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2.
Proc Natl Acad Sci U S A ; 113(35): 9751-6, 2016 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-27573833

RESUMO

Ecosystems on the verge of major reorganization-regime shift-may exhibit declining resilience, which can be detected using a collection of generic statistical tests known as early warning signals (EWSs). This study explores whether EWSs anticipated human population collapse during the European Neolithic. It analyzes recent reconstructions of European Neolithic (8-4 kya) population trends that reveal regime shifts from a period of rapid growth following the introduction of agriculture to a period of instability and collapse. We find statistical support for EWSs in advance of population collapse. Seven of nine regional datasets exhibit increasing autocorrelation and variance leading up to collapse, suggesting that these societies began to recover from perturbation more slowly as resilience declined. We derive EWS statistics from a prehistoric population proxy based on summed archaeological radiocarbon date probability densities. We use simulation to validate our methods and show that sampling biases, atmospheric effects, radiocarbon calibration error, and taphonomic processes are unlikely to explain the observed EWS patterns. The implications of these results for understanding the dynamics of Neolithic ecosystems are discussed, and we present a general framework for analyzing societal regime shifts using EWS at large spatial and temporal scales. We suggest that our findings are consistent with an adaptive cycling model that highlights both the vulnerability and resilience of early European populations. We close by discussing the implications of the detection of EWS in human systems for archaeology and sustainability science.


Assuntos
Agricultura/história , Arqueologia/métodos , Modelos Estatísticos , Dinâmica Populacional/história , Simulação por Computador , Ecossistema , Europa (Continente) , História Antiga , Humanos , Dinâmica Populacional/estatística & dados numéricos , Datação Radiométrica
3.
Proc Natl Acad Sci U S A ; 113(25): 6886-91, 2016 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-27274049

RESUMO

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.


Assuntos
Agricultura , Antropologia , Europa (Continente) , Genética Populacional , Humanos , Região do Mediterrâneo , Análise de Componente Principal
4.
Proc Natl Acad Sci U S A ; 112(46): 14218-23, 2015 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-26578766

RESUMO

Theories for the origins of agriculture are still debated, with a range of different explanations offered. Computational models can be used to test these theories and explore new hypotheses; Bowles and Choi [Bowles S, Choi J-K (2013) Proc Natl Acad Sci USA 110(22):8830-8835] have developed one such model. Their model shows the coevolution of farming and farming-friendly property rights, and by including climate variability, replicates the timings for the emergence of these events seen in the archaeological record. Because the processes modeled occurred a long time ago, it can be difficult to justify exact parameter values; hence, we propose a fitting to idealized outcomes (FIO) method to explore the model's parameter space in more detail. We have replicated the model of Bowles and Choi, and used the FIO method to identify complexities and interactions of the model previously unidentified. Our results indicate that the key parameters for the emergence of farming are group structuring, group size, conservatism, and farming-friendly property rights (lending further support to Bowles and Choi's original proposal). We also find that although advantageous, it is not essential that farming productivity be greater than foraging productivity for farming to emerge. In addition, we highlight how model behaviors can be missed when gauging parameter sensitivity via a fix-all-but-one variation approach.


Assuntos
Agricultura , Simulação por Computador , Modelos Teóricos , Humanos
5.
Philos Trans R Soc Lond B Biol Sci ; 365(1559): 3865-74, 2010 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-21041211

RESUMO

Phylogenetic approaches to culture have shed new light on the role played by population dispersals in the spread and diversification of cultural traditions. However, the fact that cultural inheritance is based on separate mechanisms from genetic inheritance means that socially transmitted traditions have the potential to diverge from population histories. Here, we suggest that associations between these two systems can be reconstructed using techniques developed to study cospeciation between hosts and parasites and related problems in biology. Relationships among the latter are patterned by four main processes: co-divergence, intra-host speciation (duplication), intra-host extinction (sorting) and horizontal transfers. We show that patterns of cultural inheritance are structured by analogous processes, and then demonstrate the applicability of the host-parasite model to culture using empirical data on Iranian tribal populations.


Assuntos
Evolução Cultural , História do Século XV , História do Século XVI , História do Século XVII , História do Século XVIII , História do Século XIX , História do Século XX , História do Século XXI , História Medieval , Humanos , Irã (Geográfico) , Modelos Teóricos , Filogenia , Dinâmica Populacional , Grupos Populacionais/história , Têxteis/história
6.
7.
Proc Biol Sci ; 271(1547): 1443-50, 2004 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-15306315

RESUMO

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.


Assuntos
Evolução Cultural , Modelos Teóricos , Patentes como Assunto/estatística & dados numéricos , Distribuições Estatísticas , Simulação por Computador , Teoria da Decisão , Humanos , Manufaturas/economia , Manufaturas/estatística & dados numéricos , Nomes , Ciências Sociais , Processos Estocásticos
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