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Rescue behavior: Distinguishing between rescue, cooperation and other forms of altruistic behavior

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  • Université Sorbonne Paris Nord

Abstract

Reports of rescue behavior in non-human animals are exceedingly rare, except in ants where rescue is well known, but has not been explored experimentally until recently. Although we predict that rescue behavior should be limited to circumstances in which the victim and the rescuer are highly related to one another, or in which unrelated individuals must cooperate very closely with one another, we also predict that it is likely to be far more common than the current literature would suggest. To address this oversight, we propose a rigorous definition of rescue behavior, one that helps researchers to focus on its necessary and sufficient components, at the same time that it helps to differentiate rescue behavior from cooperation and other forms of helping behavior. In this way we also hope to expand our understanding of altruism in particular and kin selection in general.
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... Some ant species have developed a unique means of defending themselves (Beponis et al., 2014). If an ant is caught, nestmates may exhibit rescue behavior to save it (Czechowski et al., 2002;Nowbahari et al., 2009;Nowbahari & Hollis, 2010;Miler, 2016). This behavior can be exhibited by one or more workers, known as first responders, and is directed towards another individual (the victim), in order to rescue it from a predator situation (Nowbahari & Hollis, 2010;Miler, 2016). ...
... If an ant is caught, nestmates may exhibit rescue behavior to save it (Czechowski et al., 2002;Nowbahari et al., 2009;Nowbahari & Hollis, 2010;Miler, 2016). This behavior can be exhibited by one or more workers, known as first responders, and is directed towards another individual (the victim), in order to rescue it from a predator situation (Nowbahari & Hollis, 2010;Miler, 2016). Such behavior can involve relatively simple digging around the victim, with pulling of its limbs, to more precise behaviors such as directly attacking and stinging the trapping animal or object (Taylor & Visvader, 2013;Miler, 2016). ...
... Three different help request situations were simulated, in order to evaluate whether workers from a particular colony might respond to a request for help from non-nestmate ants (Nowbahari & Hollis, 2010;Miler, 2016;Uy et al., 2018). ...
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In social insects, situations can arise that threaten an individual or an entire colony. When the call for help goes out, different behavioral responses are elicited by signals emitted from nestmates. In ants, the response can be one of redemptive behavior by the worker receiving it. However, little is known about the evolution of this behavior and in which group of ants it manifests. Therefore, this study investigates whether workers of Odontomachus brunneus Patton can act as rescuers, able to detect and respond to calls for help from nestmates. Laboratory experiments were carried out in which the legs of ants were trapped by tape, simulating capture by a predator. Nearby were nestmates able to receive and respond to a request for help. Two experiments were performed: 1. Calls for help were made at different distances, in order to test the response latency. 2. Evaluation of whether rescuers would respond differently to calls for help from nestmates, non-nestmates of the same species, and ants of another species. Finally, evaluation was made of the behaviors of the rescuers when they responded to requests for help from nestmates and ants of another species. It could be concluded from the results that O. brunneus workers respond to signals emitted by workers who may have been captured by a potential predator, prompting the performance of behaviors related to rescue attempts. The signals involved appear to have an optimal range and are species-specific. When exposed to a capture situation, this species transmits audible signals by stridulation, so it is possible that this type of signal may be involved, in addition to chemical signaling.
... Finally, Hachiga et al. (2020) 12 proved that the stay in the restraint tube was not stressful for the trapped rats but rather rewarding. Therefore, the design of experimental paradigm, measuring physiological or emotional responses to restraint, and the succession of rescuer actions are crucial in disentangling the motivators of rescue behaviour 1,8,[16][17][18] . ...
... Whether driven by empathy or not, some researchers suggest that rescue behaviour might also be present in other taxa 1,19 . However, because of the rare occasions where this phenomenon is documented, only a few studies on a handful of species are available to support this claim (see Table 1). ...
... The absence of further photos from that night proves that the group did not return to the trapping site. Indirect benefits, in terms of kin selection or reciprocal altruism, are possible 1,47 . ...
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Here, we provide unique photo documentation and observational evidence of rescue behaviour described for the first time in wild boar. Rescue behaviour represents an extreme form of prosocial behaviour that has so far only been demonstrated in a few species. It refers to a situation when one individual acts to help another individual that finds itself in a dangerous or stressful situation and it is considered by some authors as a complex form of empathy. We documented a case in which an adult female wild boar manipulated wooden logs securing the door mechanism of a cage trap and released two entrapped young wild boars. The whole rescue was fast and particular behaviours were complex and precisely targeted, suggesting profound prosocial tendencies and exceptional problem-solving capacities in wild boar. The rescue behaviour might have been motivated by empathy because the rescuer female exhibited piloerection, a sign of distress, indicating an empathetic emotional state matching or understanding the victims. We discuss this rescue behaviour in the light of possible underlying motivators, including empathy, learning and social facilitation.
... Other recent examples of risky rescue operations included those described in Matabele ants Megaponera analis saving wounded nest mates after direct confrontation with termites (Frank et al. 2017) and in weaver ants Oecophylla smaragdina and harvester ants Veromessor pergandei trying to save endangered individuals who became stuck on spider webs (Uy et al. 2018;Kwapich and Hö lldobler 2019). Rescue may be considerably more widespread in nature than these reports demonstrate (Nowbahari and Hollis 2010). ...
... Notably, the maximum number of active rescuers did not exceed 3 in the laboratory and 5 in the field, although more than 1 rescuer in any test was rare. One possible explanation for this is related to energy limitations as ants might have evolved ways to prevent the elicitation of potentially costly rescue behaviors simultaneously in many individuals (Nowbahari and Hollis 2010). In many cases, we observed active rescuers to cease their rescue activity during a test to interact with other freely moving workers, possibly exchanging signals and changing behavior of both the rescuer and the other surroundings ants (Mallon and Franks 2000;Pratt et al. 2001;McLeman et al. 2002). ...
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Rescue behaviour is observed when one individual provides help to another individual in danger. Most reports of rescue behaviour concern ants (Formicidae), in which workers rescue each other from various types of entrapment. Many of these entrapment situations can be simulated in the laboratory using an entrapment bioassay, in which ants confront a single endangered nest mate entrapped on a sandy arena by means of an artificial snare. Here, we compared numerous characteristics of rescue actions (contact between individuals, digging around the entrapped individual, pulling at its body parts, transport of the sand covering it and biting the snare entrapping it) in Formica cinerea ants. We performed entrapment tests in the field and in the laboratory, with the latter under varying conditions in terms of the number of ants potentially engaged in rescue actions and the arena substrate (marked or unmarked by ants’ pheromones). Rescue actions were more probable and pronounced in the field than in the laboratory, regardless of the type of test. Moreover, different test types in the laboratory yielded inconsistent results and showed noteworthy variability depending on the tested characteristic of rescue. Our results illustrate the specifics of ant rescue actions elicited in the natural setting, which is especially important considering the scarcity of field data. Furthermore, our results underline the challenges related to the comparison of results from different types of entrapment tests reported in the available literature. Additionally, our study shows how animal behaviour differs in differing experimental setups used to answer the same questions.
... In conceptual terms, Nowbahari and Hollis (2010) defined rescue behavior as the provision of aid to a distressed individual at a cost and without immediate reward to the rescuer. Based on this definition, to our best knowledge, only a single study to date has directly addressed rescue behavior in dogs. ...
... Last, a cognitively more complex explanation of dogs' rescue behavior involves goal-directedness, namely the possibility that dogs opened the door with the intention to aid the person and end his/her stress. Indeed, this explanation is considered by some authors as a definitive feature of rescue behavior (Nowbahari et al. 2010). It would be interesting to tackle this possibility in future studies by, for example, changing the contingency between the dogs' rescue response and its consequence. ...
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Rescue behavior is considered a type of pro-social response, defined as a voluntary action directed to benefit another individual who is in a stressful or dangerous situation. In two experiments, we investigated whether dogs would rescue their owners when the person was trapped inside a wooden box and emitted clear signs of stress. The performance of these dogs was compared against that of a control group in which the owners remained calm while trapped. In addition, to assess if training modulated this behavior, we tested a group of dogs from the military trained in search and rescue tasks (Experiment 1). Results showed that dogs opened the box more frequently when the owner pretended to be stressed than when calm. Training shortened latencies to open the door but not the frequency of the behavior. In Experiment 2, we investigated if emotional contagion could be a possible mechanism underlying dogs' rescue responses by measuring dogs’ behavior, heart rate, and saliva cortisol level in the stressed and calm conditions, and also controlled for obedience by having the calm owners call their pets while trapped. We replicated the findings of Experiment 1 as more dogs opened the door in the stressed owner condition than in the calm condition. In addition, we observed an increase in heart rate across trials in the stressed condition and a decrease across trials in the calm condition, but no differences in cortisol levels or stress-related behaviors between conditions. In brief, we found evidence that approximately half of the dogs without previous training showed spontaneous rescue behaviors directed to their owners. Neither was this behavior motivated by obedience nor by the motivation to re-establish social contact with the owner. We conclude that emotional contagion is a plausible mechanism underlying dogs’ rescue behavior in the present protocol.
... Classical developmental theories emphasized the role of peer interaction in providing children with experiences they need to construct social norms (Kohlberg, 1981;Piaget, 1932). Several recent studies on infancy changed the prediction of a slow developmental course, supporting alternative views that posit a richer initial state Mikhail, 2011) and domainspecific biological adaptation (Baillargeon et al., 2015;Boehm, 2012). ...
... This proves the fact that they have attributed a positive value to protective action and a negative value to ignore action. This data is coherent with recent biological and evolutionary perspectives, in which there is an interplay between altruism and kin selection theory in general (Hamilton, 1964;Lehmann & Keller, 2006;Nowbahari & Hollis, 2010;O'Brie, 2014). ...
Article
This study investigates the interplay between social evaluation and relationship context in the second year of life. We examined how 21-month-olds (N = 50) evaluate a 'protective puppet' over to an 'ignore puppet' in three different types of relationship: in the first one a puppet observes from a distance a child playing alone and eventually falls down (uninvolved); in the second two puppets play together when one accidentally falls down (social); in the third two puppets play together when an aggressor disturbs one of the two players (defence). We assessed with two test trials: (a) toddlers' preferences through a choice phase; (b) social evaluations through a rewarding/punishing phase. The results reveal how social relationship context affects toddlers' personal preferences and evaluations. On the choice task, toddlers preferred a puppet who protected a victim to one who ignored only when the victim was identified as a member of a social interaction and a playmate. On the allocation task, toddlers were more likely to give tasty cookies to the protective and ignore puppet in all cases, except when the receiver was the ignore puppet in the social and defence relationship context. The findings support a developmental continuity and provide further evidence of a rich prosociality, which before the second year of life proves to be based on well-defined principles.
... Rescue behavior is a prosocial response that refers to the actions of one individual to help another who is stressed or in danger to terminate this negative state (Nowbahari and Hollis 2010). Recent studies have investigated whether dogs are able to display such behavior towards their owners when they pretend to be stressed. ...
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Rescue behavior is a kind of prosocial response that involves the provision of help to a stressed individual. This behavior has been observed in domestic dogs assisting their owners when they pretended to be trapped. Given the role of the hormone oxytocin as a facilitator for prosocial behavior, we aimed to evaluate the effects of its intranasal administration on the rescue behavior of dogs directed to their owners. In addition, we used the Monash Dog Owner Relationship Scale (MDORS) to assess whether the dog-owner bond was associated with this behavior. After receiving either oxytocin or saline, dogs participated in a stressed condition in which their owner pretended to be stressed inside of a box, or a control one, in which the owner was in a calm state. Dogs released their owners more frequently in the stressed condition. Contrary to our expectations , dogs who received oxytocin were less likely to open the box and took longer to do so than those that received saline. Regarding the dog-owner bond, dogs in the stressed condition who received oxytocin exhibited a lower rate and a higher latency of openings the more intense the bond was, while the opposite pattern was observed in dogs in the control condition who received saline. In conclusion, dogs would rescue their owners when they pretended to be trapped and stressed. Both oxytocin administration and the bond with the owner appear to modulate this behavior, but further studies are needed to inquire into the involved mechanisms.
... Similarly, Carballo et al. (2020) found that dogs were more likely to open for a stressed owner than a calm one, and that heart rate was increased in the dog when the owner was stressed. Trapped-other paradigms, however, do not require cognitively complex explanation as similar rescue behaviours are even seen in ants, which suggests simpler mechanisms are likely at work (Nowbahari, Scohier, Durand, & Hollis, 2009;Nowbahari & Hollis, 2010;Vasconcelos, Hollis, Nowbahari, & Kacelnik, 2012). ...
Article
Dogs have a reputation for empathy toward their owners, which is also supported by some research (e.g., Carballo et al., 2020; Sanford, Burt, & Meyers-Manor, 2018). Many dog owners anecdotally report that dogs comfort them by making visual and/or physical contact when they cry or help them when they are sick. These behaviours provide a good way to assess the capacity for empathy and its physiological correlates in dogs. This study is a replication and extension of Custance and Mayer (2012). We examined whether using laughing as an alternative stimulus to humming produced similar responses to crying. Dogs were tested in their homes while a stranger and owner pretended to cry, laugh, and while the owner and stranger were talking. During each counterbalanced condition, the dog was observed for person-oriented behaviours and simultaneously had their heart rate variability measured. Like Custance and Mayer, dogs showed more behaviours directed toward the person crying, whether the owner or the stranger, than during baseline or laughing conditions. We did not find an effect of laughing on person-oriented behaviours, suggesting that dogs respond to the crying uniquely and not as a novel stimulus. In the condition when the stranger was crying, dogs that showed higher stress responses, as indicated by lower heart rate variability, were most likely to show person-oriented behaviours toward the stranger. This suggests that dogs that experience more distress, through emotional contagion, are more likely to show person-oriented behaviours toward the distressed stranger, indicating a possible mechanism for empathy-like behaviours. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
... However, cooperative rescues from predatory attacks, like the case we describe here, are rarely observed in wild vertebrates and to our knowledge, have only been reported for primates ( Table 1; see also Ref. 27 ), humpback whales (Megaptera novaeagliae 28 ), banded mongoose (Miunfos mungo 29 ), and possibly dolphins (Delphinidae 30 ). These rescue behaviors are considered a special form of cooperation as they involve one or more individuals putting themselves at risk to aid another, with no guarantee that the outcome will be successful, and no direct gain for the rescuer(s) 31,32 . ...
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The threat of predation by snakes is considered to have played a significant role in the evolution of primate sensory systems and behavior. However, we know relatively little about individual and group responses given the rarity of observed predation events. Here we report an observed (filmed) predation attempt by an adult Boa constrictor (~ 2 m) on a juvenile white-faced capuchin (Cebus imitator) in the Sector Santa Rosa of the Área de Conservación Guanacaste, Costa Rica. The snake caught the juvenile monkey on the ground during a terrestrial play session. When the victim screamed, the alpha male, alpha female, and another adult female ran to the scene, physically attacked the snake (with bites and hits), and pulled the victim to safety. Most group members participated in the vocal mobbing of the snake both during and after the attack. Based on the outcomes of this predation attempt and published reports of other B. constrictor attacks on primates, the coordinated efforts of ≥ 2 group members is needed for a successful rescue. This observation adds to our growing knowledge of cooperative group behavior and its importance in predator defense.
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In a species of Mediterranean desert-dwelling ant, Cataglyphis piliscapa (formerly, C. cursor), some individuals, mostly foragers, engage in highly orchestrated behavior to free a trapped nestmate. Their behavior, which we have labeled rescue, is a heritable trait in this species, and it appears fully formed within a few days of an ant’s emergence as an adult. Not only is the rescue behavior by these ant specialists precisely targeted, but also it involves a complex, dynamic sequence of behavioral patterns. That is, each rescue operation is responsive both to the specific circumstances of the nestmate’s entrapment and to the way in which that particular rescue operation unfolds, relying on the rescuer’s short-term memory of its previous actions to increase efficiency and to decrease energy expenditure. Rescue appears in several other ant species as well, and, although the specific behavioral patterns and contexts vary across species, the outcome—namely, releasing a distressed nestmate—remains the same. Here, we describe research designed to address questions about the function, evolution, cause, and development of rescue behavior in C. piliscapa—a behavior ecological approach—drawing on research in other species, and by other researchers, both to highlight comparative similarities and differences and, importantly, to draw attention to still unanswered questions. In addition, by shedding light on the rescue behavior of ants, we also hope to engender increased attention to, and research on, this extraordinary form of helping behavior in multiple other taxa.
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Altruism is defined as an action that decreases the lifetime direct fitness of an actor and benefits one or more recipients. This phenomenon, which is generally difficult to understand and explain, requires special research attention. The subject of this review, rescue, is a type of altruistic behavior in which the actor puts itself at risk to save another individual, the recipient, that is in danger. The highest numbers of published empirical works have been devoted to rescue behavior in ants and they have enormous potential for further study. We review studies devoted to the subject and group them into four main areas of research on ant rescue actions: (1) variation in rescue behavior activity on a between-individual scale, (2) factors contributing to the evolution of rescue behavior on a between-species scale, (3) rescue behavior releaser signals and (4) rescue behavior benefits and costs. We highlight the progress in research on rescue behavior in ants, indicate that this behavior is probably much more common than previously thought yet thus far demonstrated in only a few species, and uncover research gaps and open questions that remain unexplored. We additionally point out some gaps in knowledge that become evident when research devoted to rescue behavior in rats, the second most studied group of animals in this context, is briefly overviewed. We hope to help navigate among studies on rescue behavior and provide the most up-to-date summary of the relevant literature. Moreover, we hope to encourage and facilitate researchers in behavioral ecology and other subdisciplines to further experimentally analyze rescue behavior, not only in ants but also in other taxa.
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We report the results of field observations and experiments demonstrating that workers of Formica sanguinea Latr. and F. cinerea Mayr caught by a larva of an ant lion (Myrmeleon formicarius L.) can induce rescue behaviour in their nestmates. Typical rescue behaviour involves both the attempts to pull away the attacked ant by tugging at its limbs, and rapid, intense digging behaviour. In natural mixed colonies of F. sanguinea and F. fusca L., enslaved F. fusca workers display rescue behaviour when their heterospecific nestmate is caught by an ant lion larva. On the other hand, we did not observe nestmate rescue behaviour in monospecific F. fusca colonies. These data suggest that workers of F. sanguinea and F. cinerea caught by an ant lion emit some signals which summon their nestmates to arrive at their rescue. Workers of F. fusca either do not emit such signals, or their danger signals fail to elicit rescue behaviour in other ants. Exprcssion of rescue behaviour in the studied ant species is discussed in the context of their life strategies, of their position in the interspecific competitive hierarchy, and of our knowledge about nestmate rescue behaviour, and signals eliciting alarm and digging behaviour in ants.
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A number of instances of apparent solicitude on the part of adult dolphins for their young, either alive or dead, have been reported in the recent literature. These have particularly related to the mother's habit of holding her young at the surface in an apparent effort to aid it in breathing. Instances of such solicitude in captivity have been reported for the Atlantic bottlenose dolphin, Tursiops truncatus , by McBride (Nat. Hist., 45: 29, 1940), McBride and Hebb (Jour. Comp. & Physiol. Psych., 41: 115, 1948), and McBride and Kritz-ler (Jour. Mamm., 32: 254, 1951). Examples of this phenomenon in nature have been given by Moore (Amer. Midi. Nat., 49: 136, 1953) for T. truncatus , and by Hubbs (Jour. Mamm., 34: 498, 1953) for the Pacific bottlenose dolphin, T. gilli . As far as we can discover, there has been only one other instance reported in which an adult made an apparently definite effort to protect another adult that was injured. This behavior was described by Hubbs ( loc. cit. ) where he reports a case in which a striped dolphin, Lagenorhynchus obliquidens , stayed close by a harpooned companion “frequently forcing its way between the dying beast and the ship and pushing it away.” Two related instances, perhaps showing an even higher level of intelligence, have recently been observed during collecting operations for the new Gulfarium, The Living Sea, at Fort Walton Beach, Florida. The first such instance occurred on October 30, 1954, while the …
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Kin-selection theory (Hamilton's "genetical theory") explains how aid that is self-sacrificing (in terms of classical individual fitness), or "altruism," can evolve if sufficiently beneficial to relatives. It is discussed here in order to clarify the meaning of kin selection and inclusive fitness (the total reproductive valve of an individual, both its production of offspring and effects on the reproduction of relatives). Hamilton's condition K > 1/r, the relationship of benefit/cost and relatedness necessary for advantageous altruism, is reformulated so as to be applicable to altruism by descendents, and from the point of view of any member of a population (e.g., affected parties other than the altruist). A General expression is derived which defines inclusive fitness in terms of a classical and a kinship component. A unit of inclusive fitness-"offspring equivalents"-is defined. An index of the liklihood that altruism will occur in different social and ecological situations. K1, is employed to evaluate c...