Do silica phytoliths really wear mammalian teeth?

There is considerable literature suggesting that silica (opal) phytoliths cause dental enamel microwear in mammals. Much of this literature cites a single study from 1959 as evidence that silica phytoliths are harder than mammalian tooth enamel and so have the potential to cause dental microwear. No other studies using similar methodology have actually confirmed whether phytoliths are harder than dental enamel.     

Groundnuts as ‘economic crop’ or ‘wife of the home’ in Northern Nyasaland

This paper examines points during the 1930s in which the colonial state in Nyasaland attempted and failed to bring groundnuts more into the colonial export economy. Nyasaland colonial officials, the Department of Agriculture, European export companies and the British Colonial Office attempted to establish the groundnut as an ‘economic crop’ for African smallholder farmers in the Northern Province of Nyasaland in the 1930s. Their failure was in part due to competing and conflicting interests: payment of hut taxes, reduction of millet production, improvement of food security, payment of railway costs, and reduction of migration. Farmers actively resisted colonial efforts to sell groundnuts to European buyers. The paper addresses the question: how can we understand the nature of colonial state power in relation to Nyasaland peasant agricultural practices in the 1930s? I argue that conflicting interests within the colonial state, as well as external constraints led to efforts to both stabilize and exploit the Nyasaland farmer in the Northern Province. These competing agendas helped lead to a failed effort at groundnut promotion. Colonial officials' actions were linked to ideas about gender, ethnicity and migration. Lack of colonial scientific knowledge about groundnuts, including their gendered role in the local food system contributed to the failure. The focus on groundnuts is a lens through which to understand the nature of colonial power in Nyasaland and the role of agricultural science in the colonial state. The paper contributes to broader discussions about multiple historical geographies of colonialism, the nature of African colonial states, and the relationship of African farmers to colonial states.     

Obituaries

Abstract

A rich variety of processes have modified the glacial landscape of the Scottish Highlands since the last glaciers disappeared 11,500 years ago. Many of these processes can be described as paraglacial (glacially-conditioned): retreat of glacier ice has resulted in exposure of metastable sediment sources (rock slopes, drift-mantled slopes and valley-floor glacigenic deposits) that have been reworked over a range of timescales. Much of the reworked sediment has been deposited in paraglacial sediment stores (talus accumulations, debris cones, alluvial fans, valley fills, river terraces and deltas). The trajectory of paraglacial sediment transfer can be approximated by an exhaustion model. A corollary of this model is that all sediment stores eventually undergo a change from net accumulation to net erosion, reflecting the non-renewable nature of sediment sources. This concept helps to explain why most talus accumulations, debris cones and alluvial fans in the Highlands are now relict, and why many floodplains appear to have experienced an initial period of aggradation followed by later river incision and terrace development. Since deglaciation, rock slopes have experienced paraglacial stress release due to differential deglacial unloading. Many rock slopes have remained stable or experienced gradual adjustment through intermittent rockfall. At over 600 sites, however, large-scale rock-slope failure has occurred, either in the form of catastrophic failure with complete or arrested debris runout, or as major slope deformations. Modification of drift-mantled slopes has been dominated by rainstorm-generated debris flows activity, which have stripped sediment from slopes and redeposited it in debris cones. Radiocarbon dating of buried organic horizons shows that debris flows have occurred intermittently throughout the Holocene. Snow avalanches have played only a localized role in paraglacial sediment transfer. The Holocene alluvial history of the Highlands is poorly understood. Some alluvial fans formed during a few exceptional flood events, and there is evidence that postglacial floodplain aggradation peaked in the late Holocene and was succeeded by floodplain incision and terrace development, possibly reflecting upstream reduction in paraglacial sediment supply. Other processes have operated independently of glacial conditioning. The effects of wind action are dominant in the coastal zone, forming dunefields through aeolian reworking of beach sand, and on plateaux in the form of deflation surfaces and sand sheets. Extensive erosion of plateau-top sands and aeolisols occurred in the period AD 1550–1700, a period of exceptional storminess. Small-scale periglacial processes have also been active on high ground throughout the Holocene, including granular weathering of exposed rock surfaces, the development of small-scale frost-sorted patterned ground on unvegetated terrain, and slow downslope movement of solifluction sheets, solifluction lobes and ploughing boulders.     

Ally or competitor? Militant Basque nationalism's reaction to the new Spanish left

With the 2011 ceasefire declaration the Basque patriotic left (IA) has committed itself more firmly to constitutional politics. Concurrently, Spain has experienced an upsurge in the popularity of new political parties in the historically two party dominant general elections. The emergence of a political challenger on the left of the political spectrum (Podemos) may pose an opportunity or a threat to the IA's unilateral strategy, as the parties have numerous points of ideological concurrence. This paper analyses how the IA seeks to translate its strategies into mainstream constitutional politics, by exploring how it responds to the question posed by Podemos – ally, competitor, or both? Using an historical institutionalist approach, the conditions at two critical junctures – those surrounding the formation of new political parties during the democratic transition period and the more recent change in the electoral landscape – are compared to assess the initial impact of Podemos on IA cohesion.