Testing inter-observer error under a collaborative research framework for studying lithic shape variability.

Unlabelled: Evaluating error that arises through the aggregation of data recorded by multiple observers is a key consideration in many metric and geometric morphometric analyses of stone tool shape. One of the most common approaches involves the convergence of observers for repeat trails on the same set of artefacts: however, this is logistically and financially challenging when collaborating internationally and/or at a large scale. We present and evaluate a unique alternative for testing inter-observer error, involving the development of 3D printed copies of a lithic reference collection for distribution among observers.

A spatiotemporally explicit paleoenvironmental framework for the Middle Stone Age of eastern Africa.

Eastern Africa has played a prominent role in debates about human evolution and dispersal due to the presence of rich archaeological, palaeoanthropological and palaeoenvironmental records. However, substantial disconnects occur between the spatial and temporal resolutions of these data that complicate their integration. Here, we apply high-resolution climatic simulations of two key parameters, mean annual temperature and precipitation, and a biome model, to produce a highly refined characterisation of the environments inhabited during the eastern African Middle Stone Age.

Evaluating refugia in recent human evolution in Africa.

have adapted to an incredible diversity of habitats around the globe. This capacity to adapt to different landscapes is clearly expressed within Africa, with Late Pleistocene populations occupying savannahs, woodlands, coastlines and mountainous terrain. As the only area of the world where have clearly persisted through multiple glacial-interglacial cycles, Africa is the only continent where classic refugia models can be formulated and tested to examine and describe changing patterns of past distributions and human phylogeographies.

The Importance of Noise Colour in Simulations of Evolutionary Systems.

Simulations of evolutionary dynamics often employ white noise as a model of stochastic environmental variation. Whilst white noise has the advantages of being simply generated and analytically tractable, empirical analyses demonstrate that most real environmental time series have power spectral densities consistent with pink or red noise, in which lower frequencies contribute proportionally greater amplitudes than higher frequencies. Simulated white noise environments may therefore fail to capture key components of real environmental time series, leading to erroneous results.

Neural networks differentiate between Middle and Later Stone Age lithic assemblages in eastern Africa.

The Middle to Later Stone Age transition marks a major change in how Late Pleistocene African populations produced and used stone tool kits, but is manifest in various ways, places and times across the continent. Alongside changing patterns of raw material use and decreasing artefact sizes, changes in artefact types are commonly employed to differentiate Middle Stone Age (MSA) and Later Stone Age (LSA) assemblages. The current paper employs a quantitative analytical framework based upon the use of neural networks to examine changing constellations of technologies between MSA and LSA assemblages from eastern Africa.

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.

Climatic variability, plasticity, and dispersal: A case study from Lake Tana, Ethiopia.

The numerous dispersal events that have occurred during the prehistory of hominin lineages are the subject of longstanding and increasingly active debate in evolutionary anthropology. As well as research into the dating and geographic extent of such dispersals, there is an increasing focus on the factors that may have been responsible for dispersal. The growing body of detailed regional palaeoclimatic data is invaluable in demonstrating the often close relationship between changes in prehistoric environments and the movements of hominin populations.

Food and social complexity at Çayönü Tepesi, southeastern Anatolia: Stable isotope evidence of differentiation in diet according to burial practice and sex in the early Neolithic.

The identification of early social complexity and differentiation in early village societies has been approached in the past most notably through the evaluation of rituals and architectural layouts. Such studies could be complemented by an approach that provides data about everyday behaviours of individuals. We took 540 human and animal bone samples for stable carbon and nitrogen isotope analysis from the Neolithic site of Çayönü Tepesi in southeastern Anatolia.

Recurrent patterning in the daily foraging routes of hamadryas baboons (Papio hamadryas): spatial memory in large-scale versus small-scale space.

The benefits of spatial memory for foraging animals can be assessed on two distinct spatial scales: small-scale space (travel within patches) and large-scale space (travel between patches). While the patches themselves may be distributed at low density, within patches resources are likely densely distributed. We propose, therefore, that spatial memory for recalling the particular locations of previously visited feeding sites will be more advantageous during between-patch movement, where it may reduce the distances traveled by animals that possess this ability compared to those that must rely on random search.

The evolution of spatial memory.

Models of foraging behaviour often assume either that animals are searching for resources, and therefore have no prior knowledge of resource locations, or that they are effectively omniscient, with a comprehensive knowledge of their habitat. By contrast, few attempts have been made to examine the actual conditions under which spatial memory will provide net benefits to foragers. To redress this balance, a model is developed that relates the sensory acuity of the forager and key indices of resource structure to the expected foraging efficiency via calculation of inter-patch distances.

Fission-fusion and the evolution of hominin social systems.

The course of hominin evolution has involved successive migrations towards higher absolute latitudes over the past three million years. Poorer habitat quality further from the equator has led to the necessity for groups occupying higher latitudes to live at lower population densities. Coupled with a trend towards increasing group size over this time period, this tendency towards expansion has led to exponential increases in the area requirements of hominin groups, and a concomitant need to adjust foraging patterns.

Speciation, diversity, and Mode 1 technologies: the impact of variability selection.

Over geological timescales, organisms encounter periodic shifts in selective conditions driven by environmental change. The variability selection hypothesis suggests that increases in environmental fluctuation have led to the evolution of complex, flexible behaviours able to respond to novel and unpredictable adaptive settings. This hypothesis is tested via the framework of a single locus genetic model in which an invading 'versatilist' allele competes with two opposed specialists in a selection regime driven by a fluctuating environment, modelled initially as a sine wave and subsequently as an empirical climate curve covering the past 5 million years.