important experimental manipulation to facilitate systematic analyses of the effects of psychosocial factors on behavior and potentially even immunology.     

Dyadic relationships and operational performance of male and female owners and their male dogs

In the paper we investigate how owner personality, attitude and gender influence dog behavior, dyadic practical functionality and the level of dog salivary cortisol. In three meetings, 12 female and 10 male owners of male dogs answered questionnaires including the Neo-FFI human personality inventory. Their dyadic behavior was video-taped in a number of test situations, and saliva samples were collected. Owners who scored highly in neuroticism (Neo-FFI dimension one) viewed their dogs as social supporters and spent much time with them. Their dogs had low baseline cortisol levels, but such dyads were less successful in the operational task. Owners who scored highly in extroversion (Neo-FFI dimension two) appreciated shared activities with their dogs which had relatively high baseline cortisol values. Dogs that had female owners were less sociable-active (dog personality axis 1) than dogs that had male owners. Therefore, it appears that owner gender and personality influences dyadic interaction style, dog behavior and dyadic practical functionality.     

Hormonal responses differ when playing violent video games against an ingroup and outgroup

For 14 teams of three young men, salivary testosterone and cortisol were assessed twice before and twice after competing in within-group and between-group video games that simulated violent male–male competition. Men who contributed the most to their teams' between-group victory showed testosterone increases immediately after the competition, but only if this competition was played before the within-group tournament. High-scoring men on losing teams did not show this immediate effect, but they did show a delayed increase in testosterone. In contrast, high-ranking men tended to have lower testosterone and higher cortisol during within-group tournaments. The results are consistent with the hypothesis that men's competitive testosterone response varies across ingroup and outgroup competitions and is muted during the former. The testosterone response during the between-group competition also suggests that violent multiplayer video games may be appealing to young men because they simulate male–male coalitional competition.     

Affiliative and disciplinary behavior of human handlers during play with their dog affects cortisol concentrations in opposite directions

It has been shown that cortisol concentrations change characteristically in the course of agonistic interactions; our aim was to find out how a playful situation may affect concentrations of this hormone in the saliva. We studied dogs' behavior and the changes of cortisol concentrations in a play situation, where the dogs played with their handler for 3 min with a tug toy. In this experiment working dogs were divided into two groups by the type of their work, namely police dogs and border guard dogs. We found that the cortisol concentrations of old police dogs significantly increased, while the adult border guard dogs' hormone levels decreased, which shows that playing with the handler has an effect on both groups, but interestingly this effect was opposite. Behavior analysis showed differences only in the behavior of the human handlers during the play sessions, while the behavior analysis did not reveal significant differences in the two groups of dogs, except that old border guard dogs generally needed more time to begin playing than old police dogs. During the play sessions police officers were mainly disciplining their dogs, while the border guards were truly playing with them (including affiliative and affectionate behavior). Our results are in accordance with those of recent studies, which show that behaviors associated with control, authority or aggression increase cortisol concentrations, while play and affiliative behavior decrease cortisol levels.     

Early life maternal sociality predicts juvenile sociality in blue monkeys

Maternal effects are widespread in living organisms though little is known about whether they shape individual affiliative social behavior in primates. Further, it remains a question whether maternal effects on affiliative behavior differ by offspring sex, as they do in other physiological systems, especially in species with high levels of adult sexual dimorphism and divergence in social niches. We explored how direct and indirect experiences of maternal affiliative behavior during infancy predicted affiliative behavior approximately 1–6 years later during the juvenile period, using behavioral data from 41 wild blue monkey juveniles and their 29 mothers, and controlling for individual age, sex, and maternal rank. Female juveniles spent less time grooming with any partner and with peers the more maternal grooming they received during infancy, whereas males groomed more with any partner and with peers. Similarly, the more that mothers groomed with other adult females during subjects’ infancy, female subjects played less with peers, and male subjects played more as juveniles. Further, this maternal effect on social behavior appears specific to early life, as the same aspects of mothers’ sociality measured throughout subjects’ development did not predict juvenile behavior. Overall, our results suggest that both direct and indirect experience of mother's affiliative behavior during infancy influence an individual's affiliation later in life that sexes respond differently to the maternal affiliation, and that the first year of life is a critical window.     

Two Sides of the City: Dog-keeping Practices in Russian Urban Areas

This article examines dog–owner relations and dog ownership in Omsk, Russia. We describe typical dog-keeping practices and reveal how diverse urban environments can influence these practices. A two-stage survey was conducted in 2014 to determine the numbers and management of dogs owned. In total, some 1,583 households at the first stage of the research and 323 households at the second stage were interviewed face-to-face. About 23% of all households in Omsk owned dogs, but this proportion varied markedly for different parts of the city. In the city's single-story area, 71.5% of households had dogs, while in the multi-story area this was only 10.8%. Dog-keeping practices were different in these areas. Significant differences in these practices were shown for almost all aspects: the selection criteria, dog feeding, veterinary treatment, dog walking, the roles of dogs, and owners’ attitudes toward them. Owners living in the single-story area demonstrated a utilitarian or functional approach to their dogs—influencing the sex, size, and the breed of the animal. Dogs often lived outside the house; they were vaccinated and taken to the veterinarian less often than dogs from the multi-story area. The owners in the multi-story area described more affectionate feelings toward their dogs. This is reflected in both the choice and treatment of the animals. We observed a larger proportion of pedigree dogs, a larger proportion of female animals, more vaccinations, and the owners making a variety of purchases for their dogs.     

Primates Face to Face: Conservation Implications of Human–Nonhuman Primate Interconnections Edited by Agustín Fuentes and Linda D. Wolfe

ABSTRACT

Sterilization of companion animals is in most cases an expression of the caretaker's will. However, little is known about caretakers' attitudes toward pet sterilization in general—these can influence their decision to sterilize their own animals. Three hundred and twelve Romanian caretakers of non-sterilized companion animals (194 women and 118 men) were surveyed before the implementation of a pet management program in Transylvania, the North-Western part of Romania. The caretakers were administered a questionnaire that gathered demographic data and measured their general attitude toward pet sterilization and their attitude toward the sterilization of their own pet (male or female). Questionnaires were filled in by caretakers of 202 dogs and 110 cats. Romanian pet owners showed an overall level of slight disagreement toward the sterilization of companion animals. Gender-biased attitudes of the Romanian caretakers toward the sterilization of their own pets emerged only when the sex of the animals was taken into consideration, regardless of the type of pet. Romanian men disagreed with neutering male pets while Romanian women were more likely to agree with neutering male pets. No gender difference was detected regarding the spaying of female pets, with both genders showing a slight level of disagreement. The results are discussed from sociological, anthropological, and evolutionary perspectives.     

Hormonal response to competition among male coalitions

Previous research has shown that testosterone (T) and cortisol (C) are released in response to a wide variety of social stimuli including dyadic (one on one) competitive events, but humans also compete as groups. Here we report results from a pilot study of hormonal responses to competition between male coalitions. Salivary T and C levels were assessed in adult males from a rural Caribbean village who competed at dominoes, as two-man teams, against (a) familiar men from their own village (within coalition), and (b) strangers from another village (between coalitions). Analyses indicate that both T and C levels were higher and responses more pronounced for between-village competition than for within-village competition, but we could not compare responses to victory and defeat in the between-village case, since our subjects happened to win both such contests. Further studies of endocrine responses in the context of coalitional competition are warranted.     

Sizing‐up the Competition: Factors Modulating Male Display Behavior During Mate Competition

When competing for mates, males of many species use cues from their rivals to evaluate their chances of success. Signaling behavior is a vital component of male–male contests and courtship, and may inform males of a rival's quality or intentions. We used eastern fence lizards (Sceloporus undulatus) to investigate how the time a male spent signaling during mate competition is influenced by his quality, his rival's quality relative to his own, and the value of a contested female. Furthermore, we examined how a male's behavioral response to a competitor's signals would be mediated by his relative quality. We simulated natural encounters by allowing two males to compete over a single female in the laboratory. We measured the time males spent performing two types of displays (pushups and shudders) and categorized male behavioral responses to rival pushup and shudder displays. Time spent signaling was not related to a male's absolute quality (body and head size, condition, and badge sizes), or his quality relative to that of his rival, although males did spend more time performing pushups when competing over females in better condition. Male behavior was also influenced by his rival's signals, such that males of relatively lower quality than their opponents were more likely to aggressively respond to rival pushups and shudders. We discuss these results with respect to the evolution and function of signaling behavior in courtship and male–male contests.     

Dog and owner demographic characteristics and dog personality trait associations

The aim of this study was to analyze the relationships between four personality traits (calmness, trainability, dog sociability and boldness) of dogs (Canis familiaris) and dog and owner demographics on a large sample size with 14,004 individuals. German speaking dog owners could characterize their dog by filling out a form on the Internet. There were five demographic variables for dogs and nine for owners. Two statistical methods were used for investigating the associations between personality and demographic traits: the more traditional general linear methods and regression trees that are ideal for analyzing non-linear relationships in the structure of the data. The results showed that calmness is influenced primarily by the dog's age, the neutered status, the number of different types of professional training courses (e.g. obedience, agility) the dog had experienced and the age of acquisition. The least calm dogs were less than 2.5 years old, neutered and acquired after the first 12 weeks of age, while the calmest dogs were older than 6.9 years. Trainability was affected primarily by the training experiences, the dog's age, and the purpose of keeping the dog. The least trainable dogs had not received professional training at all and were older than 3 years. The most trainable dogs were those who participated in three or more types of professional training. Sociability toward conspecifics was mainly determined by the age, sex, training experience and time spent together. The least sociable dogs were older than 4.8 years and the owners spent less than 3 h with the dog daily. The most sociable dogs were less than 1.5 years old. Males were less sociable toward their conspecifics than females. Boldness was affected by the sex and age of the dog and the age of acquisition. The least bold were females acquired after the age of 1 year or bred by the owner. The boldest dogs were males, acquired before the age of 12 weeks, and were younger than 2 years old. Other variables, including the owner's gender, age, education, previous experience with dogs, the number of people and dogs in the household, and purpose of keeping the dogs had minor, but detectable effects. The results suggest that on-line questionnaires are a very effective means for collecting data about dog behavior, especially if owners are motivated by instant feedback. However, note that the characteristics of dogs in the present study were reported by the owners, and the associations with the traits do not necessarily represent a causal relationship.     

Social contact and hormonal changes predict post-conflict cooperation between friends

Long-term cooperation between individuals necessitates repairing damage arising from inevitable competing interests. How two members of a valuable relationship switch from competing to cooperating constitutes an important problem for any social species. Observations of non-human animals suggest that affiliative contact immediately following a contest facilitates continued cooperation. Behavioral studies further indicate that winners and losers frequently differ in hormonal changes following a competition. We tested the hypothesis that immediate contact with increases in cortisol (and testosterone for men) for winners following competition would facilitate subsequent cooperation between adult same-sex friends. Results show that contact (versus no contact) immediately following competition enhanced subsequent cooperation between female friends. During contact, increases in winner's cortisol for both sexes, and in testosterone for men, predicted future cooperation. Our results suggest two mechanisms that maintain social bonds following competition between established allies.     

The importance of mate attraction for intrasexual competition in men and women

Buss (1988a), using an evolutionary perspective, tested hypotheses about intrasexual competition within the context of behavior to attract mates. He found sex differences in intrasexual competition predicted by the goal of mate attraction. We used Buss's methodology while asking subjects about the acts they performed to compete with members of the same sex, rather than about acts for attracting potential mates. Competitive acts were nominated and placed into 26 tactics in Study 1. Study 2 obtained self-reports of male and female act performance frequency. Study 3 replicated Study 2 using observer-reports. Study 4 obtained act effectiveness judgments for men and women. We largely replicated Buss's results despite the focus on intrasexual competition instead of mate attraction. Thus, we provide strong evidence for the importance of mate attraction in intrasexual competition.     

Salivary hormone concentrations in mothers and fathers becoming parents are not correlated

A time- and date-matched set of saliva samples (N = 229) from nine couples first expecting, and then caring for, their first child were used to test whether hormone changes in the father could be predicted by the hormonal status of the mother. Testosterone, cortisol, and estradiol were quantified from saliva. Neither testosterone nor estradiol concentration was correlated within couples before or after the birth, although there was a positive correlation for cortisol concentration in the mother and father before the birth. As the hormone that might be influenced by chemical signals, that already played a similar role in men and women, and that had been empirically linked to paternal behavior, cortisol concentration was also compared with sex steroid concentrations. The mother's cortisol concentration was positively correlated to the father's testosterone concentration, and the mother's testosterone concentration was positively correlated with the father's cortisol concentration. However, both effects were similar in magnitude to the cortisol to cortisol correlation, and all could parsimoniously be explained by similar responses to a shared environment. Thus, this analysis rejects parallels in peripheral hormone concentrations of estradiol, testosterone, and cortisol in mothers and fathers. However, the available data were not able to test or reject hypotheses about local neuroendocrine homology, nor to control for masking effects of other hormonal demands on men and women, nor to determine the relative importance of shared environment versus mother-father signaling.     

Sex-specific difference in the interconversion of cortisol and cortisone in men and women

Objective: Our objective was to demonstrate that the smaller oxoreductase activity of 11β‐HSD1 in women would shift the interconversion of cortisol and cortisone toward cortisone, resulting in a larger amount of generated labeled cortisone in healthy women than in healthy men. Research Methods and Procedures: Using mass spectrometry, the amount of cortisone generated from a continuous infusion (8 am to 6 pm ) of stable‐labeled cortisol (1α,2α‐d‐cortisol) was determined in non‐obese and in obese (BMI >35 kg/m²) men and women during steady‐state conditions (from 2 pm to 6 pm ). In this setting, the amount of generated labeled cortisone (expressed as % of the achieved steady‐state concentrations of labeled cortisol) reflects the sum of the bi‐directional conversion of cortisol into cortisone (and vice versa) by 11β‐hydroxysteroid dehydrogenase. Results: The amount of generated labeled cortisone was higher in men than in women (p < 0.0001). This sex difference was higher in obese than in non‐obese patients (p = 0.0062). Conclusions: The interconversion of cortisol and cortisone during steady‐state conditions is shifted toward cortisol in men as compared with women. This suggests a higher overall oxoreductase activity of 11β‐hydroxysteroid dehydrogenase type 1 in men than in women. This sex‐specific difference is maintained in obesity.     

Acute pre-learning stress and declarative memory: impact of sex,cortisol response and menstrual cycle phase

This study explores the influence of pre-learning stress on performance on declarative memory tasks in healthy young adults in relation to sex and menstrual cycle phase. The sample was composed of 119 students (32 men and 87 women) from 18 to 25 years of age. The women were tested in different hormonal stages (30 in follicular phase, 34 in luteal phase, and 23 using oral contraceptives). The participants were exposed to the Trier Social Stress Test (TSST) or a control condition. Afterwards, their memory performance was measured using a standardized memory test (Rey's Auditory Verbal Learning Test). In the control condition, all groups of women recalled more words than men, but these differences disappeared in the group exposed to TSST because men's performance on the memory test improved, but only to the level of women. In addition, our data suggest that in women the relationship between cortisol and memory can be modulated by sex hormone levels, since in luteal women a negative relationship was found between memory performance and peak cortisol level. These results confirm that sex differences need to be considered in the relationship between pre-learning stress and memory performance.     

Sequence of pituitary-adrenal cortical hormone responses to low-dose physostigmine administration in young adult women and men

We previously demonstrated greater HPA axis activation in adult men compared to adult women following low-dose administration of the anticholinesterase inhibitor, physostigmine (PHYSO). Because blood sampling was done infrequently following PHYSO, the rise times of AVP, ACTH1-39, and cortisol could not be determined. In the present study, we determined the sequence of hormone increases by frequent blood sampling following PHYSO. Twelve adult women and 12 adult men underwent three test sessions 5-7 days apart: PHYSO, saline control, and repeat PHYSO. As in the earlier study, PHYSO produced no side effects in half the subjects and mild side effects in the other half, with no significant female-male differences. None of the hormone responses was significantly correlated with the presence or absence of side effects. In both women and men, the AVP increase preceded the ACTH1-39 increase, which in turn preceded the cortisol increase. The AVP and ACTH AUCs were significantly positively correlated in both women and men, supporting AVP as an acute stimulus to ACTH secretion. Also as in the earlier study, the AVP response to PHYSO was more than twice as great in men as in women, but the difference was not statistically significant. We therefore analyzed the results of both studies combined (N=26 women and 26 men). The men had a significantly greater AVP response and a trend toward a greater ACTH1-39 response compared to the women. These findings further support the concept of sexual diergism (functional sex difference) in the influence of CNS cholinergic systems on HPA hormone secretion.     

A Comparison of Bahamian Cat and Dog Caregivers on New Providence

This article offers the first comparison of actions and attitudes of Afro-Caribbean caregivers who keep only cats or only dogs. A total of 330 Bahamian caregivers found that women primarily keep cats; men primarily keep dogs. Cat keepers were more attached to their companion animals but no more sensitive toward nonhuman animal-welfare issues than dog keepers. When considering actions toward pets, the study noted few differences between the two types of caregivers. Both types reported low neutering rates and lack of confinement. Findings suggest that although both cat and dog caregivers thought themselves good pet caregivers, both types would benefit from animal-welfare education. In communities where cat populations pose a threat to indigenous wildlife and current care-keeping practices may be a cause for concern, caregivers may need education as to the implications of their actions. Given the similarity in dog-keeping practices in the West Indies, the findings about cat caregivers reported here may be applicable to other Afro-Caribbean communities. Further research on cats should be done to allow better understanding of the dynamics and behavior of cat populations on small islands.     

ALTERNATIVE MODELS OF CHARACTER DISPLACEMENT AND NICHE SHIFT. I. ADAPTIVE SHIFTS IN RESOURCE USE WHEN THERE IS COMPETITION FOR NUTRITIONALLY NONSUBSTITUTABLE RESOURCES

This paper analyzes the influence of the nutritional status of resources on the adaptive response to interspecific competition in a consumer of those resources. The two cases compared are that in which the resources are nutritionally perfectly substitutable (in the sense of Leon and Tumpson [1975]) and that in which the resources are nonsubstitutable. Each nonsubstitutable resource must be consumed at a certain rate for population growth to occur. Evolutionarily stable strategies of resource utilization are found using models of competition for two resources. If competition occurs solely via the consumer species's effects on resource density, the adaptive response in a consumer's resource-acquisition traits is: a) divergence away from its competitor's resource-acquisition traits if resources are perfectly substitutable and b) convergence towards the competitor's resource-acquisition traits if resources are nonsubstitutable. Exceptions to both of these generalizations may occur if competitor population density affects a consumer species's per capita growth rate independently of effects on resource density. Plants and herbivores often use nonsubstitutable resources. The lack of studies of adaptive responses to competition in these organisms may be responsible for the lack of documented examples of competitive convergence.