Measuring the isotopic landscape: bone chemistry, the environment, and ancient agriculture in the Thames Valley
Lead Research Organisation:
University of Oxford
Department Name: Archaeology and History of Art Res Lab
Abstract
Summary
This proposal is to develop deeper, more detailed, ways to learn about farming in Southern England and how it changed from Neolithic to Roman times. We have chosen a well researched region with detailed archaeological knowledge and, for many sites, a good record of the environmental context. We propose to analyse chemically the bones from a statistically robust number of domesticated animals from 32 well studied sites. We will measure 'stable isotopes', that is atoms of the actual animals' food, which remain in their bones. We know that slight variations in stable isotopes are due to changes in diet, which can come about from changes in management, or changes in food-plant isotopes. Plant isotopes cannot be measured directly, but do depend on subtle changes in their environment. Actually, although we have an understanding of several types of environmental influence, we do not know clearly and exactly how the environment is reflected in animal bone isotope values; but we do know that animal bone isotopes from various sites show intriguing patterns of variation and correlation, in a site over time, or between species, or between sites in different settings. This research is to characterise what sorts of pattern occur in settings where we can relate the results to known environments, and then to use it to extend our knowledge of these sites. This combination of chemical isotopy and environmental information has not been made before, perhaps because it requires to be at a large scale to be successful, and relies on a lot of experience of both isotopic and environmental methodologies.
The kind of information we hope to learn includes the following:- when and why did pig husbandry change, and were they then fed more household scraps, milk whey, or just rooted about nearer human refuse pits ? Is there any sign that soils became progressively depleted in nitrogen, and can a manuring signal be detected ? Do cattle (particularly) show evidence that their management moved from a more wooded to a more open environment ? Where increased flooding occurs in the valley floodplains, does this have a recognisable effect on plant and bone isotopes (as suspected) ? Is a change in the nitrogen isotope we have seen on one site we studied really due to the cultivation of hay and therefore an increase in leguminous species (which have lower nitrogen isotope ratio values) in the sward ?
Furthermore, we hope that by getting much more focussed results than anyone has so far, we will see new patterns in the isotopic compositions that will lead to new thoughts about what can be learnt from isotopes. This also important for understanding how the bones of humans, who eat the animals, acquire their isotopic composition, and therefore for understanding how to reconstruct ancient human diet.
This proposal is to develop deeper, more detailed, ways to learn about farming in Southern England and how it changed from Neolithic to Roman times. We have chosen a well researched region with detailed archaeological knowledge and, for many sites, a good record of the environmental context. We propose to analyse chemically the bones from a statistically robust number of domesticated animals from 32 well studied sites. We will measure 'stable isotopes', that is atoms of the actual animals' food, which remain in their bones. We know that slight variations in stable isotopes are due to changes in diet, which can come about from changes in management, or changes in food-plant isotopes. Plant isotopes cannot be measured directly, but do depend on subtle changes in their environment. Actually, although we have an understanding of several types of environmental influence, we do not know clearly and exactly how the environment is reflected in animal bone isotope values; but we do know that animal bone isotopes from various sites show intriguing patterns of variation and correlation, in a site over time, or between species, or between sites in different settings. This research is to characterise what sorts of pattern occur in settings where we can relate the results to known environments, and then to use it to extend our knowledge of these sites. This combination of chemical isotopy and environmental information has not been made before, perhaps because it requires to be at a large scale to be successful, and relies on a lot of experience of both isotopic and environmental methodologies.
The kind of information we hope to learn includes the following:- when and why did pig husbandry change, and were they then fed more household scraps, milk whey, or just rooted about nearer human refuse pits ? Is there any sign that soils became progressively depleted in nitrogen, and can a manuring signal be detected ? Do cattle (particularly) show evidence that their management moved from a more wooded to a more open environment ? Where increased flooding occurs in the valley floodplains, does this have a recognisable effect on plant and bone isotopes (as suspected) ? Is a change in the nitrogen isotope we have seen on one site we studied really due to the cultivation of hay and therefore an increase in leguminous species (which have lower nitrogen isotope ratio values) in the sward ?
Furthermore, we hope that by getting much more focussed results than anyone has so far, we will see new patterns in the isotopic compositions that will lead to new thoughts about what can be learnt from isotopes. This also important for understanding how the bones of humans, who eat the animals, acquire their isotopic composition, and therefore for understanding how to reconstruct ancient human diet.