Pleistocene and Holocene herbivore diets and palaeoenvironments in the Gebel Akhdar (Libya): Implications for past human populations

Abstract

9The Gebel Akhdar massif in Cyrenaica, northeast Libya, has yielded a long record of human 10 occupation going back at least 100,000 years. To date, there is only a limited understanding of 11 how the landscape of the region varied in response to the climatic fluctuations of the last 12 glacial-interglacial cycle, and the implications of these changes for local human populations 13 remain largely unexplored. This study provides an isotope-based interpretation of past 14 environments directly linked to the archaeological record. Tooth enamel stable carbon isotope 15 ratios (δ 13 C) from herbivore species hunted by past human populations are used to infer the 16 isotopic characteristics of past diet and vegetation, and in turn the likely environmental 17 conditions that prevailed during periods when humans were active within the landscape. To 18 provide a baseline from which to interpret the archaeological δ 13 C data, modern samples are 19 considered in relation to their diet and environmental origin. Archaeological samples come 20 from 2 cave sites, Haua Fteah and Hagfet ed Dabba, and span a period from oxygen isotope 21 stage 4 to the mid-Holocene. While results indicate a more arid environment in the 22Pleistocene and an increase in humidity at the onset of the Holocene, the overall picture is one 23 of relative environmental stability. The biggest landscape change observed in the data occurs 24 during the mid-Holocene Neolithic, when C 4 plant species become evident in the herbivore 25 diet for the first time. There is little evidence to suggest that this occurred at a time of any 26 large-scale climate variation, and thus the contribution of anthropogenic influences to 27 vegetation change is considered likely. 28

Social but lonely: Species delimitation of social voles and the evolutionary history of the onlyMicrotusspecies living in Africa

“…M. cyrenae had also shorter and narrower cheek teeth, with smaller angles and thinner enamel than M. mustersi (Bate, ). Smaller body size and less powerful, flattened teeth could point to an alteration from a mild climate with plentiful soft vegetation to one of drier environments with harder vegetation (Bate, ) and is a feature found in other Microtus species (McGuire, ) and several herbivorous animals of Cyrenaica (Reade et al, ).…”

“…Dating may be affected by the high degree of homoplasy, especially at the 3rd codon position, and the fact that genetic variation seems to differ across codon sites and among phylogenetic lineages (Martínková et al, 2013). Fossil dating depends heavily on the method used for the age calibration of stratigraphical layers (e.g., see Reade, Stevens, O'Connell, & Barker, 2016), and the systematic attribution of fossils which suffers from the morphological uniformity, and abundant parellelisms among early Microtus forms (Martin & Tesakov, 1998).…”

Of herds and societies—Seasonal aspects of Vinča culture herding and land use practices revealed using sequential stable isotope analysis of animal teeth

“…In general, plant stomata during dry periods, particular in regions with hot summers, will close to minimizing water loss and reduce the discrimination against 13 C, resulting in higher carbon isotopes values in plant tissues. For example, in semi-arid regions where the mean annual precipitation is less than 500mm, the mean value of C 3 plants, adjusted for the Suess effect, were between −24.7‰ to −23.9‰ [ 87 ]. We propose that animals pastured all-year round on a landscape with seasonal flooding under a strong continental climate will exhibit carbon values that reflect a strong seasonal pattern.…”

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

“…However, faunal evidence comes solely from archaeological deposits, such that it is not possible to infer whether these changes reflect changing environments and habitats, or changing cultural preferences and subsistence strategies. Carbon isotope studies indicate no significant (isotopic) change in vegetation throughout the last glacial-interglacial cycle until the mid-Holocene, when a notable C4 vegetation component is identified (Reade et al, 2016b). It has been postulated that this change is indicative of human influence on the environment, rather than a response to climatic changes (Reade et al, 2016b).…”

“…However, the possible influence of dietary changes on the Gebel Akhdar caprid isotope δ 18 Oen signal in the Neolithic, namely the considerable increase of C4 plants to the diet, should also be considered (Reade et al, 2016b).…”