Periodic Reporting for period 4 - PALEODEM (Late Glacial and Postglacial Population History and Cultural Transmission in Iberia (c.15,000-8,000 cal BP))
Reporting period: 2021-01-01 to 2022-09-30
The study of Late Glacial and Postglacial demographic dynamics and social networks raise relevant questions given its broader implications to understand processes of cultural evolution and human resilience to climate change .The Paleodem project investigates the population history and processes of cultural transmission in Iberia between the Upper Magdalenian and the Final Mesolithic. This period witnessed major cultural and environmental changes. Our project addresses three research objectives: 1) to reconstruct the population patterns of the Iberian Peninsula; 2) to examine the role of gradual and punctuated processes of climate change on prehistoric hunter-gatherers demography; and 3), to examine how social networks affected cultural change. Regarding the two first research objectives, we have identified the demographic phases: the first one of exponential growth (c.16.6-12.9 ky,) followed by a phase of sustained population contraction and stagnation (12.9-10.2 ky) and a third phase of density-dependent logistic growth (10.2-8 ky). Some differences are found regionally during the Late Mesolithic period, indicating different demographic responses to the 8.2 kyr cold climatic event. Regarding the onbective 3), our project has applied new methods based on social network analysis on archaeological data sets on two different case studies. In the first one, we used ornaments to compare the social networks between the Early and the Late Mesolithic. For the second one, we analysed the role of Mesolithic social networks on the spread of trapezes industries in the Iberian Peninsula. Our results suggest that network-mediated cultural diffusion, originated in the Pyrenees, was the main mechanism explaining the rapid diffusion of trapezes industries in Iberia.
In the following, we detail the work performed from the beginning to the end of the project in each working package.
At WP1 we have completed the fieldwork at the Early Holocene open-air sites of Arenal de la Virgin and Casa Corona (in the Villena dune field). The excavation results have been published in 4 preprints of submitted scientific papers and have been subject of a doctoral dissertation. These include the presentation of new chrono-stratigraphic data and occupational evidence, the technological and intra-site spatial analyses of lithic assemblages, the geoarchaeological study of hearth-pits. Results have been presented in major scientific conferences (UISSP 2018, Paris; EAA 2018, Barcelona; INQUA 2019, Dublin; Meso2020, Toulouse).
For the WP2 we have published two research papers on case studies focused on the Iberian Peninsula and the Portugal radiocarbon record. New ad hoc R and Python scripts for the statistical analysis of radiocarbon time series (SPDs and demographic models) have been created. In addition, we have co-edited a special issue of prehistoric demography.
Regarding the WP3, we have completed two different case studies applying social network analysis to the Mesolithic archaeological record of Iberia and published different review papers. Results have been presented in major conferences (EAA 2018, Barcelona; EAA 2020, Budapest; Meso2020, Toulouse) and scientific meetings (Arizona State University 2022; University of Califonia SantaBarbara 2022).
For the whole period, we have published 8 scientific papers and 5 article preprints (of scientific papers currently under review). We have presented 32 conference papers at international meetings (conferences and workshops). The dissemination actions for the general public cover 4 interviews in TV and radio station programs, a fieldwork open day visit, 10 press releases and the participation in one exhibition at the National Museum of Science and Technology (Alcobendas, Madrid).
At WP1 we have completed the fieldwork at the Early Holocene open-air sites of Arenal de la Virgin and Casa Corona (in the Villena dune field). The excavation results have been published in 4 preprints of submitted scientific papers and have been subject of a doctoral dissertation. These include the presentation of new chrono-stratigraphic data and occupational evidence, the technological and intra-site spatial analyses of lithic assemblages, the geoarchaeological study of hearth-pits. Results have been presented in major scientific conferences (UISSP 2018, Paris; EAA 2018, Barcelona; INQUA 2019, Dublin; Meso2020, Toulouse).
For the WP2 we have published two research papers on case studies focused on the Iberian Peninsula and the Portugal radiocarbon record. New ad hoc R and Python scripts for the statistical analysis of radiocarbon time series (SPDs and demographic models) have been created. In addition, we have co-edited a special issue of prehistoric demography.
Regarding the WP3, we have completed two different case studies applying social network analysis to the Mesolithic archaeological record of Iberia and published different review papers. Results have been presented in major conferences (EAA 2018, Barcelona; EAA 2020, Budapest; Meso2020, Toulouse) and scientific meetings (Arizona State University 2022; University of Califonia SantaBarbara 2022).
For the whole period, we have published 8 scientific papers and 5 article preprints (of scientific papers currently under review). We have presented 32 conference papers at international meetings (conferences and workshops). The dissemination actions for the general public cover 4 interviews in TV and radio station programs, a fieldwork open day visit, 10 press releases and the participation in one exhibition at the National Museum of Science and Technology (Alcobendas, Madrid).
The work done and the obtained results until the end of the project are beyond the state of the art in three different areas:
First, at the micro-regional scale, the excavation results at the Arenal de la Virgen site and the integrated geoarchaeological, chronological and paleoecological program represent one of the very few case studies with multi-proxy evidence of severe impacts of the 8.2 kya cold climatic event on human systems. Particularly, the work performed conciliates human occupation and paleoecological records at a local scale, in one of the most arid areas of Southwestern Europe during the Early Holocene, providing a secure framework to analyse regional population dynamics. In addition, it must be stressed the focus on open-air sites, usually underrepresented in the archaeological record and long- term research programs of southern Europe. Other significant results are the multiproxy geoarchaeological study of Mesolithic hearthpits and the application of intra-site spatial analyses in the Arenal de la Virgen site.
Second, this project has reported the first reconstruction of long- term changes in population size during the Last Glacial-Early Holocene transition in Iberia through the statistical analysis of the radiocarbon record. We have uncovered evidence of relative population changes and developed a best-fitting demographic model composed by three different phases. Our findings suggest that the population of Iberia increased during most of GI-1 until a rapid decrease occurred at the onset of the YD stadial, subject to certain variability at regional and sub-regional scales, which was followed by a sustained period of stationary growth. During the second half of the Early Holocene (c. 10.2-8 kya), we identified a recovery of relative population levels, when growth rates were similar or slightly greater than those of the first phase, but this soon attenuated towards a pattern of fluctuation around stationary growth. Importantly, this pattern of population dynamics agrees with recent aDNA studies, suggesting that a major population turnover occurred in Europe at the end of the Late Glacial, but we can now also suggest that the timing of this process can be pushed slightly forward to encompass the Younger Dryas and the Early Holocene of the Iberian Peninsula and the rapid environmental changes that occurred. Our modelling results illustrate that human populations have an inherent capacity for rapid growth, but it seems that in the past this was often checked by the constraints of the environment, especially for prehistoric hunter-gatherers during episodes of climate change.
Finally, the Paleodem project has brought Social Network Analysis in Archaeology to the centre of the research agenda in cultural evolution. The introduction of a new cross-disciplinary framework ‘network thinking in cultural evolution’ as a research field has allowed us to integrate different perspectives from Evolutionary Anthropology, Psychology and Archaeology into a common conceptual basis. From here, the two case studies analysed during the project (the comparison between Early and Late Mesolithic social networks, and the study of network mediated cultural diffusion of technological innovations) have produced relevant results and open new research venues for the application of social network analyses to the stone age prehistory.
Certainly, this kind of hypothesis-driven approach has the potential of moving the study cultural transmission processes in hunter-gatherers well beyond the state of the art.
First, at the micro-regional scale, the excavation results at the Arenal de la Virgen site and the integrated geoarchaeological, chronological and paleoecological program represent one of the very few case studies with multi-proxy evidence of severe impacts of the 8.2 kya cold climatic event on human systems. Particularly, the work performed conciliates human occupation and paleoecological records at a local scale, in one of the most arid areas of Southwestern Europe during the Early Holocene, providing a secure framework to analyse regional population dynamics. In addition, it must be stressed the focus on open-air sites, usually underrepresented in the archaeological record and long- term research programs of southern Europe. Other significant results are the multiproxy geoarchaeological study of Mesolithic hearthpits and the application of intra-site spatial analyses in the Arenal de la Virgen site.
Second, this project has reported the first reconstruction of long- term changes in population size during the Last Glacial-Early Holocene transition in Iberia through the statistical analysis of the radiocarbon record. We have uncovered evidence of relative population changes and developed a best-fitting demographic model composed by three different phases. Our findings suggest that the population of Iberia increased during most of GI-1 until a rapid decrease occurred at the onset of the YD stadial, subject to certain variability at regional and sub-regional scales, which was followed by a sustained period of stationary growth. During the second half of the Early Holocene (c. 10.2-8 kya), we identified a recovery of relative population levels, when growth rates were similar or slightly greater than those of the first phase, but this soon attenuated towards a pattern of fluctuation around stationary growth. Importantly, this pattern of population dynamics agrees with recent aDNA studies, suggesting that a major population turnover occurred in Europe at the end of the Late Glacial, but we can now also suggest that the timing of this process can be pushed slightly forward to encompass the Younger Dryas and the Early Holocene of the Iberian Peninsula and the rapid environmental changes that occurred. Our modelling results illustrate that human populations have an inherent capacity for rapid growth, but it seems that in the past this was often checked by the constraints of the environment, especially for prehistoric hunter-gatherers during episodes of climate change.
Finally, the Paleodem project has brought Social Network Analysis in Archaeology to the centre of the research agenda in cultural evolution. The introduction of a new cross-disciplinary framework ‘network thinking in cultural evolution’ as a research field has allowed us to integrate different perspectives from Evolutionary Anthropology, Psychology and Archaeology into a common conceptual basis. From here, the two case studies analysed during the project (the comparison between Early and Late Mesolithic social networks, and the study of network mediated cultural diffusion of technological innovations) have produced relevant results and open new research venues for the application of social network analyses to the stone age prehistory.
Certainly, this kind of hypothesis-driven approach has the potential of moving the study cultural transmission processes in hunter-gatherers well beyond the state of the art.