Monday, March 26, 2007

Evolution and Human Behavior

It looks like the Bentley, Lipo, Herzog and Hahn paper Regular rates of popular culture change reflect random copying paper is going to published in Evolution and Human Behavior some time this week. You can download a copy of the paper here: We are also doing a press release for this through CSULB and the University of Durham. Here's the text of the PR that is slated to go out shortly. (Cal State Long Beach draft v. 3/26/07) March 27, 2007 #2007-XXX Random Copying Influences Popular Trends More Than Rational Choices, Says International Study Group Including Cal State Long Beach Professor Identifying the next trend-forward thing can be a crucial prediction worth billions of dollars to marketers. Yet, the popularity of things like baby names, music, dog breeds or fashions will change at a constant rate regardless of population size through a process of people randomly copying trends, according to a new study by an international team of academics including a California State University, Long Beach professor. Controversially, this contradicts classic economic models which believe that people make rational choices about the clothes they wear, the way they dance or the music they listen to. Researchers at Durham University, England, as well as CSULB, Western Carolina University and Indiana University authored an article titled “Regular rates of popular culture change reflect random copying” that appears in the May issue of the journal Evolution and Human Behavior. It shows that almost all of us are copycats and it is guaranteed that our taste in music or baby names will change at a consistent rate over time, but there is no way of predicting how it will change as it is completely random. New ideas become highly popular by chance alone, and then over time are replaced by others, all through the process of copying with occasional innovation. Carl Lipo, an associate professor in anthropology at Cal State Long Beach and research scientist at CSULB’s Institute for Integrated Research on Materials, Environments and Society (IIRMES), said that the results demonstrate how relatively simple models can be used to explain remarkably complex phenomena. “What we demonstrate,” he stated, “is that the aggregate effect of simple rules often underlie what we see as organization at higher scales. We don’t need to invoke the idea of some individual or group for patterns to emerge.” Led by Alex Bentley of the Durham University Anthropology Department, the team looked at the Billboard Top 200 chart and found that it turned over at a constant average rate for over 30 years between 1950 and 1980. The number of albums entering and exiting the chart varied from day to day and month to month, but overall the average stayed fixed at 5.6 percent per month for the full 30-year period. A similar consistent turnover rate was established for the top baby names and dog breeds. Bentley also is associated with the Centre for the Evolution of Cultural Diversity, funded by UK’s Arts and Humanities Research Council. Psychology Professor Harold A. Herzog of Western Carolina University and biology Professor Matthew W. Hahn of Indiana University also participated in the study. Their real-world data was matched by computer simulations of a random copying model with 2,000 individuals copying each other from one instant to the next, with a small proportion of innovators (two percent or less). During the simulation, they kept track of the Top 40, Top 100 and other lists of popular trends and monitored how much turnover there was. The model predicted continuous and regular turnover matching the proof of the real-world data from the charts of baby names, music and dog breeds. How quickly a list will change depends on the size of the list—the more choices people have, the quicker trends become popular or unpopular. However, the research has found that the size of the population does not have an impact on the turnover of lists. Although a higher population means more new ideas are out there, the turnover on a top 100 list does not increase as there is more competition for any particular idea to reach the list. Marketing professionals who use viral marketing, which spreads information by word-of-mouth through social networks and the Web, often classify people as innovators, early adopters and copiers. “Innovators are the cool ones who don’t bother imitating other people, but instead ‘pump’ new fashions into our world,” Bentley said. “Most are ignored, but some get copied. If the innovator is already a ‘cool’ celebrity, it means something shoots up in popularity much faster than you would predict likely via random copying. However, turnover over time will still be constant. “The model we have discovered predicts that the turnover of fashion will be proportional to the square root of the proportion of innovators, regardless of population size,” he noted. Since it is a game of chance, the model cannot predict how any one particular fad will fare, or which trends will become fashionable, just that new trends will definitely emerge at a regular and predictable rate. The discovery that change is continual and regular under the random copying model means it could be a useful tool to predict change rates as well as distinguish copying from other forms of collective behavior. There are areas in society where random copying is desired. For example, community campaigns to recycle waste benefit by people randomly copying each other’s behavior. However, in other areas such as politics, rational, informed choices are desirable. # # # For further information, contact:
  • Dr. Carl P. Lipo, California State University, Long Beach, Department of Anthropology; Tel: +01 (562) 985-2393; e-mail:
  • Anne Ambrose, Public Affairs Office, California State University Long Beach, Tel: +01 (562) 985-2582,; or Rick Gloady, Tel: +01 (562) 985-5454; e-mail:
  • Dr Alex Bentley, Durham University, Anthropology Department; Tel: +44 (0)191 334 6198;
  • e-mail
  • Media and Public Affairs Office, Durham University; Tel: +44 (0)191 334 6075; e-mail
Notes to Editors About California State University, Long Beach California State University, Long Beach (CSULB) is one of 23 campuses of the California State University, the nation’s largest public university system. For the third consecutive year, U.S. News and World Report ranked CSULB among the top three public master’s universities in the western United States, and Princeton Review again named it a Best in the West. With an enrollment of 35,576, Cal State Long Beach is committed to being an outstanding teaching-intensive, research-driven university that emphasizes student engagement, scholarly and creative achievement, civic participation and global perspectives. Founded in 1949, CSULB offers bachelor’s, master’s and doctor of education (Ed.D.) degrees, along with several joint Ph.D.s with other institutions. Visit About IIRMES The Institute for Integrated Research in Materials, Environments, and Society (IIRMES) at California State University, Long Beach provides opportunities for research collaborations between faculty and students from CSULB’s College of Natural Sciences and Mathematics and College of Liberal Arts, as well as with other institutions, in a new interdisciplinary field that attempts to integrate the physical, natural and social sciences. Visit About the Anthropology Department at Durham University The Department is one of the very few anthropology departments in the UK that teaches and conducts research in both biological and social areas of the subject; with 29 permanent members of academic staff it is also one of the UK’s largest. In the last Research Assessment Exercise the Department was awarded a 5, denoting international excellence. Reflecting the department’s interdisciplinary research strategy, four of the department’s five research groups bridge the bio-social boundary. About Durham University Founded in 1832, Durham University aims to provide internationally recognised research, scholarship and learning within a distinctive collegiate environment. Based on two sites in Durham city and Stockton on Tees in the North East of England it has 15,000 students, employs 3,000 staff, has created 16 spin out companies since 2000 and has an annual turnover of over £175m, making it the equivalent of a top 50 North-East business. The Sunday Times University Guide for potential students named Durham University as ‘University of the Year in 2005.’ The University is collegiate, with colleges providing residential, social and welfare facilities for their student members, and creating a sense of community for staff and students together. Its academic teaching and research programmes are delivered through departments contained within three faculties: Arts and Humanities, Science, and Social Sciences and Health.

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