Identifying early modern human ecological niche expansions and associated cultural dynamics in the South African Middle Stone Age

Abstract

The archaeological record shows that typically human cultural traits emerged at different times, in different parts of the world, and among different hominin taxa. This pattern suggests that their emergence is the outcome of complex and nonlinear evolutionary trajectories, influenced by environmental, demographic, and social factors, that need to be understood and traced at regional scales. The application of predictive algorithms using archaeological and paleoenvironmental data allows one to estimate the ecological niches occupied by past human populations and identify niche changes through time, thus providing the possibility of investigating relationships between cultural innovations and possible niche shifts. By using such methods to examine two key southern Africa archaeological cultures, the Still Bay [76-71 thousand years before present (ka)] and the Howiesons Poort (HP; 66-59 ka), we identify a niche shift characterized by a significant expansion in the breadth of the HP ecological niche. This expansion is coincident with aridification occurring across Marine Isotope Stage 4 (ca. 72-60 ka) and especially pronounced at 60 ka. We argue that this niche shift was made possible by the development of a flexible technological system, reliant on composite tools and cultural transmission strategies based more on "product copying" rather than "process copying." These results counter the one niche/one human taxon equation. They indicate that what makes our cultures, and probably the cultures of other members of our lineage, unique is their flexibility and ability to produce innovations that allow a population to shift its ecological niche.Middle Stone Age | Still Bay | Howiesons Poort | ecological niche modeling | paleoclimate R esearch on animal behavior has made it clear that culture represents a second inheritance system that may have changed the dynamics of evolution on a broad scale (1-3). Understanding how this process has affected the evolution of our genus is a major challenge in paleoanthropology. In what ways, and through what phases of evolutionary history, has human culture extended beyond culture seen in other species? Are the cultural adaptations and associated cultural innovations that we observe in the archaeological record the direct consequence of our biological evolution, or are they the outcome of mechanisms largely independent of it? In our lineage, if cultural innovations were directly linked to classic Darwinian evolutionary processes, such as isolation, random mutation, selection, and speciation, one would expect a clear correspondence between the emergence of a new species and a related set of novel cultural behaviors. By shaping a new hominin species, natural selection would provide this species with a new cognitive setting resulting in the capacity for particular cultural innovations or behaviors. Such a mechanism would provide the possibility for cultural variability but would narrow its range of expression to the species' biologically dictated potential. Although some would still argue ...

How language shapes the cultural inheritance of categories

“…Similarly, cultural evolution requires both conformity and innovation (134)(135)(136)(137), and we suggest that the linguistic presuppositions discussed above-norms and essentialism-contribute to both these processes. Because labels and generics are fundamentally normative (conventional and prescriptive), they provide stable representations that are easily shared with great fidelity.…”

Did our species evolve in subdivided populations across Africa, and Why does it matter?

“…For example, challenging environments (e.g., deserts, rainforest) and isolation have likely played a significant role in shaping the population structure of Holocene African foragers and isolated hunter-gatherers across the tropics [25,27]. [35]; (Q) from [47]; and (R-Ab) from [35,47,48].…”

The extension of biology through culture

“…Similarly, the beginnings of what has been labeled "symbolic culture," indexed by such features as decorative items, like beads, has been pushed back from the previous "cave art" dates of around 30 ka to closer to 100 ka, or in the case of some elements like ochre, to even earlier dates, through a diversity of striking archaeological finds (66). Here, d'Errico et al (67) provide a rich and detailed account of the ways in which cultural repertoires and their associated ecological niches differentiated and evolved in these periods.…”