Frans B. M. de Waal’s research while affiliated with Emory University and other places

Early maternal loss can have lasting detrimental effects on primate social development. While many rehabilitation settings provide enriching environments to buffer against such effects in orphans, previous research indicates that young bonobo (Pan paniscus) orphans exhibit striking deficiencies in socio-emotional competence compared to their mother-reared peers. However, such studies are generally cross-sectional, without accounting for changes across the lifespan. We conducted longitudinal observations in bonobos living in an accredited African ape sanctuary to examine how rearing background, sex and age predict social tendencies including affiliation, consolation and aggression risk. Affiliative tendencies increased in females and decreased in males with age but were overall lower in orphans compared to mother-reared bonobos. Consolation tendencies decreased with age in mother-reared bonobos, while orphans showed consistently lower consolation (akin to levels of older mother-reared individuals). Young and male bonobos were more likely to receive aggression, while mother-reared and older females were more likely aggressors. Our study highlights the potential that ape sanctuaries like this can have by demonstrating that orphans exhibit decreased affiliative tendencies yet show social functioning ranging within patterns of their mother-reared peers. We discuss these results in the context of bonobos’ natural social ecology and ongoing rehabilitation efforts in this species.

Empathy and its subcomponents are well documented throughout the animal kingdom, indicating the deep evolutionary origins of this socioemotional capacity. A key behavioural marker of empathy is consolation, or unsolicited bystander affiliation directed towards distressed others. Consolation has been observed in our closest living relatives, bonobos (Pan paniscus) and chimpanzees (P. troglodytes). However, systematic comparisons are absent, despite potential for interspecific differences. Bonobos are often considered less aggressive, more emotionally sensitive, and more socially tolerant than chimpanzees—key characteristics purported to drive consolation. Furthermore, social and individual factors also appear to drive intraspecific variation in empathy. To address within- and between-species variability in Pan consolation, we systematically tested the consolatory tendencies of large sanctuary-living groups of both species. Bonobos and chimpanzees exhibited similar consolation tendencies; however, within-species analyses revealed further similarities and variation. Bonobo consolation was most often directed towards and received by younger individuals, while chimpanzee consolation was most often directed towards close social partners. In addition, whilst males and females of both species showed decreased consolation with age, young chimpanzee males may console more than young females. These findings suggest that within-species variation in Pan socio-emotional abilities is greater than between-species differences, highlighting the presence of striking behavioural diversity across our two closest cousins.

Cuando se trata de nuestra relación con la naturaleza, no hay forma de escapar de la tensión entre percepción y proyección. A menudo, lo que descubrimos en la naturaleza es lo que antes pusimos en ella. En consecuencia, la forma en que los naturalistas han contribuido a la misión de ‘la humanidad ha de conocerse a sí misma’, sólo puede entenderse en el contexto del cristal con que se mire el espejo de la naturaleza. Dado que no nos es posible quitarnos los cristales de esas gafas, la segunda mejor opción que nos queda es comparar otras alternativas.

Suele suceder que la evolución del comportamiento se considera irrelevante para la comprensión de la moral humana, por el hecho de que carece de carácter normativo (el ‘debe’) y consiste enteramente en descripciones de cómo son las cosas o cómo sucedieron (el ‘es’). No obstante, el comportamiento que es producto de la evolución, incluido el de otros animales, no está completamente desprovisto de normatividad. Si se define la normatividad como la adhesión a un ideal o estándar, existe amplia evidencia de que los animales tratan a sus relaciones sociales de esta manera. En otras palabras, persiguen valores sociales. En este artículo reviso la evidencia sobre el hecho de que los primates no humanos intentan activamente preservar la armonía dentro de su red social, por ejemplo, reconciliándose después de un conflicto, protestando contra las divisiones desiguales y deteniendo peleas. Al hacerlo, corrigen las desviaciones respecto de un estado ideal. Sumado a ello, y con el fin de prevenir tales desviaciones, muestran autocontrol emocional y resolución anticipada de conflictos. El reconocimiento de la orientación hacia una meta y el carácter normativo del comportamiento social animal nos permite cerrar parcialmente la brecha entre el ‘es’ y el ‘debe’ erigida en relación con el comportamiento moral humano.

Empathy is a complex, multi‐dimensional capacity that facilitates the sharing and understanding of others' emotions. As our closest living relatives, bonobos ( Pan paniscus ) and chimpanzees ( P. troglodytes ) provide an opportunity to explore the origins of hominin social cognition, including empathy. Despite certain assumptions that bonobos and chimpanzees may differ empathically, these species appear to overlap considerably in certain socio‐emotional responses related to empathy. However, few studies have systematically tested for species variation in Pan empathic or socio‐emotional tendencies. To address this, we synthesise the growing literature on Pan empathy to inform our understanding of the selection pressures that may underlie the evolution of hominin empathy, and its expression in our last common ancestor. As bonobos and chimpanzees show overlaps in their expression of complex socio‐emotional phenomena such as empathy, we propose that group comparisons may be as or more meaningful than species comparisons when it comes to understanding the evolutionary pressures for such behaviour. Furthermore, key differences, such as how humans and Pan communicate, appear to distinguish how we experience empathy compared to our closest living relatives.

The first characterization of the bonobo reached science even before it had recognized the species. Unbeknownst to him, American primatologist Robert Yerkes (1925) had a bonobo named “Prince Chim,” whom he considered more sensitive, empathetic, and intelligent than any other ape he knew. This impression was confirmed by one of the earliest behavioral studies, which was conducted in the 1930s at a German zoo. Tratz and Heck (1954) published their findings after World War II in a German-language paper that is still very much to the point. They reported on the bonobo’s uniquely high-pitched vocalizations, its variety of sexual habits, its gentle predisposition, and even details such as that they are more prone to kick each other with their feet than are chimpanzees.

This opinion piece aims to tackle the biological, psychological, neural and cultural underpinnings of laughter from a naturalistic and evolutionary perspective. A naturalistic account of laughter requires the revaluation of two dogmas of a longstanding philosophical tradition, that is, the quintessential link between laughter and humour, and the uniquely human nature of this behaviour. In the spirit of Provine's and Panksepp's seminal studies, who firstly argued against the anti-naturalistic dogmas, here we review compelling evidence that (i) laughter is first and foremost a social behaviour aimed at regulating social relationships, easing social tensions and establishing social bonds, and that (ii) homologue and homoplasic behaviours of laughter exist in primates and rodents, who also share with humans the same underpinning neural circuitry. We make a case for the hypothesis that the contagiousness of laughter and its pervasive social infectiousness in everyday social interactions is mediated by a specific mirror mechanism. Finally, we argue that a naturalistic account of laughter should not be intended as an outright rejection of classic theories; rather, in the last part of the piece we argue that our perspective is potentially able to integrate previous viewpoints—including classic philosophical theories—ultimately providing a unified evolutionary explanation of laughter. This article is part of the theme issue ‘Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience’.

One contribution of 17 to a theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology, and neuroscience'.

Laughter affects conversational schemes, supports speech production, establishes social bonds and is connected to playfulness. Despite the pervasiveness of this behaviour, research on laughter has long been underdeveloped, probably because it does not sound like a serious topic. Also, its social and expressive nature represents a major technical difficulty for both laboratory and naturalistic studies. The quest to uncover the processes underlying the production and perception of laughter is still in its early days, but a renewed interest in this behaviour has boosted the emergence of new ecological studies in a set of fields encompassing a broad spectrum of disciplines. This Theme Issue aims to tackle the biological, psychological, neural and cultural underpinnings of laughter in humans and other animals from a naturalistic and evolutionary perspective. A new naturalistic account of laughter has been boosted by the work of the psychologist Robert Provine (1943–2019) and the neuroscientist Jaak Panksepp (1943–2017), to whom this issue is dedicated. According to this view, laughter must be studied considering the behavioural intentions it conveys and the response it elicits in the recipient. Notably, such an approach shifts the focus of attention from the cognitive underpinnings of humour processing to the adaptive socio-emotional nature of laughter, which signals not only reward and amusement but also affiliation and benign intentions. The naturalistic study of human laughter is also supported by the wide acceptance that other species show a homologue of laughter. Playful laugh expressions of the great apes and other primates not only morphologically resemble human laughter but they share important social functions and neural substrates. However, similar play vocalizations have probably evolved multiple times in evolution, as in the case of play vocalizations in rats. This Theme Issue synthesizes existing knowledge on laughter in humans and other animals through the lens of an evolutionary approach. The great variety of contributions proposed in this issue includes new insights from ethology, anthropology, social psychology and cognitive and affective neuroscience, thus providing an overarching perspective of the laughter phenomenon.

Do animals, including invertebrates, have felt emotions and does this morally matter?