Bitumen in Neolithic Iran: Biomolecular and Isotopic Evidence

Abstract

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A New Method for Extraction, Isolation and Transesterification of Free Fatty Acids From Archaeological Pottery

“…Sixty‐five pottery fragments (Table 1) from nine Neolithic sites in the Fertile Crescent were assembled for microwave‐assisted solvent extraction as part of a research project examining the early uses of pottery in the Middle East (Gregg 2003, in press; Gregg et al. 2007, 2009).…”

“…As part of a wider study of the initial development and use of pottery in the Middle East (Gregg 2003, in press; Gregg et al. 2007, 2009), one of the current authors (MWG) attempted to extract organic residues from 231 pottery fragments from 18 early agricultural villages or pastoral encampments in the Middle East using the ‘conventional’ solvent extraction (DCM:MeOH, 2:1, v/v) and BSTFA derivatization techniques.…”

“…Diagnostic molecular compounds have been recovered from only a small number of pottery fragments from Neolithic sites in Europe or the Middle East solely through the use of 'conventional' solvent extraction techniques (Heron et al 1994;Connan et al 2004Connan et al , 2006Gregg et al 2007;Mirabaud et al 2007). Long carbon chain lipids identified as beeswax have been extracted from pottery fragments from a Neolithic site in Great Britain using chloroform/methanol (2:1, v/v) (Heron et al 1994), while steranes and terpanes characteristic of bitumen have been recovered from potsherds found at Neolithic sites in northeastern Syria and southeastern Turkey through the use of dichloromethane (Connan et al 2004(Connan et al , 2006.…”

Ötzi, the Tyrolean Iceman

“…Although many of these techniques have proven successful in the recovery and identification of organic residues from different archaeological contexts in many regions, 20 years of intensive research have shown that unique molecular biomarkers or diagnostic distributions of longer carbon chain compounds are rarely preserved at archaeological sites for more than 2 or 3,000 years (Heron et al, 1994;Boëda et al, 1996;Connan et al, 2004;Mirabaud et al, 2007;Gregg et al, 2007). It is suspected that the delayed decomposition of lipids within archaeological pottery is due to their being absorbed into the clay fabric of vessels (Evershed et al, 1990;Heron et al, 1991), but diagnostic long carbon chain molecules survive only under exceptional circumstances, such as the anaerobic conditions at the submerged fourth millennium BCE site at Clairvaux XIV in the French Jura (Mirabaud et al, 2007) or the continuously desiccated 18th dynasty Egyptian capital at Amarna (Stern et al, 2000).…”

“…It is suspected that the delayed decomposition of lipids within archaeological pottery is due to their being absorbed into the clay fabric of vessels (Evershed et al, 1990;Heron et al, 1991), but diagnostic long carbon chain molecules survive only under exceptional circumstances, such as the anaerobic conditions at the submerged fourth millennium BCE site at Clairvaux XIV in the French Jura (Mirabaud et al, 2007) or the continuously desiccated 18th dynasty Egyptian capital at Amarna (Stern et al, 2000). Bitumen appears to be the one notable exception, with extant molecular signatures having been identified in pottery vessels from 8th millennium BCE sites in southern Mesopotamia (Connan et al, 2004;Gregg et al, 2007) and on the surface of 40,000-year-old Middle Paleolithic tools from northern Syria (Boëda et al, 1996). Robert White's Principles and Practice of Soil Science (2006) provides a useful guide to the physical and chemical process involved in biodegradation of organic compounds under different soil and climatic conditions.…”