Author

# Stephen Shennan

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

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05 Jun 2009-Science
TL;DR: A population model shows that demography is a major determinant in the maintenance of cultural complexity and that variation in regional subpopulation density and/or migratory activity results in spatial structuring of cultural skill accumulation.
Abstract: The origins of modern human behavior are marked by increased symbolic and technological complexity in the archaeological record. In western Eurasia this transition, the Upper Paleolithic, occurred about 45,000 years ago, but many of its features appear transiently in southern Africa about 45,000 years earlier. We show that demography is a major determinant in the maintenance of cultural complexity and that variation in regional subpopulation density and/or migratory activity results in spatial structuring of cultural skill accumulation. Genetic estimates of regional population size over time show that densities in early Upper Paleolithic Europe were similar to those in sub-Saharan Africa when modern behavior first appeared. Demographic factors can thus explain geographic variation in the timing of the first appearance of modern behavior without invoking increased cognitive capacity.

758 citations

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TL;DR: It is shown that the introduction of agriculture into Europe was followed by a boom-and-bust pattern in the density of regional populations, and the results suggest that the demographic patterns may have arisen from endogenous causes, although this remains speculative.
Abstract: Following its initial arrival in SE Europe 8,500 years ago agriculture spread throughout the continent, changing food production and consumption patterns and increasing population densities. Here we show that, in contrast to the steady population growth usually assumed, the introduction of agriculture into Europe was followed by a boom-and-bust pattern in the density of regional populations. We demonstrate that summed calibrated radiocarbon date distributions and simulation can be used to test the significance of these demographic booms and busts in the context of uncertainty in the radiocarbon date calibration curve and archaeological sampling. We report these results for Central and Northwest Europe between 8,000 and 4,000 cal. BP and investigate the relationship between these patterns and climate. However, we find no evidence to support a relationship. Our results thus suggest that the demographic patterns may have arisen from endogenous causes, although this remains speculative.

465 citations

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TL;DR: It is suggested that the model has major implications for the origins of modern human culture in the last 50,000 years, which may be seen not as the result of genetic mutations leading to improved cognitive capacities of individuals, but as a population consequence of the demographic growth and increased contact range which are evident at this time.
Abstract: In recent years there has been a major growth of interest in exploring the analogies between the genetic transmission of information from one generation to the next and the processes of cultural transmission, in an attempt to obtain a greater understanding of how culture change occurs. This article uses computer simulation to explore the implications of a specific model of the relationship between demography and innovation within an evolutionary framework. The consequences of innovation appear far more successful in larger populations than in smaller ones. In conclusion, it is suggested that the model has major implications for the origins of modern human culture in the last 50,000 years, which may be seen not as the result of genetic mutations leading to improved cognitive capacities of individuals, but as a population consequence of the demographic growth and increased contact range which are evident at this time. It is also proposed that the model may be of general relevance for understanding the process of cultural evolution in modern and pre-modern humans.

460 citations

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TL;DR: It is concluded that cultural and economic choices often reflect a decision process that is value–neutral; this result has far–reaching testable implications for social–science research.
Abstract: We show that the frequency distributions of cultural variants, in three different real–world examples—first names, archaeological pottery and applications for technology patents—follow power laws that can be explained by a simple model of random drift. We conclude that cultural and economic choices often reflect a decision process that is value–neutral; this result has far–reaching testable implications for social–science research.

359 citations

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TL;DR: This study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia.
Abstract: Farming and sedentism first appeared in southwestern Asia during the early Holocene and later spread to neighboring regions, including Europe, along multiple dispersal routes. Conspicuous uncertainties remain about the relative roles of migration, cultural diffusion, and admixture with local foragers in the early Neolithization of Europe. Here we present paleogenomic data for five Neolithic individuals from northern Greece and northwestern Turkey spanning the time and region of the earliest spread of farming into Europe. We use a novel approach to recalibrate raw reads and call genotypes from ancient DNA and observe striking genetic similarity both among Aegean early farmers and with those from across Europe. Our study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia.

304 citations

##### Cited by
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TL;DR: The African Middle and early Late Pleistocene hominid fossil record is fairly continuous and in it can be recognized a number of probably distinct species that provide plausible ancestors for H. sapiens, and suggests a gradual assembling of the package of modern human behaviors in Africa, and its later export to other regions of the Old World.
Abstract: Proponents of the model known as the "human revolution" claim that modern human behaviors arose suddenly, and nearly simultaneously, throughout the Old World ca. 40-50 ka. This fundamental behavioral shift is purported to signal a cognitive advance, a possible reorganization of the brain, and the origin of language. Because the earliest modern human fossils, Homo sapiens sensu stricto, are found in Africa and the adjacent region of the Levant at >100 ka, the "human revolution" model creates a time lag between the appearance of anatomical modernity and perceived behavioral modernity, and creates the impression that the earliest modern Africans were behaviorally primitive. This view of events stems from a profound Eurocentric bias and a failure to appreciate the depth and breadth of the African archaeological record. In fact, many of the components of the "human revolution" claimed to appear at 40-50 ka are found in the African Middle Stone Age tens of thousands of years earlier. These features include blade and microlithic technology, bone tools, increased geographic range, specialized hunting, the use of aquatic resources, long distance trade, systematic processing and use of pigment, and art and decoration. These items do not occur suddenly together as predicted by the "human revolution" model, but at sites that are widely separated in space and time. This suggests a gradual assembling of the package of modern human behaviors in Africa, and its later export to other regions of the Old World. The African Middle and early Late Pleistocene hominid fossil record is fairly continuous and in it can be recognized a number of probably distinct species that provide plausible ancestors for H. sapiens. The appearance of Middle Stone Age technology and the first signs of modern behavior coincide with the appearance of fossils that have been attributed to H. helmei, suggesting the behavior of H. helmei is distinct from that of earlier hominid species and quite similar to that of modern people. If on anatomical and behavioral grounds H. helmei is sunk into H. sapiens, the origin of our species is linked with the appearance of Middle Stone Age technology at 250-300 ka.

2,048 citations

01 Jul 2006

1,452 citations

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TL;DR: In this article, the authors 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 for females and males.
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.

1,444 citations

Journal ArticleDOI
11 Jun 2015-Nature
TL;DR: In this paper, the authors 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.
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.

1,080 citations

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TL;DR: 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, is reviewed.
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.

1,049 citations