Robert M. Seyfarth's research while affiliated with University of Pennsylvania and other places
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Publications (215)
Is it possible to slow the rate of ageing, or do biological constraints limit its plasticity? We test the ‘invariant rate of ageing’ hypothesis, which posits that the rate of ageing is relatively fixed within species, with a collection of 39 human and nonhuman primate datasets across seven genera. We first recapitulate, in nonhuman primates, the hi...
Is it possible to slow the rate of aging, or do biological constraints limit its plasticity? We test this ‘invariant rate of aging’ hypothesis with an unprecedented collection of 39 human and nonhuman primate datasets across seven genera. We first recapitulate, in nonhuman primates, the highly regular relationship between life expectancy and lifesp...
Dorothy L. Cheney studied the social behaviour, communication, and cognition of monkeys. Her goal was to uncover the selective forces that have shaped the evolution of the human mind.
Baboons, members of the genus Papio, comprise six closely related species distributed throughout sub-Saharan Africa and southwest Arabia. The species exhibit more ecological flexibility and a wider range of social systems than many other primates. This article summarizes our current knowledge of the natural history of baboons and highlights directi...
Baboons, members of the genus Papio, comprise six closely related species distributed throughout sub-Saharan Africa and southwest Arabia. The species exhibit more ecological flexibility and a wider range of social systems than many other primates. This article summarizes our current knowledge of the natural history of baboons and highlights directi...
The production of vocalizations by monkeys and apes is often described as highly constrained and fundamentally different from human speech. We review recent field studies of baboons and bonobos that suggest greater flexibility. Calls function to reduce the uncertainty inherent in social interactions. Vocal production, like individuals’ responses to...
There is growing evidence that social bonds have adaptive consequences for individuals in many mammalian species, including savannah baboons. While the majority of studies have shown that the strength of social bonds and the extent of social integration enhance female fitness, several other investigations have suggested that the number of social bo...
Significance
When compared with humans, nonhuman primates have small vocal repertoires that show little acoustic modification during development. These limitations pose a dilemma for those interested in the evolution of language. Recent research, however, suggests that monkeys and apes show an extensive ability to modify their use of calls in diffe...
It is often assumed that measures of temperament within individuals are more correlated to one another than to measures of problem solving. However, the exact relationship between temperament and problem-solving tasks remains unclear because large-scale studies have typically focused on each independently. To explore this relationship, we tested 11...
Significance
A successful guide dog must navigate a complex world, avoid distractions, and respond adaptively to unpredictable events. What leads to success? We followed 98 puppies from birth to adulthood. Puppies were enrolled in a training program where only ∼70% achieved success as guide dogs. More intense mothering early in life was associated...
Many primates use objects in courtship and dominance displays, but little is known about such displays in other contexts. Bonobos (Pan paniscus) frequently perform “branch drag” displays in which an individual runs along the ground while holding a branch in one hand. We aim to understand how bonobos use branch drags in the context of group travel....
Many primates produce vocalizations when initiating travel. These “travel calls” are often acoustically similar to vocalizations unrelated to travel, and listeners appear to rely on a shared context with callers to correctly interpret the calls. When individuals use vocalizations to coordinate movement with out-of-sight group mates, however, such p...
In both humans and non-humans, differences in maternal style during the first few weeks of life can be reliably characterized, and these differences affect offspring's temperament and cognition in later life. Drawing on the breeding population of dogs at The Seeing Eye, a guide dog school in Morristown, New Jersey, we conducted videotaped focal fol...
The vocal repertoire of nonhuman primates is largely fixed. Individuals produce their species-specific vocalizations from a young age, and do not acquire new call types over their lifetime. Despite these limitations, however, monkeys and apes are able to increase their vocal flexibility in several ways, including subtle acoustic modification, call...
Although vocal production in non-human primates is highly constrained, individuals appear to have some control over whether to call or remain silent. We investigated how contextual factors affect the production of grunts given by wild female chacma baboons, Papio ursinus, during social interactions. Females grunted as they approached other adult fe...
Despite their differences, human language and the vocal communication of nonhuman primates share many features. Both constitute forms of coordinated activity, rely on many shared neural mechanisms, and involve discrete, combinatorial cognition that includes rich pragmatic inference. These common features suggest that during evolution the ancestors...
In many social mammals, females who form close, differentiated bonds with others experience greater offspring survival and longevity. We still know little, however, about how females' relationships are structured within the social group, or whether connections beyond the level of the dyad have any adaptive value. Here, we apply social network analy...
Over 40 years ago, Peter Marler proposed that animal signals were adaptive because they provided listeners with information (Marler, 1961, Journal of Theoretical Biology, 1, 295–317). But what was the nature of this information? How did it influence behaviour? And how might the information in animal signals compare with the information in human lan...
Studies of the factors affecting reproductive success in group-living monkeys have traditionally focused on competitive traits, like the acquisition of high dominance rank. Recent research, however, indicates that the ability to form cooperative social bonds has an equally strong effect on fitness. Two implications follow. First, strong social bond...
In multi-male, multi-female groups of mammals, males usually compete aggressively over access to females. However, species vary in the intensity of male contest competition, which has been linked to differences in testosterone and glucocorticoid profiles. Chacma (Papio ursinus) and Guinea (P. papio) baboons constitute an intriguing model to examine...
The alarm calls of vervet monkeys (Chlorocebus pygerythrus) constitute the classic textbook example of semantic communication in nonhuman animals, as vervet monkeys give acoustically distinct calls to different predators and these calls elicit appropriate responses in conspecifics. They also give similar sounding calls in aggressive contexts, howev...
Calls that catalyse group defence, as in the mobbing of predators, appear to facilitate cooperation by recruiting receivers to act collectively. However, even when such signals reliably precede cooperative behaviour, the extent to which the calls function as recruitment signals is unclear. Calls might simply arouse listeners' attention, setting off...
The social intelligence hypothesis argues that competition and cooperation among individuals have shaped the evolution of cognition in animals. What do we mean by social cognition? Here we suggest that the building blocks of social cognition are a suite of skills, ordered roughly according to the cognitive demands they place upon individuals. These...
Sexual selection theory predicts that males in polygynous species of mammals will invest more reproductive effort in mate competition than parental investment. A corollary to this prediction is that males will mount a stress response when their access to mates is threatened. Indeed, numerous studies have shown that males exhibit elevated stress hor...
Despite their differences, human language and the vocal communication of nonhuman primates share many features. Both constitute a form of joint action, rely on similar neural mechanisms, and involve discrete, combinatorial cognition. These shared features suggest that during evolution the ancestors of modern primates faced similar social problems a...
A chimpanzee interrupts Peter Marler's recording of vocalizations at the Gombe Stream Reserve in Tanzania. Courtesy of the Marler family and reproduced with permission.Primatology lost one of its founding scientists on July 5, 2014, when Peter Marler died at the age of 86. Marler received his first Ph.D. in botany from University College London in...
Previous analyses indicate that female baboons that form strong and stable social bonds reproduce more successfully than others, and that some elements of females' personalities are associated with the tendency to form close social bonds. Here we use a new method to confirm that females' personalities were stable over time, although not fixed, and...
Among male chacma baboons (Papio hamadryas ursinus), rank positions in the dominance hierarchy are fiercely contested. Physical fighting is costly but relatively rare in this species. Instead, disputes are frequently resolved using displays that include loud, repetitive “wahoo” (two-syllable bark) vocalizations. We previously found that males of al...
Behavioral ecologists have devoted considerable effort to identifying the sources of variation in individual reproductive success. Much of this work has focused on the characteristics of individuals, such as their sex and rank. However, many animals live in stable social groups and the fitness of individuals depends at least in part on the outcome...
To understand the evolution of a Theory of Mind, we need to understand the selective factors that might have jumpstarted its initial evolution. We argue that a subconscious, reflexive appreciation of others' intentions, emotions, and perspectives is at the roots of even the most complex forms of Theory of Mind and that these abilities may have evol...
Studies of personality in nonhuman primates have usually relied on assessments by humans and seldom considered the function of the resulting "trait" classifications. In contrast, we applied exploratory principal component analysis to seven behaviors among 45 wild female baboons over 7 y to determine whether the personality dimensions that emerged w...
During the past 20 years, research on cognition in primates and other animals has shifted from the laboratory to the field—from studies of animals' knowledge of objects to research on what they know about each other. Primates and many other animals live in rich, complex societies where animals form highly differentiated relationships and selection...
Because female reproductive success in social mammals is determined largely by parental rather than mating effort, intrasexual competition among females has typically been assumed to occur primarily over food. Recently, however, renewed attention has been paid to the importance of other sources of variation in female fitness, with a concomitant foc...
In a wide range of taxa, including baboons, close social bonds seem to help animals cope with stress and enhance long-term reproductive success and longevity. Current evidence suggests that female baboons may benefit from establishing and maintaining highly individuated relationships with a relatively small number of partners. Here, we extend previ...
After a wild chimpanzee encounters a model of a dangerous snake, whether or not he gives an alarm call depends on his perception of another individual's knowledge.
It has long been hypothesized that the demands of establishing and maintaining social relationships in complex societies place strong selective pressures on cognition and intelligence. What has been less clear until recently is whether these relationships, and the skills they require, confer any reproductive benefits, and whether such benefits vary...
Our book examines the mechanisms that underlie social behavior and communication in East African vervet monkeys. Our goal is to describe the sophistication of primate intelligence and to probe its limits. We suggest that vervets and other primates make good primatologists. They observe social interactions, recognize the relations that exist among o...
This chapter reviews what has been learned about animal thinking from the study of animal communication, and considers what we might hope to learn in the future. It begins with a discussion on the importance of informational versus non-informational interpretations of animal communication and then considers what inferences can be drawn about the co...
Convergent evidence from many species reveals the evolutionary origins of human friendship. In horses, elephants, hyenas, dolphins, monkeys, and chimpanzees, some individuals form friendships that last for years. Bonds occur among females, among males, or between males and females. Genetic relatedness affects friendships. In species where males dis...
Analyses of the pattern of associations, social interactions, coalitions, and aggression among chacma baboons (Papio hamadryas ursinus) in the Okavango Delta of Botswana over a 16-year period indicate that adult females form close, equitable, supportive, and enduring social relationships. They show strong and stable preferences for close kin, parti...
A growing body of evidence suggests that a wide range of animals can recognize and respond appropriately to calls produced by other species. Social learning has been implicated as a possible mechanism by which heterospecific call recognition might develop. To examine whether familiarity and/or shared vulnerability with the calling species might inf...
Among monkeys and apes, both the recognition and classification of individuals and the recognition and classification of vocalizations constitute discrete combinatorial systems. One system maps onto the other, suggesting that during human evolution kinship classifications and language shared a common cognitive precursor.
Longevity is a major component of variation in fitness in long-lived iteroparous species [1-4]. Among female baboons, variation in breeding lifespan accounts for approximately 50% of the variation in lifetime fitness [5, 6]. However, we know little about the causes of variation in longevity in primates or other long-lived mammals. Savannah baboons...
The concept of information plays a central role in studies of animal communication. Animals’ responses to the calls of different individuals, to food calls, alarm calls, and to signals that predict behaviour, all suggest that recipients acquire information from signals and that this information affects their response. Some scientists, however, want...
The apparent rarity of contingent cooperation in animals has convinced many investigators that such reciprocity is unimportant, stimulating consideration of alternative explanations for cooperation, such as by-product mutualism and biological markets motivated by the likelihood of immediate reward. Nevertheless, there is also limited evidence that...
In chacma baboons (Papio hamadryas ursinus), adult males and lactating females form preferential associations, or ‘friendships’, that provide protection against potentially infanticidal attacks. Little is known about the mechanisms by which males and females form friendships, or the function of friendships for males. We examined the relationship be...
Adult vervet monkeys effectively classify animals in the world around them by giving alarm calls to some species but not to others, and by giving acoustically different alarms to leopards, martial eagles, pythons, and baboons. When compared to adults, infant vervet monkeys give alarm calls to a significantly wider variety of species. Even for infan...
Here, we review some questions in the production and perception of nonhuman primate vocalizations, focusing on three related issues. First, flexible vocal production separates humans not only from nonhuman primates but also from most other mammals and birds. The rarity of learned, modifiable call production in most mammals suggests that important c...
As Darwin noted, competition for limited resources is ubiquitous in animals. Competition in group-living species, however, creates a dilemma: how do individuals simultaneously compete with one another and remain in the same social group? Communication alleviates the effects of aggression in two ways. Competitive encounters typically take the form o...
This chapter reviews current understanding of vocal communication in primates. It argues that primate communication calls convey information about both the caller's affective state, and objects and events in the world. This mixed referential signaling mechanism appears to be fundamentally social in nature and thus crucial for the representation of...
We review the social and environmental influences of stress and its alleviation in female primates, focusing on wild female baboons in the Okavango Delta of Botswana. Female primates exhibit elevated glucocorticoids (GCs) primarily in response to those events that directly affect their own survival and reproduction, including in particular predatio...
Underground storage organs (USOs) have been proposed as critical fallback foods for early hominins in savanna, but there has been little discussion as to which habitats would have been important sources of USOs. USOs consumed by hominins could have included both underwater and underground storage organs, i.e., from both aquatic and terrestrial habi...
In this review, we place equal emphasis on production, usage, and comprehension because these components of communication may exhibit different developmental trajectories and be affected by different neural mechanisms. In the animal kingdom generally, learned, flexible vocal production is rare, appearing in only a few orders of birds and few specie...
Males in sexually dimorphic species like baboons appear to have surprisingly little influence on the reproduction and dominance
ranks of their female kin, even though they could potentially increase their fitness by helping their relatives improve their
ranks. Male baboons are able to dominate females several years before they emigrate, but their p...
Despite significant advances in our knowledge of how testosterone mediates life-history trade-offs, this research has primarily focused on seasonal taxa. We know comparatively little about the relationship between testosterone and life-history stages for non-seasonally breeding species. Here we examine testosterone profiles across the life span of...
Adult male chacma baboons (Papio hamadryas ursinus) form preferential associations, or friendships, with particular lactating females. Males exhibit high levels of affiliative contact with their friends' infants and defend them from potentially infanticidal attacks (Palombit et al. 1997). Little is known about males' associations with juveniles onc...
Sociality has evolved in many animal taxa, but primates are unusual because they establish highly differentiated bonds with other group members. Such bonds are particularly pronounced among females in species like baboons, with female philopatry and male dispersal. These relationships seem to confer a number of short-term benefits on females, and s...
Imagine that you're working in your office and you hear two voices outside in the hallway. Both are familiar. You immediately picture the individuals involved. You walk out to join them and there they are, looking exactly as you'd imagined. Effortlessly and unconsciously you have just performed two actions of great interest to cognitive scientists:...
A widely accepted view holds that human infants' knowledge of the world develops not from a single, general-purpose ability
to reason about objects and events but instead from several “core” systems of knowledge, each specialized for representing
and reasoning about entities of different kinds. One functionally specialized system concerns knowledge...
We examine the relationship between glucocorticoid (GC) levels and grooming behavior in wild female baboons during a period of instability in the alpha male rank position. All females' GC levels rose significantly at the onset of the unstable period, though levels in females who were at lower risk of infanticide began to decrease sooner in the foll...
We examined the social correlates of fecal glucocorticoid (GC) levels in wild female baboons during a period of social and demographic stability. Females' GC levels were not affected by individual attributes such as number of kin or dominance rank, nor could we detect any significant seasonal effects. Instead, GC levels were influenced by behaviora...
Primate vocal communication is very different from human language. Differences are most pronounced in call production. Differences
in production have been overemphasized, however, and distracted attention from the information that primates acquire when
they hear vocalizations. In perception and cognition, continuities with language are more apparen...
In 1838 Charles Darwin jotted in a notebook, âHe who understands baboon would do more towards metaphysics than Locke.â Baboon Metaphysics is Dorothy L. Cheney and Robert M. Seyfarthâs fascinating response to Darwinâs challenge. Cheney and Seyfarth set up camp in Botswanaâs Okavango Delta, where they could intimately observe baboons and th...
Many animals appear to monitor changes in other individuals' dominance ranks and social relationships and to track changes in them. However, it is not known whether they also track changes in very transient relationships. Rapid recognition of a temporary separation between a dominant male and a sexually receptive female, for example, should be adap...
It has been hypothesized that group-living mammals engage in reconciliation (post-conflict affiliation between former opponents) to reduce the disruptive costs of aggression and restore opponents' tolerance to baseline levels. Recipients of aggression are sometimes reluctant to tolerate the proximity of a recent opponent, however, in apparent fear...
Theory predicts that females in species with matrilineal dominance hierarchies should use nepotistic support systems to maintain
their family’s rank. Female Old World monkeys, however, form alliances against other females at surprisingly low rates. Nonetheless,
in many species, females utter threat vocalizations when observing others’ disputes, sug...
Changes in vocalizations during ontogeny can in principle be related to three factors: growth, maturation, and experience,
i.e., learning. While learning is a prerequisite for the proper development of speech, it hardly appears to play a role in
the development of the species-typical vocal behavior of nonhuman primates. Nonetheless, subjects of dif...
Female baboons (Papio hamadryas spp.) must contend with myriad potential stressors on a daily basis. In a previous study on female chacma baboons, Papio hamadryas ursinus, living in the Okavango Delta of Botswana, increases in glucocorticoid (GC) concentrations were associated with female reproductive stage, male immigration and the threat of infan...
In humans, bereavement is associated with an increase in glucocorticoid (GC) levels, though this increase can be mitigated by social support. We examined faecal GC levels and grooming behaviour of free-ranging female baboons to determine whether similar effects were also evident in a non-human species. Females who lost a close relative experienced...
We describe a playback experiment designed to test whether free-ranging baboons, Papio hamadryas ursinus, recognize when a call is directed at themselves rather than at other individuals. Female subjects were played the threat-grunt of a more dominant female under one of two conditions: after they had been threatened by that female and after they h...
Predation, food competition, and infanticide all negatively impact female reproductive success. Female dominance rank may mitigate these effects, if competitive exclusion allows high-ranking females to gain priority of access to critical food resources. It may also exacerbate them, if low-ranking females are forced to feed or rest in marginal habit...
Predation, food competition, and infanticide all negatively impact female reproductive success. Female dominance rank may
mitigate these effects, if competitive exclusion allows high-ranking females to gain priority of access to critical food resources.
It may also exacerbate them, if low-ranking females are forced to feed or rest in marginal habit...
In male baboons, social instability is known to increase concentrations of glucocorticoids (GCs), a class of steroid hormones associated with the vertebrate stress response. The stress response may be particularly marked among male chacma baboons, whose social groups often demonstrate a strong mating skew and high rates of infanticide. Here we test...
Are the cognitive mechanisms underlying language unique, or can similar mechanisms be found in other domains? Recent field experiments demonstrate that baboons' knowledge of their companions' social relationships is based on discrete-valued traits (identity, rank, kinship) that are combined to create a representation of social relations that is hie...
In chacma baboons, Papio hamadryas ursinus, young adult males often rise to the top of the dominance hierarchy shortly after immigrating to a new group. Such events are potentially disruptive for pregnant and lactating females because high-ranking immigrant males often commit infanticide. In this preliminary study, we assessed the effects of upheav...
To conclude that language evolved from vocalizations, through gestures, then back to vocalizations again, one must first reject the simpler hypothesis that language evolved from prelinguistic vocalizations. There is no reason to do so. Many studies – not cited by Arbib – document continuities in behavior, perception, cognition, and neurophysiology...