Climatic controls on Later Stone Age human adaptation in Africa's southern Cape

Abstract

Africa's southern Cape is a key region for the evolution of our species, with early symbolic systems, marine faunal exploitation, and episodic production of microlithic stone tools taken as evidence for the appearance of distinctively complex human behavior. However, the temporally discontinuous nature of this evidence precludes ready assumptions of intrinsic adaptive benefit, and has encouraged diverse explanations for the occurrence of these behaviors, in terms of regional demographic, social and ecological conditions. Here, we present a new high-resolution multi-proxy record of environmental change that indicates that faunal exploitation patterns and lithic technologies track climatic variation across the last 22,300 years in the southern Cape. Conditions during the Last Glacial Maximum and deglaciation were humid, and zooarchaeological data indicate high foraging returns. By contrast, the Holocene is characterized by much drier conditions and a degraded resource base. Critically, we demonstrate that systems for technological delivery - or provisioning - were responsive to changing humidity and environmental productivity. However, in contrast to prevailing models, bladelet-rich microlithic technologies were deployed under conditions of high foraging returns and abandoned in response to increased aridity and less productive subsistence environments. This suggests that posited links between microlithic technologies and subsistence risk are not universal, and the behavioral sophistication of human populations is reflected in their adaptive flexibility rather than in the use of specific technological systems.

Late Quaternary micromammals and the precipitation history of the southern Cape, South Africa: response to comments by F. Thackeray, Quaternary Research 95, 154–156

“…Our interpretations provide just that. In Faith et al (2019), we emphasized the broad similarities between our record of moisture availability and that provided by isotopic analysis of the Seweweeksport hyrax middens (Chase et al, 2017(Chase et al, , 2018, located in a similar environment ∼70 km west of Boomplaas. Also important is that the nearby Cango Cave speleothem (∼3 km east of Boomplaas) shows a hiatus from the late glacial to the middle Holocene, signaling a lack of drip water availability (Vogel, 1983;Talma and Vogel, 1992).…”

“…To be clear, a relatively humid LGM could result from greater precipitation, cooler temperatures, or a combination of both. There is no question that cooler temperatures during the LGM would have contributed to greater moisture availability by reducing evapotranspiration (as suggested by Chase et al, 2017Chase et al, , 2018, but whether this was accompanied by higher or lower precipitation cannot be ascertained from our analysis. Indeed, we are skeptical that any analysis of faunal community composition can inform directly on rainfall amount sensu stricto, when it is moisture availability that determines habitat structure and the availability of the key resources (e.g., forage, standing water) on which faunas depend (Faith and Lyman, 2019).…”

Developmental stress in South African hominins: Comparison of recurrent enamel hypoplasias in Australopithecus africanus and Homo naledi

“…They are drawn from greatly different time periods but lived in similar geographical areas and were likely subject to comparable annual cycles of insolation and moisture characteristic for the latitude. 22,23 The climate today in the area is decidedly seasonal and quite arid generally. The A. africanus sample is drawn from Member 4 Sterkfontein, aged >2 million years 24 and Makapansgat Member 3 (aged >2.6 my) 25 .…”

A high-resolution record of Holocene climate and vegetation dynamics from the southern Cape coast of South Africa: pollen and microcharcoal evidence from Eilandvlei

“…Chase et al ., , , ,b; Neumann et al ., ; Valsecchi et al ., ; Carr et al ., ; Quick et al ., ). Important questions remain, however, regarding the past dynamics of temperate and tropical systems in the region, particularly at the WRZ–SRZ interface, and their impact on regional environments (Chase et al ., , ). The developing regional dataset indicates that at multi‐millennial timescales variations in mid‐ to high‐latitude Southern Hemisphere atmospheric and oceanographic circulation have driven environmental changes in the southern Cape through changes in the position and influence of the westerly storm track (Chase et al ., , ).…”