Search

One of the primary goals of the palaeosciences is to produce robust understandings of palaeoecologies of extinct ecosystems. The time has arrived where such palaeoecologies can be significantly improved—agent-based models (ABMs) that synthesize our modern understandings of animal ecology with past conditions provide a unique opportunity for this. The Palaeo-Agulhas Plain (PAP), a now submerged landscape off the south coast of South Africa, formed a novel ecosystem during the lower sea levels of the Pleistocene. Here we provide a review of the utility of ABMs for understanding herbivores in prehistoric environments using the Paleoscape Model. The Paleoscape Model is fortunate to have features models of climate, geology and vegetation upon which we can understand how herbivores used the PAP environment. To incorporate aspects of herbivore behaviour and habitat suitability into the model requires analogies from extant systems. In addition to reconstructions of the availability of resources and associated risks, data on herbivore behaviour and physiology are imperative to our understanding of these systems. Behaviour, driven by changes in the environment, is interpreted by species, leading to selection of suitable habitats ultimately driving the herbivore's decisions within ABMs. Finally, we discuss herbivore integration into these models that can be used in numerous other scenarios (past, present and future). [ABSTRACT FROM AUTHOR]

Throughout much of the Quaternary, lower sea levels in the southern Cape of South Africa exposed a different landscape to what we see today, the Palaeo‐Agulhas Plain (PAP). The PAP was dominated by large‐bodied and gregarious grazing species contrasting with the small‐bodied predominantly solitary species we find in the region today. The distribution of these herbivores would likely have been driven by similar drivers we see in contemporary herbivore ecology. Importantly, the occurrence of early humans and their associated technology would have also influenced the probability of herbivores occurring in an area. Here we create a predictive model for large herbivores using probability of occurrence of functional grouping in relation to environmental drivers and humans. We show how early humans influenced the distribution of large herbivores on the PAP alongside other environmental drivers. In the fynbos biome, probability of occurrence was highest for the medium‐sized social mixed feeders' functional group in the thicket for small non‐social browsers, large browsers, and non‐ruminants and in grasslands for water‐dependent grazers. In our models, human influence affected functional groups to varying degrees but had the strongest effect on medium‐sized social mixed feeders. [ABSTRACT FROM AUTHOR]

Herbivore distribution throughout Africa is strongly linked to mean annual precipitation. We use that relationship to predict functional group composition of herbivore communities during the last glacial maximum (ca. 21 ka) on the now submerged Palaeo-Agulhas Plain (PAP), South Africa. We used metabolic large herbivore biomass (MLHB) from 39 South African protected areas, in five functional groups (characterized by behavior and physiology). We examined how modern factors influenced MLHB and considered the effects of biome, annual rainfall, percentage winter rainfall, and protected area size. Overall, biome was the most important factor influencing the relationship between MLHB and rainfall. In general, MLHB increased with rainfall, but not for the grassland biome. Outside grasslands, most functional groups' metabolic biomass increased with increasing rainfall, irrespective of biome, except for medium-sized social mixed feeder species in savanna and thicket. Protected area size was influential for medium-sized social mixed feeders and large browsers and rainfall influenced medium-sized social mixed feeders, offering some perspectives on spatial constraints on past large herbivore biomass densities. These results improve our understanding of the likely herbivore community composition and relative biomass structure on the PAP, an essential driver of how early humans utilized large mammals as a food resource. [ABSTRACT FROM AUTHOR]

The origins and significance of an aquatic diet in hominin evolution is a scientific research topic of high significance. Some have argued that marine shellfish collection was a key ingredient in the emergence of modern human behavioral and cultural complexity. The collection of marine resources, which can be productive and predictable, may have evolved into a coastal adaptation that led to reduction in residential mobility and other important changes in behavior and culture. Therefore, studying the emergence and intensity of coastal occupations is important to understand the rise of this particular aspect of modern humans' behavioral and cultural evolution. In this article, we use an agent-based model to explore the interaction between foraging behavior and the environment, and the impact of such interaction on sites' length of occupation, which in turn affects the accumulation of artifacts and ecofacts. The results of the model suggest that the intensive occupation of coastal sites is likely to be influenced by their position within a restricted band of productive coastal habitat. Even when foragers spend most of their time in other habitats, the cyclical reoccupation of coastal sites – due to the coast's cyclical productivity as well as the low number of locations that can be occupied there – could naturally result in higher artifact density in coastal than inland sites. Here, we argue that, given those results, coastal locations should accumulate large and dense deposits of occupation debris. These will be obvious features on the landscape and should be easier to find than inland occupations because of the coastal habitats' confined space. Finally, given the higher find densities of those sites, this may lead archaeologists to overestimate the contribution of marine resources in prehistoric diets. Therefore, what archaeologists have interpreted as intensive coastal adaptation in the past may be more the result of geographical constraints rather than important evolutionary changes. [ABSTRACT FROM AUTHOR]

The Palaeo-Agulhas Plain formed an important habitat exploited by Pleistocene hunter-gatherer populations during periods of lower sea level. This productive, grassy habitat would have supported numerous large-bodied ungulates accessible to a population of skilled hunters with the right hunting technology. It also provided a potentially rich location for plant food collection, and along its shores a coastline that moved with the rise and fall of sea levels. The rich archaeological and paleontological records of Pleistocene sites along the modern Cape south coast of South Africa, which would have overlooked the Palaeo-Agulhas Plain during Pleistocene times of lower sea level, provides a paleoarchive of this extinct ecosystem. In this paper, we present a first order illustration of the " palaeoscape modeling " approach advocated by Marean et al. (2015). We use a resourcescape model created from modern studies of habitat productivity without the Palaeo-Agulhas Plain. This is equivalent to predominant Holocene conditions before recent landscape modifications for farming. We then run an agent-based model of the human foraging system to investigate several research questions. Our agent-based approach uses the theoretical framework of optimal foraging theory to model human foraging decisions designed to optimize the net caloric gains within a complex landscape of spatially and temporally variable resources. We find that during the high sea-levels of MIS 5e (+5–6 m asl) and the Holocene, the absence of the Plain left a relatively poor food base supporting a much smaller population relying heavily on edible plant resources from the current Cape flora. Despite high species diversity of plants with edible storage organs, and marine invertebrates, encounter rates with highly profitable resources were low. We demonstrate that without the Palaeo-Agulhas Plain, human populations must have been small and low-density, and exploited plant, mammal, and marine resources with relatively low caloric returns. The exposure and contraction of the Palaeo-Agulhas Plain was likely the single biggest driver of behavioural change during periods of climate change through the Pleistocene and into the transition to the Holocene. • Agent-based model of Later Stone Age human foraging in coastal South Africa. • Reconstructed food resource landscape including mammals, shellfish, and plants. • Sustainable population is under 20 individuals/100 km^2. • Long foraging days (10 + hours per day) and small groups needed to survive. • Edible plants, including USOs, make up 80% or more of the diet. [ABSTRACT FROM AUTHOR]