The Ontogeny of Prehensile-Tail Use in Cebus capucinus and Alouatta palliata

A study of the platyrrhine prehensile tail provides an opportunity to better understand how ecological and biomechanical factors affect the ability of primates to distribute mass across many different kinds of arboreal supports. Young individuals experience ontogenetic changes in body mass, limb proportions, and motor skills that are likely to exert a strong influence on foraging strategies, social behaviors, support use, and associated prehensile-tail use. In this research, I examine ontogenetic patterns of prehensile-tail use in Cebus capucinus and Alouatta palliata. I collected behavioral data on activity, positional context, support size, and prehensile-tail use in five age categories of whitefaced capuchins and mantled howlers during a 12-month period at Estación Biológica La Suerte in northeastern Costa Rica. Infant and juvenile howlers and capuchins were found to use their prehensile tails significantly more often than adults during feeding, foraging, and social behavior. Prehensile-tail use did not show predictable increases during growth. In both species, adults used their prehensile tails in mass-bearing modes significantly less often than juveniles. Despite differences in tail anatomy in Cebus and Alouatta, prehensile-tail use was observed to follow an increasing trajectory from infancy, peaking during juvenescence, and then decreasing in older juveniles and adults. In both species, it appeared that adult patterns of prehensile-tail use reflected the demands placed on young juveniles

An Invitation for Engagement: Assigning and Assessing Field Notes to Promote Deeper Levels of Observation

This paper explores current practices for teaching the discipline of keeping field notes within academic natural history courses. We investigate how journal projects can be structured to promote engagement with the natural world while emphasizing the importance of recording accurate and honest observations. Particular attention is paid herein to the assignment of field notes, and to the process of assessing the results of these assignments. Our discussion includes results from an informal survey of best practices among colleagues representing numerous natural history disciplines

News and Perspectives: Words matter in primatology

Postings on social media on Twitter (now X), BioAnthropology News (Facebook), and other venues, as well as recent publications in prominent journals, show that primatologists, ecologists, and other researchers are questioning the terms “Old World” and “New World” due to their colonial implications and history. The terms are offensive if they result in erasing Indigenous voices and history, ignoring the fact that Indigenous peoples were in the Americas long before European colonization. Language use is not without context, but alternative terminology is not always obvious and available. In this perspective, we share opinions expressed by an international group of primatologists who considered questions about the use of these terms, whether primatologists should adjust language use, and how to move forward. The diversity of opinions provides insight into how conventional terms used in primatological research and conservation may impact our effectiveness in these domains

News and Perspectives: Words matter in primatology

Postings on social media on Twitter (now X), BioAnthropology News (Facebook), and other venues, as well as recent publications in prominent journals, show that primatologists, ecologists, and other researchers are questioning the terms “Old World” and “New World” due to their colonial implications and history. The terms are offensive if they result in erasing Indigenous voices and history, ignoring the fact that Indigenous peoples were in the Americas long before European colonization. Language use is not without context, but alternative terminology is not always obvious and available. In this perspective, we share opinions expressed by an international group of primatologists who considered questions about the use of these terms, whether primatologists should adjust language use, and how to move forward. The diversity of opinions provides insight into how conventional terms used in primatological research and conservation may impact our effectiveness in these domains

Ontogenetic Patterns of Positional Behavior in Cebus Capucinus and Alouatta Palliata

Positional behavior is the measurable and observable link between the biology and behavior of an animal in its environment. In this dissertation, I examine ontogenetic patterns of positional behavior in infant, juvenile, and adult white-faced capuchins (Cebus capucinus) and mantled howling monkeys (Alouatta palliata) inhabiting the same tropical forest in Costa Rica. During growth and development ontogenetic changes in body size, limb proportions, and motor skills are likely to influence locomotion and posture through the arboreal canopy. I collected data on positional behavior, activity, prehensile-tail use, branch size, branch angle, and crown location during a 12 month period at Estación Biológica La Suerte in northeastern Costa Rica. The data set is comprised of 401.3 hours of data on Cebus capucinus and 554.3 hours of data on Alouatta palliata totaling 955.7 hours of data or 57,344 individual activity records.Life history timing and differences in rates of growth did not predictably influence the development of adult-like positional behaviors in Cebus and Alouatta. In both species, infancy was characterized by high proportions of dorsal, ventral, and side riding on the mother with smaller proportions of independent positional modes observed during play, explore, active posture, and feed/forage. Young Cebus resembled the adult pattern of positional behavior by six months of age while howlers exhibited significant differences in several positional behavior categories through 24 months of age. The positional repertoire of both species revealed similarities in the types of modes used during feed/forage and travel in juveniles and adults. For example, in juvenile and adult age categories of Cebus, feeding and foraging included high proportions of quadrupedal walk, sit, and squat in conjunction with climbing, leaping, and suspensory behaviors. In howlers, the degree to which coordination and increases in body mass during ontogeny as limiting factors in the development of adult-like positional competence is unclear. Data presented here suggest that the environment exerts different pressures on growing Cebus and Alouatta that may relate to diet, energy expenditure, foraging skill, and/or social learning

Tales of the Ex-Apes

What do we think about when we think about human evolution? With his characteristic wit and wisdom, anthropologist Jonathan Marks explores our scientific narrative of human origins—the study of evolution—and examines its cultural elements and theoretical foundations. In the process, he situates human evolution within a general anthropological framework and presents it as a special case of kinship and mythology. Tales of the Ex-Apes argues that human evolution has incorporated the emergence of social relations and cultural histories that are unprecedented in the apes and thus cannot be reduced to purely biological properties and processes. Marks shows that human evolution has involved the transformation from biological to biocultural evolution. Over tens of thousands of years, new social roles—notably spouse, father, in-laws, and grandparents—have co-evolved with new technologies and symbolic meanings to produce the human species, in the absence of significant biological evolution. We are biocultural creatures, Marks argues, fully comprehensible by recourse to neither our real ape ancestry nor our imaginary cultureless biology.https://scholarcommons.scu.edu/faculty_books/1006/thumbnail.jp

Storytelling Apes

The annals of field primatology are filled with stories about charismatic animals native to some of the most challenging and remote areas on earth. There are, for example, the chimpanzees of Tanzania, whose social and family interactions Jane Goodall has studied for decades; the mountain gorillas of the Virungas, chronicled first by George Schaller and then later, more obsessively, by Dian Fossey; various species of monkeys (Indian langurs, Kenyan baboons, and Brazilian spider monkeys) studied by Sarah Hrdy, Shirley Strum, Robert Sapolsky, Barbara Smuts, and Karen Strier; and finally the orangutans of the Bornean woodlands, whom Biruté Galdikas has observed passionately. Humans are, after all, storytelling apes. The narrative urge is encoded in our DNA, along with large brains, nimble fingers, and color vision, traits we share with lemurs, monkeys, and apes. In Storytelling Apes, Mary Sanders Pollock traces the development and evolution of primatology field narratives while reflecting upon the development of the discipline and the changing conditions within natural primate habitat. Like almost every other field primatologist who followed her, Jane Goodall recognized the individuality of her study animals: defying formal scientific protocols, she named her chimpanzee subjects instead of numbering them, thereby establishing a trend. For Goodall, Fossey, Sapolsky, and numerous other scientists whose works are discussed inStorytelling Apes, free-living primates became fully realized characters in romances, tragedies, comedies, and never-ending soap operas. With this work, Pollock shows readers with a humanist perspective that science writing can have remarkable literary value, encourages scientists to share their passions with the general public, and inspires the conservation community.https://scholarcommons.scu.edu/faculty_books/1005/thumbnail.jp

Conversations on Human Nature.

Recent empirical and philosophical research into the evolutionary history of Homo sapiens, the origins of the mind/brain, and the development of human culture has sparked heated debates about what it means to be human and how knowledge about humans from the sciences and humanities should be understood.Conversations on Human Nature, featuring 20 interviews with leading scholars in biology, psychology, anthropology, philosophy, and theology, brings these debates to life for teachers, students, and general readers. The book • outlines the basic scientific, philosophical and theological issues involved in understanding human nature; • organizes material from the various disciplines under four broad headings: (1) evolution, brains and human nature; (2) biocultural human nature; (3) persons, minds and human nature, (4) religion, theology and human nature; • concludes with the editors’ discussion of what researchers into human nature agree on, what they disagree on, and what we need to learn to resolve those differences.https://scholarcommons.scu.edu/faculty_books/1004/thumbnail.jp