Center for Behavior, Evolution, and Culture

Lisa O'Bryan - Communication and the Coordination of Collective Behavior in Non-human and Human Social Groups
2022-03-28 12:00 - 13:30 (America/Los_Angeles)
Lisa O’Bryan, Rice University
In order to obtain social benefits, individuals must remain cohesive, coordinate their behavior, and collectively process information. The field of collective behavior focuses on understanding how group-wide properties such as these emerge from the interactions of many individuals. Most studies of collective behavior examine how coordination is achieved through visual cues about others’ positions and behavior. However, in many complex social and ecological environments, communication can be critical for achieving successful outcomes since many signals have evolved to advertise location, express motivational state and share information. My research focuses on how vocal communication both influences, and is influenced by, individual and group-wide properties, with the aim of better understanding the behavioral mechanisms underlying the successful (and unsuccessful) functioning of social groups. I study this topic using technology to obtain detailed, continuous measurements of individual behaviors and interactions in both non-human and human social groups. In this talk I will review my work using wearable dataloggers to study how vocalizations influence the collective movements of domesticated herds and wild baboons. I will also discuss current studies focused on the role conversational turn-taking plays in the decision-making and collective intelligence of human teams. The long-term goal of my research program is to gain new insights into the function and evolution of communication systems involved in the mediation of collective behaviors and how we can engineer communication systems within our own societies to produce more favorable group-wide outcomes.

Kelsey McCune - Space Use, Exploratory Behavior and Rapid Range Expansion in Great-Tailed Grackles
2022-04-04 12:00 - 13:30
Humans are rapidly changing the natural world, leading to decreasing native fauna and increasing non-native fauna. Problematic species range expansions are occurring across the globe, but not all species are able to become established outside of their original range. It is still unclear which characteristics facilitate successful invasions or native species persistence in human-modified environments. One hypothesis is that variation in behavior may be important when certain individuals possess traits that make them more likely to succeed when venturing into new habitats and outcompeting heterospecifics. For example, variation in the ability (movement) and motivation (exploratory tendency) to encounter conspecifics and novel food sources could facilitate range expansions. However, no previous research has compared measures of exploration to the natural movement behavior of individuals along the range of a currently invading species. In this talk I will discuss my research on movement and exploratory behaviors in a species that has rapidly expanded its range in the U.S., the great-tailed grackle. I consider whether individuals consistently differ in their movement behavior such that it can be considered an inherent individual trait, whether movement relates to performance on an exploration task, and whether movement and exploration differ between grackles in the center of the range and those on the invasion front. Invasive species are implicated as a leading cause of biodiversity loss, so this research will facilitate a better understanding of the importance of these behavioral characteristics in predicting potential invasions in other systems.

James Higham - Insights into Life-History from the Cayo Santiago Rhesus Macaques
2022-04-11 12:00 - 13:30
We humans come from a diverse order, the primates, which make excellent model systems for studying the interface between the biological and the social. In this talk, I focus on our long-running field studies of the rhesus macaques of Cayo Santiago, Puerto Rico. Decades of individual-based demographic data allow us to explore variation in life history, including the impacts of interbirth intervals and infant birth weights on infant survival, and both the development and senescence of reproduction in the same individuals across the lifespan. Our studies leverage behavioral observations, cognitive experiments, physiological measures, genomic and transcriptomic data from blood and tissues, measurements of soft-tissues and skeletons, microbiome samples, and more. I show how long-term integrative study allows us to explore the interactions between the biological and the social from two perspectives: bottom-up and top-down. From the bottom-up perspective, we are beginning to ask how variation in the genome and epigenome, via the transcriptome, constructs cellular, tissue- and organ-level biology in individuals, and in turn, how individual-level behaviors structure societies and populations. From the top-down perspective, we study how variation in the social environment can get under the skin and impact health and disease. I finish by discussing the Anthropocene, and by demonstrating the top-down effects of climate change-linked natural disasters on rhesus macaque societies, and on individual health via effects on the transcriptome. Combining approaches from behavioral ecology, physiology, quantitative genetics, genomics and transcriptomics, computer vision, and comparative psychology, this talk is part demonstration of the value of integrative research, and part love-letter to long-term field studies.

Luke Premo - How Cultural Evolutionary Forces Affect Regional Variation in Structured Populations and the Archaeological Assemblages They Leave Behind
2022-04-25 12:00 - 23:30
Paleolithic archaeologists have employed expectations generated from models developed in evolutionary anthropology to aid in the investigation of the origins of high-fidelity cultural transmission. Based on the notion that copying error ought to yield high levels of between-group cultural variation under unbiased cultural transmission, archaeologists have interpreted ostensibly “lower-than-expected” levels of cultural variation among regional archaeological assemblages as evidence of widespread conformist biased transmission. But a closer inspection of cultural evolutionary theory suggests the expectation that unbiased transmission yields high between-group differentiation holds only for a narrow, idealized set of conditions that are likely to be violated in empirical cases. Additionally, it is unclear how or if this expectation translates to time-averaged assemblages of artifacts even under special conditions. I’ve developed a relatively simple agent-based model of cultural transmission in a structured population to improve our understanding of how cultural evolutionary forces affect between-group variation in a selectively neutral discrete trait under a wide range of conditions. My experimental design addresses how intergroup transmission and copying error affect regional cultural variation under four different mechanisms of cultural transmission (unbiased, vertical, conformist, or prestige biased) and two different models of copying error (finite or infinite variants). I quantify cultural differentiation not only between groups in a structured population but also between time-averaged assemblages of culture material. The results highlight three points: 1) there are many conditions—not just widespread conformity—in which one should expect relatively low variation among semi-, or even completely, isolated groups (and the archaeological assemblages they create through time) despite the effects of copying error, 2) the way in which intergroup transmission and copying error affect between-group (and between-assemblage) variation varies among cultural transmission mechanisms, and 3) time-averaging affects between-assemblage variation differently under different cultural transmission mechanisms. Considering these findings, I propose a list of questions one should answer before attempting to infer mechanisms of cultural transmission from time-averaged archaeological assemblages. Answers to these questions will help researchers better match expectations of regional cultural variation with the empirical case at hand.

https://anthro.wsu.edu/faculty-and-staff/luke-premo/

Sasha Kimel - Meatborne Xenophobia: Understanding When Disgust Fuels Outgroup Hate
2022-05-02 12:00 - 13:30
Given that animal-borne pathogens pose especially high disease risks and, moreover, that a growing body of research suggests that the evolved function of disgust is the avoidance of disease, it is largely unsurprising that the consumption of non-normative meat would evoke strong disgust reactions. Yet, it is largely unclear whether and when concerns about disease can also evoke negative reactions to third-parties who engage in such norm-violations. In a series of experiments, participants in the U.S. were randomly assigned to learn about cuisine from another culture (i.e., fabricated and real) that contained a meat that was either relatively neutral (i.e., beef), disgusting due to disease threat (i.e., rat) or disgusting due to a combination of disease threat and the immorality of causing a cared-for animal harm (i.e., dog, monkey). Our results suggest that disgust may only exacerbate negative judgements and behaviors towards third-parties when the disease threat also has a strong immorality component (e.g., eating of dogs but not rats) and, moreover, that this may increase depending on how cared-for the being is. Implications for theories on disgust, compassion and third-party punishment will be addressed.

Jaimie Krems - Tackling Friendship: Appraising, Finding, Getting, and Keeping Partners
2022-05-09 12:00 - 13:30
Friends have recurrently provided social, material, and emotional support—helping humans meet a range of recurrent challenges tributary to fitness. But friendships are not the first type of relationship that comes to mind when thinking about research in social psychology or evolutionary social science. Moreover, when friendships are the focus, work typically foregrounds the friendship dyad. Taking an evolutionary approach suggests a different natural ecology for friendship psychology—one that implies the challenges of friendship are more and more complex than we might typically consider them to be. Perhaps, then, the challenges one must solve to reap the benefits of friendship should be thought of not (only) as two-person games, so to speak, but (also) as n-person games. I illustrate this by exploring several major friendship challenges—identifying good friends, competing for friends, and maintaining friendships. I also propose and test some of the possible means by which our social minds might meet these challenges, toward ultimately maximizing the benefits and minimizing the costs of our sociality.
https://www.kremslab.com/

Richard Wrangham - Hunter-Gatherers, Homo duplex and the Evolution of Human Groupishness
2022-05-16 12:00 - 13:30
Groupishness is a tendency to commit prosocial acts for which the pathway to
compensatory fitness benefits is unpredictable. It is unique to humans, and its evolution is
not well understood. A difficulty is that the adaptive value of groupishness comes from
indirect reciprocity, which is hard to explain in societies that contain power asymmetries
such that a dominant can appropriate resources at will. To date the only solution is Boehm’s
proposal, namely that morality was favored because allied males were selected to use
coercive behavior first to eliminate tyrants, then subsequently to favor prosociality and
punish antisociality. Using information on self-domestication, a topic that Boehm did not
explore, I present several tests of Boehm’s thesis. All are supportive, while also modifying
Boehm’s ideas. I conclude that a major increase in evolved groupishness began with the
origin of Homo sapiens and the ability to execute tyrants. This process generated Homo
duplex, including the uniquely human tension between selfishness and duty seen in hunter-
gatherers and other societies.

Dietrich Stout - The Evolution of Technology
2022-05-23 12:00 - 13:30
For better or worse, humans are now one of the major causal forces acting on the earth’s biosphere. Many would point to technology as the reason, but what exactly is technology? In this lecture, I will develop an evolutionarily grounded definition of technology that highlights three key features: material production, social collaboration, and cultural reproduction. Using examples from my own lab’s studies of stone tool making, I will argue that these features implicate a wide range of perceptual, motor, and cognitive capacities as well as multiple channels of cultural inheritance and biocultural evolutionary processes. This perspective blurs presumed distinctions between social and individual learning that have shaped formal modeling approaches to cultural evolution. In so doing it calls into question the idea that one key capacity, event, or evolutionary Rubicon initiated cumulative technological evolution and a pattern of sustained autocatalytic biocultural feedback in human evolution. This interpretation is consistent with growing paleoanthropological and archaeological evidence of the multi-lineal, intermittent, asynchronous course of human evolution, and presents a view of technological evolution as a complex and contingent process spanning a scale from neurons to societies and beyond. Nevertheless, some synthesis may be possible with respect to a smaller number of recurring processes and relationships. In this vein, I advance a “Perceptual Motor Hypothesis” proposing that human technological cognition has been evolutionarily and developmentally constructed from ancient primate perceptual-motor systems for body awareness and engagement with the world. Testing such hypotheses will require a multidisciplinary and comparative approach to identify patterned relations between contexts, mechanisms, and functions across diverse technological systems.

Joe Manson - Nine years of research on life history strategy and individual differences, or: How I learned to start worrying about constructs and instruments
2022-05-31 15:00 - 17:00
This is a special BEC talk in honor of the retirement of one of BEC‘s core faculty members, Joe Manson. Please note the special time! Refreshments and snacks on the balcony of the anthropology department will follow Joe’s talk.

Barbara Natterson-Horowitz - The 600-million-year history of human affective disorder
2023-10-02 12:00 - 13:30 | 352 Haines Hall
The 600-million-year history of human affective disorder
Barbara Natterson-Horowitz
Division of Cardiology, UCLA School of Medicine
Department of Ecology and Evolutionary Biology, UCLA
Department of Human Evolutionary Biology, Harvard University
Department of Global Health and Social Medicine, Harvard Medical School
Fifty years ago this October, the Nobel Prize in Medicine was awarded to three animal behaviorists based on the belief that the emerging field of ethology could transform our understanding of human biobehavioral health. Unfortunately, the promise was not realized within the lifetimes of the scientists themselves. In the decades that followed, advances in biological psychiatry challenged psychoanalysis as the singular source of explanatory insights into mental illness. Regrettably, highly reductive biological approaches that lack a broader, integrated organismal and ecological context have not led to much needed transformational knowledge.
Today, broadly comparative and ecologically-informed studies of animal behavior are revealing: 1) the ancient origins of human affective systems and affective disorders in the social brain networks of early social animals, 2) the important links between brain biology promoting adaptive behavior in chronically subordinated animals and neurovegetative symptoms in depressed human beings, and 3) evidence that withdrawn behavior, anhedonia, and reduced cognitive and motoric activity in chronic subordinates increases survival in certain individuals. Recent studies connecting social defeat to severe depression point, once again, to animal behavior as a source of insights into human mental health. In fact, phylogenetic perspectives can provide much needed scaffolding on which to layer, with context, the rapidly growing body of reductive knowledge about the human brain in health and illness.
Dr Natterson-Horowitz’s lecture will first survey the historical and scientific settings in which both insights were recognized and overlooked. She will then present an up-to-date summary of insights into human affective disorders emerging at the intersection of behavioral ecology, neurobiology, psychopharmacology, and evolutionary biology.

Caleb Finch - The Gero-Exposome, a life history approach to diversity of human longevity
2023-10-16 12:00 - 13:30 | 352 Haines Hall
The Gero-Exposome, a life history approach to diversity of human longevity
Caleb Finch, PhD
ARCO and Kieschnick Professor, Leonard Davis School of Gerontology, USC
From egg to exit, human life history is determined by environmental interactions with our genome (GxE). The Gero-Exposome provides a framework for analyzing GxE interactions with life style, biomes, and systemic factors. Lifespans difference of 15 years across the socio-economic status (SES) have corresponding differences in the onset of cardiovascular disease and dementia. Moreover, SES influences the development of brain and vasculature, by greater gestational exposure to air pollution and cigarette smoke in low SES. Multiple postnatal phases have environmental influences throughout the lifespan. As an experimental model for these complexities, mice were gestationally exposed to air pollution. Young adults had more body fat and glucose intolerance, while brains had lower levels of hypothalamic neuropeptides and neuronal stem cells in the hippocampus. These findings are relevant to the multi-generational stability of SES differences in health and lifespan, for which the GxE basis is undefined.

Bridget Callaghan - Intergenerational impacts of adversity on mind-body health: pathways through interoception and the gut-brain axis
2023-10-23 12:00 - 13:30 | 352 Haines Hall
Intergenerational impacts of adversity on mind-body health – pathways through interoception and the gut-brain axis
Bridget Callaghan
Assistant Professor, Department of Psychology, UCLA
Children’s early experiences with caregivers impact their mental and physical health across the lifespan. Such early caregiving experiences can become biologically and psychologically embedded within an individual, contributing to intergenerational transmission of adversity. My research program investigates the neurobiological mechanisms via which early caregiving experiences impact children’s mental and physical health, and how those experiences may be transmitted to impact future generations. I will present data from several studies demonstrating how early life adversity gets ‘under the skin’ to influence children’s emotional health and physical health, paying particular attention to gastrointestinal distress, which is tightly connected to emotional wellbeing. Zooming in on the gastrointestinal and oral microbiomes, I will show how adversity impacts biological systems tied to emotional and physical wellbeing. Finally, I will show that mind-body adaptations to the state of pregnancy, through changing interoception, may be one pathway through which experiences of adversity are perpetuated across generations.

Katie Karlsgodt - Reward and Cognitive Function in Adolescent Psychopathology
2023-10-30 12:00 - 13:30 | 352 Haines Hall
Reward and Cognitive Function in Adolescent Psychopathology
Katie Karlsgodt
UCLA Departments of Psychology and Psychiatry
Adolescence is a time when exploration, and even risk-taking, can be considered an adaptive part of the typical developmental experience. This period of enhanced risk-taking allows for new learning, particularly about the social world, and is a critical part of establishing independence. Risk-taking is a complex behavior, often considered to rely on many factors, including reward sensitivity and reward behaviors, response to punishment, and executive function skills that allow the balancing of competing factors and the selection of choices. However, in addition to being a time of exploration and independence, adolescence is also the period of onset for many psychological disorders including schizophrenia and depression. Many such disorders include alterations in both reward and executive function, which has the potential to impact learning and exploration during this time, with ultimate effects on social function, and long term daily life function. In this talk, I will address the existing literature in this area, recent relevant work from my lab on reward function, adolescence, and psychopathology, and future directions.

Michael Wells - Exploration of human genetic and phenotypic diversity through cell villages
2023-11-06 12:00 - 13:30 | 352 Haines Hall
Exploration of human genetic and phenotypic diversity through cell villages
Michael Wells
Assistant Professor, UCLA Department of Human Genetics
Human genome variation contributes to diversity in neurodevelopmental outcomes and vulnerabilities; recognizing the underlying molecular and cellular mechanisms will require scalable approaches. Here, I will describe a ‘‘cell village’’ experimental platform we used to analyze genetic, molecular, and phenotypic heterogeneity across neural progenitor cells from 44 human donors cultured in a shared in vitro environment using algorithms (Dropulation and Census-seq) to assign cells and phenotypes to individual donors. Through rapid induction of human stem cell-derived neural progenitor cells, measurements of natural genetic variation, and CRISPR-Cas9 genetic perturbations, we identified a common variant that regulates antiviral IFITM3 expression and explains most inter-individual variation in susceptibility to the Zika virus. We also detected expression QTLs corresponding to GWAS loci for brain traits and discovered novel disease-relevant regulators of progenitor proliferation and differentiation such as CACHD1. The village approach provides scalable ways to elucidate the effects of genes and genetic variation on cellular phenotypes, and can help elucidate the mechanisms guiding brain development and associated diseases.

Zarin Machanda - Social aging in wild chimpanzees
2023-11-13 12:00 - 13:30 | 352 Haines Hall
Social aging in wild chimpanzees
Zarin Machanda
Tufts University, Departments of Anthropology and Biology
Humans are living longer lives than ever before and so it is critical to understand the process of aging. It has become increasingly recognized that successful aging is not just about physical health but also about our social lives. Chimpanzees are our closest living relative and lead long and complex lives making them an ideal model to better understand our own patterns of social aging. In this talk, Dr. Machanda will discuss the patterns of social aging in wild chimpanzees from her decades-long research project studying the Kanyawara chimpanzees living in Kibale National Park, Uganda.

Theo Samore - Traditionalism, pathogen avoidance, and competing tradeoffs during a global pandemic
2023-11-27 12:00 - 13:30 | 352 Haines Hall
Traditionalism, pathogen avoidance, and competing tradeoffs during a global pandemic
Theo Samore
University of Otago
Individuals vary in the extent to which they embrace their society’s traditions, as well as in the perception of threats as salient and necessitating mitigation. Traditionalism and threat sensitivity may be linked if—over evolutionary time—traditions offered avenues for reliably addressing threats, either through instrumental and/or ritual and cooperative benefits. Alternatively, if traditionalists are attuned to group-destabilizing threats, they may also exhibit greater threat sensitivity in certain domains. These possibilities – which are not mutually exclusive – suggest that greater traditionalism may associate with stronger mitigating responses toward some threats. However, threat-avoidance motivations can conflict with competing priorities and epistemic commitments in the real world. The COVID-19 pandemic represented a moment in time in which people across the world undertook costly threat-mitigating behaviors, providing an important test of the traditionalism-threat avoidance relationship under complex real-world conditions. We investigated the relationship between COVID-19 precautions, traditionalism, and perceptions of competing tradeoffs in both the U.S. and a large 27-country cross-cultural sample. Results indicated that, across study sites, traditionalism tended to positively correlate with behaviors intended to mitigate the threat of COVID-19. Further, despite possible epistemic conflict between religion and science, individuals tended to report engaging in both scientifically and religiously rooted precautions. Nevertheless, at some study sites, the relationship between public health precautions and traditionalism was suppressed by competing priorities, such as lower trust in scientists and greater concerns about personal liberties.

Nikhil Chaudhary - Hunter-gatherers, evolutionary mismatch and mental disorder
2023-12-04 12:00 - 13:30 | 352 Haines Hall
Hunter-gatherers, evolutionary mismatch and mental disorder
Nikhil Chaudhary
Leverhulme Centre for Human Evolutionary Studies, University of Cambridge
*Note: This speaker will be remote; However, we will still be meeting in Haines 352 to watch the talk and conduct the Q&A.
Humans lived as hunter-gatherers for the vast majority of our evolutionary history, therefore it has been proposed that aspects of our psychology may be adapted to a hunter-gatherer lifestyle. There are several assumptions in this proposal, however, research with contemporary hunter-gatherers can offer a useful starting point for exploring the potential for evolutionary mismatch—when an organism faces conditions that differ from those that some trait of the organism is adapted to, resulting in pathology or maladaptation. Drawing on my fieldwork and previous research, I will discuss how discordances between the social organisation of hunter-gatherers and WEIRD (Western, Educated, Industrialised, Rich, Democratic) societies may affect vulnerability to mental disorders in the latter. I will pay particularly attention to differences in residence patterns, hierarchical structures, and social networks. I will also discuss differences in childcare strategies and their implications for psychological development.

Emily Lindsey - Dawn of the Anthropocene: How humans in a warming climate drove Pleistocene mammal extinctions and re-shaped California’s landscapes
2024-01-22 12:00 - 13:30 | 352 Haines Hall
Dawn of the Anthropocene: How humans in a warming climate drove Pleistocene mammal extinctions and re-shaped California’s landscapes
Emily Lindsey
Tar Pits/UCLA

The relative roles late-Quaternary climate changes and human actions played in the extinction of most of the world’s large mammals at the end of the Ice Age have been long-debated. One key challenge is that the fossil record in most regions is too poorly-constrained to precisely pinpoint the disappearance times of different species and align these with environmental and anthropogenic phenomena. In this talk, I will describe how a large-scale, interdisciplinary effort brought together several remarkable records from southern California to unveil a regional story of fire, extinction, and ecosystem state shift. This discovery has significant implications for global megafaunal extinctions research as well as modern conservation efforts.

Elsa Ordway - Insights from the tropics: a social-ecological systems approach to understanding climate change
2024-01-29 12:00 - 13:30 | 352 Haines Hall
Insights from the tropics: a social-ecological systems approach to understanding climate change
Elsa Ordway
UCLA
The tropics are experiencing dramatic changes as a result of climate change and land-use change. Shifts in carbon flux dynamics, water cycling, and species composition are resulting in feedbacks with globally important consequences. However, tropical forests are not a monolith. They vary enormously in terms of species diversity, climate, soils, human interactions, and much more. As a result, tropical forest ecosystems are already beginning to show evidence of distinct responses to climate and land-use change. Yet, these differences remain highly uncertain and poorly understood. An integrated social-ecological systems approach is critical for understanding drivers of and responses to change, as well as for identifying solutions.

Jazlyn Mooney - On the Number of Genealogical Ancestors: Tracing to the Source Groups of an Admixed Population
2024-02-05 12:00 - 13:30 | 352 Haines Hall
On the Number of Genealogical Ancestors: Tracing to the Source Groups of an Admixed Population
Jazlyn Mooney
USC
In genetically admixed populations, admixed individuals possess ancestry from multiple source groups. Studies of human genetic admixture frequently estimate ancestry components corresponding to fractions of individual genomes that trace to specific ancestral populations. However, the same numerical ancestry fraction can represent a wide array of admixture scenarios. Using a mechanistic model of admixture, we characterize admixture genealogically: how many distinct ancestors from the source populations does the admixture represent? We consider African Americans, for whom continent-level estimates produce a 75-85% value for African ancestry on average and 15-25% for European ancestry. Genetic studies together with key features of African-American demographic history suggest ranges for model parameters. Using the model, we infer that if genealogical lineages of a random African American born during 1960-1965 are traced back until they reach members of source populations, the expected number of genealogical lines terminating with African individuals is 314, and the expected number terminating in Europeans is 51. Across discrete generations, the peak number of African genealogical ancestors occurs for birth cohorts from the early 1700s. The probability exceeds 50% that at least one European ancestor was born more recently than 1835. Our genealogical perspective can contribute to further understanding the admixture processes that underlie admixed populations. For African Americans, the results provide insight both on how many of the ancestors of a typical African American might have been forcibly displaced in the Transatlantic Slave Trade and on how many separate European admixture events might exist in a typical African-American genealogy.

Eduardo Amorim - How Past Pandemics Shaped the Evolution of Human Immunity – Lessons from Ancient Genomes
2024-02-12 12:00 - 13:30 | 352 Haines Hall
How Past Pandemics Shaped the Evolution of Human Immunity – Lessons from Ancient
Genomes
Eduardo Amorim
Cal State Northridge
Pathogen exposure has played a pivotal role in shaping human evolution. Genome-wide association studies (GWAS) reveal that the genetic predisposition to infections arises from the contribution of thousands of loci across the genome, indicating a polygenic mode of inheritance. At California State University Northridge, our research lab utilizes ancient DNA (aDNA) data to investigate the evolution of polygenic traits in humans, focusing on phenotypes related to immunity and adaptation to extreme environmental conditions. In this presentation, I will explore how past epidemics shaped the genetic makeup of our ancestors, impacting various biological pathways relevant to human health. While addressing the limitations of our methods, I will emphasize the growing potential of paleogenomics, employing time-series genetic data built with aDNA to enhance our understanding of human adaptation and the evolution of polygenic traits. The talk will conclude with a brief overview of other ongoing projects in our lab, including the study of high-altitude adaptation and the coevolution of the human host and the oral microbiome.

Michael Campbell - The effect of population history on patterns of genetic diversity at the TAS2R bitter taste receptor genes in West Central and Central African populations
2024-02-26 12:00 - 13:30 | 352 Haines Hall
The effect of population history on patterns of genetic diversity at the TAS2R bitter taste receptor genes in West Central and Central African populations
Michael Campbell
USC
Bitter taste perception is a highly variable trait in humans, and the ability to detect bitter compounds has been largely attributed to genetic variants in 25 bitter taste receptor (TAS2R) genes. Furthermore, bitter taste perception has been hypothesized to be a dietary adaptation in humans. However, few studies have characterized patterns of diversity and signatures of selection at the TAS2R genes in distinct African populations. Given the extensive genetic substructure and evidence for local adaptation in Africa, we hypothesized that Africans practicing diverse subsistence strategies could have distinct patterns of selection resulting from divergent diets. To test this hypothesis, we examined sequence variation at 22 bitter taste receptor genes in rainforest hunter-gatherers and Bantu-speaking agriculturalists from Cameroon. Here, we identified 353 single nucleotide polymorphisms (SNPs) across the TAS2R genes, 35 of which have never been previously described. We also observed striking signatures of positive selection, including unusually long haplotypes around alleles at the TAS2R genes. In addition, some of these signals of selection were shared between rainforest hunter-gatherers and Bantu-speaking agriculturalists. To better understand these results, we performed genomic genotyping in our African populations. Interestingly, we observed varying proportions of ancestry originating from Bantu-speakers in hunter-gatherers with the highest levels of admixture occurring in the Bakola population. These findings demonstrate that gene flow from neighboring agriculturalists has also shaped patterns of diversity in hunter-gatherers, including variation in the TAS2R genes. Overall, this research provides new insights into the evolution of biologically relevant bitter taste genes in highly understudied African populations.

Patricia Greenfield
2024-03-04 12:00 - 13:30 | 352 Haines Hall
Patricia Greenfield
Distinguished Professor, UCLA Department of Psychology
Associate, Harvard Department of Human Evolutionary Biology
A Theoretical and Empirical Approach to Cultural Evolution: Intergenerational Transmission, Cognition, and Creativity
For the theoretical approach, I will present my multilevel theory of ecological change, cultural evolution, and human development. For the empirical evidence, I will report findings from longitudinal study of a Zinacantec Maya community in Chiapas, Mexico over a span of 43 years. This research has explored the intergenerational transmission of weaving, cognitive development, and creativity in three generations of mothers and children. From Generation 1 to Generation 2, the main ecological change was the transition from subsistence agriculture to money and commerce. From Generation 2 to Generation 3, the main ecological change was from informal education at home to formal education at school. In the domain of intergenerational transmission, the first shift created more independent weaving learners; the second shift created more school-like transmission of weaving technique. Both ecological shifts moved cognition towards greater abstraction and creativity towards greater innovation. These ecological shifts also produced cultural losses: Fewer girls learning to weave on a backstrap loom, less detail-oriented visual representation, and the declining importance of traditional, community-wide woven patterns. The processes of cultural evolution identified in this Maya community are similar to cultural shifts going on in many communities around the world, communities have transitioned from subsistence ecologies to commercial, urbanized, and technologically more sophisticated environments.

Holly Dunsworth - To Save Humankind, Kill Off the Hero’s Journey of Human Evolution
2024-03-11 12:00 - 13:30 | 352 Haines Hall
To Save Humankind, Kill Off the Hero’s Journey of Human Evolution
Holly Dunsworth
University of Rhode Island
In Narratives of Human Evolution, Misia Landau revealed that late 19th and early 20th century fathers of human evolutionary theory, including Charles Darwin, unconsciously conformed their stories to the key structural elements of Russian folktales. Dunsworth argues that the enduring habit—within science, academia, and throughout popular culture—of projecting a hero’s journey onto lineages that blend and weave across deep time is fundamental to the perpetuation of untrue patriarchal and racist reconstructions of human origins and human nature, which we continue to enact to our peril, and to the planet’s. In this presentation, Dunsworth breaks down the hero’s journey into its parts and compares them to contemporary human evolutionary biology. In the end, the hero’s journey does not triumph. This presentation is based on a chapter in Dunsworth’s upcoming book (Viking/Penguin, 2025).

David Reby - What can deer tell us about our voice? How sexual selection may have shaped human vocal diversity
2024-04-01 12:00 - 13:30 | 352 Haines Hall
What can deer tell us about our voice? How sexual selection may have shaped human vocal diversity
David Reby
Professor of Ethology, Equipe de Neuro-Ethologie Sensorielle, Université Jean Monnet of Saint-Etienne

Many animal species use vocal communication, but humans are unique in the ability to control the vocal production of an incredible diversity of sounds, enabling us to exchange information of extreme complexity. In this talk, I will propose that sexual selection, which is responsible for the evolution of astonishing visual and auditory signals in many animal species, may have played a key role in the emergence of our vocal diversity. I will show that in a wide range of polygynous species, sexual selection has modified the vocal apparatus of males to support the exaggeration of body size conveyed by vocalizations. These modifications have in turn opened up the acoustic space along a male/female continuum, where low frequencies convey dominance and/or masculinity, and high frequencies convey subordination and/or femininity. I will suggest that this widening of the vocal space, which can be found in modern humans in the expression of gender in children’s and adults’ voices, may have favored the evolution of vocal control by allowing us to play along this frequency continuum to signal emotions and motivations. I will also suggest that size exaggeration may even have shaped the evolution of mechanisms necessary for the production and perception of vowels in speech.

Jazlyn Mooney - On the Number of Genealogical Ancestors: Tracing to the Source Groups of an Admixed Population
2024-04-08 12:00 - 13:30 | 352 Haines Hall
On the Number of Genealogical Ancestors: Tracing to the Source Groups of an Admixed Population
Jazlyn Mooney
Dept. of Quantitative and Computational Biology, University of Southern California
In genetically admixed populations, admixed individuals possess ancestry from multiple source groups. Studies of human genetic admixture frequently estimate ancestry components corresponding to fractions of individual genomes that trace to specific ancestral populations. However, the same numerical ancestry fraction can represent a wide array of admixture scenarios. Using a mechanistic model of admixture, we characterize admixture genealogically: how many distinct ancestors from the source populations does the admixture represent? We consider African Americans, for whom continent-level estimates produce a 75-85% value for African ancestry on average and 15-25% for European ancestry. Genetic studies together with key features of African-American demographic history suggest ranges for model parameters. Using the model, we infer that if genealogical lineages of a random African American born during 1960-1965 are traced back until they reach members of source populations, the expected number of genealogical lines terminating with African individuals is 314, and the expected number terminating in Europeans is 51. Across discrete generations, the peak number of African genealogical ancestors occurs for birth cohorts from the early 1700s. The probability exceeds 50% that at least one European ancestor was born more recently than 1835. Our genealogical perspective can contribute to further understanding the admixture processes that underlie admixed populations. For African Americans, the results provide insight both on how many of the ancestors of a typical African American might have been forcibly displaced in the Transatlantic Slave Trade and on how many separate European admixture events might exist in a typical African-American genealogy.

Kelsey Jorgensen - Surviving the heights: Environmental adaptations and multispecies genetics in the Andes
2024-04-15 12:00 - 13:30 | 352 Haines Hall
Surviving the heights: Environmental adaptations and multispecies genetics in the Andes
Kelsey Jorgensen
Postdoctoral Scholar, Department of Anthropology, UCLA
Human populations have thrived in the Peruvian Andes for thousands of years despite extreme environmental stressors of hypoxia, cold temperatures, and times of food scarcity. These evolutionary environmental pressures have shaped unique genetic adaptations and continue to influence health in human populations today. In this talk, I bridge genotype-phenotype to identify genetic variants in modern Peruvians linked to diet and high-altitude resulting from evolutionary environmental adaptation. In addition, I explore this intersection of biology, culture, and environment to infer ancient human migration patterns across the Andes in the absence of aDNA by using multispecies genetics.

Michael Greenfield - Rhythm coordination in animal species, including humans: Entrainment from bushcricket chorusing to the philharmonic orchestra
2024-04-22 12:00 - 13:30 | 352 Haines Hall
Rhythm coordination in animal species, including humans: Entrainment from bushcricket chorusing to the philharmonic orchestra.
Michael Greenfield
ENES Bioacoustics Research Lab, CRNL, University of Saint-Etienne, CNRS
Department of Ecology and Evolutionary Biology, University of Kansas
Repetitive cycles of an activity or state, generally known as rhythm, are ubiquitous in living organisms, occurring in all branches of the tree of life. In animal species rhythms play prominent roles in physiology and behavior, and they are commonly expressed as long-term (period > 12 h) cycles, entrained to recurring astronomical phenomena, at one end of the temporal spectrum, or as very short (< 10 s) ultradian cycles at the other. In behavior, ultradian rhythms often involve movement or the broadcast of communication signals, and in some species neighboring individuals coordinate their rhythms in time. Such coordination fascinates us because of its flawless precision and complexity, the horde of individuals that may participate, and the resulting crescendo of the communal display. But aesthetic sensibilities aside, coordinated rhythms pose major questions concerning mechanisms and evolution : How is coordination achieved, which individuals in a local population participate, why do neighbors bother to coordinate their activity and what is the phylogenetic distribution of these displays among animal taxa?
This seminar covers the diverse ways in which animals coordinate relatively fast behavioral rhythms. We concentrate on the coordination of rhythms expressed in sexual advertisement and social communication, as these tend to be conspicuous to observers and their parameters can normally be measured unambiguously. We begin with the various timing schemes found in rhythm coordination, noting the relative timing of the signaling by individual participants, how those participants tend to be arranged in space, and the signaling modalities used. From the receiver’s perspective, we ask who perceives the signals, where these potential receivers are located (whether within or outside of the coordinated group), and how receivers may respond to the group display. Because of moderate to extreme precision found in coordinated group displays, we pay special attention to the mechanisms with which individual signaling rhythms are aligned in different animal species. We show how an understanding of mechanism is critical for the next step : evaluating adaptive explanations for synchrony and other group coordinations. Although our survey of rhythm coordination among animals is certainly incomplete and probably reflects sampling bias favouring signals and species that are readily observed and that have been studied traditionally, some striking patterns emerge. Rhythm coordination of both moderate and high precision appears mostly among certain arthropods and ‘lower’ vertebrates in the chordates, but also in humans where synchronous coordination is central in music, dance and other group activities. We consider this curious, disjunct phylogenetic distribution, and specifically ask how and why strictly timed rhythmic synchrony operates in these very different organisms. Importantly, this comparative approach holds promise for unraveling the origins of human musicality.

Marcia Inhorn - Motherhood on ice: The mating gap and why women freeze their eggs
2024-04-29 12:00 - 13:30 | 352 Haines Hall
Motherhood on ice: The mating gap and why women freeze their eggs
Marcia Inhorn
Professor of Anthropology and International Affairs, Yale University
Why are women freezing their eggs in record numbers? Contrary to media reports, which suggest that women’s career ambitions are the main determinant of women’s fertility postponement, women themselves offer different explanations for fertility preservation through egg freezing. The growing momentum toward this new reproductive technology masks an underlying but little discussed global reality—namely, a mating gap, in which women in the United States and more than half the world’s nations (including Australia) are outperforming men in higher education, resulting in the lack of eligible, educated, and equal partners with whom to pursue marriage and childbearing. Although egg freezing is touted for its “revolutionary” potential, it is a costly technological concession to growing gender inequalities, whereby educated women are “buying time” while experiencing reproductive partnership problems beyond their individual control.

Nelson Ting - Primate Extinction in the Anthropocene and the Tail of Miss Waldron’s Red Colobus
2024-05-20 12:00 - 13:30 | 352 Haines Hall
Primate Extinction in the Anthropocene and the Tail of Miss Waldron’s Red Colobus
Nelson Ting
Professor, Department of Anthropology & Institute of Ecology and Evolution, University of Oregon
There have been five mass extinction events in the history of Earth, and it is thought we are in the midst of a sixth. The consequences of this current event are far reaching, from losses in biodiversity and ecosystem services to damages in human food systems and global health security. Thus far, only one primate is thought to have recently gone extinct – Miss Waldron’s red colobus monkey. A dried tail procured from a hunter 25 years ago may provide clues as to how primates fit into this sixth extinction. Using results from whole genome sequencing from this specimen, I attempt to piece together the factors that drove this animal to extinction and discuss the implications for current conservation policy for primates. Based on these results and other lines of evidence, I argue that red colobus monkeys may play an important role in the conservation of tropical forests in Africa, and that holistic approaches to the protection of these animals will benefit both biodiversity and human livelihoods. Finally, to this end, I highlight recent activities my colleagues and I have undertaken as we implement recommendations from the IUCN Red Colobus Conservation Action Plan.
