Climates during the Spread of Farming in Mediterranean

Thomas Huet

University of Oxford

Niccolò Mazzucco

Università di Pisa

with the collaboration of Andrea Manica

University of Cambridge

Introduction

Introduce the archaeological cultures. Materials and Methods.

Late Foragers and Early Farmers

Baume de Montclus	EM - Early Mesolithic Continuation of the hunter-gatherer lifestyle. Pleistocene/Holocene transition. Late Last Glacial Maximum climate.
	MM - Middle Mesolithic Increased specialization in tool production, territorialisation. New climates: new species.
	LM - Late Mesolithic Late Foragers. Residenciality increase. Circular mobility to access discontinuous resources in time and space. Climates: Near East is temperate and wet, North Africa transitioned to arid conditions, Southern Europe experienced is warmer and wetter.
Franchthi cave	EN - Early Neolithic Early farmers. Permanent settlements, soil fertility for agriculture (cereals) and climates for livestock. Climates: broadly warm and stable.
	MN - Middle Neolithic Craftware, crops and livestock specialization. Deforestation. Warm and stable climate.
	LN - Late Neolithic Apparition of copper industry. Marginal land brought into cultivation. More variable climate conditions.

The different periods defines characteristic anthropological moments. Conventional division in 3 phases, both for the Mesolithic and Neolithic. Standardized and heuristic way to represent the evolution of a culture. We represent here, using large brushes

Materials and Methods

Data: radiocarbon dates and palaeoclimatic data.

Radiocarbon data

• Sources
• Neonet equivalences
• Outlier dates

https://github.com/ropensci/c14bazAAR

https://github.com/zoometh/neonet

Neonet classes

EM - Early Mesolithic

MM - Middle Mesolithic

LM - Late Mesolithic

EN - Early Neolithic

MN - Middle Neolithic

LN - Late Neolithic

• 8 different databases and datasets. Among which 2 are the Neonet datasets. We collect using the c14bazAAR and curated with NeoNet functions.
• mapping table with period and culture coming from different datasest to be mapped to the Neonet main classes (10 classes, among which 4 are undefined and period transition).
• Using

c14_aberrant_dates.tsv

• With R functions coming from the C14bazaar R package and curated with the NeoNet R series of functions, we are gathering some 10,000 radiocarbon dates coming from 8 different datasets and databases.
• We map these dates to the Neonet periods (here on the left class).
• Then we remove duplicated dates and discard outliers (currently in process).
• Some 4,000 dates are now available for the study.

Climates data

• Sources

Mid-Holocene (c. 6,000 BP)
Mean annual temperature (ºC)

Annual precipitation (mm year ^-1)

Biome (pollen-based)

Beyer et al. 2020¹

https://github.com/EvolEcolGroup/pastclim

http://shinyserver.cfs.unipi.it:3838/C14dev/

• pastclim R package to recreate the Koppen Climate classification (KCC) for past periods, currently from 8,000 BC to 5,000 cal BC (expressed here in cal BP)
• KCC based on average temperature and precipitation patterns, dividing them into five main types: tropical, dry, temperate, continental, and polar. Each type is further subdivided based on seasonal precipitation and temperature patterns (30 classes).
• The pastclim KCC current resolution is 30” = 0.5 degrees = c. 50 km. It uses the Beyer et al. 2020 dataset.

Climates by radiocarbon dates

• Dates selection
• Dates medians and Koppen classes

The most recent LM date median

The most ancient EN date median

• For a given site, we select either the most recent LM date (ex: Monte Frignone) or simetrically the most ancient EN date (ex: Le Baratin)
• Extract on the radiocarbon date weighted median from the Summed probability density (SPD)

Results

Radiocarbon dates are still being revised, and many of them need to be verified. First modeling

Climates evolution

• Late Foragers
• Early Farmers
• Comparisons

• Late foragers: Drop of the inhabited cold climates from 11k BP to 7k BP. In 9k BP newly occupied occupied Cold, dry summer, cold summer, possibly corresponding to the higher mountain range (Atlas, Alps, Pyrenees, etc.)
• Early Farmers: 11k and 10k 2 main climates, continuous area: Fertile Crescent. Arid climates increases in 9k: arid margins (oasis). 8k and 7k: neolithisation of cold and temperated areas (Bulgaria, Southern Germany, etc.)
• Comparison: LM occupied a larger diversity of ecozones. EF replace HG in cold climate over 4,000 years
  

Discussion

Rproductible methods. Enhancement of cultural and climatic data

productible methods

• Modeling
• Cultural data
• Climate data

Ammerman, A. J., & Cavalli-Sforza, L. L. (1971). Measuring the rate of spread of early farming in Europe. Man, 674-688.

Fort, J. (2022). The spread of agriculture: quantitative laws in prehistory?. In Simulating Transitions to Agriculture in Prehistory (pp. 17-28). Cham: Springer International Publishing.

Betti, L., Beyer, R. M., Jones, E. R., Eriksson, A., Tassi, F., Siska, V., … & Manica, A. (2020). Climate shaped how Neolithic farmers and European hunter-gatherers interacted after a major slowdown from 6,100 BCE to 4,500 BCE. Nature Human Behaviour, 4(10), 1004-1010.

https://github.com/zoometh/neonet

https://github.com/EvolEcolGroup/pastclim

• All models are wrong but some are usefull
• Dates curation
• Possibility of having 1 km of resolution and aggregating in 5” (~10 km) with TraCE21k

Conclusion

https://github.com/zoometh/neonet

• Contribution: mapping table (archaeologists), interpolation methods (mathematician), aggregating data from other sources (aDNA, etc.), etc.

Footnotes

1. Beyer, R. M., Krapp, M., & Manica, A. (2020). High-resolution terrestrial climate, bioclimate and vegetation for the last 120,000 years. Scientific data, 7(1), 236.