Nonhuman Research Articles

Introducing a Novel Initiative for Mitigating the Impacts of Road Mortality on Turtles in Brampton, Ontario Using 3D Printed Models: A One Health Perspective

With 7 out of 8 turtle species in Ontario classified as at-risk, vehicular-reptile collisions on roads pose a serious threat to turtle populations provincially. These species, however, play crucial roles in maintaining the health of humans, non-human animals, and the environment. By providing ecosystem services like nutrient cycling, population control, and pollination, turtles are essential in semi-aquatic ecosystems like wetlands. However, the need for road infrastructure to support human populations, failures in exclusion fencing and eco-passages, and the varied perspectives of numerous stakeholders make this issue particularly difficult to solve. Despite these challenges, a novel initiative taking place at Heart Lake Conservation Area in Brampton, Ontario may provide an alternative solution. Using 3D printed models, Toronto and Region Conservation Authority (TRCA), in partnership with the Brampton Library and Heart Lake Turtle Troopers, is attempting to reduce mortality along roads by leveraging knowledge about the nesting preferences of female turtles. From a One Health perspective, this novel initiative engages multiple stakeholders to create an interdisciplinary solution combining technology, art, and science to protect turtle populations in the region.

Prospective control by reinforcers in human choice: Misallocation and bias, but not time orientation, influences reinforcer control

Research with nonhuman animals and children suggests reinforcer control is prospective; that is, behaviour is organised according to the likely future, as extrapolated from past experience. The present experiment extended this work to adult choice, and also explored the effects of individual differences in past, present, and future time-orientation on reinforcer control. Participants (N = 163) responded in a concurrent schedule in which the probability of a reinforcer at the same location as the previous reinforcer varied across conditions. Choice tracked these probabilities, albeit imperfectly, indicating that reinforcers controlled behaviour prospectively. Deviations in choice from reinforcer probabilities were well-captured by a quantitative model assuming that such deviations arise because reinforcers are misallocated to the wrong alternative and because of biases towards one alternative. This replicates previous findings in pigeons and children, hence demonstrating the cross-species generality and developmental continuity of prospective reinforcer control. Individual differences in time orientation appeared not to influence reinforcer control, although further work is needed to explore the conditions under which time orientation modulates prospective reinforcer control.

Porphyry on the Value of Nonhuman Animals

Porphyry on the Value of Nonhuman Animals

Models of animal coalitions and their implications for human evolution.

Social interaction is a prime driver for the evolution of animal behaviour. Dyadic interaction, in particular, has been the focus of intensive research on the evolution of mutualistic, altruistic, selfish or spiteful behaviours. Meanwhile, triadic interaction has been the minimal framework for the study of animal coalition as observed in some species of primates, as well as in carnivores and cetaceans, where two or more individuals act jointly against a third party in a competitive context. Previous mathematical models of animal coalition have either failed to explain the observed diversity in the configuration of coalition or presumed fine-tuned decision-making that may be unrealistic for non-human animals. To approach these issues, the present study develops a new model that is fairly simple, but still able to account for the observed diversity in animal coalitions. Analysis of the model specifies key parameters affecting the predicted types of coalition: the nature of the benefit being contested, the cost-to-benefit ratio associated with fighting and the synergistic effect in coalition formation. Additionally, the model is used to evaluate the social selection hypothesis, which claims that coalition formation induced social selection favouring reduced aggression and lower fighting abilities during human evolution.

Sentience and the Issue of Animal Welfare

Abstract In this article, I discuss a precondition of moral consideration that sets the bar lower at sentience. The popular sentience thesis identifies the capacity to feel pain as its condition of consideration. By appealing to the capacity to feel, it is possible to address some fundamental questions about anthropocentrism such as a threat to sentient animals in factory farming and unnecessary experimentation on nonhuman animals. This article interrogates the issue of animal welfare and exposes how discussions on moral considerations focusing on animal sentience exclude non-sentience animals from public welfare policy. While the sentience thesis is a well-established approach in the animal welfare literature, I argue that it lacks robust normative force and, as such, is inadequate for promoting animal welfare since it forces fragmentation of our moral life.

Vocal functional flexibility in a nonprimate vocal learning species

Abstract Can nonhuman animals use the same acoustic signal to transmit different illocutions on different occasions? This communicative capacity is known as vocal functional flexibility and occurs, for example, in speech, when a sentence serves different illocutionary forces or functions on different occasions based on changes to visual and intonational cues. Although common in human speech, there is a lack of clear evidence for this ability in other species. Here, we examined a likely candidate, the Brown-headed Cowbird (Molothrus ater), which is a vocal-learning songbird species that develops a repertoire of structurally distinct song types. Most of this species’ songs are directed towards conspecific males and females less than a meter away, making it unusually easy to determine the apparent target of songs, unlike the broadcast songs done by most songbirds. Songs directed to other males have clear aggressive/threatening intent, while those to females involve courtship/sexual intent. Extensive prior work shows that male cowbirds perform the visual display that accompanies singing differently in these two social settings and also modulate the intonation of song types differently. Because of these display and tonal modulations, constancy of song type usage across male- vs female-directed singing would provide evidence of vocal functional flexibility. Herein, we examined 4,828 songs in three captive flocks containing twenty-four males and thirty females during the breeding season. Males did not use their song types randomly and had strongly favored songs and less commonly used ones. Importantly, favored song types and less commonly used ones were the same whether directing courtship song to a female, aggressive song to another male or singing nonsocially with no receiver nearby. Results were consistent within and across the three flocks, providing strong evidence of vocal functional flexibility. These findings indicate that some species may evolve the ability to modulate and exaggerate visual display components and prosody more than vocal presentation per se because a learned phonological system in this and possibly other species is constrained by its vital role as an indicator trait.

Third-party punishment-like behavior in a rat model

Third-party punishment (TPP) is an altruistic behavior or sense willing to punish transgressors as a third party not directly involved in the transgression. TPP is observed worldwide, regardless of tradition and culture, and is essential for morality in human society. Moreover, even preverbal infants display TPP-like judgement, suggesting that TPP is evolutionarily conserved and innate. Thus, it is possible that non-human animals display TPP-like behavior, although TPP has been said to be human-specific. We investigated whether or not male mature Wistar rats displayed TPP-like behaviors when they witnessed deadly aggression by an unknown aggressive mouse toward another unknown victim mouse. Normally reared rats did not display TPP-like behaviors, but rats reared with extensive affectionate handling by human caretakers as beloved pets contacted the unknown aggressive mice in a gentle manner leading to reduced aggression toward the unknown victim mice, even when the aggressive mice fought back. Furthermore, the handled rats touched unknown rat pups that were drowning in water and anesthesia-induced comatose rats more frequently than control rats. These findings suggest a possibility that TPP is not in fact human-specific and innate but rather an acquired behavior that flourishes in affectionate circumstances.

Simulated animal and simulated umwelt: Towards a method of analysing and critiquing nonhuman animals in consumer settings

Simulated animal and simulated umwelt: Towards a method of analysing and critiquing nonhuman animals in consumer settings

Nuancing 'Emotional' Social Play: Does Play Behaviour Always Underlie a Positive Emotional State?

This review focuses on social play, a complex behaviour that is often difficult to categorize. Although play has been typically associated with positive emotional states, a thorough examination of the literature indicates that it may relate to different emotional systems, from attachment to conflict. Play oscillates between competition and cooperation, and includes a spectrum in between; thus, quantitatively identifying and demonstrating the emotional nature of play remains challenging. We considered examples from human and non-human animal studies and explored the emotional and neuro-hormonal systems involved in play. We assessed ethological data possibly indicating the emotional states underlying play, and we focused on the cooperative and competitive elements of play. We investigated the relationship between play and affiliative/aggressive behaviours, the communicative meaning of play signals (especially primate play faces), and the motor and possibly emotional contagion function of rapid motor mimicry during play. From all the literature on play, this review selects and combines studies in an innovative way to present the methods (e.g., play indices and social network analysis), tools (e.g., sequential analysis and facial coding software), and evidence indicative of the emotional states underlying play, which is much more complex than previously thought.

Episodic Memory and Posttraumatic Stress Disorder in Non-human Animals: A Methodological Proposal

The traditional conception of episodic memory, as a capacity that enables the conscious and personal re-experience of a past event, has led to methodological difficulties in attributing it to non-linguistic beings. The present work proposes to study the attribution of this capacity in non-human animals based on animal models of post-traumatic stress disorder (PTSD). For this purpose, evidence is presented suggesting that flashbacks, a characteristic symptom of PTSD, are a product of the episodic memory system. If that is true, then the ability to remember episodes is required to develop PTSD and having PTSD would be a compelling reason for attributing episodic memories. In this way, the present work opens a new field of research on the problem of episodic memory attribution in animals.

Nonanthropocentric climate ethics

AbstractAnthropogenic climate change poses increasingly severe long‐term threats to living things worldwide. It may even contribute to a mass extinction that would leave biodiversity depleted for millions of years—quite possibly longer than the duration of the human species. Such effects are obviously of ethical concern, but because traditional ethical theories have focused on the relatively short‐term interests of human beings, they offer little guidance. In the late 20th century, a growing number of ethical activists and theorists sought to expand moral consideration to nonhuman animals and to the diverse life forms and habitats of wild nature. Simultaneously and at first independently, others began to develop long‐term (sometimes called “intergenerational”) ethics, which extends moral consideration into the distant future. Concerns about future climate change quickly became a central focus of this work. But only in this century have there been concerted efforts to integrate these lines of thought into far‐sighted nonanthropocentric climate ethics. These efforts are the subject of this review.This article is categorized under: Climate, Nature, and Ethics > Ethics and Climate Change Integrated Assessment of Climate Change > Assessing Climate Change in the Context of Other Issues Climate, Nature, and Ethics > Comparative Environmental Values

Cultured Meat as a Transitional Step Towards Interspecies Justice?

Abstract For some, cultured animal products ought to be celebrated for the potential they offer to replace factory farming. Others argue that, for the same reason, there is a duty to support their production and consumption. This paper argues that the ethical status of cultured animal products ought to be assessed not just in comparison with factory farming, but also in terms of its potential to bring about interspecies justice. The claim is made that the attitudes embodied within cultured animal products show a lack of proper respect for nonhuman animals and are at odds with those required by justice. Although cultured animal products have the potential to greatly reduce harms done to nonhuman animals, this paper argues that their adoption ought to nevertheless be regarded with some regret. Using a Rawlsian framework for assessing transitional steps towards justice, the paper shows that, whilst the adoption of cultured animal products may be permissible, the case for regarding it as a duty is much weaker. For cultured meats to be permissible, it must first be shown that alternatives that respect the value of nonhuman animals as ends-in-themselves do not exist.

The function of episodic memory in animals.

The best-known example of episodic memory in animals came from food-storing birds. One of the beauties of the food-storing system was that inherent in the behaviour were the elements that (at the time) made up episodic memory: what, where and when. While there were then already plenty of data on animals' ability to put together what and where, the addition of the time element in animals' memory and its testing was one that was both new and experimentally challenging. It has, however, led to an increasing variety of examples showing that animals can put together all three informational components. If episodic memories can be described as those memories that make any one of us who we are, why should non-human animals have such memories? Here, we argue that episodic memories play a significant functional role in the lives of real animals, in particular, enabling them to make decisions about how they might or should act in their future. We support our argument with data from a range of examples, focussing on data from the field.This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Mental time travel in animals: the 'when' of mental time travel.

While many aspects of cognition have been shown to be shared between humans and non-human animals, there remains controversy regarding whether the capacity to mentally time travel is a uniquely human one. In this paper, we argue that there are four ways of representing when some event happened: four kinds of temporal representation. Distinguishing these four kinds of temporal representation has five benefits. First, it puts us in a position to determine the particular benefits these distinct temporal representations afford an organism. Second, it provides the conceptual resources to foster a discussion about which of these representations is necessary for an organism to count as having the capacity to mentally time travel. Third, it enables us to distinguish stricter from more liberal views of mental time travel that differ regarding which kind(s) of temporal representation is taken to be necessary for mental time travel. Fourth, it allows us to determine the benefits of taking a stricter or more liberal view of mental time travel. Finally, it ensures that disagreement about whether some species can mentally time travel is not merely the product of unrecognized disagreement about which temporal representation is necessary for mental time travel. We argue for a more liberal view, on the grounds that it allows us to view mental time travel as an evolutionarily continuous phenomenon and to recognize that differences in the ways that organisms mentally time travel might reflect different temporal representations, or combinations thereof, that they employ. Our ultimate aim, however, is to create a conceptual framework for further discussion regarding what sorts of temporal representations are required for mental time travel.This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Measuring episodic memory and mental time travel: crossing the species gap.

Mental time travel is the projection of the mind into the past or future, and relates to experiential aspects of episodic memory, and episodic future thinking. Framing episodic memory and future thinking in this way causes a challenge when studying memory in animals, where demonstration of this mental projection is prevented by the absence of language. However, there is good evidence that non-human animals pass tests of episodic memory that are based on behavioural criteria, meaning a better understanding needs to be had of the relationship between episodic memory and mental time travel. We argue that mental time travel and episodic memory are not synonymous, and that mental time travel is neither a requirement of, nor an irrelevance to, episodic memory. Mental time travel can allow improved behavioural choices based on episodic memory, and work in all species (including humans) should include careful consideration of the behavioural outputs being measured. This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

Of popsicles and crackers: when spatio-temporal memory is not integrated into children's decision-making.

Prior research has used innovative paradigms to show that some non-human animal species demonstrate behavioural choices (i.e. foraging for a food item at a specific location, and at a time that guarantees it has not yet decayed), reflecting episodic-like or 'WWW' memory (memory for 'what' happened, 'where' and 'when'). These results raised the question of whether similar approaches could be used to examine memory in young children in order to reduce verbal demands. The present research examines the extent to which children's WWW memory aligns with memory-based choices in 3- to 5-year-olds (n = 95; study 1) and in 7- to 11-year-olds and adults (n = 168; study 2). Results indicate that preschoolers' struggle with choice-based tasks probably reflects difficulty integrating their WWW memory with an understanding that certain items decay over time. Moreover, a convergence between verbal recall measures and choice-based measures is observable in 7-year-olds and beyond, reflecting a stronger integration of memory signals, understanding of state transformation, and decision-making. This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.

‘Point and Kill’ vs Animal Rights: A Moral Examination

This study critically examines the ethical implications of the practice known as "point and kill," wherein nonhuman animals are selected and immediately killed for food, a practice that has become commonplace in many African cultures. While food is essential for the survival and growth of both human and nonhuman animals, the manner in which nonhuman animals are often treated as mere commodities raises significant ethical concerns. Despite extensive debates in contemporary animal ethics, the focus has predominantly been on issues such as biomedical research, animal confinement, and entertainment, with relatively little attention given to the ethical ramifications of using animals for food, particularly in the context of practices like "point and kill." This paper addresses the gap in the literature by interrogating the moral worth of nonhuman animals and questioning the justification for their wanton killing for human consumption. Employing critical and conceptual analysis, the study draws on the Igbo philosophy of ‘ugwu anu’ (animal integrity) to argue against speciesism and advocate for the moral consideration of nonhuman animals. It contends that nonhuman animals deserve care, respect, and fair treatment, and that the practice of "point and kill" reflects a speciesist attitude that undermines the inherent value of animal life. By bringing this issue to the forefront, the study contributes to the broader discourse on animal ethics and calls for a reevaluation of culturally ingrained practices that perpetuate animal suffering.

What Would Miffy Do? Applying Informed Consent by Proxy to All Sentient Animals.

If we want to take sentient non-human animals and their interests seriously, we can try to ask for their consent before using them for human purposes. With mentally competent humans, we speak of informed consent: for them to participate in scientific studies, for example, it is required that they consent explicitly, in full understanding of the risks and benefits. This full understanding cannot be expected from non-human animals. We must therefore look for ways to know what they want and to estimate what they would do if they had a deep understanding of their options and the consequences of these options for themselves and others. This concept is explored by applying it to animal experiments. The most promising method is to gain informed consent by proxy from thoroughly informed competent humans, in combination with seeking assent where possible and being alert to dissent.

Transitive Inference over Affective Representations in Non-Human Animals

Transitive Inference over Affective Representations in Non-Human Animals

Cleaner fish with mirror self-recognition capacity precisely realize their body size based on their mental image

Animals exhibiting mirror self-recognition (MSR) are considered self-aware; however, studies on their level of self-awareness remain inconclusive. Recent research has indicated the potential for cleaner fish (Labroides dimidiatus) to possess a sophisticated level of private self-awareness. However, as this study revealed only an aspect of private self-awareness, further investigation into other elements is essential to substantiate this hypothesis. Here, we show that cleaner fish, having attained MSR, construct a mental image of their bodies by investigating their ability to recall body size. A size-based hierarchy governs the outcomes of their confrontations. The mirror-naïve fish behaved aggressively when presented with photographs of two unfamiliar conspecifics that were 10% larger and 10% smaller than their body sizes. After passing the MSR test, they refrained from aggression toward the larger photographs but still behaved aggressively toward the smaller ones without re-examining their mirror images. These findings suggest that cleaner fish accurately recognize their body size based on mental images of their bodies formed through MSR. Additionally, mirror-experienced fish frequently revisited the mirror when presented with an intimidating larger photograph, implying the potential use of mirrors for assessing body size. Our study established cleaner fish as the first non-human animal to be demonstrated to possess private self-awareness.