Archaeological Investigations

Chemical evidence for dairying in prehistory

This research project was jointly funded through NERC and English Heritage. Domesticated animals formed an important element of farming practices in prehistoric Britain, revealed through the quantity and variety of animal bone typically found at archaeological sites. However, it is not known whether these ruminant animals were raised purely for their tissues (e.g. meat), or alternatively they were exploited principally for their milk. Absorbed organic residues from pottery assemblages from British prehistoric sites were investigated for evidence of the processing of dairy products. The ability to detect dairy fats absorbed in the vessel wall rests upon the observation that the δ13C values of the C18:0 fatty acids in ruminant adipose fats are ca. 2.3‰ lower than in ruminant dairy fats. This difference can be ascribed to being due to (i) the inability of the mammary gland to biosynthesise C18:0; (ii) the biohydrogenation of dietary unsaturated fatty acids in the rumen; and (iii) differences (e.g. ca. 8.1‰) in the δ13C values of the plant dietary fatty acids and carbohydrates. The lipids from ca. 1000 archaeological pottery vessels were extracted, and the compound-specific δ13C values of preserved fatty acids (C16:0 and C18:0) were determined via gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS).  Figure 1 displays, as a scatter plot, the δ13C values obtained from the C16:0 and C18:0 fatty acids extracted from Neolithic, Bronze Age and Iron Age potsherds. Also plotted are confidence ellipses (p = 0.683) that indicate the δ13C values of the reference animal fats, from which the extracts are classified. These results provided direct evidence for the exploitation of domesticated ruminant animals for dairy products at settlements in prehistoric Britain. Most significantly, studies of pottery from a range of key early Neolithic sites confirmed that dairying was a widespread activity during this period and therefore probably well developed when farming was introduced into Britain in the 5th Millennium BC.

 

Crossplots of the stable carbon isotopic signature of C16:0 and C18:0 fatty acids extracted from potsherds
Figure 1

References
Copley, M. S., Berstan, R., Dudd, S. N., Docherty, G., Mukherjee, A. J., Straker, V., Payne, S., Evershed, R. P. (2003) Direct chemical evidence for widespread dairying in prehistoric Britain. Proceedings of the National Academy of Sciences of the United States of America 100, 1524-1529.
Copley, M. S., Berstan, R., Dudd, S. N., Straker, V., Payne, S., Evershed, R. P. (2005) Dairying in antiquity. I. Evidence from absorbed lipid residues dating to the British Iron Age. Journal of Archaeological Science 32, 485-503.
Copley, M. S., Berstan, R., Straker, V., Payne, S., Evershed, R. P. (2005) Dairying in antiquity. II. Evidence from absorbed lipid residues dating to the British Bronze Age. Journal of Archaeological Science 32, 505-521.
Copley, M. S., Berstan, R., Dudd, S. N., Mukherjee, A. J., Straker, V., Payne, S., Evershed, R. P. (2005) Dairying in antiquity. III. Evidence from absorbed lipid residues dating to the British Neolithic. Journal of Archaeological Science 32, 523-546.