Alison S. Brooks

Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets (Shanidar III, Iraq; Spy I and II, Belgium).

The nature and causes of the disappearance of Neanderthals and their apparent replacement by modern humans are subjects of considerable debate. Many researchers have proposed biologically or technologically mediated dietary differences between the two groups as one of the fundamental causes of Neanderthal disappearance. Some scenarios have focused on the apparent lack of plant foods in Neanderthal diets. Here we report direct evidence for Neanderthal consumption of a variety of plant foods, in the form of phytoliths and starch grains recovered from dental calculus of Neanderthal skeletons from Shanidar Cave, Iraq, and Spy Cave, Belgium. Some of the plants are typical of recent modern human diets, including date palms (Phoenix spp.), legumes, and grass seeds (Triticeae), whereas others are known to be edible but are not heavily used today. Many of the grass seed starches showed damage that is a distinctive marker of cooking. Our results indicate that in both warm eastern Mediterranean and cold northwestern European climates, and across their latitudinal range, Neanderthals made use of the diverse plant foods available in their local environment and transformed them into more easily digestible foodstuffs in part through cooking them, suggesting an overall sophistication in Neanderthal dietary regimes.

The environmental context for the origins of modern human diversity: A synthesis of regional variability in African climate 150,000-30,000 years ago

We synthesize African paleoclimate from 150 to 30 ka (thousand years ago) using 85 diverse datasets at a regional scale, testing for coherence with North Atlantic glacial/interglacial phases and northern and southern hemisphere insolation cycles. Two major determinants of circum-African climate variability over this time period are supported by principal components analysis: North Atlantic sea surface temperature (SST) variations and local insolation maxima. North Atlantic SSTs correlated with the variability found in most circum-African SST records, whereas the variability of the majority of terrestrial temperature and precipitation records is explained by local insolation maxima, particularly at times when solar radiation was intense and highly variable (e.g., 150-75 ka). We demonstrate that climates varied with latitude, such that periods of relatively increased aridity or humidity were asynchronous across the northern, eastern, tropical and southern portions of Africa. Comparisons of the archaeological, fossil, or genetic records with generalized patterns of environmental change based solely on northern hemisphere glacial/interglacial cycles are therefore imprecise. We compare our refined climatic framework to a database of 64 radiometrically-dated paleoanthropological sites to test hypotheses of demographic response to climatic change among African hominin populations during the 150-30 ka interval. We argue that at a continental scale, population and climate changes were asynchronous and likely occurred under different regimes of climate forcing, creating alternating opportunities for migration into adjacent regions. Our results suggest little relation between large scale demographic and climate change in southern Africa during this time span, but strongly support the hypothesis of hominin occupation of the Sahara during discrete humid intervals ~135-115 ka and 105-75 ka. Hominin populations in equatorial and eastern Africa may have been buffered from the extremes of climate change by locally steep altitudinal and rainfall gradients and the complex and variable effects of increased aridity on human habitat suitability in the tropics. Our data are consistent with hominin migrations out of Africa through varying exit points from ~140-80 ka.

Plant foods and the dietary ecology of Neanderthals and early modern humans

One of the most important challenges in anthropology is understanding the disappearance of Neanderthals. Previous research suggests that Neanderthals had a narrower diet than early modern humans, in part because they lacked various social and technological advances that lead to greater dietary variety, such as a sexual division of labor and the use of complex projectile weapons. The wider diet of early modern humans would have provided more calories and nutrients, increasing fertility, decreasing mortality and supporting large population sizes, allowing them to out-compete Neanderthals. However, this model for Neanderthal dietary behavior is based on analysis of animal remains, stable isotopes, and other methods that provide evidence only of animal food in the diet. This model does not take into account the potential role of plant food. Here we present results from the first broad comparison of plant foods in the diets of Neanderthals and early modern humans from several populations in Europe, the Near East, and Africa. Our data comes from the analysis of plant microremains (starch grains and phytoliths) in dental calculus and on stone tools. Our results suggest that both species consumed a similarly wide array of plant foods, including foods that are often considered low-ranked, like underground storage organs and grass seeds. Plants were consumed across the entire range of individuals and sites we examined, and none of the expected predictors of variation (species, geographic region, or associated stone tool technology) had a strong influence on the number of plant species consumed. Our data suggest that Neanderthal dietary ecology was more complex than previously thought. This implies that the relationship between Neanderthal technology, social behavior, and food acquisition strategies must be better explored.

Geoarchaeology at Gi, a Middle Stone Age and Later Stone Age site in the northwest Kalahari

Abstract Gi with sealed middle stone age and later stone age occurrences is located in the Dobe Valley along the Botswana-Namibia border. The phases of middle stone age settlement were linked to a semiarid streamway during the early Upper Pleistocene. A major humid interval followed, when a large lake was ponded in the Dobe Valley. Later stone age settlement appeared after this lake disappeared and was replaced by a mosaic of pans (ephemeral lakes). Subsequently, another period of humid environment favoured another valley-wide lake during the late Upper Pleistocene. Later stone age settlement resumed when this second lake deteriorated into the modern pan terrains of the Dobe Valley. In total, the Gi beds record multiple environmental changes both more humid and more arid than present during the Upper Pleistocene and Holocene, as well as a variable array of adaptive opportunities for prehistoric settlement.

Across Forests and Savannas: Later Stone Age Assemblages from Ituri and Semliki, Democratic Republic of Congo

This article characterizes Later Stone Age quartz industries from several sites in the rainforests and woodland-savanna mosaics of the northeastern Democratic Republic of Congo, with an emphasis on various reduction strategies that include simple debitage, bipolar percussion, discoidal centripetal percussion, Modes 4 and 5, pebble tools, flaw propagation, and formal tools. Comparisons between forest and woodland-savanna sites establish strong similarities among them over time, determine deliberate cultural choices as to raw material selection and overall reduction strategies, provide further evidence for an early inception of the Later Stone Age across tropical Africa, and show that ecologically distinct or highly specialized extractive technologies were not required to settle rainforests.

Human evolution: We are what we ate

A little under two million years ago there was a significant innovation in human evolution. This ‘grade shift’ betweenAustralopithecus and Homowas marked by an increase in body size and a commitment to walking on two legs. These changes were thought to be set off with the advent of hunting, but a new hypothesis contends that they were, in fact, due to systematic foraging for roots and tubers.

The nature of 'stone-lines' in the African Quaternary record: archaeological resolution at the rainforest site of Mosumu, Equatorial Guinea

Abstract ‘Stone-lines’ are widespread Quaternary features that appear in tropical and subtropical regions. They have a diverse nature and genesis, and are frequently associated with archaeological assemblages. However, archaeological deposition and ‘stone-line’ configuration may be unrelated geological events separated by thousands of years. The energetics involved in ‘stone-line’ formation, coarse and fine material translocation across space and in depth, and overall assemblage integrity vary from one site to another. This paper presents quantitative and spatial geoarchaeological data from the site of Mosumu, in the tropical rain forest of continental Equatorial Guinea. Mosumu yielded Middle and Later Stone Age assemblages dated to at least the last 30,000 years in a ‘stone-line’ context. Special attention to the study of vertical and horizontal variations of artifacts, sedimentary features, and taphonomic indicators allows analysis of the nature, meaning, and archeological resolution at this site. The results are placed in the wider debate over the meaning of ‘stone-lines’ in the African Quaternary record.

An Experimental Study of Hafting Adhesives and the Implications for Compound Tool Technology

Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, focusing on replicating ancient applications of adhesive technology. In contrast, this study tested several glues based on Acacia resin within a materials science framework to better understand the effect of each adhesive ingredient on compound tool durability. Using an overlap joint as a model for a compound tool, adhesives formulated with loading agents from a range of particle sizes and mineral compositions were tested for toughness on smooth and rough substrates. Our results indicated that overlap joint toughness is significantly increased by using a roughened joint surface. Contrary to some previous studies, there was no evidence that particle size diversity in a loading agent improved adhesive effectiveness. Generally, glues containing quartz or ochre loading agents in the silt and clay-sized particle class yielded the toughest overlap joints, with the effect of particle size found to be more significant for rough rather than smooth substrate joints. Additionally, no particular ochre mineral or mineral mixture was found to be a clearly superior loading agent. These two points taken together suggest that Paleolithic use of ochre-loaded adhesives and the criteria used to select ochres for this purpose may have been mediated by visual and symbolic considerations rather than purely functional concerns.

First early hominin from central Africa (Ishango, Democratic Republic of Congo).

Despite uncontested evidence for fossils belonging to the early hominin genus Australopithecus in East Africa from at least 4.2 million years ago (Ma), and from Chad by 3.5 Ma, thus far there has been no convincing evidence of Australopithecus, Paranthropus or early Homo from the western (Albertine) branch of the Rift Valley. Here we report the discovery of an isolated upper molar (#Ish25) from the Western Rift Valley site of Ishango in Central Africa in a derived context, overlying beds dated to between ca. 2.6 to 2.0 Ma. We used µCT imaging to compare its external and internal macro-morphology to upper molars of australopiths, and fossil and recent Homo. We show that the size and shape of the enamel-dentine junction (EDJ) surface discriminate between Plio-Pleistocene and post-Lower Pleistocene hominins, and that the Ishango molar clusters with australopiths and early Homo from East and southern Africa. A reassessment of the archaeological context of the specimen is consistent with the morphological evidence and suggest that early hominins were occupying this region by at least 2 Ma.

Reply to Collins and Copeland: Spontaneous gelatinization not supported by evidence

We thank Collins and Copeland (1) for raising the point that a better understanding of starch granule behavior in archaeological settings would be useful. However, we disagree with their assessment that the cooked starch granules we observed on Neanderthal teeth (2) were an effect of diagenesis.