Stephen Shennan

Bio: Stephen Shennan is an academic researcher from University College London. The author has contributed to research in topics: Population & Prehistory. The author has an hindex of 52, co-authored 192 publications receiving 10207 citations. Previous affiliations of Stephen Shennan include Massachusetts Institute of Technology & Arts and Humanities Research Council.

Archaeology, demography and life history theory together can help us explain past and present population patterns.

Abstract: Population matters. Demographic patterns are both a cause and a consequence of human behaviour in other important domains, such as subsistence, cooperation, politics and culture. Demographers interested in contemporary and recent historical populations have rich data at their fingertips; the importance of demography means many interested parties have gathered demographic data, much of which is now readily available for all to explore. Those interested in the demography of the distant past are not so fortunate, given the lack of written records. Nevertheless, the emergence in recent years of a new interest in the demography of ancient populations has seen the development of a range of new methods for piecing together archaeological, skeletal and DNA evidence to reconstruct past population patterns. These efforts have found evidence in support of the view that the relatively low long-term population growth rates of prehistoric human populations, albeit ultimately conditioned by carrying capacities, may have been owing to 'boom-bust' cycles at the regional level; rapid population growth, followed by population decline. In fact, this archaeological research may have come to the same conclusion as some contemporary demographers: that demography can be remarkably hard to predict, at least in the short term. It also fits with evidence from biology that primates, and particularly humans, may be adapted to environmental variability, leading to associated demographic stochasticity. This evidence of the fluctuating nature of human demographic patterns may be of considerable significance in understanding our species' evolution, and of understanding what our species future demographic trajectories might be. This article is part of the theme issue 'Cross-disciplinary approaches to prehistoric demography'.

Introduction: Demography and Cultural Macroevolution

Abstract: The papers in this special issue of Human Biology, which derive from a conference sponsored by the Arts and Humanities Research Council (AHRC) Center for the Evolution of Cultural Diversity, lay some of the foundations for an empirical macroevolutionary analysis of cultural dynamics. Our premise here is that cultural dynamics-including the stability of traditions and the rate of origination of new variants-are influenced by independently occurring demographic processes (population size, structure, and distribution as these vary over time as a result of changes in rates of fertility, mortality, and migration). The contributors focus on three sets of problems relevant to empirical studies of cultural macroevolution: large-scale reconstruction of past population dynamics from archaeological and genetic data; juxtaposition of models and evidence of cultural dynamics using large-scale archaeological and historical data sets; and juxtaposition of models and evidence of cultural dynamics from large-scale linguistic data sets. In this introduction we outline some of the theoretical and methodological issues and briefly summarize the individual contributions.

A Future for Archaeology

Abstract: Over the last thirty years issues of culture, identity and meaning have moved out of the academic sphere to become central to politics and society at all levels from the local to the global. Archaeology has been at the forefront of these moves towards a greater engagement with the non-academic world, often in an extremely practical and direct way, for example in the disputes about the repatriation of human burials. Such disputes have been central to the recognition that previously marginalized groups have rights in their own past that are important for their future. The essays in this book look back at some of the most important events where a role for an archaeology concerned with the past in the present first emerged and look forward to the practical and theoretical issues now central to a socially engaged discipline and shaping its future. This book is published in honor of Professor Peter Ucko, who has played an unparalleled role in promoting awareness of the core issues in this volume among archaeologists.

Demography and Cultural Evolution

Abstract: Trying to explain the increase in cultural complexity over the long term of human history has long been an interest of anthropology and of historical social sciences more generally. In recent years, interest has grown rapidly in the idea that a key factor in accounting for it might be the size of the human population itself and the extent of interaction between people, because of the effect these have on the innovation rates in populations and on the success with which innovations are transmitted. An important driver of this growth of interest has been the emergence of the new interdisciplinary field of cultural evolution, which makes extensive use of mathematical techniques, especially methods derived from population genetics. The result has been the development of a range of analytical and computer simulation models that make various predictions about the way in which population size influences cultural change, and in particular the growth of cumulative culture, including the processes that have led from the very simple forms of culture possessed by other great apes to those characteristic of Homo sapiens. The aim of this review is to distinguish them, so that future work can focus on evaluating their strengths and weaknesses and the circumstances in which they are useful. Keywords: cultural evolution; cumulative culture; cultural complexity; effective population size; transmission fidelity; innovation; cultural loss; demography; population growth

Evolutionary Biological Methods and Cultural Data

Abstract: As BENTLEY ET AL. note in chapter 8 of this volume, Darwinian approaches to archaeology are rapidly gaining popularity, fueled in part by the recognition that cultural evolution can be fruitfully studied by adapting the analytical tools that evolutionary biologists and paleobiologists use to study biological evolution. The goal of this chapter is to illustrate how two of these methods, population genetics modeling and cladistic techniques of phylogenetic reconstruction, can be used to explain temporal and geographic variation in cultural phenomena as a result of transmission, innovation, and selection. We will begin by discussing the conceptual foundations of this novel approach. We will then outline some of the ways in which models rooted in population genetics theory have been used to investigate cultural evolution. Lastly, we will discuss some cultural evolutionary applications of the cladistic method of phylogenetic reconstruction.

The Web of Human Sexual Contacts

Abstract: Many ``real-world'' networks are clearly defined while most ``social'' networks are to some extent subjective. Indeed, the accuracy of empirically-determined social networks is a question of some concern because individuals may have distinct perceptions of what constitutes a social link. One unambiguous type of connection is sexual contact. Here we analyze data on the sexual behavior of a random sample of individuals, and find that the cumulative distributions of the number of sexual partners during the twelve months prior to the survey decays as a power law with similar exponents $\alpha \approx 2.4$ for females and males. The scale-free nature of the web of human sexual contacts suggests that strategic interventions aimed at preventing the spread of sexually-transmitted diseases may be the most efficient approach.

Massive migration from the steppe was a source for Indo-European languages in Europe

Abstract: We generated genome-wide data from 69 Europeans who lived between 8,000-3,000 years ago by enriching ancient DNA libraries for a target set of almost 400,000 polymorphisms. Enrichment of these positions decreases the sequencing required for genome-wide ancient DNA analysis by a median of around 250-fold, allowing us to study an order of magnitude more individuals than previous studies and to obtain new insights about the past. We show that the populations of Western and Far Eastern Europe followed opposite trajectories between 8,000-5,000 years ago. At the beginning of the Neolithic period in Europe, ∼8,000-7,000 years ago, closely related groups of early farmers appeared in Germany, Hungary and Spain, different from indigenous hunter-gatherers, whereas Russia was inhabited by a distinctive population of hunter-gatherers with high affinity to a ∼24,000-year-old Siberian. By ∼6,000-5,000 years ago, farmers throughout much of Europe had more hunter-gatherer ancestry than their predecessors, but in Russia, the Yamnaya steppe herders of this time were descended not only from the preceding eastern European hunter-gatherers, but also from a population of Near Eastern ancestry. Western and Eastern Europe came into contact ∼4,500 years ago, as the Late Neolithic Corded Ware people from Germany traced ∼75% of their ancestry to the Yamnaya, documenting a massive migration into the heartland of Europe from its eastern periphery. This steppe ancestry persisted in all sampled central Europeans until at least ∼3,000 years ago, and is ubiquitous in present-day Europeans. These results provide support for a steppe origin of at least some of the Indo-European languages of Europe.

A cross-cultural analysis of the behavior of women and men: implications for the origins of sex differences.

Abstract: This article evaluates theories of the origins of sex differences in human behavior. It reviews the cross-cultural evidence on the behavior of women and men in nonindustrial societies, especially the activities that contribute to the sex-typed division of labor and patriarchy. To explain the cross-cultural findings, the authors consider social constructionism, evolutionary psychology, and their own biosocial theory. Supporting the biosocial analysis, sex differences derive from the interaction between the physical specialization of the sexes, especially female reproductive capacity, and the economic and social structural aspects of societies. This biosocial approach treats the psychological attributes of women and men as emergent given the evolved characteristics of the sexes, their developmental experiences, and their situated activity in society.