Lesley Gregoricka 1 Alicia Cooper 2 Mark Schurr

Lesley Gregoricka 1, Alicia Cooper 2, Mark Schurr, Ph. D. 2, and Susan Guise Sheridan, Ph. D. 2 ∂15 N The purpose of this study is to explore weaning behavior in the children found at Byzantine St. Stephen’s monastery (5 th-7 th C AD). Despite the ambiguity of their presence in a monastic setting, the subadults provide an opportunity to unravel a fascinating component of urban Byzantine life. Stable nitrogen isotopes and strontium/calcium (Sr/Ca) ratios in bone were analyzed to determine the duration of breastfeeding and weaning periods, ending with the full incorporation of local foodstuffs into the diets of these subadults. A newly born infant shares nitrogen values comparable to that of its mother. Breastfeeding changes its nitrogen composition, producing a sharp rise in δ 15 N levels (Katzenberg et al. , 1996). This occurs because the δ 15 N levels in breast milk are approximately 2 -3. 6‰ higher than the values in the mother’s diet (Fogel et al. , 1989; Steele and Daniel, 1978). Therefore, the infant develops a higher 15 N buildup, in comparison with the mother and the local population in general. This value gradually decreases once weaning begins as breast milk is supplemented with new foods, illustrated by the occurrence of a nitrogen peak that signals the end of nursing followed by a decline in nitrogen levels. This reduction stems from the Age (yrs) lower levels of nitrogen found in most diets in comparison to Figure 1. Expected changes in stable nitrogen-isotope ratios breast milk (Schurr, 1998). The changes in nitrogen ratios with age during nursing and weaning (from Schurr, 1998) from subadult to juvenile and adulthood are apparent when comparing age and expected δ 15 N values shown in Figure 1. This study also examined the Sr/Ca content of cortical bone, providing a further estimate of the duration of breastfeeding. The chemical behavior of strontium mimics that of calcium; therefore, strontium often substitutes for calcium in the hydroxyapatite matrix (Knudson, 2004). The intestine selectively absorbs calcium during digestion, however the small amount of strontium that is absorbed becomes incorporated into the individual’s skeleton. In breastfeeding infants, the skeletal Sr/Ca ratio is low due to the negligible Sr/Ca content of human milk (Sillen, 1984). As infants are weaned, diets of solid food provide comparatively high Sr/Ca ratios. The juvenile digestive system is less discriminating than that of an adult, thus skeletal Sr/Ca ratios are typically at their peak subsequent to weaning. After this point, the values begin to more closely resemble adult Sr/Ca ratios (Mays, 2003). This study is not limited to physical evidence alone; instead, it is important to develop a biocultural model, using chemical analysis in conjunction with historical documents to gain better insight into the lives of the children found at the monastery. By incorporating different areas of research into this study, a more complete picture of how these children lived and died can be achieved. of Anthropology, The Ohio State University 2 Department of Anthropology, University of Notre Dame experts such as Soranus of Ephesus and Claudius Galen of the second century AD, inserting this advice into their own prescriptions, while concurrently becoming critical of more ancient remedies and customs (Lascaratos and Poulakou, 2003; Garrison, 1923; Fildes, 1986; Aetios, 1950). Recommendations, trends, and other records from the Roman and later Byzantine era regarding the feeding of infants still exist. The introduction of food as a means of initiating weaning was not a process to be rushed, but a specifically- timed occurrence. Children were weaned based on an evaluation of health and strength, thereby having the means to begin taking in solid foods (Garrison 1923). This was generally held to a minimum age of six months old, an acceptable starting point for weaning that would inevitably last for another year to a year and a half (Garrison, 1923; Still, 1931). At this point, infants could begin experimenting with the ingestion of softened foods that did not require chewing, such as bread wetted with sweetened waters, honey, or even wine (Garrison, 1923). However, this does not imply that breastfeeding immediately ended, but instead suggests a combination of breast milk and food. In order to establish a liquid replacement for the breast milk, a gradual substitution of water or diluted wine was utilized, as well as an ‘artificial nipple’ (Garrison, 1923). Finally, following successful attempts at the introduction of foreign food and drink when a child was deemed ready to be weaned more completely, Soranus recommended a broth soup composed of wheat and eggs, a concoction that was believed to be indigestible if coupled with milk (Garrison, 1923). If a child should react badly to the process of weaning, food became more varied based on recommendations by physicians (Garrison, 1923). Should such a reaction result in serious illness, weaning was stopped and breastfeeding reinstated until the child regained its health (Garrison, 1923). In cases of infantile diarrhea, while the mother or wet nurse was usually treated first by changes in diet or medication, an infant could be treated with certain juices (Garrison, 1923). Thus, weaning was not a speedy event but instead a long process. Oribasius along with the seventh-century doctor Paulus Aeginata argued for complete weaning at around two years old (Fildes, 1986; Moffatt, 1986). Correspondingly, Aetios of Amida, a sixth century obstetrician and imperial physician at Constantinople, suggested that mothers wean their children at twenty months of age (Fildes, 1986; Still, 1931 b). Other influential, respected practitioners of earlier times generally fell within this range, including the second-century physician Soranus, who contended that weaning should occur at tooth eruption, or around one and a half to two years old, a view that undoubtedly influenced Oribasius (Fildes, 1986; Moffatt, 1986; Lascaratos and Poulakou, 2003; Garrison, 1923). Galen from Pergamum, though also a physician in the second century, recommended a later weaning date (Fildes, 1986; Moffatt, 1986). Galen promoted the introduction of solid foods in addition to breast milk only after the eruption of the front teeth of a child (Still, 1931). More broadly, Byzantine weaning practices may have possessed a larger, more flexible period of time, from two to three years of age (Moffatt, 1986). Such recommendations by these medical experts were reinforced by religious authorities. The Byzantine church encouraged lengthy breastfeeding and criticized mothers who weaned too early, going so far as to assign penances to these women (Lascaratos and Poulakou, 2003). Therefore, according to the opinions from some of the most prolific thinkers in the field, an acceptable weaning period from approximately twenty months to three years old was the probable norm of the era. A previous study of the St. Stephen’s subadults illustrated how nitrogen age profiles corresponded to the cessation of breastfeeding during the Byzantine period. Regan et al. (2005) tested six subadult innominates in the St. Stephen’s collection for nitrogen ratios. The high δ 15 N values of these samples coupled with their young age reflected a nitrogenrich diet of breast milk. The six individuals followed the expected δ 15 N path as outlined by Schurr (1998), with high nitrogen values peaking just before the process of weaning began. The current study expands upon this small sample size, with δ 15 N values tested for subadults and adults, to represent not only nursing but the gradual acclimation to local foodstuff through weaning. An analysis of Sr/Ca ratios likewise enhances the analysis. Using Teflon-coated spatulas, 0. 1 (+/-0. 02) g. powdered bone was dissolved in 2. 0 m. L Tracepur nitric acid, heated for 90 minutes in a Dry-Bath at 100ºC. While heating, each tube was covered with a polyethylyne ball (to prevent loss of trace elements while allowing excess vapor to escape). Samples were vortexed repeatedly throughout the heating process. Samples were cooled and added to 45 m. L ultrapure 18. 2 mΩ distilled, de-ionized water. An Inductively Coupled Plasma-Optical Emission Spectrometer equipped with a Perkin-Elmer AS 90 auto-sampler and Win. Lab 32 ICP continuous software located at the Center for Environmental Science and Technology at the University of Notre Dame was used for the Sr/Ca analysis. Extraction yields were satisfactory at above 2%. C/N ratios were within the acceptable 2. 9 -3. 6 range for fifty of the fifty-six samples, indicating good protein preservation (De. Niro, 1985). The 15 N range was 6. 6 to 13. 5‰ (n=50; x=10. 0± 1. 7‰). Ca/P ratios of bone were found to be 2. 098 and 2. 140 in adults and sub-adults, respectively. These are in keeping with a characteristic value of 2. 21 -2. 27 in modern living bone, indicating a high quality of bone preservation (Mays, 2003). Age of Weaning: Figure 2 illustrates the relationship between age and 15 N for the St. Stephen’s subadults, and Table 1 compares the subadult values to a variety of archaeological collections. The 15 N age profiles among the subadults reflect breastfeeding and weaning trends, consisting of an initial rise in nitrogen levels that culminates in a peak. This is followed by a more gradual leveling to juvenile and adult values. Infants at St. Stephen’s experienced a sudden elevation in 15 N with the onset of breastfeeding, peaking at approximately six months to one year of age and hence indicating the end of a diet composed only of breast milk. This peak was enriched in 15 N by approximately 4 -5‰, slightly higher than the predicted Age (yrs) enrichment of 2 -3. 6‰. However, the peak values of the Figure 2. Age profile of ∂15 N for the subadults at St. subadults may simply appear elevated when comparing Stephen’s them to adolescent 15 N levels (x=8. 75± 0. 8‰ for those over three years old), which are typically lower than adult averages (Schurr, 1997). 15 N values increase slightly after adolescence and level off once more in adulthood. When evaluated against the adults (x=9. 44± 1. 36‰) of St. Stephen’s monastery, the enhanced nitrogen levels of the subadults fall within the anticipated range at approximately 3 -4‰. Weaning followed this nitrogen climax, as demonstrated by declining 15 N values, although breast milk continued to supplement the diet of these children until ages two to three years old, when complete weaning occurred. ∂15 N 1 Department The generally higher bone Sr/Ca Byzantine St. Stephen’s Project values in adults are expected. Young Laboratory for Biocultural Studies children typically lack the digestive ability to discriminate between strontium and calcium, University of Notre Dame and consequently exhibit higher Sr/Ca ratios with the commencement of weaning. Bone strontium Department of Anthropology content tends to rise gradually until the young adult stage, after which point levels are generally unchanging (Aufderheide, 1989). Sillen and Smith (1984) note that after weaning is complete, calculated dietary values of subadults mirror those of adults, assuming the same nutritional intake. Typically, plant foods have high Sr/Ca values, and meats have fairly high Sr/Ca content relative to human milk, thus the trend of increasing Sr/Ca bone values is not surprising. In the future, an increased sample size and broader trace element analysis might help determine more specifically what foods were being used in dietary supplementation during weaning. This research illustrates the compatibility of two methodologies in determining weaning patterns at Byzantine St. Stephen’s monastery. Nitrogen stable isotope ratios revealed an initial weaning age of six months to 1 yr with full termination of breastfeeding occurring between the ages of two to three. Strontium/calcium ratios reinforce these results, expressing a slightly extended breastfeeding period but positing the completion of weaning at around three years of age. Moreover, strontium/calcium values provide evidence of a juvenile diet distinctly different from that of the adult monks. This pattern is corroborated by the lower juvenile versus adult nitrogen values, possibly indicative of a dissimilar dietary regime. While no corresponding skeletal sample exists, the adult members of the monastery provide a starting point from which to begin dietary comparisons. Historical texts suggest that Byzantine children began the weaning process at around six months of age, with the continued supplementation of local foodstuffs until ages two to three. Evidence from the bones reflects such a pattern to a degree, but may indicate an extended breastfeeding period beyond the age of six months for up to a year or two. While these methodologies are rarely used in conjunction with one another, such collaboration may prove a valuable tool in studying weaning traditions in the past. Aetios. 1950. Aetios of Amida: the gynaecology and obstetrics of the VIth century, A. D. Tran. Ricci JV. Philadelphia: The Blakiston Company. Aufderheide AC. 1989. Chemical analysis of skeletal remains. In: Reconstruction of life from the skeleton. New York: Wiley-Liss, Inc. p. 237 -260. Bass WM. 1987. Human osteology: a laboratory and field manual, fourth edition. Columbia, MO: Missouri Archaeological Society, Inc. Brown J. 1981. A fine and private place. In: The cult of the saints: its rise and function in Latin Christianity. Chicago: University of Chicago Press. p 23 -49. Dupras TL. 1999. Dining in the Dakhleh Oasis: determination of diet using stable isotope analysis and documents. Ph. D. Dissertation, Mc. Master University. Table 1. Comparative distributions of Fildes VA. 1986. Infant feeding from antiquity to the Renaissance: sources for a study. In: Breasts, Bottles and Babies. p 3 -77. ∂15 N Fogel ML, Tuross N, Owsley DW. 1988 -89. Nitrogen isotope tracers. Yearbook, Carnegie Institution of Washington 88: 133 -134. Fuller BT, Molleson TI, Harris DA, Gilmour LT, Hedges REM. 2006. Isotopic evidence for breastfeeding and possible adult dietary differences from Late/Sub-Roman Britain. Am J Phys Anthropol 129: 45 -54. Weaning practices: Much of the information and protocol regarding breastfeeding and weaning practices during the Byzantine period originated from Roman thought. Byzantine physicians went so far as to copy entire chapters from Garrison FH. 1923. A system of pediatrics: history of pediatrics. In: Abt IA, ed. Pediatrics. London: W. B. Saunders Company. p 1 -170. Hoppa RD, Gruspier KL. 1996. Estimating diaphyseal length from fragmentary subadult skeletal remains: implications for palaeodemographic reconstructions of a Southern Ontario ossuary. Am J Phy Anthropol 100: 341 -354. Katzenburg MA, Herring DA, and Saunders SR. 1996. Weaning and infant mortality: evaluating the skeletal evidence. Yearbook Phys Anthropol 39: 177 -199. Keegan W. 1989. Stable isotope analysis of prehistoric diet. In: Iscan MY, Kennedy KAR, editors. Reconstruction of life from the skeleton. New York: Alan R. Liss, Inc. p 223 -236. Stable Isotope Analysis: The study sample consisted of fifty-six subadults and young adults, ranging from newborn to approximately twenty years old. Right proximal femoral diaphyses were sampled from the commingled remains to prevent repetition. Age was determined based on total length of the femur when possible; when only the proximal end was available, measurements of the femoral head were taken (Bass, 1987; Scheuer and Black, 2000; Ubelaker, 1999; Hoppa and Gruspier, 1996). For the sake of age comparison between authors, all applicable methods were applied when feasible and age results averaged. Sample preparation and comparison of age and δ 15 N were drawn from Schurr (1998). Samples were cut from each femur with a Dremel® Multi. Pro® Model Rotary Tool and coded in order to achieve double blind standards and thus avoid corruption of data interpretation. Specimens of 0. 1 -0. 2 grams were washed in distilled water with a toothbrush to eliminate contaminants on the external surface of the cortical bone They were sonicated in deionized water for 30 minutes, rinsed three times, then dried at 70ºC forty-eight hours. Samples were then soaked in a diluted hydrochloric acid solution (0. 25 M) for 14 days and stirred daily. This demineralization stripped the bone of inorganic materials, leaving collagen behind. The collagen samples were rinsed with distilled water and freeze-dried. The elemental analyzer (CHNS-O EA 1108) and stable isotope mass spectrometer (Finnegan Delta Plus) operating in continuous flow mode at the University of Notre Dame’s Center for Environmental Science and Technology measured the nitrogen stable isotope ratios of the samples. Sulfanilamide (C 8 H 8 N 2 O 2 S) was used as a working standard. Blanks and the standards were placed throughout the sequences at regular intervals so as to assure consistency within the mass spectrometer. Strontium/Calcium Element Analysis: Forty-five femora were used for trace element analysis. One to two grams of bone were removed from the femoral shaft of each sample. The periosteal and endosteal surfaces of each bone section were then cleaned with an aluminum oxide grinding stone fitted to a Dremel® Multi. Pro® Model 395 drill. The samples were sonicated with 30 -35 m. L of ultrapure 18. 2 mΩ distilled, de-ionized water for thirty minutes, twice. They were then sonicated in 30 m. L of 5% acetic acid for thirty minutes, followed by a second sonication in 5% acetic acid for five minutes. Specimens were dried for two hours, then ashed at 750 C for eight hours in open, nitric acid-cleaned porcelain crucibles. Finally, the ashed bone was crushed and powdered using an agate mortar and pestle. Knudson KJ, Price TD, Buikstra JE, Blom DE. 2004. The use of strontium isotope analysis to investigate Tiwanaku migration and mortuary ritual in Bolivia and Peru. Archaeometry 46: 5 -18. Lascaratos J, Poulakou-Rebelakou E. 2003. Oribasius (fourth century) and early Byzantine perinatal nutrition. J Pediatric Gastroenterology and Nutrition 36: 186 -189. Mays S. 2003. Bone strontium: calcium ratios and duration of breastfeeding in a Mediaeval skeletal population. J Archaeol Sci 30: 731 -741. Miller TS. 1996. The care of orphans in the Byzantine empire. In: Itnyre CJ, ed. Medieval Family Roles: a book of essays. New York: Garland Publishing, Inc. p 121 -136. Miller TS. 1997. The birth of the Byzantine hospital. Baltimore: The Johns Hopkins University Press. p 167 -189. Moffatt A. 1986. The Byzantine child. Soc Research 53(4): 705 -723. Ogrinc N, Budja M. 2005. Paleodietary reconstruction of a Neolithic population in Slovenia: a stable isotope approach. Chem Geol 218: 103 -116. Regan M, Gregoricka L, Schurr MR, Sheridan SG. 2005. Stable isotope analysis of diet in a Byzantine monastic community. AJPA Supp 40: 174. Richards MP, Pearson JA, Molleson TI, Russell N, Martin L. 2003. Stable isotope evidence of diet at Neolithic Çatalhöyük, Turkey. J Archaeol Sci 30: 67 -76. To estimate the dietary Sr/Ca ratios, the observed ratio (ORbone-diet) values were used. The observed ratio accounts for changes in the digestive system’s ability to discriminate between strontium and calcium absorption (Sillen, 1984). Sr/Ca(x 104) The presence of children in a monastic setting is not unusual, as monasteries often served as social welfare institutions during the Byzantine period. The St. Stephen’s subadults may have been members of an orphanage run by the monastery, or simply children whose parents wanted them buried in close proximity to important religious figures (Miller, 1996; 1997; Brown, 1981). Most of the children were too young to have been oblates (young monks in training), and the proximity of St. Stephen’s to a large nearby hospital likely precluded this function. Sr/Cabone Sr/Ca diet = OR When plotted against age (Figure 3), the dietary values exhibit a steep rise between the ages of 6 months and two years followed by a leveling of values around age three. This is indicative of weaning between two and three years of age—by 3 years, breast milk no longer makes up a significant part of the diet and values begin to mirror the Age (yrs) ratios of older children. With the higher Sr/Ca values in infants, it is likely that supplementation of the breast milk Figure 3. Age profile of Sr/Ca (x 104) for the subadults at Byzantine St. Stephen’s diet was occurring. Such sources of higher dietary Sr/Ca ratios include cereal-based food (Mays, 2003). According to Byzantine sources, such dietary additions were not uncommon--moistened breads and wheat-based soups, for instance, could account for the rise in Sr/Ca values at the onset of weaning (Garrison, 1923). Scheuer L, Black S. 2000. The lower limb. In: Developmental Juvenile Osteology. London: Academic Press. p 392 -395. Schurr MR. 1997. Stable nitrogen isotopes as evidence for the age of weaning at the Angel Site: a comparison of isotopic and demographic measures of weaning age. J Archaeol Sci 24: 919 -927. Schurr MR. 1998. Using stable nitrogen-isotopes to study weaning behavior in past populations. World Archaeol 30: 327 -342. Sillen A, Smith P. 1984. Weaning patterns are reflected in strontium-calcium ratios of juvenile skeletons. J Archaeol Sci 11: 237 -245. Steele KW, Daniel RM. 1978. Fractionation of nitrogen isotopes by animals: a further complication to the use of variations in the natural abundance of 15 N for tracer studies. J Agric Sci 90: 7 -9. Still GF. 1931. Soranus: Galen. In: The History of Paediatrics: the Progress of the Study of Diseases of Children up to the end of the XVIIIth Century. London: Oxford University Press. p 25 -35. Ubelaker DH. 1999. Sex, stature, and age. In: Human skeletal remains: excavation, analysis, interpretation, 3 rd ed. Washington, D. C. : Taraxacum. p 71. White CD, Pendergast DM, Longstaffe FJ, Law KR. 2001. Social complexity and food systems at Altun Ha, Belize: the isotopic evidence. Latin Am Antiq 12(4): 371 -393. • • • National Science Foundation Research Experiences for Undergraduates (SES #0244096) Institute for Scholarship in the Liberal Arts; University of Notre Dame Dennis Birdsell, Center for Environmental Science & Technology, University of Notre Dame Polly Hussman, National Park Service L'École Biblique et Archéologique Française de Jérusalem & Couvent St-Étienne A copy of this poster can be downloaded at the following website: http: //www. nd. edu/~sheridan/AAPAs. html