Phytoliths from Middle Stone Age habitats in the Mozambican Rift (105-29 ka).

The detection of areas suitable for hominins during late Pleistocene drought intervals is currently a priority for Middle Stone Age research. Predicting the location of populations and dispersal pathways through the East African Rift System during the last glacial phase is a challenging task due to scarce direct archaeo-vegetation data. We present a Mozambican phytolith record spanning 105-29 ka and argue for the necessity and utility of using local plant microbotanical data from archaeological sites to understand the past environments in which early modern humans lived. We assess biome structure, spatial variability, and compare phytolith-based to lacustrine environmental reconstructions to conclude that dense wooded landscapes dominated the area over much of the last glacial phase. Archaeological and botanical data suggest the hypothesis of a palaeodispersal along a montane woodland archipelago that could have attracted hominin settlement and facilitated dispersals through an inland bridge that connected southern, central and East Africa, and the two branches of the East African Rift System.

The bow and cultural complexity of the Canadian Plains.

The timing and circumstances of the introduction of the bow and arrow into past North American economic and social lifeways have been sources of interest and controversy among archeologists for a very long time. Initial interpretations of the adoption of the bow and arrow generally seem to have been based on the rather straightforward assumption of functional superiority as a hunting tool. That is, the bow and arrow was simply a better instrument than the atlatl-dart technology it replaced. More recently, however, researchers exploring the effectiveness of the atlatl as a hunting tool have responded with studies that challenge the assumed universal functional superiority of the bow and arrow as a hunting device. Social coercion and warfare theory presents an alternative perspective on the adoption of the bow and arrow.

Microbotanical residues for the study of early hominin tools.

More than 2 million years ago in East Africa, the earliest hominin stone tools evolved amidst changes in resource base, with pounding technology playing a key role in this adaptive process. Olduvai Gorge (now Oldupai) is a famed locality that remains paramount for the study of human evolution, also yielding some of the oldest battering tools in the world. However, direct evidence of the resources processed with these technologies is lacking entirely. One way to obtain this evidence is through the analysis of surviving residues. Yet, linking residues with past processing activities is not simple. In the case of plant exploitation, this link can only be established by assessing site-based reference collections inclusive of both anthropogenic and natural residues as a necessary first step and comparative starting point. In this paper, we assess microbotanical remains from rock clasts sourced at the same quarry utilized by Oldowan hominins at Oldupai Gorge. We mapped this signal and analysed it quantitatively to classify its spatial distribution objectively, extracting proxies for taxonomic identification and further comparison with freestanding soils. In addition, we used blanks to manufacture pounding tools for blind, controlled replication of plant processing. We discovered that stone blanks are in fact environmental reservoirs in which plant remains are trapped by lithobionts, preserved as hardened accretions. Tool use, on the other hand, creates residue clusters; however, their spatial distribution can be discriminated from purely natural assemblages by the georeferencing of residues and statistical analysis of resulting patterns. To conclude, we provide a protocol for best practice and a workflow that has the advantage of overcoming environmental noise, reducing the risk of false positive, delivering a firm understanding of residues as polygenic mixtures, a reliable use of controls, and most importantly, a stronger link between microbotanical remains and stone tool use.

Phytoliths in woody plants from the Miombo woodlands of Mozambique.

BACKGROUND AND AIMS: There are no descriptions of phytoliths produced by plants from the 'Zambezian' zone, where Miombo woodlands are the dominant element of the largest single phytochorion in sub-Saharan Africa. The preservation of phytoliths in fossil records of Africa makes phytoliths a tool to study early plant communities. Paleo-ethnobotanical interpretation of phytoliths relies on the comparison of ancient types with morphotypes extracted from living reference collections. METHODS: Phytoliths were extracted from plant samples representing 41 families, 77 genera and 90 species through sonic cleaning, dry ashing and acid treatment; and phytoliths thus extracted were quantified. For each species, an average of 216 phytoliths were counted. The percentage of each morphotype identified per species was calculated, and types were described according to the descriptors from the International Code for Phytolith Nomenclature. Phytolith assemblages were subject to discriminant analysis, cluster analysis and principal component analysis. KEY RESULTS: Phytoliths were grouped into 57 morphotypes (two were articulated forms and 55 were discrete shapes), and provide a reference collection of phytolith assemblages produced by Miombo woody species. Common and unique morphotypes are described and taxonomic and grouping variables are looked into from a statistical perspective. CONCLUSIONS: The first quantitative taxonomy of phytoliths from Miombos is presented here, including new types and constituting the most extensive phytolith key for any African ecoregion. Evidence is presented that local woody species are hypervariable silica producers and their phytolith morphotypes are highly polymorphic. The taxonomic significance of these phytoliths is largely poor, but there are important exceptions that include the morphotypes produced by members from >10 families and orders. The typical phytolithic signal that would allow scientists to identify ancient woodlands of 'Zambezian' affiliation comprises only half of the original number of phytoliths originally produced and might favour the more resilient blocky, cylindroid, globular and tabular forms.

Soil and plant phytoliths from the Acacia-Commiphora mosaics at Oldupai Gorge (Tanzania).

This article studies soil and plant phytoliths from the Eastern Serengeti Plains, specifically the Acacia-Commiphora mosaics from Oldupai Gorge, Tanzania, as present-day analogue for the environment that was contemporaneous with the emergence of the genus Homo. We investigate whether phytolith assemblages from recent soil surfaces reflect plant community structure and composition with fidelity. The materials included 35 topsoil samples and 29 plant species (20 genera, 15 families). Phytoliths were extracted from both soil and botanical samples. Quantification aimed at discovering relationships amongst the soil and plant phytoliths relative distributions through Chi-square independence tests, establishing the statistical significance of the relationship between categorical variables within the two populations. Soil assemblages form a spectrum, or cohort of co-ocurring phytolith classes, that will allow identifying environments similar to those in the Acacia-Commiphora ecozone in the fossil record.