Center for Behavior, Evolution, and Culture

Olav Sorenson - Social networks and exchange: Self-confirming dynamics in Hollywood
2003-11-24 00:00 (America/Los_Angeles)
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:
