Essays
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Cooperative Breeding and Human Evolution - Kramer, Karen L.
The demographic success of humans compared to other closely related species is one of the remarkable stories of our evolutionary history. This can be attributed both to high fertility and improved chances of survival. But it is also fundamentally shaped by features of human parenting, cooperation, and social organization. The concept and theory of cooperative breeding combines these features and is a useful framework to consider child‐rearing patterns characteristic of humans. Cooperative breeding theory was developed in biology to explain a social system found in relatively few animals in which nonparental members of a social group help to support offspring. In traditional human societies, numerous studies document that a variety of kin and nonkin of different ages and sex help mothers and contribute to infant childcare and provisioning juveniles. Cooperative breeding theory offers a well‐developed theoretic and empirical context in which to evaluate cross‐cultural diversity and to understand why humans cooperate in this way. This review situates humans compared to other species of cooperative breeders by outlining what we share in common and what are distinctly human aspects of parenting and childrearing. Attention is paid to both foundational research and new questions that have more recently surfaced through comparative research. Cooperative breeding is relevant to recent debates concerning the evolution of human life history, sociality, and psychology and has implications to demographic patterns, family formation, and social organization in the past as well as in today's world. -
Culture, Diffusion, and Networks in Social Animals - Mann, Janet
Long‐term studies of social animals provide detailed data on individual attributes, behaviors, and associations that enable us to explore cultural diffusion in networks. In this essay, we describe how network science can be used to improve our understanding of cultural and information transmission. After presenting an operational definition of culture, we discuss methodologies and research questions applicable to unweighted, weighted, and dynamic networks. We then highlight relevant studies and methods for both descriptive and predictive analyses that have been used to identify culture and social learning in animal networks. Applying and extending the techniques presented will improve our understanding of information transmission, social learning, and embedded subcultures in the context of human networks. -
Food Sharing - Gurven, Michael
Food sharing is a human universal trait that forms the centerpiece of economic and social life in hunter‐gatherer societies. Human livelihoods require sharing at all life stages: to support infancy, childhood, and adolescence, and to help reduce risk of daily food shortfalls in adulthood. Attempts to understand the evolved human life history require an examination of the conditions that led to the evolution of food sharing. We summarize key findings and recent directions, and raise unexplored questions. Past emphases included testing predictions from several evolutionary models, and the role that sharing may have played in shaping human family formation. The functions of sharing fall into two categories: reducing food shortages that come with relying on a difficult foraging niche, and advertising attractive qualities of the donor. New directions include multivariate analyses of larger samples from a variety of diverse small‐scale subsistence populations, greater consideration of the interdependency between producing food and sharing it, incorporation of bargaining theory into exchange models, and greater attention to proximate psychological mechanisms. Future studies need to explain cross‐cultural variation in sharing norms and behavior and use a variety of methods to better bridge observed sharing patterns with the study of underlying social preferences and beliefs. -
Gestural Communication in Nonhuman Species - Pika, Simone
The evolution of language remains one of science's greatest mysteries. Although first comparative investigations into language origins focused on vocal abilities of nonhuman animals, especially primates, the number of publications reporting new and fascinating results about gestural skills of nonhuman animals has notably increased. To get a better insight in this intriguing scientific field, the present essay will provide a brief overview of its history and will then pinpoint current trends and future avenues. -
Kin‐Directed Behavior in Primates - Berman, Carol M.
Kinship was one of the first foundational principles of primate social organization to be recognized and to be viewed within an explicit evolutionary framework, specifically kin selection theory. Over time we have come to appreciate how much kinship structures and kin preferences vary between and within species, and how they are constrained by demography, life history characteristics, ecology, and mechanisms for recognizing kin. We have only recently discovered that many species are able to recognize paternal kin and to express preferences for them, but we have much to learn about how individuals do this, and how they make choices among different classes of kin and nonkin. Many potential benefits of close kin relationships have been uncovered, and some have been firmly linked to fitness benefits. Questions about kin selection versus mutualism or reciprocity as an explanation for kin preferences continue to pose challenges. Recent empirical studies support the operation of kin selection, but suggest that it may extend only within fairly narrow limits of relatedness. Much current theoretical research focuses on modeling the ways in which kinship interacts with dispersal patterns, reproductive skew, habitat saturation, and other ecological and life history patterns to produce various selective regimes related to cooperation. Some recent promising theoretical models of the origins of human social systems also rely in part on principles of kin selection and on a greatly expanded understanding of kin‐related behavior in nonhuman primates. -
Leadership - Tecza, Adrienne
Historically, research on human leadership has been the sole domain of the social sciences, and has focused on the formalized role leaders have come to play in modern institutions. However, an independent yet parallel body of work has recently emerged in biology, where evolutionary theory is being used to investigate the origins and function of leader–follower dynamics in nonhuman animals. In recent years, interdisciplinary scholars in evolutionary psychology have attempted to merge these previously disparate research traditions, investigating whether the leader–follower relationships that evolved to help our species overcome challenges in the past holds insights for leadership strategies in our modern world. In this essay, we investigate the feasibility of such an interdisciplinary approach, the obstacles it faces, and the promise it holds for the future of leadership research. -
Primate Allomaternal Care - Tecot, Stacey
Allomaternal care (AMC) (i.e., infant care that is provided by group members other than an infant's mother) is a rare, although phylogenetically widespread, mammalian infant care strategy. In primates, however, AMC occurs at unusually high frequencies, particularly among several haplorhine (monkey and ape) taxa. In fact, AMC is present in every major primate radiation and has been described in 74% of 154 species for which data are available. Its widespread presence in the Order Primates suggests that there may have been strong selective pressure for AMC early in primate evolution, but it is currently unknown why these behaviors are so common in primates. Research focused on captive callitrichids (tamarins and marmosets) has contributed greatly to our understanding of the potential causes and consequences of highly derived forms of AMC (i.e., cooperative breeding). Recent efforts have shifted focus to understand the selective pressures leading to the expansion and diversification of AMC throughout the Primate Order, thus expanding research to investigate the causes and consequences of less derived forms of AMC. Here we review the broad‐scale patterns observed in primates and outline innovative and exciting avenues of research moving forward. -
Vocal Communication in Primates - Slocombe, Katie E.
Vocal communication is common in the animal kingdom. Researchers often examine vocal communication in nonhuman primates (primates) with the aim of identifying similarities and differences with human language and speech, in order to trace the evolutionary origins of our complex communication system. Primates can produce distinct calls in response to specific events, such as the discovery of a certain predator, and listeners seem to understand what these calls refer to. Although on the surface there are similarities between this type of communication and human referential words, the mental processes that underlie them may be very different. While in general the flexibility shown by primate receivers may demonstrate some commonalities with humans, there is much more controversy over whether there are similarities between the production of primate vocalizations and language. It is widely accepted that primates, unlike humans, lack the ability to generate new vocalizations. Although this means primates have a closed repertoire of calls that cannot be expanded, primates are capable of combining their existing calls to generate new messages. The degree of voluntary control and intentionality involved in the use of calls is also a matter of debate, with recent evidence on both a neural and behavioral level challenging traditional assumptions that primate vocalizations are used in an automatic, reflexive manner. More research is needed to examine the mental processes underlying communicative behavior in both the producer and the receiver. In the future adopting a more holistic, multimodal approach to studying primate communication is likely to challenge and ultimately improve our understanding of primate communication and the evolution of human language.