description
- Morphometric analysis of wheat grains/chaff will be used to assess two potential sources of morphological variation: 1. Intra-species diversity i.e. between landraces and 2. Variation relating to environmental conditions/stresses. Data from analysis of modern wheat will be applied to archaeobotanical assemblages in a series of case studies. The research will explore how farmers may have cultivated different wheat varieties or 'landraces' in certain environments to produce desired characteristics and/or mitigate environmental risk-factors. Focus is placed on wheat due to its role as a major dietary staple in the past and present. Loss of genetic diversity in modern cereal crops has prompted increasing concerns over sustainability; particularly in the face of climate change. In this context, studying archaeological intra-species diversity allows us, not only to assess adaptability of past arable strategies, but also to make comparisons with modern arable systems. Equally, research will seek to identify vulnerability of yields by identifying symptoms of wheat impacted by stress factors, e.g. drought or soil exhaustion. It is hypothesised that intra-species diversity and vulnerability to environmental conditions will manifest themselves distinctly in wheat morphology, and that such distinctions will be discernible in archaeobotanical material. Research Context Recent studies have demonstrated the potential for identifying intra-species variation through morphometric analysis of modern wheat and barley grains respectively (Bonhomme et al. 2017; Wallace et al. 2018). Both studies established applicability of the methodology to charred archaeological material. However, it remains unresolved whether morphometrics can discern effects of environmental stresses and whether these can be distinguished from differences between landraces. While there has been substantial research into the effect of environmental factors such as water availability and temperature on wheat growth, this has tended to be quantified in terms of overall yield. For archaeobotanical applications, quantitative data on the morphology of environmentally-stressed grain/chaff is needed. Methodology Intra-species variation will be studied through morphometric analyses of multiple varieties of modern wheat with Momocs in R. Environmentally-determined variation will be assessed using existing plant experiment archives, with supplementation through further growing experiments possible. Across both categories, multivariate analysis will test the degree to which different types are successfully separated by the quantitative variables generated by morphometric description. Analysis will be repeated after charring to test the model's applicability to the most commonly encountered form of archaeobotanical remains. Archaeological Application The modern wheat study will indicate the potential for distinguishing between morphological differences deriving from intra-species variation and those caused by environmental stress. These findings will be applied to archaeobotanical case studies, including early medieval data available via the ongoing 'FeedSax' project. Evidence of landraces and/or growth-stressed grains, when supported by environmental and contextual data, may be used to develop theories on the strategies utilised, and challenges faced, by past farmers. For example, stable isotope values of anomalous types may shed light on conditions in which distinct landraces were grown and/or provide independent confirmation of environmental stress. More broadly, the research should aid interpretation of morphological anomalies previously observed within the archaeobotanical record, such as 'short-grained' wheat types. Categories of variation could be described and made available to researchers via an open-access platform. This would provide a tool for archaeobotanists to study biodiversity and resilience in past arable systems and inform debates concerning our future food-