Documenting the diet in ancient human populations through stable isotope analysis of hair.
Fundamental to the understanding of human history is the ability to make interpretations based on artefacts and other remains which are used to gather information about an ancient population. Sequestered in the organic matrices of these remains can be information, for example, concerning incidence of disease, genetic defects and diet. Stable isotopic compositions, especially those made on isolates of collagen from bones, have been used to help suggest principal dietary components. A significant problem in the use of collagen is its long-term stability, and the possibility of isotopic alteration during early diagenesis, or through contaminating condensation reactions. In this study, we suggest that a commonly overlooked material, human hair, may represent an ideal material to be used in addressing human diets of ancient civilizations. Through the analysis of the amino-acid composition of modern hair, as well as samples that were subjected to radiation (thus simulating ageing of the hair) and hair from humans that is up to 5200 years old, we have observed little in the way of chemical change. The principal amino acids observed in all of these samples are essentially identical in relative abundances and content. Dominating the compositions are serine, glutamic acid, threonine, glycine and leucine, respectively accounting for approximately 15%, 17%, 10%, 8% and 8% of the total hydrolysable amino acids. Even minor components (for example, alanine, valine, isoleucine) show similar constancy between the samples of different ages. This constancy clearly indicates minimal alteration of the amino-acid composition of the hair. Further, it would indicate that hair is well preserved and is amenable to isotopic analysis as a tool for distinguishing sources of nutrition. Based on this observation, we have isotopically characterized modern individuals for whom the diet has been documented. Both stable nitrogen and carbon isotope compositions were assessed, and together provide an indication of trophic status, and principal type (C3 or C4) of vegetation consumed. True vegans have nitrogen isotope compositions of about 7/1000 whereas humans consuming larger amounts of meat, eggs, or milk are more enriched in the heavy nitrogen isotope. We have also analysed large cross-sections of modern humans from North America and Europe to provide an indication of the variability seen in a population (the supermarket diet). There is a wide diversity in both carbon and nitrogen isotope values based at least partially on the levels of seafood, corn-fed beef and grains in the diets. Following analysis of the ancient hair, we have observed similar trends in certain ancient populations. For example, the Coptics of Egypt (1000 BP) and Chinchorro of Chile (5000-800 BP) have diets of similar diversity to those observed in the modern group but were isotopically influenced by local nutritional sources. In other ancient hair (Egyptian Late Middle Kingdom mummies, ca. 4000 BP), we have observed a much more uniform isotopic signature, indicating a more constant diet. We have also recognized a primary vegetarian component in the diet of the Neolithic Ice Man of the Oetztaler Alps (5200 BP). In certain cases, it appears that sulphur isotopes may help to further constrain dietary interpretations, owing to the good preservation and sulphur content of hair. It appears that analysis of the often-overlooked hair in archaeological sites may represent a significant new approach for understanding ancient human communities. (+info
How microbial ancient DNA, found in association with human remains, can be interpreted.
The analysis of the DNA of ancient micro-organisms in archaeological and palaeontological human remains can contribute to the understanding of issues as different as the spreading of a new disease, a mummification process or the effect of diets on historical human populations. The quest for this type of DNA, however, can represent a particularly demanding task. This is mainly due to the abundance and diffusion of bacteria, fungi, yeasts, algae and protozoans in the most diverse environments of the present-day biosphere and the resulting difficulty in distinguishing between ancient and modern DNA. Nevertheless, at least under some special circumstances, by using rigorous protocols, which include an archaeometric survey of the specimens and evaluation of the palaeoecological consistency of the results of DNA sequence analysis, glimpses of the composition of the original microbial flora (e.g. colonic flora) can be caught in ancient human remains. Potentials and pitfalls of this research field are illustrated by the results of research works performed on prehistoric, pre-Columbian and Renaissance human mummies. (+info
Chagas disease and human migration.
Human Chagas disease is a purely accidental occurrence. As humans came into contact with the natural foci of infection might then have become infected as a single addition to the already extensive host range of Trypanosoma cruzi that includes other primates. Thus began a process of adaptation and domiciliation to human habitations through which the vectors had direct access to abundant food as well as protection from climatic changes and predators. Our work deals with the extraction and specific amplification by polymerase chain reaction of T. cruzi DNA obtained from mummified human tissues and the positive diagnosis of Chagas disease in a series of 4, 000-year-old Pre-Hispanic human mummies from the northern coast of Chile. The area has been inhabited at least for 7,000 years, first by hunters, fishers and gatherers, and then gradually by more permanent settlements. The studied specimens belonged to the Chinchorro culture, a people inhabiting the area now occupied by the modern city of Arica. These were essentially fishers with a complex religious ideology, which accounts for the preservation of their dead in the way of mummified bodies, further enhanced by the extremely dry conditions of the desert. Chinchorro mummies are, perhaps, the oldest preserved bodies known to date. (+info
The omnivorous Tyrolean Iceman: colon contents (meat, cereals, pollen, moss and whipworm) and stable isotope analyses.
The contents of the colon of the Tyrolean Iceman who lived ca. 5300 years ago include muscle fibres, cereal remains, a diversity of pollen, and most notably that of the hop hornbeam (Ostrya carpinifolia) retaining cellular contents, as well as a moss leaf (Neckera complanata) and eggs of the parasitic whipworm (Trichuris trichiura). Based almost solely on stable isotope analyses and ignoring the work on the colon contents, two recently published papers on the Iceman's diet draw ill-founded conclusions about vegetarianism and even veganism. Neither the pollen nor the moss is likely to have been deliberately consumed as food by the Iceman. All the available evidence concerning the Iceman's broad-based diet is reviewed and the significance of the colon contents for matters other than assessment of food intake is outlined. (+info
Neurology in ancient faces.
BACKGROUND: Clinical paleoneurology is almost non-existent, but recognition of neurological diseases in ancient people might be possible by scrutinising portraits apparently representing people as they appeared in life. METHODS: About 200 mummy portraits painted in colour at the beginning of the first millennium were examined. Thirty two skulls excavated at Hawara in the Fayum (northern Egypt), where most of the portraits were found were measured, and nine caliper measures on each side of the skulls were taken. The right/left ratios were statistically analyzed by analysis of variance (ANOVA). One skull was subjected to 3D CT scanning and transilluminated. RESULTS: Two patients were found with progressive facial hemiatrophy (Parry-Romberg syndrome), three with deviations of the visual axes (tropia) and one with oval pupils (corectopia). CONCLUSIONS: Clinical paleoneurology is possible in the absence of a living nervous system. The patients probably had focal epilepsy, hemiplegic migraine, and autonomic nervous system dysfunction. (+info
Fecal steroids of the coprolite of a Greenland Eskimo mummy, AD 1475: a clue to dietary sterol intake.
BACKGROUND: Sterols in feces reflect sterols in the diet. In previous analyses of the fecal steroids in 1000-2000-y-old Native American coprolites found in the dry caves of Nevada, we showed that the sterol nucleus was stable. The coprolites provided useful dietary information. OBJECTIVE: In the present study, we analyzed the fecal steroids of an Eskimo mummy buried and frozen >500 y ago in Greenland. We compared these analyses with our findings in the coprolites from Nevada and in present-day stool samples from Tarahumara Indians of Mexico and Americans consuming low- and high-cholesterol diets. DESIGN: The fecal material from the Eskimo mummy was subjected to saponification, extraction, and digitonin precipitation. The sterols and bile acids were further analyzed by thin-layer chromatography and gas-liquid chromatography. RESULTS: The fecal steroids of the Greenland Eskimo mummy were remarkably similar to those of present-day stool samples. However, unlike in the stool of modern humans, a portion of the neutral steroids in the coprolite had been converted to sterol epimers. Instead of deoxycholic acid, 3alpha,6beta,12alpha-trihydroxycholanic acid was one of the major fecal bile acids. The plant sterol output in the coprolite was only 0.4% of the output of Americans consuming 250-400 mg plant sterols/d. The ratio of bile acid to cholesterol in the coprolite was similar to that in stool from Tarahumara Indians consuming a low-cholesterol diet. CONCLUSION: The sterol nucleus is stable when frozen. The analysis of coprolite showed that the young Eskimo woman had consumed a diet very low in plant sterols and moderate to low in cholesterol content. (+info
Otzi's last meals: DNA analysis of the intestinal content of the Neolithic glacier mummy from the Alps.
Samples of the intestinal content were collected from the ileum and colon of the Neolithic glacier mummy popularly known as the Tyrolean Iceman, or Otzi. DNA was extracted from the samples and PCR amplified, using a variety of primer pairs designed to bind to different genes (mammal mitochondrial 12S ribosomal RNA gene, plant/fungal nuclear 18S ribosomal RNA gene, plant chloroplast ribulose bisphosphate carboxylase large subunit gene). This made it possible to distinguish between animal and plant food residues (macroremains) and pollen (microremains). According to the DNA reconstruction, the man's last meal was composed of red deer (Cervus elaphus) meat, and, possibly, cereals; this meal had been preceded by another one based on ibex (Capra ibex), different species of dicots, and cereals. The DNA spectrum corresponding to pollen residues in the colon, on the other hand, fits with the hypothesis that the last journey of the Neolithic hunter/warrior was made through a subalpine coniferous forest to the site at over 3,200 m above sea level, where his mummified body was to be discovered 5,000 years later. (+info
Detection of mycobacterial DNA in Andean mummies.
The identification of genetic material from pathogenic organisms in ancient tissues provides a powerful tool for the study of certain infectious diseases in historic populations. We have obtained tissue samples from the genital areas of 12 mummies in the American Museum of Natural History collection in New York, N.Y. The mummies were excavated in the Andes Mountain region of South America, and radiocarbon dating estimates that the mummies date from A.D. 140 to 1200. DNAs were successfully extracted from all tissues and were suitable for PCR analysis. PCRs were carried out to detect Mycobacterium tuberculosis complex and mycobacteria other than M. tuberculosis (MOTB). M. tuberculosis complex was detected in 2 out of 12 samples, and MOTB were detected in 7 samples. This study confirmed the adequate preservation of genetic material in mummified tissues and the existence of mycobacteria, including M. tuberculosis, in historic populations in South America. (+info