Indications of habitat association of Australopithecus robustus in the Bloubank Valley, South Africa

Paleoecological evidence for environmental specialization in Paranthropus boisei compared to early Homo

Since the discovery of Paranthropus boisei alongside early Homo at Olduvai Gorge and East Turkana, paleoanthropologists have attempted to understand the different evolutionary paths of these two hominin lineages. Conventional wisdom is that their prolonged phase of sympatry in eastern Africa reflects different adaptive strategies, with early Homo characterized as the ecologically flexible generalist and Paranthropus as the less versatile specialist. If correct, this should imply differences in their use of ancient environments, with early Homo occurring in a broader range of environmental contexts than Paranthropus. This prediction has yet to be subject to rigorous quantitative evaluation. In this study, we use the 2.0-1.4 Ma fossil bovid assemblages associated with early Homo and P. boisei at East Turkana (Kenya) to quantify the breadth of their environmental associations. We find that early Homo occurs in faunal assemblages indicative of a broader range of environments than P. boisei. A null model taking sampling into account shows that the broad environmental associations of early Homo are indistinguishable from random, whereas P. boisei is one of just a handful of large mammal taxa from East Turkana that has a narrower range of environmental associations than expected by chance. These results support the characterization of P. boisei as an ecological specialist relative to the more generalist Homo. Moreover, the narrow environmental associations observed of P. boisei, unlike those of almost all other C₄ grass-consumers in the Turkana Basin, suggest that it likely did not feed on a spatially widespread C₄ resource like the leaves, seeds, or rhizomes of grass.

Reference database of teeth images from the Family Bovidae

Researchers typically rely on fossils from the Family Bovidae to generate African paleoenvironmental reconstructions due to their strict ecological tendencies. Bovids have dominated the southern African fauna for the past four million years and, therefore, dominate the fossil faunal assemblages, especially isolated teeth. Traditionally, researchers reference modern and fossil comparative collections to identify teeth. However, researchers are limited by the specific type and number of bovids at each institution. B.O.V.I.D. (Bovidae Occlusal Visual IDentification) is a repository of images of the occlusal surface of bovid teeth. The dataset currently includes extant bovids from 7 tribes and 20 species (~3900). B.O.V.I.D. contains two scaled images per specimen: a color and a black and white (binarized) image. The database is a useful reference for identifying bovid teeth. The large sample size also allows one to observe the natural variation that exists in each taxa. The binarized images can be used in statistical shape analyses, such as taxonomic classification. B.O.V.I.D. is a valuable supplement to other methods for taxonomically identifying bovid teeth.

Measurement(s)	occlusal surface of bovid teeth were outlined
Technology Type(s)	GIMP
Factor Type(s)	Bovidae taxonomic identification
Sample Characteristic - Organism	Bovidae
Sample Characteristic - Location	southern Africa

Early Pleistocene hominin subsistence behaviors in South Africa: Evidence from the hominin-bearing deposit of Cooper's D (Bloubank Valley, South Africa)

Evidence of the consumption of meat through hunting or scavenging by Early Pleistocene hominins is scarce, particularly in South Africa. Moreover, the interpretations of taphonomic evidence are subject to an important discussion commonly called the 'hunting-vs-scavenging debate.' Until today, only the Swartkrans Members 1-3 site has yielded a butchered bone assemblage large enough to permit reconstruction of carcass acquisition strategies by Early Pleistocene hominins in South Africa. This leaves an information gap between 1.4 and 1.0 Ma. Here, we provide the first evidence of meat consumption by hominins during this gap, based on the zooarchaeological study of the large mammal bone assemblage recovered from the Cooper's D site, South Africa. Based on skeletal part representation, our results show density-mediated attrition of bovid bones due to predepositional and postdepositional destruction. We argue that this attrition is the result of both abiotic (i.e., decalcification) and biotic (i.e., carnivore ravaging) processes. Bovid mortality profiles point out the involvement of ambush predators such as large felids. Bone surface modifications also indicate that the assemblage has been accumulated mostly by carnivores but with some hominin involvement as well. We observe all the stages of animal carcass processing (skinning, disarticulation, defleshing, marrow extraction) as well as the exploitation of a diversity of prey size classes at both Swartkrans Members 1-3 and Cooper's D. Thus, our study shows the importance of the Cooper's D bone assemblage for understanding Early Pleistocene hominin subsistence behaviors. Moreover, this article highlights the need for including long bone flake specimens in the analysis of large bone assemblages from South African caves to better understand the Early Pleistocene hominin bone damage record.

Early hominins evolved within non-analog ecosystems

Present-day African ecosystems serve as referential models for conceptualizing the environmental context of early hominin evolution, but the degree to which modern ecosystems are representative of those in the past is unclear. A growing body of evidence from eastern Africa's rich and well-dated late Cenozoic fossil record documents communities of large-bodied mammalian herbivores with ecological structures differing dramatically from those of the present day, implying that modern communities may not be suitable analogs for the ancient ecosystems of hominin evolution. To determine when and why the ecological structure of eastern Africa's herbivore faunas came to resemble those of the present, here we analyze functional trait changes in a comprehensive dataset of 305 modern and fossil herbivore communities spanning the last ∼7 Myr. We show that nearly all communities prior to ∼700 ka were functionally non-analog, largely due to a greater richness of non-ruminants and megaherbivores (species >1,000 kg). The emergence of functionally modern communities precedes that of taxonomically modern communities by 100,000s of years, and can be attributed to the combined influence of Plio-Pleistocene C₄ grassland expansion and pulses of aridity after ∼1 Ma. Given the disproportionate ecological impacts of large-bodied herbivores on factors such as vegetation structure, hydrology, and fire regimes, it follows that the vast majority of early hominin evolution transpired in the context of ecosystems that functioned unlike any today. Identifying how past ecosystems differed compositionally and functionally from those today is key to conceptualizing ancient African environments and testing ecological hypotheses of hominin evolution.

The Equidae from Cooper's D, an early Pleistocene fossil locality in Gauteng, South Africa

Cooper’s D is a fossil locality in the Bloubank Valley close to other important sites such as Sterkfontein and Kromdraai in Gauteng, South Africa. The fossil deposits of Cooper’s D date to 1.38 ± 0.11 Ma. Hominins like Paranthropus robustus and early Homo have been recovered from Cooper’s Cave. We report here on the Equidae remains. Our sample contains specimens from the extinct Equus capensis, and a specimen which represents an extinct hipparion Eurygnathohippus cf. cornelianus. This particular specimen was previously identified as plains zebra (Equus quagga). The contribution of Equidae to the total fossil assemblage of Cooper’s D is relatively low, and these remains were likely accumulated by various predators such as spotted and brown hyenas and leopards. The Equidae, as well as the other fauna from Cooper’s D supports the existence of grassland, wooded and water components in the vicinity of the site.

The ecomorphology of southern African rodent incisors: Potential applications to the hominin fossil record

The taxonomic identification of mammalian fauna within fossil assemblages is a well-established component of paleoenvironmental reconstructions. However, many fragmentary specimens recovered from fossil sites are often disregarded as they can be difficult to identify with the precision required for taxonomic methods. For this reason, the large numbers of isolated rodent incisors that are often recovered from hominin fossil bearing sites are generally regarded as offering little interpretive value. Ecomorphological analysis, often referred to as a “taxon-free” method, can potentially circumvent this problem by focusing on the adaptive, rather than the taxonomic significance of rodent incisor morphology. Here, we determine if the morphology of the upper incisors of modern southern African rodents reflects dietary behavior using discriminant function analysis. Our model suggests that a strong ecomorphological signal exists in our modern sample and we apply these results to two samples of isolated incisors from the hominin fossil bearing sites, Sterkfontein and Swartkrans.

The spatio-temporal distribution of archaeological and faunal finds at Liang Bua (Flores, Indonesia) in light of the revised chronology for Homo floresiensis

Liang Bua, the type site of Homo floresiensis, is a limestone cave on the Indonesian island of Flores with sedimentary deposits currently known to range in age from about 190 thousand years (ka) ago to the present. Recent revision of the stratigraphy and chronology of this depositional sequence suggests that skeletal remains of H. floresiensis are between ∼100 and 60 ka old, while cultural evidence of this taxon occurs until ∼50 ka ago. Here we examine the compositions of the faunal communities and stone artifacts, by broad taxonomic groups and raw materials, throughout the ∼190 ka time interval preserved in the sequence. Major shifts are observed in both the faunal and stone artifact assemblages that reflect marked changes in paleoecology and hominin behavior, respectively. Our results suggest that H. floresiensis and Stegodon florensis insularis, along with giant marabou stork (Leptoptilos robustus) and vulture (Trigonoceps sp.), were likely extinct by ∼50 ka ago. Moreover, an abrupt and statistically significant shift in raw material preference due to an increased use of chert occurs ∼46 thousand calibrated radiocarbon (¹⁴C) years before present (ka cal. BP), a pattern that continues through the subsequent stratigraphic sequence. If an increased preference for chert does, in fact, characterize Homo sapiens assemblages at Liang Bua, as previous studies have suggested (e.g., Moore et al., 2009), then the shift observed here suggests that modern humans arrived on Flores by ∼46 ka cal. BP, which would be the earliest cultural evidence of modern humans in Indonesia.

A two-million-year-long hydroclimatic context for hominin evolution in southeastern Africa

The past two million years of eastern African climate variability is currently poorly constrained, despite interest in understanding its assumed role in early human evolution^1-4. Rare palaeoclimate records from northeastern Africa suggest progressively drier conditions^2,5 or a stable hydroclimate⁶. By contrast, records from Lake Malawi in tropical southeastern Africa reveal a trend of a progressively wetter climate over the past 1.3 million years^7,8. The climatic forcings that controlled these past hydrological changes are also a matter of debate. Some studies suggest a dominant local insolation forcing on hydrological changes^9-11, whereas others infer a potential influence of sea surface temperature changes in the Indian Ocean^8,12,13. Here we show that the hydroclimate in southeastern Africa (20-25° S) is controlled by interplay between low-latitude insolation forcing (precession and eccentricity) and changes in ice volume at high latitudes. Our results are based on a multiple-proxy reconstruction of hydrological changes in the Limpopo River catchment, combined with a reconstruction of sea surface temperature in the southwestern Indian Ocean for the past 2.14 million years. We find a long-term aridification in the Limpopo catchment between around 1 and 0.6 million years ago, opposite to the hydroclimatic evolution suggested by records from Lake Malawi. Our results, together with evidence of wetting at Lake Malawi, imply that the rainbelt contracted toward the Equator in response to increased ice volume at high latitudes. By reducing the extent of woodland or wetlands in terrestrial ecosystems, the observed changes in the hydroclimate of southeastern Africa-both in terms of its long-term state and marked precessional variability-could have had a role in the evolution of early hominins, particularly in the extinction of Paranthropus robustus.

Environmental dynamics during the onset of the Middle Stone Age in eastern Africa

Development of the African Middle Stone Age (MSA) before 300,000 years ago raises the question of how environmental change influenced the evolution of behaviors characteristic of early Homo sapiens We used temporally well-constrained sedimentological and paleoenvironmental data to investigate environmental dynamics before and after the appearance of the early MSA in the Olorgesailie basin, Kenya. In contrast to the Acheulean archeological record in the same basin, MSA sites are associated with a markedly different faunal community, more pronounced erosion-deposition cycles, tectonic activity, and enhanced wet-dry variability. Aspects of Acheulean technology in this region imply that, as early as 615,000 years ago, greater stone material selectivity and wider resource procurement coincided with an increased pace of land-lake fluctuation, potentially anticipating the adaptability of MSA hominins.

Strong influence of palaeoclimate on the structure of modern African mammal communities

Ecological research often assumes that species are adapted to their current climatic environments. However, climate fluctuations over geologic timescales have influenced species dispersal and extinction, which in turn may affect community structure. Modern community structure is likely to be the product of both palaeoclimate and modern climate, with the relative degrees of influence of past and present climates unknown. Here, we assessed the influence of climate at different time periods on the phylogenetic and functional trait structure of 203 African mammal communities. We found that the climate of the mid-Holocene (approx. 6000 years ago) and Last Glacial Maximum (approx. 22 000 years ago) were frequently better predictors of community structure than modern climate for mammals overall, carnivorans and ungulates. Primate communities were more strongly influenced by modern climate than palaeoclimate. Overall, community structure of African mammals appears to be related to the ecological flexibility of the groups considered here and the regions of continental Africa that they occupy. Our results indicate that the future redistribution, expansion and contraction of particular biomes due to human activity, such as climate and land-use change, will differentially affect mammal groups that vary in their sensitivity to environmental change.

Dietary proclivities of Paranthropus robustus from Swartkrans, South Africa

Pleistocene Paranthropus robustus fossils from Swartkrans have yielded stable isotope values suggesting some foraging on C4 plants possibly including underground storage organs. Dental microwear texture analysis on P. robustus (SK 6, SK 34 and SK 47) from Swartkrans Member 1 is performed to examine whether tooth surface damage from mastication agrees with prior dietary inferences from carbon isotopes. There is considerable variation in textural characteristics among the P. robustus specimens. Specifically, adult SK 34 stands apart from the two subadult specimens, SK 6 and SK 47, suggesting life history could be reflected in patterns of dental microwear texture characteristics, although seasonality and availability of fallback foods may also explain the variation observed in P. robustus. The fossils all exhibit elevated surface texture complexity, resembling the values for Lophocebus albigena and Cebus apella, and to a lesser extent, Pan troglodytes. Paranthropus robustus is dissimilar to primary folivores, such as Trachypithecus cristatus or folivore- frugivores such as Alouatta palliata suggesting leaves comprised very little of its diet. The textural fill volume of P. robustus differs from that observed in extant primates from tropical forests indicating extreme durophagy, perhaps a function of differences in habitat. Ingestion of extraneous grit on the underground parts of plants and from terrestrial resources, perhaps as fallback foods or as dietary staples, may account for these enamel textural properties and may help explain the mixed C3/C4 isotopic signal in P. robustus.