Center for Behavior, Evolution, and Culture

Aimee Plourde - The Evolution of Prestige Good Economies and the Origins of Sociopolitical Complexity
2004-02-09 00:00 (America/Los_Angeles)
Aimee Plourde: UCLA Dept. of AnthropologyThe emergence of social ranking and political hierarchy in human society constituted a fundamental departure from the small, egalitarian group structure thought to characterize society for most of our speciesâ€™ history. Explaining the origins of social ranking is thus key to understanding the underlying structures of modern human societies, and the evolutionary processes that have generated them. Archaeologists have argued that the emergence of an economy of prestige goods in prehistory provided a critical means for leaders in chiefdom-level societies to attract followers and establish hierarchical relations with elites in neighboring polities. However, these arguments fail to explain the initial attraction of prestige goods themselves. Here I present a model for the evolution of psychological mechanisms that value prestige goods, and outline the evolving role of prestige goods in the negotiation of hierarchy at increasing levels of political ranking. This model is assessed against archaeological excavation and survey data collected in the northern Lake Titicaca Basin of highland Peru. The data demonstrate that strong correlations exist between increasing polity size and political hierarchy on the one hand and increasingly direct control of the trade routes used to procure prestige items on the other.

Chris Boehm - Two Anthropological Models for Understanding Global Conflict Resolution
2004-02-02 00:00
Chris Boehm: USC Dept. of AnthropologyChimpanzees and human hunter-gatherers are taken as models which help to explain our troubled world of nations, which in many ways is like a chimpanzee community with dominant alpha nations that throw their weight around—but in others is like a hunter-gatherer band, in which the group sees to it that no one individual is permitted to be too “alpha.” In the latter sense, the United Nations is set up politically so that no single nation can dominate it because of the veto, and the resultant world of nations looks nothing like a single nation, which has sufficient coercive force at the political center to prevent most internecine conflict. Turning to the chimpanzee model again, there, too, coercive force is used within the society to control conflict, with alpha males displaying at combatants and separating them until they have cooled off. Distinctively, the alpha male mediation role is an even-handed one, even if the combatants are respectively allies and enemies of the alpha. Practical lessons to be learned come in the form of insights into problems and possibilities for creating a more effective world government, and in informing the world’s superpowers that conflict resolution, to be effective, should be even-handed. The Israeli-Palestinian case is taken briefly as an example.http://www.bec.ucla.edu/papers/Boehm_1-12-04.rtf

Jerome Siegel - The Phylogeny of Mammalian Sleep
2004-01-26 00:00
Jerome Siegel: UCLA Dept. of PsychiatrySleep amounts vary by more than an order of magnitude across mammalian species. Either the amount of time spent sleeping has no relation to underlying function, which would distinguish sleep from many other homeostatically regulated processes, or sleep need varies considerably across species.
Prior data and new data on primitive mammals and cetaceans indicate a strong negative correlation between total sleep time and weight. Because metabolic rate is strongly and negatively correlated with body mass, this is also a positive correlation between metabolic rate and sleep time. Some evidence suggests that brain regions with high metabolic rate have higher levels of sleep deprivation induced damage. We hypothesized that non REM sleep serves to repair damage caused by oxidative stress (Eiland et al., 2002; Ramanathan et al., 2002).
REM sleep and nonREM sleep amounts are positively correlated. One explanation for this is that REM serves to stimulate the brain to prepare for waking after a period of nonREM (Ephron, Carrington, 1966; Snyder, 1966; Vertes, 1986).
However, much of the variation in REM amounts is independent of nonREM duration. Animals born in a relatively immature state, have more REM early in development (Jouvet-Mounier, 1970). One may hypothesize that REM facilitates development. A major mystery is why immaturity at birth is correlated with REM time in adulthood.
Cetaceans show unihemispheric sleep, with both hemispheres never being in deep sleep at the same time. Fur seals show both unihemispheric sleep and bihemispheric sleep and can switch between these two modes. Unihemispheric sleep appears to largely do away with sleep rebounds after deprivation of bilateral sleep. Unihemispheric sleep is linked to low or absent REM sleep. Understanding the mechanisms and functional relations underlying these unusual sleep adaptations of marine mammals can offer a major insight into the function and mechanisms of sleep.

Gary Marcus - Language in the era of the Genome
2004-01-12 00:00
Gary Marcus: NYU Dept. of PsychologyTwo of the most central questions in understanding the nature of the uniquely human talent for language are the extent to which the underlying neural machinery is “innate” (or “built-in”), and the extent to which that machinery is specialized for language as opposed to other cognitive functions. In this talk, I show how recent research in genetics and developmental neuroscience suggests new ways of thinking about these questions.

Patricia Churchland - What Happens to Free Will if the Brain is a Causal Machine?
2003-12-01 00:00
Patricia Churchland: UCSD Dept. of PhilosophyAlthough questions concerning the nature of free choice have long been at the center of philosophical reflection, new discoveries, especially from neuropharmacology and neuropsychology, have lent them a special and very practical urgency. In the courts, in the education of children, and in general in daily life, we assume that some decisions are freely made and that agents should be held accountable for those decisions. On the other hand, there is pressure to expand of the range of allowable excuses from responsibility, as we begin to understand the role of certain neuropathologies in aberrant behavior. These developments take place against the public policy debate concerning the right balance between considerations of public safety, justice, fairness, and individual freedom. From the perspective of neurophilosophy, I shall address some of the broad questions in this arena, including the evolutionary basis for cooperative behavior, the neurobiology of the difference between being in control and being out of control, and the role of emotions in biasing moral choice.

Olav Sorenson - Social networks and exchange: Self-confirming dynamics in Hollywood
2003-11-24 00:00
Olav Sorenson: UCLA Anderson School of ManagementStudies have consistently found that social structure influences who transacts with whom, and that actors appear to benefit when exchange occurs embedded within these relations rather than in an unstructured market. Explanations for these results frequently point to their effectiveness in solving problems inherent in the trade of certain products and services, focusing on the ability of these social networks to provide access to private information regarding the quality of the goods or to allow participants to enforce the terms of the exchange agreement. In investigating these dynamics in the interaction between movie producers and distributors, this paper, however, suggests that a type of self-confirming prophecy can also produce such effects: One party frequently offers better terms of trade in transactions embedded within existing social relations, thereby contributing to the apparent benefits of such exchange patterns. In the motion picture industry, not only do distributors show a preference for carrying films involving key personnel with whom they have prior relations, but also they tend to favor these films when making decisions regarding their release â€“ in determining opening dates and the amount of resources devoted to marketing. Empirical estimates of the performance of movies in the U.S. box office reveal that â€“ when models fail to account for these key decisions â€“ distributors appear to benefit from carrying movies affiliated with known parties, suggesting that they have private information regarding the quality of the talent involved. After controlling for marketing effort and seasonality, however, these effects disappear, indicating that, rather than arbitraging price-quality inconsistencies, distributors produce these effects through their own efforts.http://www.bec.ucla.edu/papers/Sorenson_11-24-03.pdf

Michael Rose - The Evolution of Free Will
2003-11-17 00:00
Michael Rose: UC Irvine Dept. of Ecology & Evolutionary BiologyHuman behavior is unlike that of all other known animal behavior in its high degree of flexibility and versatility. A problem that is given less attention than it deserves is that flexible behavior is difficult to explain in Darwinian terms. “Free will” poses a challenge to the focus of Darwinian evolution: evolutionary fitness. With free will, individuals can choose to forego reproduction, choose to give away their resources, and so on. In this talk, a possible explanation for the evolution of such human free will is offered and the mechanism(s) by which it is constrained are considered.

Trent Smith - A Theory of Natural Addiction
2003-11-10 00:00
Trent Smith: UCLA International InstituteThe economic theory of “rational addiction” posits that drug addiction can usefully be viewed as the outcome of an informed decision undertaken on the part of the consumer. I employ a complementary approach to developing a behavioral theory of addiction by identifying circumstances under which addiction-like behavior is the solution to an adaptive problem faced by humans in the pre-industrial world. The empirical validity of this approach is then demonstrated with an in-depth review and synthesis of the biomedical literature concerning the action of opiates in the mammalian brain and their effects on behavior. There is strong evidence that addiction is the manifestation of a mismatch between behavioral algorithms encoded in the human genome and the expanded menu of choices–generated for example, by advances in drug delivery technology–of consumers in the modern world. Specific implications for economic theory and public policy will be discussed.http://www.bec.ucla.edu/papers/Smith_11-10-03.pdf

Ann Senghas - The differentiation of grammatical elements in Nicaraguan Sign Language over historical and ontogenetic developmental timelines
2003-11-03 00:00
Ann Senghas: Barnard College of Columbia University, Dept. of PsychologyThe recent emergence of a new sign language among deaf children and adolescents in Nicaragua provides an opportunity to study how linguistic features of a language arise and spread. New features that arise must be successfully transmitted from one generation to the next to survive as part of the language. During this transmission, language form is shaped by both the characteristics of ontogenetic development within individual users and by historical changes in patterns of interaction between users. To capture this process, changes over the past 25 years will be examined within two domains: expressions of manner and path of movement, and expressions of spatial co-reference. These data reveal that, as the new language is learned, holistic and analog expressions are being replaced by discrete, combinatorial expressions. It appears that these new form-function mappings arise among child learners who functionally differentiate previously equivalent forms. The new mappings are then acquired by their age peers (while children), and by subsequent generations of children who learn the language, but not by adult contemporaries. As a result, language emergence is characterized by a convergence on form within each age cohort, and a systematic mismatch in form from one age cohort to the cohort that follows. In this way, each age cohort, in sequence, systematically transforms the language environment for the next, enabling each new cohort of learners to develop further than its predecessors.

Tim German - Acquiring an understanding of design: Developmental and cross-cultural evidence
2003-10-27 00:00
Tim German: UCSB PsychologyThe human ability to make tools and use them to solve problems may not be zoologically unique, but it is certainly extraordinary. Yet little is known about the conceptual machinery that makes humans so competent at making and using tools. Do adults and children have concepts specialized for understanding human-made artifacts? If so, are these concepts deployed in attempts to solve novel problems? In this talk I will review evidence from children’s insight problem solving tasks which suggests that there are changes in the way that artifact concepts organize knowledge in problem solving over the late preschool and early school age years. I characterize this as children beginning to take a ‘design stance’ with respect to their representation of artifact concepts. One effect of this change in artifact representation manifests as decreases in the flexibility with which tools are employed to solve novel problems. I will also present preliminary evidence for the possible effect of a ‘design stance’ on adult problem solving in a non technologically promiscuous culture.http://www.bec.ucla.edu/papers/German_10-27-03.pdf

Peter Gray - Pair-bonding, parenting and human male testosterone variation
2003-10-20 00:00
Peter Gray : Charles Drew UniversityTwo hallmarks of human male reproductive strategies are the formation of long-term bonds with a mate and the provision of paternal care. These activities may, in part, be exclusive to male-male competition and mate-seeking, the main components of mating effort. From a complementary, mechanistic perspective, the steroid hormone testosterone (T) may modulate behavioral allocation to male mating and parenting effort. I present a growing body of evidence addressing this proposition. This evidence includes four studies that colleagues and I have conducted in the U.S. as well as data on Kenyan Swahili men that help provide a cross-cultural perspective.http://www.bec.ucla.edu/papers/Gray_10-20-03.pdf

Carl Bergstrom - Information in Biology
2003-10-13 00:00
Carl Bergstrom: University of Washington Dept. of BiologyOver the past 3.5 billion years, biological organisms have evolved to acquire, process, store, and transmit information. How have organisms evolved to handle the same problems with which we are confronted in this so-called Information Age: problems of information storage and processing, problems of transmission and reliability, problems of trust and deception? For all the attention that is directed toward the changing conception of information and its function in our world, remarkably little is known about the broad role of information in biological systems.
In dealing with information, similar strategic problems are faced across levels of organization. Moreover, a similar process – evolution
by natural selection – has generated the solutions that we observe. I argue for the value of a comparative theoretical approach to understanding the problems inherent in information handling, using examples at scales from intracellular regulation to human communication.http://octavia.zoology.washington.edu/signalling/peacock.pdf

Jared Diamond - Environmental fragility: What was special about Easter Island?
2003-10-06 00:00
Jared Diamond: UCLA Dept. of GeographySome societies have suffered environmental collapses in the past (Easter Island, Angkor Wat, Anasazi, Classic Mayaâ€¦), while others have remained intact for thousands of years (Japan, Northwest Europe, Java, Tikopiaâ€¦). Some countries are close to collapse today, while others are not. What makes some societies more fragile than others? Authors variously seek either geographic or cultural explanations. Barry Rolettâ€™s and my recent re-analysis of Easter Island shows the importance of both types of explanations. Analysis of a data-base of 80 Pacific islands whose societies had widely differing outcomes reveals nine geographic variables predisposing towards deforestation. Easter was especially fragile on almost all nine counts. But there were also four cultural factors that contributed. In short, collapses arenâ€™t accidents.

Peter Sozou - Discounting the future: an evolutionary approach to ageing and time-preference behaviour
2003-09-29 00:00
Peter Sozou: London School of EconomicsDiscounting occurs when an immediate benefit is systematically valued more highly than a delayed benefit. This talk is concerned with understanding both the causes and effects of discounting from an evolutionary point of view, as reflected in physiological and behavioural strategies of organisms.
I’ll start by looking at the evolutionary theory of ageing. Extrinsic mortality (together with population growth where applicable) means that immediate reproduction makes a greater contribution to fitness than an equivalent amount of potential reproduction after a delay. This leads to the principle of the diminishing importance of the future. Ageing may be the outcome of a trade-off between short-term fertility and long-term maintenance. I will (briefly) present some new results showing conditions which determine whether an ageing or a non-ageing strategy will be favoured under such a trade-off.
The effects of ageing – declining fertility and increasing mortality – give an organism additional reason to prefer immediate over delayed reproduction in its behavioural time-preference choices. That is, an animal should discount the future not only because of external factors (extrinsic mortality, population growth), but also because of its own evolutionary response to those factors in the form of ageing. By this analysis, ageing is both a consequence and a cause of discounting.
Using this framework, a series of models is developed, making different assumptions about external hazards and biological ageing. With realistic ageing assumptions – increasing mortality and an accelerating rate of fertility decline – the time-preference rate increases in old age. Under an uncertain external hazard rate, young adults should also have relatively high time-preference rates because their (Bayesian) estimate of the external hazard is high. The middle-aged may therefore be the most long-term in their outlook.http://www.bec.ucla.edu/papers/Sozou_9-29-03.pdf

Jessica Lynch Alfaro - Comparative Phylogenomics, Biogeography and Conservation of Neotropical Primates
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.

Jacinta Beehner -
Jacinta Beehner:
