SPATIAL VARIATION IN PALEO CRITICAL ZONE ECOLOGY FROM BIOMARKERS AND COMPOUND SPECIFIC δ13C EVIDENCE, OLDUVAI GORGE, TANZANIA
Central sites (including FLK Zinj) cover about 250 m2 and contain leaf-waxes with low δ13C values, which we interpret as evidence of a localized forest habitat. About 200 m to the north, plant biomarkers and their carbon-isotope signatures are consistent with the presence of aquatic plants and occur in conjunction with mound-like tufa deposits, suggesting a spring and wetland habitat. The tufa has freshwater isotopic signatures (δ18O values ranging from -5.0‰ to -1.0‰) which indicate a meteoric water source for the spring. At southern sites, plant biomarkers and their carbon-isotope signatures suggest an open grassland habitat.
The time equivalency and close physical proximity of the two environments (woodland and the spring-fed wetland) indicate the two are related. Freshwater was likely attractive to hominins, a site selected for plant resources, as well as for accessing carcasses that were then transported to the woodland for consumption in safety. These data have important implications for the interpretation of hominin behavior in meat acquisition and the ongoing debate on scavenging versus hunting.