Jessica C. Thompson

Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia

Two fossil specimens from the DIK-55 locality in the Hadar Formation at Dikika, Ethiopia, are contemporaneous with the earliest documented stone tools, and they collectively bear twelve marks interpreted to be characteristic of stone tool butchery damage. An alternative interpretation of the marks has been that they were caused by trampling animals and do not provide evidence of stone tool use or large ungulate exploitation by Australopithecus-grade hominins. Thus, resolving which agents created marks on fossils in deposits from Dikika is an essential step in understanding the ecological and taphonomic contexts of the hominin-bearing deposits in this region and establishing their relevance for investigations of the earliest stone tool use. This paper presents results of microscopic scrutiny of all non-hominin fossils collected from the Hadar Formation at Dikika, including additional fossils from DIK-55, and describes in detail seven assemblages from sieved surface sediment samples. The study is the first taphonomic description of Pliocene fossil assemblages from open-air deposits in Africa that were collected without using only methods that emphasize the selective retention of taxonomically-informative specimens. The sieved assemblages show distinctive differences in faunal representation and taphonomic modifications that suggest they sample a range of depositional environments in the Pliocene Hadar Lake Basin, and have implications for how landscape-based taphonomy can be used to infer past microhabitats. The surface modification data show that no marks on any other fossils resemble in size or shape those on the two specimens from DIK-55 that were interpreted to bear stone tool inflicted damage. A large sample of marks from the sieved collections has characteristics that match modern trampling damage, but these marks are significantly smaller than those on the DIK-55 specimens and have different suites of characteristics. Most are not visible without magnification. The data show that the DIK-55 marks are outliers amongst bone surface damage in the Dikika area, and that trampling is not the most parsimonious interpretation of their origin.

Zooarchaeological tests for modern human behaviour at Blombos Cave and Pinnacle Point Cave 13B, southwestern Cape, South Africa

Data were collected and analysed from the fossil animal bones at two archaeological sites in the southwestern Cape, South Africa: Blombos Cave and Pinnacle Point Cave 13B (PP13B). Both sites date to a time known as the Middle Stone Age (MSA), from c. 280 30 thousand years ago (kya). This was a critical period in human evolution, and recent discoveries from Blombos have shown that creativity and symbolic behaviour were present in Homo sapiens by at least 70 kya. However, the relationship between these factors and diet remains unknown. Work on this problem has been seriously hindered by a lack of empirical data: in all of southern Africa only one other faunal collection from this time period has been comprehensively analysed and published (Die Kelders Cave 1 [DK1]). The study presented here replicates many of the methods employed at DK1, effectively tripling the empirical record for faunal collections that are complete, have been fully analysed using taphonomic methods, and are comparable to one another. For the first time, behavioural comparisons of MSA faunal exploitation can be made between sites with abundant evidence for symbolic behaviour (Blombos) and those with less evidence of this kind (PP13B and DK1). This dissertation examines in detail the taphonomic histories at PP13B and Blombos, including fragmentation, the relative contributions of human and nonhuman bone accumulators, and density-mediated destruction. With these factors understood and controlled for, evaluations of MSA hunting ability, transport decisions, and carcass processing strategies are made from these sites and at DK1 using both standard zooarchaeological measures and new methods for reconstructing these behaviours from fossil collections. These analyses reveal that MSA hominins were adept hunters with a prey focus on large ungulates but also opportunistically exploited smaller ungulates, tortoises, and small mammals. There is a great deal of variability in how ungulates of all body sizes were processed and transported, but at all sites there is an intensive use of all animal resources, including bone grease, and an emphasis on the filleting of meat from shafts.

On bad terms: Problems and solutions within zooarchaeological bone surface modification studies

Abstract The identification of butchery marks in the zooarchaeological record has consistently been debated. Much experimental work has been done to understand the causal agents behind some bone surface modifications, but recent controversies show that there is still no consensus. Terminology is not consistent between researchers, and there is ambiguity in how characteristics of marks are described and interpreted. There is also a lack of understanding of what causes individual variables within marks made by different agents, which is compounded by mark morphologies being described in terms that imply their causality. This paper examines these two problems in light of historic and current trends in the taphonomic literature, and recommends ways to describe marks that will facilitate more effective communication between researchers. It is proposed that greater standardisation within zooarchaeology is needed in seven key areas, and that this is the best avenue for moving into a new phase of taphonomic research.

Crocodile ecology and the taphonomy of early Australasian sites

Abstract Humans and human ancestors have exploited wetland resources for at least two million years. The most significant predators in these landscapes are crocodiles, which leads to two potential taphonomic problems: 1) human-accumulated bones may become intermingled with crocodile-modified bones; and 2) hominins themselves may have been victims of crocodiles. Davidson and Solomon (1990) significantly contributed to this literature through theirsuggestion that a crocodile attack led to the tooth marks on the type specimen of Homo habilis (OH 7) found in Olduvai Gorge, Tanzania. The Australasian tropics were also home to a variety of crocodilian species, crocodile damage to hominin bones being inferred in Trinil and Sangiran, Java. Furthermore, two Pleistocene Australian archaeological sites have stone artefacts in association with crocodile-damaged bone. A referential taphonomic framework is needed to understand the degree and nature of crocodile-hominin interactions on paleolandscapes of Sunda, the ancient Pleistocene landmass incorporating the islands of SE Asia, and Sahul, the Pleistocene landmass of ancient Australia incorporating Papua New Guinea, Australia and Tasmania. This paper provides initial results from crocodile feeding experiments aimed at characterising feeding damage inflicted on bones by the largest extant Australasian crocodile, Crocodylus porosus. Due to close similarity among Crocodylus species in dental and cranial morphology there are some general patterns in the way they modify bones. However, some differences arise when the taphonomic signatures are compared to those of the Nile crocodile (Crocodylus niloticus). We suggest that these differences are attributable to evolved differences in the feeding ecologies of the two species.

The trajectory of bone surface modification studies in paleoanthropology and a new Bayesian solution to the identification controversy

A critical issue in human evolution is how to determine when hominins began incorporating significant amounts of meat into their diets. This fueled evolution of a larger brain and other adaptations widely considered unique to modern humans. Determination of the spatiotemporal context of this shift rests on accurate identification of fossil bone surface modifications (BSM), such as stone tool butchery marks. Multidecade-long debates over the agents responsible for individual BSM are indicative of systemic flaws in current approaches to identification. Here we review the current state of BSM studies and introduce a novel probabilistic approach to identifying agents of BSM. We use control assemblages of bones modified by modern agents to train a multivariate Bayesian probability model. The model then identifies BSM agents with associated uncertainties, serving as the basis for a predictive probabilistic algorithm. The multivariate Bayesian approach offers a novel, probabilistic, and analytical method for BSM research that overcomes much of the bias that has typified previous, more qualitative approaches.

Using GIS to Integrate Old and New Archaeological Data from Stone Age Deposits in Karonga, Malawi

The Karonga District of northern Malawi has an extensive Stone Age archaeological record, primarily represented by stone artefacts that occur in both superficial and buried contexts. Work conducted in the 1960s provided initial documentation of this record. Some of this was presented in summary form in a small number of publications. However, most data were restricted to unpublished field notes, maps, and other static or largely inaccessible formats. GIS has been an essential tool for bringing together these diverse datasets in a digital format to facilitate integration of new research and promote reinvestigation of old sites. Examples from both the regional and site scale demonstrate how old data have been combined with recent survey and excavation data to document, analyse, interpret, and archive current knowledge about the rich Stone Age record of northern Malawi. A significant result from this approach has been the suggested reinterpretation of the Mwangandas Village Site.

Taphonomic analysis of the mammalian fauna from Sandia Cave, New Mexico, and the 'Sandia Man' controversy

Sandia Cave in New Mexico was excavated in the late 1930s by Frank Hibben, who described a unique type of chipped stone artifact-the “Sandia point”-in association with a faunal assemblage that included extinct Pleistocene species. The site was interpreted as a late Pleistocene Paleoindian hunting station, making it the earliest human occupation known in America at the time. Despite the pivotal role the faunal assemblage has played in interpretations of the site, there was never a confirmed behavioral association between the artifacts and the fossils. A subsequent series of controversies about the age of the site and the integrity of the stratigraphy has since pushed Sandia Cave into obscurity. Results from a recent taphonomic study of the large and small mammal assemblages from the original excavations are reported here. These show that the majority of the fauna were accumulated by nonhuman agents (carnivores, raptors, and rodents), but that a small proportion of large mammal fragments retain human modification. The three major points of controversy are discussed in light of these and other findings, and it is shown that Sandia Cave remains an important datapoint in archaeological, paleontological, and paleoecological studies of the region.

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

We challenge the view that our species, Homo sapiens, evolved within a single population and/or region of Africa. The chronology and physical diversity of Pleistocene human fossils suggest that morphologically varied populations pertaining to the H. sapiens clade lived throughout Africa. Similarly, the African archaeological record demonstrates the polycentric origin and persistence of regionally distinct Pleistocene material culture in a variety of paleoecological settings. Genetic studies also indicate that present-day population structure within Africa extends to deep times, paralleling a paleoenvironmental record of shifting and fractured habitable zones. We argue that these fields support an emerging view of a highly structured African prehistory that should be considered in human evolutionary inferences, prompting new interpretations, questions, and interdisciplinary research directions.

Low-Survival Skeletal Elements Track Attrition, Not Carcass Transport Behavior in Quaternary Large Mammal Assemblages

Zooarchaeological analyses of carcass transport behavior require methodologies that control for the effects of density-mediated attrition on skeletal element abundances. Taphonomic observations suggest that based on differences in bone structure and density, large mammal skeletal elements can be divided into a high-survival subset of skeletal elements that more accurately reflects what was originally deposited, and a low-survival subset that does not. In this chapter we explore the applicability of this model of bone survivorship across 43 Quaternary large mammal assemblages from Africa (n = 33) and Eurasia (n = 10). We demonstrate that attrition explains a substantial degree of variation in low-survival element abundances, with nearly all low-survival elements affected. Because attrition severely overprints any potential signature of differential bone transport by humans, it follows that only the high-survival elements of large mammals are suitable for making behavioral inferences from skeletal element abundances. This supports predictions made from actualistic taphonomic observations.

The origins and early elaboration of projectile technology

The ability of Homo sapiens to kill prey at a distance is arguably one of the catalysts for our current ecological dominance. Many researchers have suggested its origins lie in the African Middle Stone Age or the European Middle Palaeolithic (∼300‐30 thousand years ago), but the perishable components of armatures rarely preserve. Most research on this subject therefore emphasises analysis of armature tip size, shape, and diagnostic impacts or residues. Other lines of evidence have included human skeletal anatomy or analyses of the species composition of faunal assemblages. Projectile Impact Marks (PIMs) on archaeofaunal remains offer an ideal complement to this work, but their potential has been restricted mainly to the later Eurasian zooarchaeological record. A review of current evidence and approaches shows that systematic PIM research could add much to our understanding of early projectile technology, especially in Africa.