Increase of tear volume in dogs after reunion with owners is mediated by oxytocin

Murata, Kaori; Nagasawa, Miho; Onaka, Tatsushi; Kanemaki, Nobuyuki; Nakamura, Shigeru; Tsubota, Kazuo; Mogi, Kazutaka; Kikusui, Takefumi

doi:10.1016/j.cub.2022.07.031

Cited by 15 publications

(7 citation statements)

References 9 publications

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“…As detailed throughout this manuscript, this has been best documented in rodents [ 5 – 12 ]. Moreover, a recent study found that dogs also shed emotional tears and that these are visually perceived by humans [ 42 ]. That study did not ask whether humans also chemically perceive dog tears, but humans clearly chemically perceive the tears of other humans.…”

Section: Discussionmentioning

confidence: 99%

A chemical signal in human female tears lowers aggression in males

Agron,

de March,

Weissgross

et al. 2023

PLoS Biol

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Rodent tears contain social chemosignals with diverse effects, including blocking male aggression. Human tears also contain a chemosignal that lowers male testosterone, but its behavioral significance was unclear. Because reduced testosterone is associated with reduced aggression, we tested the hypothesis that human tears act like rodent tears to block male aggression. Using a standard behavioral paradigm, we found that sniffing emotional tears with no odor percept reduced human male aggression by 43.7%. To probe the peripheral brain substrates of this effect, we applied tears to 62 human olfactory receptors in vitro. We identified 4 receptors that responded in a dose-dependent manner to this stimulus. Finally, to probe the central brain substrates of this effect, we repeated the experiment concurrent with functional brain imaging. We found that sniffing tears increased functional connectivity between the neural substrates of olfaction and aggression, reducing overall levels of neural activity in the latter. Taken together, our results imply that like in rodents, a human tear–bound chemosignal lowers male aggression, a mechanism that likely relies on the structural and functional overlap in the brain substrates of olfaction and aggression. We suggest that tears are a mammalian-wide mechanism that provides a chemical blanket protecting against aggression.

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Section: Discussionmentioning

confidence: 99%

A chemical signal in human female tears lowers aggression in males

Agron,

de March,

Weissgross

et al. 2023

PLoS Biol

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“…Changes in cortisol, oxytocin, heart rate, and temperature are examples of widely used indicators of internal states in dogs, that can potentially be measured and/or manipulated non-invasively (e.g., by using salivary sampling, nasal administration, and external monitors; Barber et al 2017 ; Buttner 2016 ; Katayama et al 2016 ; Kis et al 2015 ; Kuhne et al 2014 ; McGowan et al 2018 ; Siniscalchi et al 2018a , b ). Very recently, tear volume has also been examined in dogs as a new physiological indicator (Murata et al 2022 ). Since these physiological indicators are correlated with internal states, they allow us to investigate perceptual processes when an individual is exposed to emotion cues.…”

Section: What Methodologies Have Been Used To Assess the Perception O...mentioning

confidence: 99%

Visual perception of emotion cues in dogs: a critical review of methodologies

2023

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Comparative studies of human–dog cognition have grown exponentially since the 2000’s, but the focus on how dogs look at us (as well as other dogs) as social partners is a more recent phenomenon despite its importance to human–dog interactions. Here, we briefly summarise the current state of research in visual perception of emotion cues in dogs and why this area is important; we then critically review its most commonly used methods, by discussing conceptual and methodological challenges and associated limitations in depth; finally, we suggest some possible solutions and recommend best practice for future research. Typically, most studies in this field have concentrated on facial emotional cues, with full body information rarely considered. There are many challenges in the way studies are conceptually designed (e.g., use of non-naturalistic stimuli) and the way researchers incorporate biases (e.g., anthropomorphism) into experimental designs, which may lead to problematic conclusions. However, technological and scientific advances offer the opportunity to gather much more valid, objective, and systematic data in this rapidly expanding field of study. Solving conceptual and methodological challenges in the field of emotion perception research in dogs will not only be beneficial in improving research in dog–human interactions, but also within the comparative psychology area, in which dogs are an important model species to study evolutionary processes.

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“…Tail wagging is frequently associated with both positive and negative arousal, suggesting a correlation with arousal-related hormones and neurotransmitters [24][25][26][27][28][29][30][31][32]. For example, there is indirect evidence linking oxytocin and tail wagging, especially when dogs are reunited with a familiar human [33,34]. However, associations between tail wagging behaviour and cortisol levels are inconsistent across studies [24,[35][36][37][38][39][40].…”

Section: Tail Wagging and Tinbergen's Four Questionsmentioning

confidence: 99%

Why do dogs wag their tails?

Leonetti,

Cimarelli,

Hersh

et al. 2024

Biol. Lett.

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Tail wagging is a conspicuous behaviour in domestic dogs ( Canis familiaris ). Despite how much meaning humans attribute to this display, its quantitative description and evolutionary history are rarely studied. We summarize what is known about the mechanism, ontogeny, function and evolution of this behaviour. We suggest two hypotheses to explain its increased occurrence and frequency in dogs compared to other canids. During the domestication process, enhanced rhythmic tail wagging behaviour could have (i) arisen as a by-product of selection for other traits, such as docility and tameness, or (ii) been directly selected by humans, due to our proclivity for rhythmic stimuli. We invite testing of these hypotheses through neurobiological and ethological experiments, which will shed light on one of the most readily observed yet understudied animal behaviours. Targeted tail wagging research can be a window into both canine ethology and the evolutionary history of characteristic human traits, such as our ability to perceive and produce rhythmic behaviours.

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Increase of tear volume in dogs after reunion with owners is mediated by oxytocin

Cited by 15 publications

References 9 publications

A chemical signal in human female tears lowers aggression in males

A chemical signal in human female tears lowers aggression in males

Visual perception of emotion cues in dogs: a critical review of methodologies

Why do dogs wag their tails?

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