Lipid Biomarker Records of Environmental Conditions and Habitation During the Mid-Neolithic (Dalmatia Coast, Croatia)

Restricted (Penn State Only)
- Author:
- Hartke, Emma
- Graduate Program:
- Geosciences
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 21, 2022
- Committee Members:
- Mark Patzkowsky, Program Head/Chair
Kate Freeman, Thesis Advisor/Co-Advisor
Sarah J Ivory, Committee Member
Max Lloyd, Committee Member - Keywords:
- geology
geoscience
paleoclimate
human history
archaeology
lipid biomarkers
biomarkers
alkanes
n-alkanes
pahs
isotopes
paleolake
human habitation
climate change
dalmatia coast
holocene
neolithic - Abstract:
- Records of environmental change during the mid-Neolithic/Early Holocene show both pronounced global deglaciation climate trends and significant impacts from human activity. Included among these was the encroachment of human groups into Europe as they shifted from nomadic, pastoral lifestyles to more stationary, agro-pastoral lifestyles. The relationship between anthropogenic impacts and both on-going postglacial changes and punctuated climate events, however, is less clear. Separation of climate and anthropogenic signals in the paleorecord to resolve questions of timing is aided by a continuous sedimentary record that can be evaluated with a suite of geochemical tools. This study uses new abundance and distribution patterns of lipid biomarkers, including n-alkanes (plant wax compounds) and polycyclic aromatic hydrocarbons (PAHS; fire indicator compounds), and previously collected data including bulk organic carbon and bulk carbonate carbon and oxygen isotope records, charcoal data, pollen records, and archaeological findings to reconstruct the presence and pace of human and environmental changes during this period. These were applied to a continuous sediment core sampled from a paleolake near a mid-Neolithic human habitation site Krivače, located along the Dalmatia Coast (Croatia). N-alkane and PAH concentrations increased dramatically between 8000 and 6000 yrs BP, possibly due to changing climate, human activity, or a combination of both. High proportions of atypical short even-chain n-alkanes detected across this same interval were potentially sourced from autochthonous lake bacteria or derived from soil inputs. While PAHs increased in abundance during this interval, plant biomarker-normalized patterns did not increase, which suggests fire activity did not increase out of proportion to increased fuel loads. These patterns possibly indicate increased input of soil-derived contributions. Results from this project inform the timing and appearance of human-environmental events. Specifically, biomarker distributions of plant-derived n-alkanes tracked climate trends (temperature and hydroclimate), suggesting biomass increased with regionally under wetter conditions and decreased under drier conditions. PAH abundances, which tracked plant wax n-alkane inputs, indicated no large change in flammability was associated with habitation. The anomalous distributions between 8000 and 6000 yrs BP suggest significant inputs from human activity by soil disturbance, but also coincide with hydroclimate extremes (wetter conditions marked by flooding events) which could have also enhanced mobilization of soil-derived materials from the lake catchment. Further geochemical tools, such as fecal sterols and compound-specific isotope data, can help resolve these. The results of this study suggest human habitation during this period may have started earlier and extended beyond the timeframe currently documented by archaeological evidence. Additional studies can help us improve the timeline of early human history and reckon with human-environmental changes in a rapidly warming climate.