Stephen Buckley

Organic chemistry of embalming agents in Pharaonic and Graeco-Roman mummies

Chemical treatments were an essential element of ancient Egyptian mummification. Although the inorganic salt natron is recognized as having a central role as a desiccant, without the application of organic preservatives the bodies would have decomposed in the humid environment of the tombs. The nature of the organic treatments remains obscure, because the ancient Egyptians left no written record of the process. Secondary textual evidence for mummification is provided by Herodotus, Diodorus Siculus, Strabo and Pliny. The most important account is that of Herodotus (about 450 yr bc), although archaeological evidence shows that by this time the process had declined significantly and the best results had been achieved centuries before. His account mentions myrrh, cassia, palm wine, ‘cedar oil’ (still widely disputed) and ‘gum’; however, it is vague with respect to the specific natural products used. Here we report the results of chemical investigations of a substantial collection of samples of tissues, wrappings and ‘resinous/bituminous’ materials from provenanced and dated Egyptian mummies. We focused on examples of the ‘classic’ mummy-making culture of the Pharaonic or dynastic period, from which we can begin to track the development of mummification chronologically.

Complex organic chemical balms of Pharaonic animal mummies

Millions of votive mummies of mammals, birds and reptiles were produced throughout ancient Egypt, with their popularity increasing during the reign of Amenhotep III (1400 bc) and thereafter. The scale of production has been taken to indicate that relatively little care and expense was involved in their preparation compared with human mummies. The accepted view is that animals were merely wrapped in coarse linen bandages and/or dipped in ‘resin’ before death. However, as with human mummification there was a range of qualities of treatments, and visual inspection of animal mummies suggests that the procedures used were often as complex as those used in humans (for example, evisceration and elaborate bandaging). Moreover, the ancient Egyptians treated animals with great respect, regarding them both as domestic pets and representatives of the gods; for example, the cat symbolized the goddess Bastet; the hawk, Horus; the ibis, Thoth, and so on. We report here the results of chemical investigations of tissues and wrappings from Pharaonic cat, hawk and ibis mummies using gas chromatography, gas chromatography–mass spectrometry, thermal desorption–gas chromatography–mass spectrometry and pyrolysis–gas chromatography–mass spectrometry. The analyses reveal the presence of highly complex mixtures of n-alkyl and cyclic biomarker components characteristic of fats, oils, beeswax, sugar gum, petroleum bitumen, and coniferous, Pistacia and possibly cedar resins. The mixture of balms is of comparable complexity to those used to mummify humans from the same period.

Studies of organic residues from ancient Egyptian mummies using high temperature-gas chromatography-mass spectrometry and sequential thermal desorption-gas chromatography-mass spectrometry and pyrolysis-gas chromatography-mass spectrometry.

The techniques of gas chromatography-mass spectrometry (GC-MS) and sequential thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) have been utilised to characterise the constituents of tissue-derived or applied organic material from two Pharaonic Egyptian mummies with a view to identifying embalming practices/substances. The results obtained using TD-GC-MS revealed a series of monocarboxylic acids with the C16:0, C18:1 and C18:0 components dominating in both mummies. The thermal desorption products related to cholesterol, i.e., cholesta-3,5,7-triene and cholesta-3,5-diene (only in Khnum Nakht), were detected in both mummies. Khnum Nakht also contained a number of straight chain alkyl amides (C16-C18) and an alkyl nitrile (C18). Other products included the 2,5-diketopiperazine derivative (DKP) of proline-glycine (pro-gly) which was a major component (7.9%) in Khnum Nakht but only a very minor component in Horemkenesi. Py-GC-MS of samples of both specimens yielded a series of alkene/alkane doublets (Horemkenesi C6-C18, Khnum Nakht C6-C24) which dominated their chromatograms. Series of methyl ketones in the C9-C19 chain length range were also present, with C5-C7 cyclic ketones occurring in Horemkenesi only. These ketones are indicative of covalent bond cleavage, probably of polymerised acyl lipids. Nitrogenous products included nitriles (C9-C18) which were significant in both samples, and amides which were only detected in Khnum Nakht. Also present amongst the pyrolysis products were three steroidal hydrocarbons, cholest-(?)-ene, cholesta-3,5,7-triene and cholesta-3,5-diene. High temperature-GC-MS of trimethylsilylated lipid extracts yielded similar monocarboxylic acids to that obtained using TD-GC-MS, while a series of alpha, omega-dicarboxylic acids and a number of mono- and di-hydroxy carboxylic acids not seen in the thermal desorption or pyrolysis GC-MS analyses were significant constituents in both mummy samples. Overall, the use of GC-MS and sequential TD-GC-MS and Py-GC-MS has demonstrated in both mummies the presence of a complex suite of lipids and proteinaceous components whose compositions indicates extensive alteration via oxidative and hydrolytic processes during long-term interment. None of the classical embalming resins was detected but an exogenous origin for at least a proportion of these components cannot be discounted since fats, oils and gelatin have been proposed as embalming agents in mummification. The combined approach of sequential TD- and Py-GC-MS has potential for application to the characterisation of embalming materials in mummies. Most importantly these techniques virtually eliminate any destruction of the mummified bodies thereby allowing the scope of investigations of ancient Egyptian funerary practices to be significantly extended.

Dental Calculus Reveals Unique Insights into Food Items, Cooking and Plant Processing in Prehistoric Central Sudan

Accessing information on plant consumption before the adoption of agriculture is challenging. However, there is growing evidence for use of locally available wild plants from an increasing number of pre-agrarian sites, suggesting broad ecological knowledge. The extraction of chemical compounds and microfossils from dental calculus removed from ancient teeth offers an entirely new perspective on dietary reconstruction, as it provides empirical results on material that is already in the mouth. Here we present a suite of results from the multi-period Central Sudanese site of Al Khiday. We demonstrate the ingestion in both pre-agricultural and agricultural periods of Cyperus rotundus tubers. This plant is a good source of carbohydrates and has many useful medicinal and aromatic qualities, though today it is considered to be the worlds most costly weed. Its ability to inhibit Streptococcus mutans may have contributed to the unexpectedly low level of caries found in the agricultural population. Other evidence extracted from the dental calculus includes smoke inhalation, dry (roasting) and wet (heating in water) cooking, a second plant possibly from the Triticaceae tribe and plant fibres suggestive of raw material preparation through chewing.

Evidence for Prehistoric Origins of Egyptian Mummification in Late Neolithic Burials

Traditional theories on ancient Egyptian mummification postulate that in the prehistoric period (i.e. the Neolithic and Chalcolithic periods, 5th and 4th millennia B.C.) bodies were naturally desiccated through the action of the hot, dry desert sand. Although molding of the body with resin-impregnated linen is believed to be an early Pharaonic forerunner to more complex processes, scientific evidence for the early use of resins in artificial mummification has until now been limited to isolated occurrences during the late Old Kingdom (c. 2200 B.C.), their use becoming more apparent during the Middle Kingdom (c. 2000-1600 BC). We examined linen wrappings from bodies in securely provenanced tombs (pit graves) in the earliest recorded ancient Egyptian cemeteries at Mostagedda in the Badari region (Upper Egypt). Our investigations of these prehistoric funerary wrappings using a combination of gas chromatography-mass spectrometry (GC-MS) and thermal desorption/pyrolysis (TD/Py)-GC-MS have identified a pine resin, an aromatic plant extract, a plant gum/sugar, a natural petroleum source, and a plant oil/animal fat in directly AMS-dated funerary wrappings. Predating the earliest scientific evidence by more than a millennium, these embalming agents constitute complex, processed recipes of the same natural products, in similar proportions, as those utilized at the zenith of Pharaonic mummification some 3,000 years later. The antibacterial properties of some of these ingredients and the localized soft-tissue preservation that they would have afforded lead us to conclude that these represent the very beginnings of experimentation that would evolve into the famous mummification practice of the Pharaonic period.

Neanderthals, trees and dental calculus: new evidence from El Sidrón

Abstract Analysis of dental calculus is increasingly important in archaeology, although the focus has hitherto been on dietary reconstruction. Non-edible material has, however, recently been extracted from the dental calculus of a Neanderthal population from the 49 000-year-old site of El Sidrón, Spain, in the form of fibre and chemical compounds that indicate conifer wood. Associated dental wear confirms that the teeth were being used for non-dietary activities. These results highlight the importance of dental calculus as a source of wider biographical information, and demonstrate the need to include associated data within research, in particular tooth wear, to maximise this valuable resource.

Neanderthal self-medication in context

In a recent study, Hardy et al. (2012) identified compounds from two non-nutritional plants, yarrow and camomile, in a sample of Neanderthal dental calculus from the northern Spanish site of El Sidrón. Both these plants are bitter tasting and have little nutritional value but are well known for their medicinal qualities. Bitter taste can signal poison. We know that the bitter taste perception gene TAS2R38 was present among the Neanderthals of El Sidrón (Lalueza-Fox et al. 2009), and their selection of yarrow and camomile was hence probably deliberate. With few nutritional benefits, reasons must be sought for why the Neanderthals collected and ingested these plants. They could have consumed them as flavouring, but this presupposes a degree of complexity in cuisine for which there is little evidence. The widespread evidence for animal self-medication, or zoopharmacognosy, however, offers an attractive behavioural context.We propose, indeed, that these plants were selected and ingested deliberately for the purpose of self-medication.Here, we investigate the implications of this new finding for Neanderthal knowledge of plants and we offer a context for plant knowledge and self-medication among early human and hominin populations.

Shedding New Light on the 18th Dynasty Mummies of the Royal Architect Kha and His Spouse Merit

The mummies of Kha and his wife Merit were found intact in an undisturbed tomb in western Thebes near the ancient workers’ village of Deir el-Medina. Previous MDCT (this abbreviation needs spelling out) investigations showed that the bodies of Kha and Merit did not undergo classical royal 18th Dynasty artificial mummification, which included removal of the internal organs. It was, therefore, concluded that the retention of the viscera in the body, combined with an absence of canopic jars in the burial chamber, meant the couple underwent a short and shoddy funerary procedure, despite their relative wealth at death. Nevertheless, all internal organs - brain, ocular bulbs/ocular nerves, thoracic and abdominal organs - showed a very good state of preservation, which contradicts the previous interpretation above. In order to better understand the type of mummification used to embalm these bodies, both wrapped mummies were reinvestigated using new generation X-ray imaging and chemical microanalyses Here we provide evidence that both individuals underwent a relatively high quality of mummification, fundamentally contradicting previous understanding. Elucidated “recipes”, whose components had anti-bacterial and anti-insecticidal properties, were used to treat their bodies. The time and effort undoubtedly employed to embalm both Kha and Merit and the use of imported costly resins, notably Pistacia, do not support the previously held view that the two individuals were poorly mummified. Despite a lack of evisceration, the approach clearly allowed their in situ preservation as well as affording a fairly successful mummification.

Below the Salt: A Preliminary Study of the Dating and Biology of Five Salt-Preserved Bodies from Zanjan Province, Iran

Abstract We describe the finding of five male bodies from the salt mine of Chehr Abad, Zanjan province, Iran. Radiocarbon determinations suggests that two of the bodies date to the late Sassanian period, while the other three died sometime between 410 B.C. and 350 B.C. We speculate that these deaths may have been the result of an earthquake between 405–380 B.C. We have also obtained new isotopic data on skin and hair, and conclude that they may not have come from the Zanjan area. A preliminary study of stomach contents and parasite load for one of the bodies has also been carried out.

Doctors, chefs or hominin animals? Non-edible plants and Neanderthals

In 2013, Hardy et al. offered a broad behavioural context for the hypothesis that the ingestion of non-nutritional plants (yarrow and camomile) by Neanderthals was for the purpose of self-medication. Chemical traces of these plants had been detected in samples of dental calculus from Neanderthals at the site of El Sidrón, Spain, along with traces of bitumen and wood smoke, as well as starch granules that showed evidence of roasting (Hardy et al. 2012). Subsequently, the presence of traces of resin and a piece of non-edible conifer wood were also identified from these samples (Radini et al. 2016). Although not rejecting our interpretation for the presence of these two non-edible plants as evidence of medicinal plant use, two recent articles offer alternative scenarios for why and how those plants may have reached the mouth and, eventually, the dental calculus of the individual concerned. Buck and Stringer (2014) suggest that the plants were not deliberately ingested, and that the traces of yarrow and camomile were in fact embedded in the chyme, or stomach contents, of herbivore prey. Krief et al. (2015) propose two hypotheses: first, they suggest that the plants could have been used to flavour meat; second, while not ruling out the possibility that they could be medicinal, they argue on a technical point that the plants were not self-administered but were provided by a caregiver. Here, we examine these suggestions and consider their probability and feasibility as alternatives to our original proposal of self-medication.