Paleodemography of a medieval population in Japan: analysis of human skeletal remains from the Yuigahama-minami site

The purpose of this study is to obtain demographic data regarding the medieval population buried at the Yuigahama-minami site in Kamakura, Japan, and to detect a secular trend in the life expectancy of Japanese population over the last several thousand years. The Yuigahama-minami skeletal sample consists of 260 individuals, including 98 subadults (under 20 years old) and 162 adults. A Yuigahama-minami abridged life-table analysis yielded a life expectancy at birth (e0) of 24.0 years for both sexes, a life expectancy at age 15 years (e15) of 15.8 years for males, and an e15 of 18.0 years for females. The reliability of the estimated e0 was confirmed by analysis of the juvenility index. Demographic profiles comparing the Yuigahama-minami series with other skeletal series indicated that both the survivorship curve and life expectancy of the Yuigahama-minami sample are similar to those of the Mesolithic-Neolithic Jomon population, but are far lower than those of the early modern Edo population. These comparisons strongly suggest that life expectancy changed little over the thousands of years between the Mesolithic-Neolithic Jomon and medieval periods, but then improved remarkably during the few hundred years between the medieval period and early modern Edo period. The short-lived tendency of the Yuigahama-minami sample does not contradict the archaeological hypothesis of unsanitary living conditions in medieval Kamakura. This is the first investigation to address the demographic features of a medieval population in Japan, and will help refine our understanding of long-term trends in the demographic profiles of inhabitants of Japan.     

Infant and child diet in Neolithic hunter-fisher-gatherers from Cis-Baikal, Siberia: intra-long bone stable nitrogen and carbon isotope ratios

Analysis of stable nitrogen and carbon isotopes (δ(15) N and δ(13) C) from subadults and adults allows for assessment of age-related dietary changes, including breastfeeding and weaning, and adoption of an adult diet. In one of the first studies of hunter-fisher-gatherer subadults from Eurasia, three Neolithic (8,800-5,200 calBP) mortuary sites from southwestern Siberia are analyzed to evaluate hypothesized differences in weaning age between Early versus Late Neolithic groups. An intra-individual sampling methodology is used to compare bone formed at different ages. Collagen samples (n = 143) from three different growth areas of long bones-the proximal metaphysis, diaphysis, and distal metaphysis-were obtained from 49 subadults aged birth to 10 years. In infants (birth to 3 years, n = 23) contrasting the δ(15) N values of the metaphysis, which contains newer bone, to the δ(15) N values of the diaphysis, which contains older bone, permits a more precise determination of breastfeeding-weaning status. In Early and Late Neolithic groups breast milk was the major protein source until the age of 2-3 years. However, there are differences in the age of weaning completion and duration: Early Neolithic groups weaned their infants at a later age and over a shorter amount of time. Differences may have affected infant morbidity and mortality, and female fecundity and inter-birth intervals. Stable isotope values in older subadults (4-10 years, n = 26) do not differ from adults suggesting the absence of age-based food allocation.     

Quantitative Reconstruction of Weaning Ages in Archaeological Human Populations Using Bone Collagen Nitrogen Isotope Ratios and Approximate Bayesian Computation

BackgroundNitrogen isotope analysis of bone collagen has been used to reconstruct the breastfeeding practices of archaeological human populations. However, weaning ages have been estimated subjectively because of a lack of both information on subadult bone collagen turnover rates and appropriate analytical models.MethodologyTemporal changes in human subadult bone collagen turnover rates were estimated from data on tissue-level bone metabolism reported in previous studies. A model for reconstructing precise weaning ages was then developed using a framework of approximate Bayesian computation and incorporating the estimated turnover rates. The model is presented as a new open source R package, WARN (Weaning Age Reconstruction with Nitrogen isotope analysis), which computes the age at the start and end of weaning, ¹⁵N-enrichment through maternal to infant tissue, and value of collagen synthesized entirely from weaning foods with their posterior probabilities. The model was applied to 39 previously reported Holocene skeletal populations from around the world, and the results were compared with weaning ages observed in ethnographic studies.ConclusionsThere were no significant differences in the age at the end of weaning between the archaeological (2.80±1.32 years) and ethnographic populations. By comparing archaeological populations, it appears that weaning ages did not differ with the type of subsistence practiced (i.e., hunting–gathering or not). Most of -enrichment (2.44±0.90‰) was consistent with biologically valid values. The nitrogen isotope ratios of subadults after the weaning process were lower than those of adults in most of the archaeological populations (−0.48±0.61‰), and this depletion was greater in non-hunter–gatherer populations. Our results suggest that the breastfeeding period in humans had already been shortened by the early Holocene compared with those in extant great apes.     

Chronic undernutrition and traditional weaning foods are associated with fat stores in ariaal infants of Northern Kenya

The high proportion of human infant fat is hypothesized to protect infant brains by mobilizing against growth disturbances caused by acute nutritional and pathogen stress during weaning. However, individuals who experience chronic nutritional stress have been shown to store fat rather than mobilize fat stores, although this has not been demonstrated during infancy. This study investigated the relationship between fat development, diet, and nutritional status among 239 breastfeeding Ariaal infants, a group of settled pastoralists who experience both acute and chronic nutritional stress residing in Marsabit District, Kenya. This study had three goals: 1) To investigate the pattern of fat accumulation among Ariaal infants compared with a reference population; 2) to explore the relationship between chronic nutritional stress and fat deposits; and 3) to determine the relationship between traditional weaning foods, particularly cow's milk, and infant's fat. Infants, particularly infants experiencing chronic nutritional stress, were found to accumulate fat deposits in a manner that suggests reduced oxidation of fat stores. Infant upper arm fat area significantly increases with age over the weaning period compared with reference populations, who show a decline in body fat. Chronically undernourished infants were particularly likely to have increased levels of upper arm fat compared with normal infants or acutely undernourished infants. In addition, infants who consume cow's milk are significantly fatter than those that do not. These results suggest that Ariaal infants have both physiological and cultural mechanisms for fat storage in the face of their nutritionally stressed environment. Am J Phys Anthropol 153:286–296, 2014. © 2013 Wiley Periodicals, Inc.     

Introducing fecal stable isotope analysis in primate weaning studies

This research investigates the potential of a new, noninvasive method for determining age of weaning among primates using stable carbon and nitrogen isotope ratios in feces. Analysis of stable isotope ratios in body tissues is a well‐established method in archeology and ecology for reconstructing diet. This is the first study to investigate weaning in primates using fecal stable isotope ratios. Diets of a single François’ langur (Trachypithecus francoisi) mother–infant pair at the Toledo Zoo are reconstructed using this technique to track changes in infant suckling behavior over the weaning period. Stable isotope ratios in feces are sampled instead of more traditional samples such as bone or hair to enable daily, noninvasive snapshots of weaning status. Isotopic assessments of weaning status are compared to visual assessments to identify any discordance between the two. Three measurements documented the transition from breast milk to solid foods: stable carbon isotope ratios (δ¹³C), stable nitrogen isotope ratios (δ¹⁵N), and nitrogen content of feces (%N). It appears that solid foods were introduced at approximately 2 months of infant age, but that nursing continued into the 12th month, when sample collection ceased. Stable isotope data exposed a much longer weaning period than what was expected based on previously published data for captive langurs, and clarified visual estimates of weaning status. This reflects the method's sensitivity to suckling at night and ability to distinguish actual nursing from comfort nursing. After testing this method with zoo animals, it can readily be applied among wild populations. An isotopic approach to weaning provides a new, accurate, and biologically meaningful assessment of interbirth intervals, and facilitates a better understanding of mother–infant interactions. Both of these outcomes are critical for developing successful conservation strategies for captive and wild primates. Am. J. Primatol. 74:926‐939, 2012. © 2012 Wiley Periodicals, Inc.     

Using stable isotope analysis to examine the effect of economic change on breastfeeding practices in Spitalfields, London, UK

Breastfeeding patterns were subject to a number of fads in 18th and 19th century Britain. Feeding infants by hand, rather than maternal breastfeeding or wet-nursing, became more prevalent among both the wealthy and poor. Substitute foods may have been a convenient alternative for mothers employed away from the household. This study used stable isotope ratio analysis to examine the weaning schedule in the 18th and 19th century skeletal assemblage from Spitalfields, London, UK. Analysis of 72 juvenile ribs revealed δ(15) N elevations of 2-3‰ above the adult mean for individuals up to the age of two, while elevations of 1-2‰ were observed in δ(13) C for the first year of life. This suggests that the introduction of solid foods took place before the end of the first year, and that breastfeeding had entirely ceased by 2 years of age. The age at death of many of these infants is known from historical records, and can be used to pinpoint the amount of time required for the breast milk signal to be observed in the stable isotope ratios of rib collagen. Results show that a δ(15) N elevation can be detected in the ribs of individuals who died as young as 5-6 weeks. Not all individuals at Spitalfields were breastfed, and there may not have been a single uniformly practiced weaning scheme. There is, however, more evidence for prolonged breastfeeding during the 19th century than the 18th century.     

Biochemical and palaeopathological investigations on weaning and infant mortality in the early Middle Ages

Weaning age of the children of the early medieval population at Wenigumstadt (Ldkr. Aschaffenburg, southern Germany, 500-700 AD) was estimated by stable nitrogen isotope analysis of bone collagen. The onset of weaning was by one year of age, when solid vegetal food subsequently replaced breast milk. In total, the change from mother's milk to solid adult food took about three years, the infants being fully weaned at this age. While the growing infant was sufficiently supported in utero and during the first months of life, the weanling's diet was insufficient for further growth and development. Starting with about 18 months of age, more and more symptoms of malnutrition are detectable on the skeletal remains, and the peak of both morbidity and mortality is reached at four years of age. Especially unspecific stress markers like Harris' lines and enamel hypoplasia clearly indicate the infants' risk of falling ill or die between three and four years of age. Malnutrition weakens the immune response, therefore the majority of inflammations detectable on the skeleton are found among the inadequately nourished children. The assumption that weaning is responsible for pathological skeletal lesions and early death in history is thus supported by archaeometry.     

Detection of breastfeeding and weaning in modern human infants with carbon and nitrogen stable isotope ratios

Carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope ratios were longitudinally measured in fingernail and hair samples from mother-infant pairs where infants were exclusively breastfed (n = 5), breast- and formula-fed (n = 2), or exclusively formula-fed (n = 1) from birth. All exclusively breastfed infants had a dual enrichment in carbon ( approximately 1 per thousand) and nitrogen ( approximately 2-3 per thousand) when compared to maternal values. In contrast, breast- and formula-fed subjects had reduced enrichments compared to exclusively breastfed subjects, and the exclusively formula-fed infant showed no increase in delta(13)C or delta(15)N values. This finding of a carbon trophic level effect in breastfeeding infants suggests that (13)C-enrichments of approximately 1 per thousand in archaeological populations are not necessarily the result of the consumption of C(4)-based weaning foods such as maize or millet. During the weaning process, the delta(13)C results for breastfed infants declined to maternal levels more rapidly than the delta(15)N results. This suggests that delta(13)C values have the potential to track the introduction of solid foods into the diet, whereas delta(15)N values monitor the length of time of breast milk consumption. These findings can be used to refine the isotopic analysis of breastfeeding and weaning patterns in past and modern populations.     

Relationship between subsistence and age at weaning in “preindustrial” societies

Cross-cultural studies have revealed broad quantitative associations between subsistence practice and demographic parameters for preindustrial populations. One explanation is that variationin the availability of suitable weaning foods influenced the frequency and duration of breastfeeding and thus the length of interbirth intervals and the probability of child survival (the “weaning food availability” hypothesis). We examine the available data on weaning age variation in preindustrial populations and report results of a cross-cultural test of the predictions that weaning occurred earlier in agricultural and pastoral populations because dairy and cereal production increased the availability of easily digestible, nutrientrich foods appropriate for weaning. We found that, contrary to predictions, supplementation with liquid foods other than breast milk was delayed in agricultural populations relative to less agriculturally dependent ones and complementary feeding with solid foods was delayed in pastoral populations relative to those less dependent on herding. Although the duration of breastfeeding was longer in populations dependent on hunting, there was no qualitative evidence that such populations lacked foods appropriate for weaning. The patterns observed suggest that the relationships between demography and subsistence observed among preindustrial societies cannot be explained by the “weaning food availability” hypothesis. We discuss the implications for understanding the mechanisms underlying prehistoric human demography, subsistence shifts, allocation to parenting and mating effort, and the evolutionary implications of tradeoffs between diet and disease. Earlier versions of this paper were presented at the 11th Annual Meeting of the Human Behavior and Evolution Society, Salt Lake City, 5 June 1999 and the 4th International Anthropological Congress of Ales Hrdlička, Prague, Czech Republic, 4 September 1999. Daniel Sellen is an assistant professor in the Department of Anthropology at Emory University; adjunct professor in the Department of International Health, Rollins School of Public Health; and an Honorary Lecturer in the Public Health Nutrition Unit at the london School of Hygiene and Tropical Medicine. His research interests are in nutritional ecology; the relations between subsistence and demography; and the evolution and current diversity of young child feeding and caregiving practices. In addition to work on demography among traditional populations, he has published “Age, Sex and Anthropometric Status of Children in an African Pastoral Community” (Annals of Human Biology 27:1–21, 2000), “Polygyny and Child Growth in a Traditional Pastoral Society: The Case of the Datoga of Tanzania” (Human Nature 10:327–371, 1999), and “Growth Patterns among Seminomadic Pastoralists (Datoga) of Tanzania” (American Journal of Physical Anthropology 109:187–209, 1999). Diana Smay is a graduate student in the Department of Anthropology, Emory University. Her research interests include bioarchaeology, paleoepidemiology, the evolution of disease, and the behavioral determinants of paleodemography. Her dissertation work concerns aspects of selective inclusion bias and short-term stress events in skeletal samples.     

Investigating the weaning process in past populations

The 19th century St. Thomas' Anglican churchyard in Belleville, Ontario, Canada is associated with a large and well-preserved infant skeletal collection (n = 149) and good-quality parish records that document interments in the graveyard (1821–1874). By using a combination of historical demographic and stable nitrogen isotope analyses on the parish records and skeletal remains, respectively, a general pattern of extended nursing for about 14 months, introduction of foods other than breast milk by around 5 months of age, and variation in breast-feeding and weaning behaviours were detected for St. Thomas' infants. The results demonstrate that it is possible to go beyond the concept of weaning age to explore the weaning process in past populations when appropriate and large samples of documentary and skeletal data are available. Am J Phys Anthropol 105:425–439, 1998. © 1998 Wiley-Liss, Inc.     

Exclusive breastfeeding status of children aged between 6 and 24 months in the nomadic population of Hadaleala district,Afar Region,northeast Ethiopia

Background

Exclusive breastfeeding (EBF) during infancy is fundamental, however it is not fully practiced in the nomadic population of Ethiopia. In Ethiopia, there is still a lack of information on the implementation of the EBF, especially among the nomadic population. This study was conducted to assess the EBF status of children during their first 6 months of life, who are now aged between 6 and 24 months, in the nomadic population of Afar region. The study also aimed to identify factors affecting exclusive breastfeeding.

Methods

A community based cross-sectional study was conducted from April to May, 2015 to assess EBF of children aged between 6 and 24 months during the first 6 months of life. Exclusive breastfeeding is defined as consuming only breast milk (including expressed breast milk) during the first 6 months and no other liquids and solid foods except medications, and non exclusive breastfeeding is taking liquids and solid foods in addition to breast milk. The cluster sampling technique was used to select the study participants. Data were collected from 254 households using a structured questionnaire.

Results

One hundred eighty eight of the children were fed breast milk exclusively for the first 6 months of age; the rate of EBF in the study area was 74% (95% CI 70, 78%). One hundred fifty four (60.6%) of the children received breast milk within 1 h immediately after birth and 207 (81.5%) of the children maintained breastfeeding at the time of the survey. Exclusive breastfeeding was statistically associated with mothers aged above 35 years (AOR 8.3, 95% CI 1.7, 40.3), commencing to breastfeed in first hour (AOR 3.5, 95% CI 1.8, 6.9), and parents who didn’t migrate or move to a more comfortable area (AOR 4.6, 95% CI 1.5, 14.4).

Conclusion

Exclusive breastfeeding was not fully practiced in the study area. Therefore, promotion of infant and young children feeding (IYCF) is needed in the area to strengthen EBF practices. Moreover, child feeding practices should be integrated with the existing health system and attention should be given to the nomadic mothers.

     

Infant feeding and weaning practices in Roman Egypt.

Current knowledge of infant feeding and weaning practices during the Roman period in Egypt is limited to scanty documentary and iconographic evidence. Stable nitrogen and carbon isotope analysis provides another avenue to explore this question. A sample of 49 infant and juvenile human skeletal remains from the Kellis 2 cemetery in the Dakhleh Oasis, Egypt, was used to determine patterns of infant feeding and weaning. delta(15)N values indicate that supplementary foods were introduced at around 6 months of age, and that weaning was complete by 3 years of age. By 6 months of age, delta(13)C values become increasingly enriched over adult values, and reach peak enrichment at approximately 1.5 years of age. Beyond this age, delta(13)C gradually declines to approach adult values. This enrichment in infant delta(13)C values is indicative of consumption of (13)C-enriched supplementary foods. Based on isotopic study of faunal and botanical remains from the ancient village of Kellis, we conclude that at approximately 6 months of age, infants were fed milk of goat and/or cow.     

Stable isotope ratio analysis of breastfeeding and weaning practices of children from medieval Fishergate House York,UK

Rib collagen of 51 juveniles and 11 adult females from the late medieval Fishergate House cemetery site (York, UK) were analyzed using nitrogen and carbon stable isotope ratio analysis to determine the weaning age for this population and to reconstruct diet. The juveniles' ages ranged from fetal to 5–6 years, while the females were of reproductive age. Previous researchers suggested that the children from Fishergate House might have been weaned later than the medieval British norm of 2 years, based on a mortality peak at 4–6 years of age. The results show weaning was complete by 2 years of age, agreeing with previous British weaning studies. The adult female δ¹⁵N values have a mean of 11.4‰ ± 1.1‰ and the δ¹³C values have a mean of ?19.4‰ ± 0.4‰. These findings are consistent with previous isotopic studies of female diet in York during this period, though slightly lower. The weaned juvenile nitrogen values were found to be higher than the adult females (12.4‰ ± 1.0‰ for δ¹⁵N and ?19.7‰ ± 0.5‰ for δ¹³C), which might indicate a dependence on higher trophic level proteins such as marine fish or pork. Marine fish is considered a high status food and children are considered low‐status individuals at this time, making this a particularly interesting finding. Weaning does not appear to coincide with peak mortality, suggesting environment factors may be playing a larger role in child mortality at Fishergate House. Am J Phys Anthropol 152:407–416, 2013. © 2013 Wiley Periodicals, Inc.     

Stable carbon and oxygen isotopes in human tooth enamel: Identifying breastfeeding and weaning in prehistory

This paper investigates the utility of stable carbon and oxygen isotopes in human dental enamel to reveal patterns of breastfeeding and weaning in prehistory. Enamel preserves a record of childhood diet that can be studied in adult skeletons. Comparing different teeth, we used δ¹³C to document the introduction of solid foods to infant diets and δ¹⁸O to monitor the decline of breastfeeding. We report enamel carbonate δ¹³C and δ¹⁸O of 33 first molars, 35 premolars, and 25 third molars from 35 burials from Kaminaljuyú, an early state in the valley of Guatemala. The skeletons span from Middle Preclassic through Late Postclassic occupations, ca. 700 B.C. to 1500 A.D. Sections of enamel were removed from each tooth spanning from the cusp to the cemento-enamel junction. Stable isotope ratios were measured on CO₂ liberated by reaction of enamel with H₃PO₄ in an automated carbonate system attached to a VG Optima mass spectrometer. Within a skeleton, teeth developing at older ages are more enriched in ¹³C and more depleted in ¹⁸O than teeth developing at younger ages. Premolars average 0.5% higher in δ¹³C than first molars from the same skeleton (P = 0.0001), but third molars are not significantly enriched over premolars. The shift from first molars to premolars may be due to the shift to solid foods from lipid-rich milk. After 2 years, when premolars begin to mineralize, the δ¹³C in childhood diets did not change systematically. First molars and premolars are similar in δ¹⁸O, but third molars average 0.7% lower than first molars (P = 0.0001) and 0.5% lower than premolars (P = 0.0003). First molar and premolar δ¹⁸O is heavier, because breast milk is more enriched in ¹⁸O than is drinking water. Hence, many children continued to nurse during the period of premolar formation. Together, these results indicate that Kaminaljuyú children had begun to eat solid maize foods before the age of 2 years but continued to drink breast milk until much later. Am J Phys Anthropol 106:1–18, 1998. © 1998 Wiley-Liss, Inc.     

Weaning at Anglo‐Saxon raunds: Implications for changing breastfeeding practice in britain over two millennia

This study investigated stable‐isotope ratio evidence of weaning for the late Anglo‐Saxon population of Raunds Furnells, Northamptonshire, UK. δ¹⁵N and δ¹³C values in rib collagen were obtained for individuals of different ages to assess the weaning age of infants within the population. A peak in δ¹⁵N values at about 2‐year‐old, followed by a decline in δ¹⁵N values until age three, indicates a change in diet at that age. This change in nitrogen isotope ratios corresponds with the mortality profile from the site, as well as with archaeological and documentary evidence on attitudes towards juveniles in the Anglo‐Saxon period. The pattern of δ¹³C values was less clear. Comparison of the predicted age of weaning to published data from sites dating from the Iron Age to the 19th century in Britain reveals a pattern of changing weaning practices over time, with increasingly earlier commencement and shorter periods of complementary feeding in more recent periods. Such a change has implications for the interpretation of socioeconomic changes during this period of British history, since earlier weaning is associated with decreased birth spacing, and could thus have contributed to population growth. Am J Phys Anthropol 151:604–612, 2013. © 2013 Wiley Periodicals, Inc.     

A biocultural investigation of the weanling's dilemma in Kathmandu, Nepal: do universal recommendations for weaning practices make sense?

The primary objective of this report is to use data from a study of infant growth and weaning practices in Kathmandu, Nepal, to investigate universal recommendations about exclusive breast-feeding up to 6 months postpartum. A secondary objective is to demonstrate the complexity of the biocultural nature of infant feeding practices. A sample of 283 children under 5 years of age and their 228 mothers living in a peri-urban district of Kathmandu participated in this study. The children's height/length and weight were measured three times over 9 months. At each session, a demographic, child health and infant feeding survey was administered; between sessions, in-depth interviews were conducted with mothers regarding infant feeding practices. While a few of the infants under 2 months were receiving non-breast milk foods, at 3 months of age half of the sample had been introduced to non-breast milk foods and by 7 months all infants were eating non-breast milk foods. A comparison of growth indices and velocities between exclusively and partially breast-fed infants from birth to 7 months of age shows no evidence for a difference in nutritional status between the two groups. Although there are cultural rules about breast-feeding that vary by ethnic group, all mothers followed a feeding method that depended on their assessment of whether the child was getting enough breast milk. The conclusion is that exclusive breast-feeding up to 6 months may not be appropriate for all infants. In this sample, breast-feeding duration is not shortened by the early introduction of non-breast milk foods, as the median age of breast-feeding cessation is 36 months. One of the main reasons for severance was the onset of another pregnancy. Investigation of infant feeding practices must be contextualized in the local ecology of the population. While cultural beliefs about breast-feeding are relevant, mothers' individual assessments of their children's nutritional needs and demographic events in parents' lives must also be considered.     

Brief Communication: Orphaned male Chimpanzees die young even after weaning

If a social‐living animal has a long life span, permitting different generations to co‐exist within a social group, as is the case in many primate species, it can be beneficial for a parent to continue to support its weaned offspring to increase the latter's survival and/or reproductive success. Chimpanzees have an even longer period of dependence on their mothers' milk than do humans, and consequently, offspring younger than 4.5–5 years old cannot survive if the mother dies. Most direct maternal investments, such as maternal transportation of infants and sharing of night shelters (beds or nests), end with nutritional weaning. Thus, it had been assumed that a mother's death was no longer critical to the survival of weaned offspring, in contrast to human children, who continue to depend on parental care long after weaning. However, in theory at least, maternal investment in a chimpanzee son after weaning could be beneficial because in chimpanzees' male‐philopatric society, mother and son co‐exist for a long time after the offspring's weaning. Using long‐term demographic data for a wild chimpanzee population in the Mahale Mountains, Tanzania, we show the first empirical evidence that orphaned chimpanzee sons die younger than expected even if they lose their mothers after weaning. This suggests that long‐lasting, but indirect, maternal investment in sons continues several years after weaning and is vital to the survival of the sons. The maternal influence on males in the male‐philopatric societies of hominids may be greater than previously believed. Am J Phys Anthropol, 153:139–143, 2014. © 2013 Wiley Periodicals, Inc.     

Isotopic evidence for breastfeeding and possible adult dietary differences from Late/Sub-Roman Britain

Historical documents indicate that breastfeeding and weaning practices have fluctuated in England through history. In order to obtain evidence for general breastfeeding patterns in Late/Sub-Roman Britain, stable carbon and nitrogen isotope values were measured in juvenile and adult skeletons (n = 87) from the cemetery of Queenford Farm, Dorchester-on-Thames, Oxfordshire. As the site contained few individuals between 0-1.5 years of age, it was not possible to determine the initial timing for the introduction of weaning foods. Between ages 2-4 years, the mean +/- SD delta(13)C results (-20.2 +/- 0.3 per thousand) are significantly more negative (t = -4.03, P < 0.001) compared to adult females (-19.7 +/- 0.3 per thousand). This is interpreted as evidence of a different diet being fed to children during weaning. After age 2, the delta(15)N values gradually decline, indicating complete cessation of breastfeeding by 3-4 years. Among adults, stature (males = 1.68 +/- 0.06 m; females = 1.58 +/- 0.07 m) and sexual dimorphism (106) were low, suggesting that the population was possibly under environmental stress. The delta(13)C results for adults are similar, but females show a small but statistically significantly (t = -2.86, P < 0.01) lower mean delta(15)N value (9.9 +/- 0.9 per thousand) compared to males (10.6 +/- 0.5 per thousand). These lower female delta(15)N values possibly reflect the different physiology of the sexes (pregnancy and/or lactation) or the reduced consumption of animal/fish protein by women, and this may have been influenced by individual preference, family needs, or societal values of the era.