Nonhuman Research Articles

Resurgence in a discrete-trial procedure in rats.

Resurgence is a transient recovery of a previously extinguished target response following a worsening of reinforcement conditions for an alternative response. Laboratory studies with nonhuman animals typically assess resurgence in free-operant situations where subjects can freely emit responses. The purpose of the current study was to investigate whether resurgence would be observed in a discrete-trial procedure where only a single response could occur in each trial, using rats as subjects. The experiment consisted of three phases, and each session ended after 200 trials. All trials began with the insertion of target and alternative levers and ended once a response was emitted. In Phase 1, both target and alternative responses were reinforced with a probability of .25. In Phase 2, the target response was extinguished while still reinforcing the alternative response with a probability of .25. Finally, resurgence was tested by placing the alternative response on extinction. All rats showed robust resurgence in this highly constrained discrete-trial situation. We also found that the latencies of resurged target responses differed from those in Phase 1. Overall, the present discrete-trial procedure could produce reliable resurgence as with typical free-operant procedures and has several potential benefits for studying resurgence.

Functional analysis and treatment of problem behavior by domesticated canines.

Functional analyses are used to assess maintaining variables of behavior. Despite the large amount of research on functional analyses with humans, there are limited examples with nonhumans and even fewer studies incorporating modifications to standard methods of assessment with nonhumans. One modification that has yet to be evaluated with nonhuman animals is the trial-based functional analysis in which control and test conditions are embedded in naturalistic environments. This study compared a standard functional analysis with a trial-based functional analysis across different topographies of problem behavior with dogs. The results of the functional analyses corresponded for every dog. Individualized treatments were designed to reduce problem behavior. Implications of the trial-based functional analysis include feasibility for privately owned dogs and dogs under the care of shelters. The trial-based functional analysis offers a modification to established functional analyses that may allow increased access to the assessment of problem behavior.

Empathy enhances decoding accuracy of human neurophysiological responses to emotional facial expressions of humans and dogs.

Despite the growing interest in the non-human animal emotionality, we currently know little about the human brain processing of non-conspecific emotional expressions. Here, we characterized the millisecond-scale temporal dynamics of human brain responses to conspecific human and non-conspecific canine emotional facial expressions. Our results revealed generally similar cortical responses to human and dog facial expressions in the occipital cortex during the first 500 ms, temporal cortex at 100-500 ms and parietal cortex at 150-350 ms from the stimulus onset. Responses to dog faces were pronounced at the latencies in temporal cortices corresponding to the time windows of early posterior negativity (EPN) and late posterior positivity (LPP), suggesting attentional engagement to emotionally salient stimuli. We also utilized support vector machine -based classifiers to discriminate between the brain responses to different images. The subject trait-level empathy correlated with the accuracy of classifying the brain responses of aggressive from happy dog faces, and happy from neutral human faces. This result likely reflects the attentional enhancement provoked by the subjective ecological salience of the stimuli.

Animal Linguistics

Animal linguistics is an interdisciplinary field that integrates animal behavior, linguistics, and cognitive science to explore issues such as (a) what animal signals mean, (b) what cognitive abilities are necessary for the production and understanding of these signals, and (c) how communication systems have evolved. Despite the traditional belief that language evolved through a single mutation in our ancestors, accumulating evidence suggests that many cognitive abilities underlying human language have also evolved in nonhuman animals. For example, several species of birds and nonhuman primates convey conceptual meanings through specific vocalizations and/or combine multiple meaning-bearing calls into sequences using syntactic rules. Using experimental paradigms inspired by cognitive science and linguistics, animal linguistics aims to uncover the cognitive mechanisms underlying animal language and explores its evolutionary principles. This review examines previous studies exploring the meanings and cognitive abilities underlying animal language and introduces key methodologies in this emerging field.

Beyond bigrams: call sequencing in the common marmoset (Callithrix jacchus) vocal system.

Over the last two decades, an emerging body of research has demonstrated that non-human animals exhibit the ability to combine context-specific calls into larger sequences. These structures have frequently been compared with language's syntax, whereby linguistic units are combined to form larger structures, and leveraged to argue that syntax might not be unique to language. Currently, however, the overwhelming majority of examples of call combinations are limited to simple sequences comprising just two calls which differ dramatically from the open-ended hierarchical structuring of the syntax found in language. We revisit this issue by taking a whole-repertoire approach to investigate combinatoriality in common marmosets (Callithrix jacchus). We use Markov chain models to quantify the vocal sequences produced by marmosets providing evidence for structures beyond the bigram, including three-call and even combinations of up to eight or nine calls. Our analyses of these longer vocal sequences are suggestive of potential further internal organization, including some amount of recombination, nestedness and non-adjacent dependencies. We argue that data-driven, whole-repertoire analyses are fundamental to uncovering the combinatorial complexity of non-human animals and will further facilitate meaningful comparisons with language's combinatoriality.

Turns around periodic spatial boundaries facilitate increasing event segmentation over time.

Event segmentation is a neurocognitive process bridging perception and episodic memory. To our knowledge, almost all segmentation work is framed towards humans, yet evolutionarily conserved mechanisms in event cognition exist across species. Here, we addressed segmentation in a way that is applicable to humans and non-human animals, inspired by research in rats; specifically, the fragmentation of grid-cell spatial representations following the insertion of boundaries into an environment (forming a corridor maze). Participants indicated when they felt a meaningful unit of activity ended and another began, while watching an agent traverse from a first-person perspective. A virtual corridor maze (experiment 1) and two other mazes were used (experiment 2), with participants viewing/segmenting the same stimuli twice. We found that people segmented more during turns relative to corridors, with elevated segmentation occurring in discrete moments around turns. Interestingly, we also found that boundaries of the corridor maze facilitated an increase in segmentation within and across viewings. These results suggest that segmentation can be driven by recognized repeating activity that can become more meaningful over time, highlighting an important link between event segmentation and pattern separation that is relevant to many species in their formation of episodic-(like) memory.

Reexamining developmental continuity and discontinuity in the 21st century: Better aligning behaviors, functions, and mechanisms.

Developmental science aims to explain development across the lifespan. Jerome Kagan observed that the same behavior can occur for different reasons, and differing behaviors can occur for the same reason. To help account for persistence, desistence, and transformation of behavior across development, Kagan introduced various types of continuity and discontinuity of forms and functions of behavior. This framework provides opportunities for identifying explanatory mechanisms in behavior development. However, misconceptions remain in applying the concepts that Kagan introduced. Much of the literature assumes developmental continuity in constructs without examining whether assumptions are supported, leading to faulty developmental inferences. For instance, the use of the same measure across time to assess development assumes that the behavior occurs for the same reason across time (homotypic continuity). In addition, just because one behavior predicts a different behavior at a later time does not necessarily indicate that age-differing behaviors occur for the same reason (heterotypic continuity). This review aims to advance conceptualizations of continuity and discontinuity from a contemporary perspective with aims to improve mechanistic understanding of behavior development across the lifespan. To better align behaviors, functions, and mechanisms, research should (a) examine (dis)continuity of individual behaviors rather than merely syndromes, (b) identify the function(s) of the given behavior(s), and (c) identify the cognitive and biological processes that underlie the behavior-function pairs. Incorporating examples from research on development of humans and nonhuman animals, I discuss challenges from work that has followed Kagan's ideas and ways to advance understanding of continuity and discontinuity across development. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Animal emotions and consciousness: a preliminary assessment of researchers' perceptions and biases and prospects for future progress.

Scientists and philosophers have long struggled with the question of whether non-human animals experience emotions or consciousness. Yet, it is unclear where the scientific consensus on these topics lies today. To address this gap, we administered a survey of professional animal behaviour researchers to assess perceptions regarding (i) the taxonomic distribution of emotions and consciousness in non-human animals, (ii) respondents' confidence in this assessment, and (iii) attitudes towards pitfalls and potential for progress when addressing these questions. Respondents (n = 100) ascribe emotionality and consciousness to a broad swath of the animal taxonomy, including non-human primates, other mammals, birds and cephalopods. Respondents' attribution of these phenomena was strongly associated with their confidence in their assessments (R 2 > 0.9), with respondents assuming an absence of emotions and consciousness when they were unsure. We also identify an emergent consensus of the components involved in a functional definition of emotions. Researchers are optimistic that tools either currently exist or will exist in the future to rigorously address these questions (>85%) and that animal behaviour, as a field, should do more to encourage research works on emotions (>70%). We discuss implications for publication bias and future work in this area as well as ethical considerations regarding animal care and use.

When Is a Dingo Not a Dingo?

In 2019 the Western Australian government recategorised the dingo ( Canis dingo) as a wild dog ( Canis familiaris) whose status is legally declared to be a pest. Despite its iconic native status, Canis dingo has been rendered non-existent and liable to be disposed of by inhumane means. Dumped in a legal black hole via a signifying regime of signs, dingoes are confronted with the fact of their own non-existence. Regarding the dingo as a dingoing, a multiplicity and a process, rather than a characteristic, I read the reclassification event symptomatologically and interrogate the constellations of symptoms and regimes of signs which legitimate the event and its performativity. I examine order-words including ‘pest’ and ‘wild dog’ to shift the focus from the words’ meaning to what they do. I subsequently enquire whether ‘dingo’ might become a pass-word, a component of passage, such that dingoes might exist under reprieve in a post-signifying regime. I argue that post-signifying regimes are codified, however, as subjects are individuated along lines of subjectification. I conclude by contemplating whether it is possible to break with subjectification, liberating these demonic nonhuman animals from the signifiers which territorialise them and permitting dingoes to become-animal.

Do kea parrots infer the weight of objects from their movement in a breeze?

Weight, though it cannot be seen directly, pervades nearly every aspect of an animal's life. However, the extent to which non-human animals reason about the property of weight remains poorly understood. Recent evidence highlights birds as a promising group for testing this ability: for example, New Caledonian crows can infer the weight of objects after observing their movements in a breeze. Here, we tested for similar weight inference abilities in kea (Nestor notabilis), a parrot species known for its sophisticated problem-solving skills. Subjects were trained to exchange objects of a target weight (light or heavy) for a food reward. They were then allowed to observe pairs of novel objects (one light and one heavy) hung in front of an electric fan in both an experimental condition (fan on, light object moving) and a control condition (fan off, both objects motionless). The birds were subsequently presented with test trials in which they could use the information from the demonstration to select an object of their target weight. We found that, unlike New Caledonian crows, kea did not perform significantly better on trials in which they observed the objects' movements and discussed our findings within the context of the kea's highly explorative nature.

Representations of Nonhuman Animals in Bulgarian Literary Education

Through an educational perspective, the paper traces the attitudes towards nonhuman animals, the human-nonhuman relations, and the ideologies included in the literature curriculum developed by the Bulgarian Ministry of Education and Sciences. Comparing the official programmes with certain literary textbooks, I examine various representations of nonhuman animals in the latter. I study which authors who wrote about nature and nonhuman animals are included in the curriculum, which of their literary works are studied in school, what interpretational directions are offered, what approaches to human-nonhuman relations are chosen, and what types of thinking are encouraged and cultivated.

Establishment of a rhesus macaque model for coxsackievirus A6 infection: Pilot study to evaluate infection initiated through the respiratory or digestive track

Coxsackievirus A6 (CVA6) is a primary pathogen associated with hand, foot, and mouth disease (HFMD) and is typified by fever, rashes or herpetic lesions at distinct locations. Although HFMD patients exhibit mild symptoms, a subset of patients may develop severe complications, such as viral encephalitis, myocarditis, pneumonia, and neurological disorders. However, in addition to rodent models, such as the CVA6-infected mouse model, no definitive nonhuman primate animal model or related research or analysis tool is available, which makes the development of suitable nonhuman primate animal models particularly crucial. In this study, 3- to 4-month-old rhesus monkeys were infected via the respiratory or digestive tract, and the pathogenic, pathological, and immunological alterations following CVA6 infection were investigated. The results revealed that the infected rhesus monkeys exhibited symptoms similar to those of patients, including signs of HFMD, blood cell changes, viremia, viral excretion, and inflammatory reactions during the acute phase (1–11 days). Pathological observations revealed inflammatory reactions in the intestinal and lymph node tissues. Notably, the acute symptoms gradually waned in the recovery phase (12–120 days), and a high level of neutralizing antibodies was sustained. Intriguingly, no significant disparity was observed between the infections initiated via the respiratory or digestive tract in terms of clinical symptoms, hemogram results or virus shedding. Overall, this study yielded a comprehensive dataset regarding the physiological, pathological, and immunological outcomes of CVA6 infection in a primate host, enhancing our comprehension of the mechanism of CVA6 infection and providing essential data for related vaccine and drug development.

Humanising the Nonhuman: An Ecocritical Toolbox for Anthropomorphic Agency

Ecocriticism tends to acknowledge anthropomorphisms as a possible tool to create empathy for nonhumans, but in doing so mostly labels said tool as too sentimental for serious environmental literature. This paper aims to establish a categorisation of anthropomorphisms in media that allows a more diverse and detailed analysis of humanised nonhumans. It seeks to overcome the prevailing idea that anthropomorphic descriptions are limited to nonhuman animals and therefore extends the term to the humanisation of anything that is not human. Following the school of thought suggested by new materialism and material ecocriticism, nonhumans are regarded as having agency and anthropomorphising them allows humans to empathise with nonhumans. The categorisation of anthropomorphism proposed here is divided into each three markers and modes. The markers signify which part of the human can be observed in the anthropomorphised subject, while the modes define how this is realised. This article exemplifies the concept of markers and modes through anthropomorphic trees in literature, but as it is not a static concept, it allows for overlaps between categories and dynamic adaptations for other cases of anthropomorphised subjects. The three markers are Physicality, Sentience, and Language and may appear also in combinations. The modes are Projection, Manifestation, and Hybridity. As anthropomorphisms strongly intersect with theories of nonhuman agency, this, too, will be discussed in the final section of this article.

TAKE AN OLD DRUG AND STAY YOUNG? METFORMIN AS AN ANTI-AGING MEDICATION – A LITERATURE REVIEW.

AIMS: Metformin is the main drug used in the treatment of type 2 diabetes mellitus, and the most widely prescribed oral antihyperglycemic medication. Its mechanism of action is still not completely understood and research into new uses for the compound is still ongoing, with one possible novel application of the medication being to combat aging on both the cellular and the macroscopic level. The aim of the study is to evaluate the current state of knowledge on metformin’s potential as a lifespan-extending and anti-senescence drug, present evidence on the matter and assess possible lanes of further study into such effects. METHODS: The literature review was performed using Internet research paper databases (PubMed, Google Scholar, Medline), using articles available in English. RESULTS: Multiple papers suggest tentative support for the notion that metformin may contribute to slowing cellular senescence, as well as to extending the human lifespan. Theoretical knowledge exists that shows possible routes of action of metformin in this regard. CONCLUSIONS: There is ample evidence in the literature for metformin’s possible effects as an anti-aging drug. Numerous cellular pathways by which it could exert lifespan-extending effects have been elucidated, and in vivo studies on some non-human animals have shown a measurable decrease in their production of aging markers, as well as an increase in the lifespan. Studies on diabetic patients have also demonstrated a significant reduction in all-cause mortality in that particular group. However, there is a lack of data and a need for more research that would investigate metformin’s potential as a universal anti-senescence agent more directly. Two large-scale studies (MILES and TAME) in the area are currently underway.

Moral Future-Thinking: Does the Moral Circle Stand the Test of Time?

Humanity's long-term welfare may lie in the hands of those who are presently living, raising the question of whether people today hold the generations of tomorrow in their moral circles. Five studies (NTotal = 1652; Prolific) reveal present-oriented bias in the moral standing of future generations, with greater perceived moral obligation, moral concern, and prosocial intentions for proximal relative to distal future targets. Yet, present-oriented bias appears stronger for socially close compared with socially distant targets and for human targets relative to non-human animals and entities in nature. Individual differences, including longtermism beliefs and subjective imaginative vividness, predict greater concern for and obligation to the future. Likewise, concern and obligation predict greater future-oriented generosity. Our studies are among the first to explore moral considerations for targets across deep temporal expanses, reconcile conflicting evidence in the extant literature on moral judgment and future-thinking, and offer practical implications for bettering the shared societal future.

Zoographics in the Journal of the Experimental Analysis of Behavior: Increasing inclusion of female animals.

We examined the zoographics, or the characteristics of nonhuman animal subjects, reported for the entirety of the Journal of the Experimental Analysis of Behavior (JEAB) through the most recent complete year (1958-2023). Animal sex in particular was evaluated to determine whether the lack of inclusion of female subjects in other disciplines extends to JEAB. Through systematic coding of all nonhuman empirical articles, we found consistent underreporting of most zoographics and a disproportionate use of male subjects relative to female subjects. Additionally, animal sex was commonly unreported and the inclusion of both male and female subjects was sparse. Recent years show some improvement, but greater inclusion is required. Lack of female subjects in research as well as underreporting of zoographics can generate unrepresentative results and hamper replication, generalization, and translation. We provide resources to guide future research and reporting suggestions such as equal inclusion and disaggregation of data by sex. We also clarify misunderstandings about the use of both sexes in research such as beliefs that it necessarily increases the cost of research.

A multi-trait embodied framework for the evolution of brains and cognition across animal phyla.

Among non-human animals, crows, octopuses and honeybees are well-known for their complex brains and cognitive abilities. Widening the lens from the idiosyncratic abilities of exemplars like these to those of animals across the phylogenetic spectrum begins to reveal the ancient evolutionary process by which complex brains and cognition first arose in different lineages. The distribution of 35 phenotypic traits in 17 metazoan lineages reveals that brain and cognitive complexity in only three lineages (vertebrates, cephalopod mollusks, and euarthropods) can be attributed to the pivotal role played by body, sensory, brain and motor traits in active visual sensing and visuomotor skills. Together, these pivotal traits enabled animals to transition from largely reactive to more proactive behaviors, and from slow and two-dimensional motion to more rapid and complex three-dimensional motion. Among pivotal traits, high-resolution eyes and laminated visual regions of the brain stand out because they increased the processing demands on and the computational power of the brain by several orders of magnitude. The independent acquisition of pivotal traits in cognitively complex (CC) lineages can be explained as the completion of several multi-trait transitions over the course of evolutionary history, each resulting in an increasing level of complexity that arises from a distinct combination of traits. Whereas combined pivotal traits represent the highest level of complexity in CC lineages, combined traits at lower levels characterize many non-CC lineages, suggesting that certain body, sensory and brain traits may have been linked (the trait-linkage hypothesis) during the evolution of both CC and non-CC lineages.

Not so social in old age: demography as one driver of decreasing sociality.

Humans become more selective with whom they spend their time, and as a result, the social networks of older humans are smaller than those of younger ones. In non-human animals, processes such as competition and opportunity can result in patterns of declining sociality with age. While there is support for declining sociality with age in mammals, evidence from wild bird populations is lacking. Here, we test whether sociality declines with age in a wild, insular bird population, where we know the exact ages of individuals. Using 6 years of sociality data, we find that as birds aged, their degree and betweenness decreased. The number of same-age birds still alive also decreased with age. Our results suggest that a longitudinal change in sociality with age may be, in part, an emergent effect of natural changes in demography. This highlights the need to investigate the changing costs and benefits of sociality across a lifetime.This article is part of the discussion meeting issue 'Understanding age and society using natural populations'.

Understanding age and society using natural populations.

Ageing affects almost all aspects of life and therefore is an important process across societies, human and non-human animal alike. This article introduces new research exploring the complex interplay between individual-level ageing and demography, and the consequences this interplay holds for the structure and functioning of societies across various natural populations. We discuss how this Special Issue provides a foundation for integrating perspectives from evolutionary biology, behavioural ecology and demography to provide new insights into how ageing shapes individuals' social behaviour and social associations, and how this in turn impacts social networks, social processes (such as disease or information transfer) and fitness. Through examining these topics across taxa, from invertebrates to birds and mammals, we outline how contemporary studies are using natural populations to advance our understanding of the relationship between age and society in innovative ways. We highlight key emerging research themes from this Special Issue, such as how sociality affects lifespan and health, the genetic and ecological underpinnings of social ageing and the adaptive strategies employed by different species. We conclude that this Special Issue underscores the importance of studying social ageing using diverse systems and interdisciplinary approaches for advancing evolutionary and ecological insights into both ageing and sociality more generally.This article is part of the discussion meeting issue 'Understanding age and society using natural populations '.

From men's violence to an ethic of care: Ecofeminist contributions to green criminology

Green criminology has made important contributions to criminological inquiry by highlighting the destructive impact of humans on the more-than-human world. However, it often adopts a gender-neutral lens that overlooks the disproportionate role of men and masculinities in perpetrating green harms. This paper places green criminology into critical dialogue with ecofeminism, arguing that harms against the environment and nonhuman animals are inextricably gendered and should be understood as interconnected forms of men's violence. Ecofeminist insights reveal that violence against the more-than-human world is rooted in hierarchical dualisms, whereby humans are placed separate from and above nature, and the masculine is defined as superior to the feminine. This hierarchical logic enables men to view others in detached, instrumental ways and serves to legitimise acts of men's violence. But just as ecofeminism provides green criminologists with a productive framework for understanding men's violence against the environment and nonhuman animals, it also provides a means of moving beyond this violence. It does this by advocating for an ethic of care that unravels hierarchical modes of thinking and promotes more harmonious relationships between humans and the more-than-human world. By building caring, egalitarian relationships with other living beings (and with their own emotional selves), it is harder for men to act in violent, dominating ways towards others, providing the foundation for more sustainable, interdependent ways of being.