Center for Behavior, Evolution, and Culture

Elly Power - Signaling, Status, and Social Networks: Religious Practice in Rural South India
2015-11-09 00:00 (America/Los_Angeles)
Elly Power: Santa Fe InstituteDiscerning the intentions and character of others is a difficult task. In South India, religious practice is seen as particularly helpful in that process of discernment. There, the ritual acts undertaken are often quite dramatic: devotees walk across hot coals, pierce their skin with hooks and spears, walk barefoot to distant temples, and sacrifice animals to the divine. What is being communicated through these acts? Drawing on reputational and social support network data, I show that greater and costlier ritual participation corresponds to greater recognition not only for being devout, but also for holding a suite of prosocial traits. Perhaps more importantly, greater and costlier ritual participation also increases the likelihood of a supportive tie between individuals. These findings provide clear support for the costly signaling theory of religion. However, I will spend much of the talk complicating these simple relationships. Not everyone performs costly ritual acts, and the reputational benefits that accrue to those who do are not equally distributed. Much of this variation can be explained by the social risks entailed in these acts and the differential ability of villagers to take on those potential costs. To fully understand this signaling system, a broader understanding of cost, a wider range of actors, and a more complete inventory of signals (including not only the dramatic but also the subtle) must all be recognized and taken into account.

Joey Cheng - Getting to the Top: Pathways to Social Rank
2015-11-16 00:00
Joey Cheng: University of Illinois at Urbana-ChampaignThe pursuit of social rank is a recurrent and pervasive challenge faced by individuals across human societies. Yet, the precise means through which individuals compete for social standing remain unclear. This talk examines the dynamics of two fundamental avenues—fear and respect—to social rank. I will begin by highlighting how these strategies differ—in terms of their characteristic personality, emotional, verbal, and nonverbal patterns. I will then present evidence demonstrating the viability of fear and respect for effectively ascending the social hierarchy in both the lab and the field. Finally, I will discuss new research that examines the impact of fear- and respect-based leadership on group functioning and follower well-being. Taken together, this emerging line of research suggests that fear and respect represent two distinct pathways to social rank. Underpinned by a unique suite of cognitive, affective, and behavioral processes, these pathways shape the hierarchical order of individuals within groups and promote collective success, albeit under different circumstances.

Melissa Emery Thompson - On Less Fertile Ground: Chimpanzee Life Histories in Context
2015-11-23 00:00
Melissa Emery Thompson: University of New MexicoAmong the most dramatic changes to occur during human evolution were those affecting our life history. The evolution of the human fertility pattern, including relatively fast birth rates, overlapping offspring dependencies, and extended postreproductive life, remains an active area of research and debate that can be greatly informed by structured comparisons to the living apes. To do so effectively, we need high quality data from natural populations, as well as more detailed information about the physiological mechanisms that regulate fertility in both species. To that end, I will discuss empirical data on reproductive lifespan, determinants of fecundity, regulation of the interbirth interval, and parental investment in wild chimpanzees with comparison to human populations. Humans and chimpanzees share remarkably similar patterns for the regulation of fertility. Despite the relatively higher cost of human infants, human mothers appear less constrained by their reproductive systems than are chimpanzee mothers. These data support the view that the social context of reproduction has been a fundamental contributor to changes in life history.

Elizabeth Cashdan - Sex Differences in Mobility and Wayfinding: Cross-Cultural Perspectives
2015-11-30 00:00
Elizabeth Cashdan: University of UtahSex differences in range size and navigation are widely reported, with males traveling farther than females, being less spatially anxious, and, in many studies, navigating more effectively. We want to know why males range farther, and what this might tell us about sex differences in wayfinding and spatial confidence. Proposed evolutionary explanations have suggested that males gain mating benefits from large ranges (mating hypothesis), while females incur greater fitness costs from such travel due to parenting constraints (parenting hypothesis). We find support for both hypotheses, but a comparison of the polygynous Twe and the monogamous Maya suggests that the importance of the two hypotheses varies facultatively with mating patterns. Our work in Utah also indicates that women’s greater harm avoidance is a partial mediator of the sex difference in mobility, which in turn affects navigational style and ability.

Brenna Henn - Answering Major Questions in Modern Human Origins with Genome Data
2016-01-04 00:00
Brenna Henn: SUNY Stony BrookOver twenty-five years ago, geneticists sequenced mitochondrial DNA from a diverse sample of human populations and hypothesized that all humans have a common origin in Africa 200,000 years ago.The broad outlines of this hypothesis remain remarkably unaltered, but many details of our African origin continue to be elusive. After decades of advances in human genetics, we are no longer data limited (either in terms of samples or genomic loci) but there is little consensus on most key issues. I will outline the models underlying the origin of modern humans. For example, was there a single ancestral population or multiple ancestral populations? Additionally, is there a discordance between anatomically modern humans and behaviorally modern humans? I will explore patterns of genetic diversity across Africa, the complex history of southern African KhoeSan groups and adaptations to African environments. I discuss whether genetic data supports archaeological data and suggest directions for future research.

Bruce Ellis - Childhood Experience, Development of Reproductive Strategies, and Health: An Integrative, Life History Framework
2016-01-11 00:00
Bruce Ellis: University of ArizonaLife history theory is used to explain how individuals adapt their physiology, behavior, and reproduction to different social and ecological conditions. Using a life history framework, I will present a program of research examining linkages between childhood experiences (including familial and extra-familial conditions), pubertal development, sexual activity, and health, highlighting the important distinction between harsh versus unpredictable environmental contexts, the special role of fathers in regulating daughters’ sexual development, differential susceptibility to environmental influences, and effects of life-history trade-offs on health. An evolutionary, life history perspective emphasizes that, when organisms encounter stressful environments, it does not so much disturb their development as direct or regulate it toward strategies that are adaptive under stressful conditions, even if those strategies are currently harmful in terms of the long-term welfare of the individual or society as a whole.

Marcus Hamilton - Biological Scaling and the Evolution of Human Ecology
2016-01-25 00:00
Marcus Hamilton: Santa Fe InstituteWe can observe, examine and study the world around us meaningfully at many scales. Biologists may study genes, populations, species, ecosystems, or the biosphere. Social scientists may study the behavior of individuals, the dynamics of cities, or aspects of the archaeological past. But of course, at a coarse-grained level we are all examining the same system, just at different scales, and so the question then becomes; how do we integrate across all these scales to understand something about the fundamental mechanisms driving the complexity of living systems, including humans? In this talk I will introduce the scaling approach to understand the structure and function of biological systems, and how we can leverage insights gained in the biological realm to understand how human ecology has evolved. I will argue that economies of scale are fundamental to life, including human societies, and the scaling approach provides a powerful mathematical and statistical framework for understanding why.

Stephanie White - Cycling in the Brain: Molecular Insights Into Vocal Learning
2016-02-01 00:00
Stephanie White: UCLAHumans and songbirds learn their vocalizations through social interactions and sensorimotor experience. These processes enlist implicit learning, a critical component of social cognition. Deficits in implicit learning including language disorders have devastating consequences for social integration and well-being. To treat or prevent these deficits, the neural mechanisms for learned vocal communication must be understood. Songbirds are one of the few animal models in which one can study the language subcomponent comprised by socially-learned vocal communication because, like humans but unlike rodents or non-human primates, they learn a significant portion of their vocalizations. They do so in a manner that exhibits key parallels to speech development and maintenance. Parallels include reliance on critical periods, cortico-basal ganglia circuitry, ongoing auditory inputs, hormonal factors and genes such as the forkhead transcription factor known as FoxP2. Using behavioral paradigms, we found that songbirds actively regulate their own levels of FoxP2 within area X, the basal ganglia sub-region dedicated to vocal learning. We paired this ethological approach with modern systems analytic techniques and found that singing activates distinct ensembles of gene expression in area X that are not similarly co-activated in adjacent tissue comprised of similar cell types. Thus, ‘molecular microcircuitry’ exists alongside anatomic and synaptic microcircuitry that, together, functionally specify the brain, in this case, for vocal learning. Behavior-linked regulation of this molecular microcircuitry appears critical for vocal learning.

Sean Prall - Immunity, Stress, and Development: The Role of Adrenal Androgens in Human Evolutionary Biology
2016-02-08 00:00
Sean Prall: University of Washington School of MedicineThe developmental pattern of adrenal androgen production is unique to humans and chimpanzees, and this pattern is thought to have important implications in human evolutionary biology. Unlike other hormones, the ultimate role of adrenal androgens is not well understood despite the important physiological roles these hormones play. The adrenal androgen DHEA in particular has been implicated in shaping cognitive evolution, acting in an adaptive fashion to buffer the effects of stress, and as an important agent in bolstering immunocompetence. Recent research in the pattern of development in orangutans suggests adrenal androgen production is shared across higher apes, and is not likely related to primate social conditions. In humans, DHEA is found to play potent and diverse roles in different aspects of immune function, suggesting an important role for human ecoimmunology. Additionally, DHEA is related to acute and chronic stress activation, and may play an adaptive role in shaping acute stress responses. These results shed light on an evolutionary and physiologically relevant hormone, and implicates DHEA as an important mediator of human life history strategies.

Paul Smaldino - Learning About Social Evolution with Extremely Unrealistic Models
2016-02-22 00:00
Paul Smaldino: UC DavisThe lives of social animals, none more so than humans, are shaped by cooperative interactions. Sharing, exchange, and synergy are the name of the game. Understanding the origins of cooperative behavior with any clarity often requires formalization of theories in the way of mathematical and computational models. These models by necessity ignore many details of an organism’s ecology, life history, and behavioral repertoire. Nevertheless, models provide crucial scaffolds for theory development, partly by explicitly declaring all of their assumptions and thereby making their limitations clear. That said, we can always stand to improve. I will discuss mathematical and computational models of the evolution of cooperative behavior, and how our assumptions about individual behavior, life history, and environmental structure influence our conclusions concerning how social populations evolve. In particular, I will focus on the advantages of complicated models in which life history and population structure are included, even when those factors are not the explicit targets of investigation.

Mirta Galesic - Early Development of Human Cooperation: The Role of Interdependence
2016-02-29 00:00
Mirta Galesic: Santa Fe InstituteThe importance and scale of cooperation in human societies is unmatched among other primates and is considered to be a major contributor to our species’ exceptional success. Given that cooperation seems so useful, it is surprising that it flourished only in humans but not in other primates who had similar cognitive abilities as our ancestors or lived in similar circumstances. Large-scale human cooperation is successfully explained by models of cultural group selection, but these models require a relatively advanced social cognition already in place. To explain early origins of human social cognition and cooperation, cooperative breeding and cooperative foraging accounts have been proposed. However, computational models of these accounts that would enable more precise understanding of the underlying mechanisms are still scarce.
We develop a computational model of one possible mechanism underlying the early development of human cooperation, based on interdependence. We show that the interdependence might have increased because several otherwise non-remarkable and ubiquitous factors came together for our early ancestors: specific physical properties of Early Pleistocene environments, characteristics of our early ancestors’ social structure, and their cognitive abilities. Together, these factors might have led to increased value of group foraging, which in turn led to increased interdependence, and eventually to higher propensity to share food with non-kin. This propensity could have been instrumental for the development of further prosocial tendencies, ultimately paving the way for the development of large-scale cooperation through cultural group selection, emerging in Middle and Late Pleistocene.

Jeff Winking - State of the Union: The Fate of the Paternal Investment Model of Human Marriage
2016-03-07 00:00
Jeff Winking: Texas A&MFathering traditionally played a central role in the evolutionary stories of human marriage. Paternal investment proved a convincing lynchpin linking together numerous hallmark aspects of the human adaptive strategy: the capacity for long-term romantic bonds, altricial infancy, extended juvenile dependence, etc. However, recent theoretical work suggests that the importance of paternal investment is an unlikely candidate for the primary selective force behind the evolution of long-term pairing in humans; indeed, paternal care likely evolved within the context of pre-existing pair-bonds. Here I explore the numerous scenarios that have been put forth to explain the “marriage-first” phylogenetic order and the role that paternal investment still plays in reconstructing the evolution of human pair-bonding.

Chris Kuzawa - Brain Energetics and The Evolution of Human Childhood
2016-03-28 00:00
Chris Kuzawa: Northwestern UniversityHumans are unusual in having a childhood stage characterized by a prolonged period of exceptionally slow growth. Many hypotheses have been proposed to explain why humans have evolved this life history stage. In this talk, Chris Kuzawa will discuss his recent collaborative work that quantifies the costs of human brain development and uses this information to shed light on the evolution of human life history. Compiling data from brain imaging studies, they find that the costs of the brain do not peak at birth, when relative brain size is largest, but at 4-5 years of age, when the brain consumes the equivalent of 66% of the body’s energy use at rest. This childhood peak in brain costs reflects the proliferation of energy-intensive synapses prior to experience-driven synaptic pruning. Consistent with the hypothesis of a brain-body growth trade-off, body weight growth rate follows an inverse, linear relationship with brain glucose demands from infancy until puberty, and maximal brain glucose demands co-occur developmentally with the age of slowest body weight gain. These findings provide rare empirical evidence that humans evolved very slow body growth to free up energy for our unusually costly brain development. In addition, the finding that the peak in brain energy needs occurs after the age of weaning in most traditional small-scale societies shows that much of the energetic costs of human brain development are not provided by maternal metabolism, but by social provisioning and allocare.

Robbie Wilson - Costs and Benefits of Dishonest Communication: Parallels Between Cheating Crustaceans and Diving Soccer Players
2016-04-04 00:00
Robbie Wilson: University of QueenslandAnimals routinely compete for access to limited resources, including food, territories or mates. Because combat is energetically costly and increases the risk of injury or death, individuals should avoid fighting unless they have a reasonable chance of winning. Specialised structures such as teeth, claws or horns can be used to show off potential strength, so that opponents can assess each other without contact and decide whether or not to escalate. In most cases, animals should only fight when the competitors are closely matched, possess similar perceived strengths, and when the resources are valued highly. But what happens if the signal is difficult to interpret, or is an unreliable indicator of strength? Crustaceans use their claws in fighting, but since the claw muscles are hidden within an exoskeleton, competitors cannot determine each other’s true strength without contact. This situation allows some individuals to deceive others and gain more resources by growing large claws that appear strong but are actually weak. In this talk, I examine the costs and benefits of dishonest communication in crustaceans to understand how such strategies evolve in nature. In addition, I use a similar approach to explore the expression of one of the most maligned behaviours in world sport – when soccer players pretend to be kicked by opponents and ‘dive’ to the ground to fool referees. Using these very different but parallel study systems, I will discuss how signals are kept mostly honest in nature and how this impacts human communication when aggression may be based on unreliable information.

Rose Scott - Can Babies Read Minds? False-Belief Reasoning in Early Childhood
2016-04-11 00:00
Rose Scott: UC MercedA large part of our daily lives involves interpreting other people’s behavior in terms of their underlying mental states. In particular, the capacity to recognize that others may hold and act on false beliefs plays a vital role in social interactions. The question of when and how false-belief understanding develops is currently the subject of considerable debate. In this talk, I will present recent evidence suggesting that a robust understanding of belief is present in infancy, but children’s ability to demonstrate this understanding depends on situational demands. I will also discuss ongoing projects that explore how cultural factors might give rise to individual variation in the use of this ability.

Ed Vul - Do People Make Decisions Via a Bag of Error-Prone Tricks?
2016-04-18 00:00
Ed Vul: UC San DiegoHuman behavior is robust, adaptable, and, human behavior often deviates from the utility maximizing “rational” agent. This is usually attributed to people relying on an assortment of cheap heuristics to make efficient, but frequently biased, decisions. While the heuristics and biases research program has highlighted the many deviations of human behavior from that of simplistic economical agents, it has also yielded a morass of idiosyncratic, unreliable, and often contradictory biases, with no method to decide which heuristics will play a role in a given situation. Here I will describe our recent progress on an alternate approach: accounting for the successes and foibles of human behavior by assuming that people are more sophisticated, robust, and probabilistic than simple economic agents, but must carry out these sophisticated inferences under cognitive resource constraints. This approach yields a single framework for human decision-making: resource-rational probabilistic inference. This parsimonious, predictive account reconciles economic and psychological models of decision making and behavior.

Jerry Siegel - Natural Sleep and Its Seasonal Variations in Three Pre-Industrial Societies
2016-04-25 00:00
Jerry Siegel: UCLAHow did humans sleep before the modern era? Because the tools to measure sleep under natural conditions were developed long after the invention of the electric devices suspected of delaying and reducing sleep, we investigated sleep in three preindustrial societies[1-3]. We find that all three show similar sleep organization, suggesting that they express core human sleep patterns, likely characteristic of pre-modern era Homo sapiens. Sleep periods, the times from onset to offset, averaged 6.9-8.5-h, with sleep durations of 5.7-7.1-h, amounts near the low end of those industrial societies[4-7]. There was a difference of nearly 1-h between summer and winter sleep. Daily variation in sleep duration was strongly linked to time of onset, rather than offset. None of these groups began sleep near sunset, onset occurring, on average, 3.3-h after sunset. Awakening was usually before sunrise. The sleep period consistently occurred during the nighttime period of falling environmental temperature, was not interrupted by extended periods of waking and terminated, with vasoconstriction, near the nadir of daily ambient temperature. The daily cycle of temperature change, largely eliminated from modern sleep environments, may be a potent natural regulator of sleep. Light exposure, was maximal in the morning greatly decreasing at noon, indicating that all three groups seek shade at midday and that light activation of the suprachiasmatic nucleus is maximal in the morning. Napping occurred on <7% of days in winter and <22% of days in summer. Mimicking aspects of the natural environment might be effective in treating certain modern sleep disorders.

Athena Vouloumanos - How Early Perceptual Biases Shape Human Communicative Development
2016-05-02 00:00
Athena Vouloumanos: New York UniversityLike many animals, human infants have biases for the vocalizations of their own species, preferring speech to many non-speech sounds just hours after birth. How do these early proclivities develop and how do they contribute to human communicative development? In her talk, Athena Vouloumanos will draw from behavioral and neural data to discuss how early human perceptual biases are quickly refined and how infants come to recognize that speech is a means for communication, allowing one person to transfer information to others. Before preverbal infants produce or understand many words, they recognize how speech is used by others to communicate about different types of entities in the world. This early communicative competence may provide infants with a channel for learning from others and lay a foundation for our social and cultural life as humans.

Anne Warlaumont - Modeling the Evolution and Development of Human Vocalization
2016-05-09 00:00
Anne Warlaumont: University of California, MercedHumans use a wide variety of types of vocal signals to communicate with other humans. Some of these sounds, such as crying, shrieking, and laughing, are thought to be closely related to those of our primate relatives. Others, especially babbling, speaking, and singing, appear to rely to a great extent on learning during infancy and early childhood. I will present a set of computational models that attempt to provide an account for how selection pressures and physiological mechanisms combined to create the adult human vocal repertoire.

Jessica Lynch Alfaro - Comparative Phylogenomics, Biogeography and Conservation of Neotropical Primates
2016-09-26 00:00
Jessica Lynch Alfaro: UCLANeotropical primates represent one of the most successful mammalian radiations in the Neotropics, and all living platyrrhine monkeys in Central and South America stem from a single common ancestor from about 22 Ma. Neotropical primates exhibit extreme morphological and behavioral diversity, from the tiny pygmy marmoset to the ape-like muriqui, and they occupy not only rainforest habitats, but dry forests, savannah-like habitats, and high altitude geography in the Andes. However, about 45% of Neotropical primate taxa are now ‘red listed’ as threatened species by the IUCN, and more information is needed to characterize Neotropical primate biodiversity. Fortunately, studies on the phylogenetic relationships and evolutionary history of Neotropical primates have increased dramatically in recent years using collaborative international efforts at data collection and new techniques in genomics and biogeography. Here I present a comparative perspective of Neotropical primate biogeography, elucidating the geographic barriers, geologic events, and biotic factors most important to shape the primate diversity we see today. I also discuss the impact that phylogenomic and biogeographic studies have had on taxonomy and conservation priorities for this important Neotropical group, and consider what behavioral or life history attributes buffer some primates’ extinction risk in the face of anthropogenic change.

Gandhi Yetish - Sleep as an Evolved Behavior: Ecological Opportunity Costs and Sleep Optimization
2016-10-03 00:00
Gandhi Yetish: University of New MexicoShort
sleep duration is associated with numerous, sometimes severe, negative health outcomes, and yet many people report regularly sleeping insufficiently. Part of the challenge in improving poor health practice lies in the fact that a consensus definition of “good”
sleep remains lacking. In the scope of my dissertation research, I (with many collaborators) have sought to implement an evolutionary and ecological perspective to address this issue (in part). We argue that sleep is not only as a physiological state of being,
but as a behavior of sorts, regulated by shifting opportunity costs. In this talk, I will present three semi-independent studies that together test the hypothesis that sleep on any given night is a flexible phenotype (or reaction norm) that responds dynamically
to short-term needs. The first study presents findings from Yetish et al., 2015, which compares sleep among three independent small-scale societies (Hadza, San, Tsimane) to assess the degree to which post-industrial sleep patterns reflect a pathological shift
in chronic sleep patterns (answer: little, if at all). The second two studies present early findings from works-in-progress that test the effects on sleep from two different types of opportunity costs: productivity and vigilance. Using a mixture of accelerometry
(for objective sleep measurements) and quantitative ethnographic interviews (for behavioral insights), we investigated how the need to procure food and the degree of exposure in a sleeping site affect sleep patterns among Tsimane hunter-horticulturalists in
Amazonian Bolivia, and find support for the proposed opportunity cost tradeoff model of sleep optimization.

Michelle Brown - Choose Your Battles: Individual Motivations for Participation in Collective Aggression
2016-10-10 00:00
Michelle Brown: University of California, Santa BarbaraGroup?level competition has important effects on individual fitness and is thought to be a crucial force in the evolution of complex social systems. However, such conflicts represent a collective action problem: if all group members share the spoils of battle but only a few incur the costs of fighting, why do participators tolerate free?riders and continue to provide a collective good? In humans, this problem is surmounted by punishing defectors and rewarding participants, but these mechanisms have not been observed in other group-living species. In a large-scale study of redtail monkeys (Cercopithecus ascanius) at the Ngogo site in Kibale National Park, Uganda, I test the underlying assumption that a collective action problem is an inherent feature of intergroup conflicts. In particular, I ask whether participants and defectors experience differing costs and similar benefits during conflicts, measured as changes in energy balance. My research indicates that individual motivations fluctuate over time, but individuals can nonetheless be categorized as either conditional participants or conditional defectors.

David Lawson - Is polygynous marriage a harmful cultural practice?
2016-10-17 00:00
David Lawson: University of California, Santa BarbaraRecent years have witnessed a widening commitment to achieving gender equality at a global scale, with corresponding, and often controversial, shifts in international and domestic policy. In developing world regions, this includes efforts to abolish long-held cultural institutions that are ostensibly harmful to women. Yet such efforts are largely driven by good intentions and ethnocentric rhetoric, rather than theoretically or empirically driven insights. In this talk I interrogate the claim that polygynous marriage in Sub-Saharan Africa represents a ‘harmful cultural practice’. Using evolutionary anthropology as a guiding theoretical framework, I review the extant literature on polygyny and its consequences and present the results of a recent study of marital status, food security and child health in Tanzania spanning over 50 villages. I conclude that polygynous marriage cannot be considered universally harmful, and that future research and policy must pay greater attention to identifying locally realizable alternatives and context dependency when considering the health implications of cultural practices.

Andrew Whalen - Integrating Social Learning Into Models of Reinforcement Learning
2016-10-31 00:00
Andrew Whalen: University of EdinburghSocial learning and asocial learning are sometimes seen as two conflicting ways in which individuals make decisions and learn about the world around them. Increasingly research has found that instead of being two conflicting learning processes, individuals, including children, will combine social and asocial sources of information to make decisions. One approach to understanding how social information might be integrated into other learning processes is by studying already well established models of human and animal learning. We present work that tries to understand how social information might be integrated into models of reinforcement learning, particularly temporal difference (TD) learning. Using a series of simulations we demonstrate that, unlike other simulation studies that treat social and asocial learning separately, social learning is nearly always beneficial, and that small amounts of social learning allows for the formation of stable traditions of complex socially transmitted behaviors in artificial populations. To better understand how social and asocial information is combined in humans, we ran a series of experiments to analyze how social learning impacts reinforcement learning, and find that individuals use social learning both to choose the actions that they perform, and as a secondary reinforcer that alters the associations they build between actions and rewards. These results highlight the importance of understanding how social and asocial sources of information are integrated on fine temporal scales for understanding the evolution of social learning and human culture.

Barney Schlinger - Sexual Selection for Grace, Speed, Strength and, Oh Yes, Noise!
2016-11-07 00:00
Barney Schlinger: UCLAManakins are a clade of extraordinary neotropical birds. In many species, the brightly–colored males are polygynous, performing no parental care duties, but they gather into leks for courtship. Over the past 20 years, my lab has performed detailed behavioral studies of golden-collared manakins (Manacus vitellinus) of Panamanian rainforests. These males clear display courts (by moving debris more than double their own body weight) where they perform elaborate, athletic courtship dances that are visually stunning, especially when viewed in slow motion. As part of court defense and courtship, males produce explosive snapping sounds by powerfully and rapidly throwing their wings together so their wrists collide over their heads. We find that females prefer to copulate with those males whose displays are quick and accurate and noisy. Anatomical (skeletal and musculature) and physiological (neural and endocrine and cardiovascular) studies show that males have evolved a variety of specializations that enable these extreme behavioral phenotypes. I describe a subset of this body of work in the context of mate choice theory, the evolution of communication and the value of perceiving the gestalt of a single organism.

Dan Conroy-Beam - A Multidimensional Approach to Human Mate Selection
2016-11-14 00:00
Dan Conroy-Beam: UC Santa BarbaraHuman mating research is largely motivated by an assumption that mate choice is guided by mate preferences. But the field knows little about the psychology responsible for translating preferences into downstream outcomes. Stated differently, what do mate preferences do and how do they do it? I present data from a series of studies exploring these questions using two empirical strategies: agent-based models and research on actual mated couples. First, I use a model of human mate choice evolution to compare the evolvability of several alternative algorithms for integrating mate preferences in mate selection. The findings support a novel hypothesis: human mate preferences are integrated by a Euclidean algorithm that represents preferences and potential mates as points within a common multidimensional preference space. I then apply this novel Euclidean algorithm to test hypotheses concerning a variety mating outcomes—attraction to potential mates, mate selection, and the calibration of mate preferences. Findings reveal that (1) Euclidean distances from ideal mate preferences predict attraction to potential mates, (2) chosen mates tend to fall close to mate preferences in preference space, (3) Euclidean measures of mate value predict people’s ability to fulfill their mate preferences and attract desirable mates, and (4) people calibrate their ideal mate preferences to their mate value as measured by a Euclidean algorithm. These findings highlight the utility of a multidimensional, Euclidean model of mate preference psychology for understanding how human psychology translates mate preferences into downstream mating outcomes.

Ian C. Gilby - Pan the hunter: Chimpanzee predation and human evolution
2016-11-21 00:00
Ian C. Gilby: Arizona State UniversityIn order to understand the causes and consequences of the significant increase in meat consumption in hominins, we must first make inferences about the behavior of the last common ancestor (LCA) of apes and humans. Chimpanzees, which regularly hunt vertebrates, are a valuable point of reference for understanding the possible range of behavior exhibited by the LCA. I use long-term data from three communities in Tanzania and Uganda to determine why and how chimpanzees hunt. While chimpanzees exhibit a wide range of cooperative abilities, I will argue that in the context of hunting, cognitively complex mechanisms involving delayed, social benefits and/or shared intentions explain only a small proportion of the cooperation observed in the wild. Therefore, reliance upon such mechanisms in humans evolved after our lineage split from the great apes. Additionally, I will discuss the constraints on hunting faced by female chimpanzees, and will argue that similar factors provided a foundation for the evolution of the sexual division of labor in hominins.

Noa Pinter-Wollman - Individual Variation in Collective Behavior
2016-11-28 00:00
Noa Pinter-Wollman: UCLAMany biological systems are aggregates of individuals working synergistically to achieve collective goals. In social insects, evolution acts on variation in the emergent collective behaviors of the colony. Variation among colonies in collective behavior can result from differences in their composition and/or from differences in the environments in which they reside. To understand how environment and group composition shape collective outcomes I study the causes and consequences of individual variation in the behavior of both workers and colonies of ants and social spiders. Using field and lab studies combined with computer simulations, image analysis, and social network theory I show that both behavioral composition and spatial constraints shape collective outcomes. For example, exploratory individuals increase a group’s ability to detect high-quality nest sites, and nest architecture influences collective foraging dynamics. These findings demonstrate that social and physical environments interact to influence complex biological processes.

Patty Gowaty - Standing on Darwin’s Shoulders: Sexual Selection and Bateman’s Principles
2017-01-09 00:00
Patty Gowaty:

Catherine Salmon - Evolutionary Perspectives on Anorexic Behavior: Ancestral Mechanisms in the Modern World UCLABEC
2017-01-16 00:00
Catherine Salmon: University of RedlandsA compelling puzzle of our modern world is the disturbing obsession of some women with body image and dieting. Why do so many women in North America place such an emphasis on being thin? Why do these desires lead to eating disorders in only some women? It is commonly assumed that the desire for a thin female physique and its pathological expression in eating disorders result from a social pressure for thinness. In recent years, anorexia nervosa and bulimia have become the most attention grabbing eating disorders with a multitude of studies being published from a variety of perspectives. With all this attention, one would think that we would have a concrete understanding of the causes of eating disorders and yet there have been a plethora of theories that have been proposed in the literature. In my talk, I will review several adaptationist approaches to the study of dieting behavior, focusing on my work with colleagues on the link between reproductive suppression, dieting, parental and social pressures, and life history strategy.
