Increased climate seasonality during the late glacial in the Gebel Akhdar, Libya

Abstract

Oxygen isotope analysis (δ 18 O) of caprine and bovine tooth enamel carbonates from the Haua Fteah cave (Gebel Akhdar massif, northeast Libya) reveals significant differences in palaeoseasonality during the last c. 70 ka. Data indicate different phases of human occupation of the region occurred under notably different climatic conditions. During the last glacial period, prior to the Last Glacial Maximum, a gradual increase in climate aridity occurred. This was followed in the late glacial (c. 16.6-14.7 ka) by considerably more arid conditions and much greater climate seasonality, which was likely produced by changing winter precipitation amounts and a strengthening of arid summer air masses. The high seasonality in the late glacial coincides with a period when human activity at the Haua Fteah greatly intensified. Significant changes in subsistence strategies and the seasonal exploitation of food resources also occurred at this time. The results presented here suggest that changes in the seasonal climate may have affected the seasonal supply of floral and faunal resources available to local human populations at the time, which resulted in changing subsistence practices.

Herbivore enamel carbon and oxygen isotopes demonstrate both Homo sapiens and Neanderthals exploited similar habitats in the Zagros Mountains

“…In contrast to metabolically dynamic bone tissue, tooth enamel does not remodel after initial formation (Suga 1982). The hypsodont teeth of herbivorous taxa capture seasonal-scale environmental inputs that can be accessed through incremental sampling of the tooth crown and subsequent isotope analysis (Reade et al, 2018). In cases where the entire tooth loph is not preserved, thus preventing characterisation of the full seasonal cycle, enamel bulk sampling provides an isotopic average over the tooth-growing time period (Reade et al, 2018).…”

“…While fragmented tooth specimens variously represent different intervals and durations of the yearly seasonal cycle, isotope values obtained from bulk sampling document shifts in environmental conditions when source specimens, ideally representing different taxa with distinct feeding and drinking requirements, are selected from separate depositional contexts, providing a framework for identifying diachronic change (e.g. Ecker et al, 2013;Reade et al, 2018). The carbon isotope ratios of herbivore tooth enamel directly reflect the carbon isotopic composition of floral dietary intake which is influenced by photosynthetic pathway, environmental conditions, and atmospheric carbon dioxide (Cerling and Harris, 1999).…”

“…The hypsodont teeth of herbivorous taxa capture seasonal‐scale environmental inputs that can be accessed through incremental sampling of the tooth crown and subsequent isotope analysis (Reade et al, 2018). In cases where the entire tooth loph is not preserved, thus preventing characterisation of the full seasonal cycle, enamel bulk sampling provides an isotopic average over the tooth‐growing time period (Reade et al, 2018). While fragmented tooth specimens variously represent different intervals and durations of the yearly seasonal cycle, isotope values obtained from bulk sampling document shifts in environmental conditions when source specimens, ideally representing different taxa with distinct feeding and drinking requirements, are selected from separate depositional contexts, providing a framework for identifying diachronic change (e.g.…”

“…While fragmented tooth specimens variously represent different intervals and durations of the yearly seasonal cycle, isotope values obtained from bulk sampling document shifts in environmental conditions when source specimens, ideally representing different taxa with distinct feeding and drinking requirements, are selected from separate depositional contexts, providing a framework for identifying diachronic change (e.g. Ecker et al, 2013; Reade et al, 2018).…”

Seasonal records of palaeoenvironmental change and resource use from archaeological assemblages

“…Mollusc shells, fish otoliths and faunal teeth in particular are routinely preserved in the archaeological record. Many archaeological sites contain freshwater, marine, terrestrial and estuarine mollusc shells, and freshwater, marine, and estuarine otoliths likely to be refuse from foraging and fishing activities (Andrus 2011;Colonese et al 2011;Prendergast and Stevens 2014;Disspain et al 2016;Twaddle et al 2016), and faunal teeth and antler likely to be the result of hunting activities (Hillson, 2005;Pryor et al 2016;Reade et al 2016Reade et al , 2018Pilaar-Birch et al 2016;Stevens and O'Connell 2016). These archives are particularly relevant to reconstructing human-environment interaction as their presence in archaeological sites is generally the result of foraging, fishing, and hunting activities (thus live-collection).…”