Child dietary patterns in Homo sapiens evolution: A systematic review

Dietary patterns spanning millennia could inform contemporary public health nutrition. Children are largely absent from evidence describing diets throughout human evolution, despite prevalent malnutrition today signaling a potential genome-environment divergence. This systematic review aimed to identify dietary patterns of children ages 6 months to 10 years consumed before the widespread adoption of agriculture. Metrics of mention frequency (counts of food types reported) and food groups (globally standardized categories) were applied to: compare diets across subsistence modes [gatherer-hunter-fisher (GHF), early agriculture (EA) groups]; examine diet quality and diversity; and characterize differences by life course phase and environmental context defined using Köppen-Geiger climate zones. The review yielded child diet information from 95 cultural groups (52 from GHF; 43 from EA/mixed subsistence groups). Animal foods (terrestrial and aquatic) were the most frequently mentioned food groups in dietary patterns across subsistence modes, though at higher frequencies in GHF than in EA. A broad range of fruits, vegetables, roots and tubers were more common in GHF, while children from EA groups consumed more cereals than GHF, associated with poor health consequences as reported in some studies. Forty-eight studies compared diets across life course phases: 28 showed differences and 20 demonstrated similarities in child versus adult diets. Climate zone was a driver of food patterns provisioned from local ecosystems. Evidence from Homo sapiens evolution points to the need for nutrient-dense foods with high quality proteins and greater variety within and across food groups. Public health solutions could integrate these findings into food-based dietary guidelines for children.

Isotopic reconstruction of short to absent breastfeeding in a 19th century rural Dutch community

Artificial feeding of young infants is considered a modern phenomenon. However, historical sources note its practice in some past European populations. This research explores factors that contributed to a short to absent period of breastfeeding in pre-modern Netherlands. Stable nitrogen and carbon isotope analysis is undertaken on 277 19^th century individuals from Beemster, a, rural, mainly Protestant, dairy farming community. An intra-individual sampling approach for ≤6 year-olds compares newer metaphyseal to older diaphyseal long bone collagen to classify feeding status at death. Archivally identified individuals permit analyses of sex and year-of-death. Few infants have isotopic evidence for breastfeeding and, if present, it was likely of short duration or a minor source of dietary protein. From only a few weeks to months of age infants were fed cow’s milk and paps with sugar. There is broad dietary homogeneity with no sex or temporal isotopic differences, but young infants (1–11 months) have the most ẟ¹⁵N and ẟ¹³C variation highlighting the effect of multiple dietary and physiological processes. Beemster had many factors associated with high rates of breastfeeding in other Dutch communities, yet, most mothers did not breastfeed, or not for long, showing that regional variation in infant feeding is influenced by community values and traditions. On top of child rearing and domestic chores, female dairy farmers were in charge of milking cattle and dairy production, an important income source, suggesting high workload was also a factor in short or absent breastfeeding periods, aided by the constant supply of fresh milk that could be fed to an infant by an older sibling.

Co-Evolution of Breast Milk Lipid Signaling and Thermogenic Adipose Tissue

Breastfeeding is a unique and defining behavior of mammals and has a fundamental role in nourishing offspring by supplying a lipid-rich product that is utilized to generate heat and metabolic fuel. Heat generation from lipids is a feature of newborn mammals and is mediated by the uncoupling of mitochondrial respiration in specific fat depots. Breastfeeding and thermogenic adipose tissue have a shared evolutionary history: both have evolved in the course of homeothermy evolution; breastfeeding mammals are termed “thermolipials”, meaning “animals with warm fat”. Beyond its heat-producing capacity, thermogenic adipose tissue is also necessary for proper lipid metabolism and determines adiposity in offspring. Recent advances have demonstrated that lipid metabolism in infants is orchestrated by breast milk lipid signals, which establish mother-to-child signaling and control metabolic development in the infant. Breastfeeding rates are declining worldwide, and are paralleled by an alarming increase in childhood obesity, which at least in part may have its roots in the impaired metabolic control by breast milk lipid signals.

Breastfeeding and weaning in Late Holocene hunter-gatherers of the lower Paraná wetland, South America

OBJECTIVE

In this study, we analyze breastfeeding and weaning practices in pre-Columbian complex hunter-gatherers from the lower Paraná River basin (South America).

MATERIALS AND METHODS

We carried out bone isotope analyses concerning δ¹³ C in collagen and apatite, the spacing between both carbon sources and δ¹⁵ N in a sample of 23 subadult and adult individuals of both sexes recovered from Late Holocene archaeological sites, ranging from 1665 ± 45 to 680 ± 80 ¹⁴ C years BP.

RESULTS AND DISCUSSION

The results indicate that exclusive breastfeeding continued until the age of ~2 years, and weaning probably until 4 years of age. Supplementary foods included C₃ plants and probably animal fats and C₄ carbohydrates. A high fractionation of 4.9‰ in δ¹⁵ N values was recognized between breastfeeding infants and adult females, perhaps reflecting episodic hyper-protein diets in women linked to men's food provisioning during women's gestational/postpartum period. Additionally, male adults present a higher protein intake than females. Although this difference is not statistically significant with the current sample size, it could be a clue related to a sexual division in food procurement.

The "weanling's dilemma" revisited: Evolving bodies of evidence and the problem of infant paleodietary interpretation

Breastfeeding is known to be a powerful mediator of maternal and childhood health, with impacts throughout the life course. Paleodietary studies of the past 30 years have accordingly taken an enduring interest in the health and diet of young children as a potential indicator of population fertility, subsistence, and mortality patterns. While progress has been made in recent decades toward acknowledging the agency of children, many paleodietary reconstructions have failed to incorporate developments in cognate disciplines revealing synergistic dynamics between maternal and offspring biology. Paleodietary interpretation has relied heavily on the "weanling's dilemma," in which infants are thought to face a bleak choice between loss of immunity or malnutrition. Using a review of immunological and epidemiological evidence for the dynamic and supportive role that breastfeeding plays throughout the complementary feeding period, this article offers context and nuance for understanding past feeding transitions. We suggest that future interpretative frameworks for infant paleodietary and bioarchaeological research should include a broad knowledge base that keeps pace with relevant developments outside of those disciplines.

Historical overview and new directions in bioarchaeological trace element analysis: a review

Given their strong affinity for the skeleton, trace elements are often stored in bones and teeth long term. Diet, geography, health, disease, social status, activity, and occupation are some factors which may cause differential exposure to, and uptake of, trace elements, theoretically introducing variability in their concentrations and/or ratios in the skeleton. Trace element analysis of bioarchaeological remains has the potential, therefore, to provide rich insights into past human lifeways. This review provides a historical overview of bioarchaeological trace element analysis and comments on the current state of the discipline by highlighting approaches with growing momentum. Popularity for the discipline surged following preliminary studies in the 1960s to 1970s that demonstrated the utility of strontium (Sr) as a dietary indicator. During the 1980s, Sr/Ca ratio and multi-element studies were commonplace in bioarchaeology, linking trace elements with dietary phenomena. Interest in using trace elements for bioarchaeological inferences waned following a period of critiques in the late 1980s to 1990s that argued the discipline failed to account for diagenesis, simplified complex element uptake and regulation processes, and used several unsuitable elements for palaeodietary reconstruction (e.g. those under homeostatic regulation, those without a strong affinity for the skeleton). In the twenty-first century, trace element analyses have been primarily restricted to Sr and lead (Pb) isotope analysis and the study of toxic trace elements, though small pockets of bioarchaeology have continued to analyse multiple elements. Techniques such as micro-sampling, element mapping, and non-traditional stable isotope analysis have provided novel insights which hold the promise of helping to overcome limitations faced by the discipline.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12520-020-01262-4.

Multi-proxy stable isotope analyses of dentine microsections reveal diachronic changes in life history adaptations, mobility, and tuberculosis-induced wasting in prehistoric Liguria (Finale Ligure, Italy, northwestern Mediterranean)

OBJECTIVE

To reconstruct breastfeeding and weaning practices, metabolic stress including tuberculosis-induced wasting, and residential mobility of children in Neolithic and Metal Ages to infer their local ecologies.

MATERIALS

Seven permanent teeth from individuals dated to the Neolithic, Copper, Bronze, and Iron Ages buried in nearby caves in western Liguria, Italy.

METHODS

Carbon, nitrogen, and sulfur stable isotope analyses on dentine microsections. Tooth maturation was used to calculate age at death.

RESULTS

Two Neolithic children present longer pattern of weaning and appear to have been weaned using animal protein in contrast to the earlier weaning of Metal Ages children, which were probably weaned with vegetable resources. Sulfur isotopes suggest local origin of Neolithic and Cooper Age children, and non-local origins for Bronze and Iron Age children. Intense catabolism in the last two years is apparent in the adolescent with tuberculosis.

CONCLUSIONS

Shortening in weaning patterns during the Metal Ages are likely driven by the intensification of agricultural practices and cultivation of new crops during Bronze and Iron Ages. Neolithic food choices and delayed weaning patterns may represent one of the strategies to maximize growth and immune potential in a local economy/ecology with high-infectious load. Tuberculosis was a chronic and long-lasting disease.

SIGNIFICANCE

The first combined carbon, nitrogen, and sulfur analysis on prehistoric dentine microsections revealing changing human life history adaptations within the same region.

LIMITATIONS

Small sample size.

SUGGESTIONS FOR FURTHER RESEARCH

Increase the sulfur isotope dataset, use new EA-IRMS equipment, and provide data on amino acid to better define weaning food composition.

Reconstructing breastfeeding and weaning practices in the Bronze Age Near East using stable nitrogen isotopes

Objectives

Breastfeeding and childhood diet have significant impact on morbidity and mortality within a population, and in the ancient Near East, it is possible to compare bioarchaeological reconstruction of breastfeeding and weaning practices with the scant textual evidence.

Materials and Methods

Nitrogen stable isotopes (δ¹⁵N) are analyzed here for dietary reconstruction in skeletal collections from five Bronze Age (ca. 2,800–1,200 BCE) sites in modern Lebanon and Syria. We employed Bayesian computational modeling on cross‐sectional stable isotope data of collagen samples (n = 176) mainly from previous studies to test whether the bioarchaeological evidence aligns with the textual evidence of breastfeeding and weaning practices in the region, as well as compare the estimated weaning times to the global findings using the WARN (weaning age reconstruction with nitrogen isotope analysis) Bayesian model.

Results

Though the Near East sites in this study had different ecological settings and economic strategies, we found that weaning was introduced to the five sites at 0.5 ± 0.2 years of age and complete weaning occurred around 2.6 ± 0.3 years of age on using the WARN computational model. These weaning processes are within the time suggested by historical texts, though average estimated weaning age on the Mediterranean coast is later than inland sites.

Discussion

Compared globally, these Near Eastern populations initiated the weaning process earlier but completed weaning within the global average. Early initial weaning may have created short spacing between pregnancies and a high impact on demographic growth within these agricultural populations, with some variation in subsistence practices accounting for the inland/coastal discrepancies.

Calling all archaeologists: guidelines for terminology, methodology, data handling, and reporting when undertaking and reviewing stable isotope applications in archaeology

Stable isotope analysis has been utilized in archaeology since the 1970s, yet standardized protocols for terminology, sampling, pretreatment evaluation, calibration, quality assurance and control, data presentation, and graphical or statistical treatment still remain lacking in archaeological applications. Here, we present recommendations and requirements for each of these in the archaeological context of: bulk stable carbon and nitrogen isotope analysis of organics; bulk stable carbon and oxygen isotope analysis of carbonates; single compound stable carbon and nitrogen isotope analysis on amino acids in collagen and keratin; and single compound stable carbon and hydrogen isotope analysis on fatty acids. The protocols are based on recommendations from the Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) as well as an expanding geochemical and archaeological science experimental literature. We hope that this will provide a useful future reference for authors and reviewers engaging with the growing number of stable isotope applications and datasets in archaeology.

Weaning practices among pastoralists: New evidence of infant feeding patterns from Bronze Age Eurasia

OBJECTIVES

This paper investigates infant feeding practices through stable carbon (δ¹³ C) and nitrogen (δ¹⁵ N) isotopic analyses of human bone collagen from Kamennyi Ambar 5, a Middle Bronze Age cemetery located in central Eurasia. The results presented are unique for the time period and region, as few cemeteries have been excavated to reveal a demographic cross-section of the population. Studies of weaning among pastoral societies are infrequent and this research adds to our knowledge of the timing, potential supplementary foods, and cessation of breastfeeding practices.

MATERIALS AND METHODS

Samples were collected from 41 subadults (<15 years) and 27 adults (15+ years). Isotopic reference sets from adult humans as well as faunal remains were utilized as these form the primary and complementary foods fed to infants.

RESULTS

Slight shifts in δ¹³ C and δ¹⁵ N values revealed that weaning was a multi-stage process (breastfeeding, weaning, and complete cessation of nursing) that began at 6 months of age, occurred over several years of early childhood, and was completed by 4 years of age.

DISCUSSION

Our results indicate that weaning was a multi-stage process that was unique among late prehistoric pastoralist groups in Eurasia that were dependent on milk products as a supplementary food. Our discussion centers on supporting this hypothesis with modern information on central and east Eurasian herding societies including the age at which complementary foods are introduced, the types of complementary foods, and the timing of the cessation of breastfeeding. Integral to this work is the nature of pastoral economies and their dependence on animal products, the impact of complementary foods on nutrition and health, and how milk processing may have affected nutrition content and digestibility of foods. This research on Eurasian pastoralists provides insights into the complexities of weaning among prehistoric pastoral societies as well as the potential for different complementary foods to be incorporated into infant diets in the past.

A novel fecal stable isotope approach to determine the timing of age-related feeding transitions in wild infant chimpanzees

OBJECTIVES

Determining nutritional development in wild primates is difficult through observations because confirming dietary intake is challenging. Physiological measures are needed to determine the relative contributions of maternal milk and other foods at different ages, and time of weaning. We used fecal stable carbon and nitrogen isotopes (δ¹³ C, δ¹⁵ N) and fecal nitrogen concentrations (%N) from wild chimpanzees at Ngogo, Uganda, to derive physiological dietary indicators during the transition from total reliance on maternal milk to adult foods after weaning.

MATERIALS AND METHODS

We analyzed 560 fecal samples collected non-invasively from 48 infants, their mothers, and 6 juvenile siblings. Most infant and juvenile samples (90%) were matched to samples collected from mothers on the same day. Isotopic assessments were compared with observations of nursing and feeding.

RESULTS

Infants ≤1 year old showed average δ¹⁵ N, δ¹³ C and %N ratios that were 2.0‰, 0.8‰ and 1.3% greater than their mothers, respectively, interpreted as trophic level effects. Although data collected on newborns were few, results suggest that solid foods were consumed within 2-5 months after birth. Trophic level differences decreased steadily after 1 year, which indicates a decreasing relative contribution of milk to the diet. Isotopic results indicated infants were weaned by 4.5 years old-more than a year earlier than observations of nipple contacts ceased, which revealed the occurrence of "comfort nursing." Juvenile isotopic signatures indicate no nursing overlap between siblings.

DISCUSSION

Our results resemble the stable isotope differences of human babies. This study contributes to a model of chimpanzee nutritional development required to understand early life history patterns in hominins.

Red deer bone and antler collagen are not isotopically equivalent in carbon and nitrogen

RATIONALE

Bone and antler collagen δ(13) C and δ(15) N values are often assumed to be equivalent when measured in palaeodietary, palaeoclimate and palaeocological studies. Although compositionally similar, bone grows slowly and is remodelled whereas antler growth is rapid and remodelling does not occur. These different patterns of growth could result in isotopic difference within antler and between the two tissue types. Here we test whether red deer (Cervus elaphus) bone and antler δ(13) C and δ(15) N values are equivalent, and whether intra-antler isotopic values are uniform.

METHODS

Bone and antler were isotopically analysed from six stags that lived in a temperate maritime climate on the Isle of Rum, Scotland. Multiple antlers from different years were sampled per individual, together with a single bone sample per individual. Up to 12 samples were taken along the length of each antler (total of 25 antlers, 259 samples) so that a chronological record of the isotopic composition during antler growth could be obtained. Collagen was extracted and its δ(13) C and δ(15) N values were measured by continuous-flow isotope ratio mass spectrometry.

RESULTS

Intra-antler collagen isotope signatures vary, and show that not all antlers from an individual or a growth year are equivalent in carbon and nitrogen isotopic ratios. δ(15) N values typically increase with distance along antler length, but no overall trend is observed in δ(13) C values. An isotopic offset is visible between bone and antler, with bone δ(13) C and δ(15) N values being higher in most cases.

CONCLUSIONS

Bone and antler collagen δ(13) C and δ(15) N values are not isotopically equivalent and are therefore not directly comparable in palaeodietary, palaeoclimate and palaeocological studies. Bone and antler collagen isotopic differences probably relate to differential metabolic processes during the formation of the two tissues. Intra- and inter-antler isotopic variations probably reflect the isotopic composition of an individual's diet rather than physiological parameters, and may have the potential to provide high-resolution individual-specific information in modern and ancient cervid populations. Copyright © 2016 John Wiley & Sons, Ltd.

Jealousy Protest

In this article, nascent jealousy’s ultimate foundation is theorized as an adapted psychological mechanism that evolved in the environment of evolutionary adaptedness (EEA) to prepare 1-year-olds for defending against premature weaning upon the closely spaced birth of a sibling. This position rests on evidence that nascent jealousy is expressed through jealousy protest, a constellation of caregiver-directed protests and bids for exclusive attention, and evidence that its onset occurs at approximately 9 months of age. Given that the period of human gestation is 9 months, we propose that jealousy protest’s form and timing were compelled by the possibility that the end of an infant’s first year could be met by competition with a newborn sibling. That possibility placed infants at risk of malnutrition and mortality due to entailing the loss of exclusive access to mother’s milk, while infants were at an age when they were still heavily reliant on breast milk for survival. At this juncture, threat posed by the birth of a sibling was compounded by conditions of the EEA, where the sole viable source of breast milk was an infant’s mother, and her supply of milk was sufficient for sustaining only one child at a time. We conclude by offering suggestions for future research and discuss implications for the theory of parent–offspring conflict as a foundation of adaptations in children.

Infant feeding practices and childhood diet at Apollonia Pontica: Isotopic and dental evidence

OBJECTIVE

This study analyzes deciduous dental pathology and stable isotopes to investigate the relationship between diet, feeding practices, and oral health in a subadult skeletal sample from the Greek colonial site of Apollonia Pontica, Bulgaria (mid-5th to mid-3rd Centuries BC).

METHODS

Stable carbon and nitrogen isotope analysis was conducted on 74 bone collagen samples, and the deciduous dentitions of 85 individuals aged 8.5 months to 11 years were examined for evidence of caries, calculus, antemortem tooth loss, abscesses, and occlusal tooth wear.

RESULTS

δ(13) C and δ(15) N values of the collagen samples indicate that weaning began between the ages of 6 months and 1 year, and was complete for most individuals by the age of 3. The isotopic data are consistent with a mixed diet of primarily terrestrial C3 resources. The dental pathology data indicate that complementary foods provided to young children had an impact on their oral health early on. Four outliers exhibited elevated δ(15) N values compared with the adult female range and lower levels of tooth wear than other members of their age groups. Possible explanations include prolonged breastfeeding, the consumption of diets elevated in (15) N, and physiological/nutritional stress.

CONCLUSIONS

The deciduous dental data correlate well with the isotopic data and are consistent with later textual sources regarding the timing and duration of weaning, and the composition of complementary foods. The results of this research demonstrate the value of combining isotopic and dental evidence to investigate the dietary practices of infants and young children and the impact of these practices on oral health.

Lower limb activity in the Cis-Baikal: entheseal changes among middle Holocene Siberian foragers

Lower limb entheseal changes are evaluated in order to reconstruct activity levels and more fully understand cultural and behavioral variation among the middle Holocene (ca. 9,000-3,000 years BP) foragers of Siberia's Cis-Baikal region. The four cemetery samples examined span a period of diachronic change characterized by an 800- to 1,000-year discontinuity in the use of formal cemeteries in the region. Two of the cemetery samples represent the early Neolithic Kitoi culture, dating from 8,000 to 7,000/6800 cal. BP; the other two represent the late Neolithic-early Bronze Age Isakovo-Serovo-Glazkovo (ISG) cultural complex, dating from 6,000/5,800 to 4,000 cal. BP. Findings suggest a dynamic pattern of cultural variability in the Cis-Baikal, with spatial distribution (i.e., site location within particular microregions) appearing to be just as important a factor as cultural/temporal affiliation in explaining intersample differences in entheseal morphology. In addition, intrasample comparisons reveal increasing sexual disparity with advancing age at death, emphasizing the influence of sex-related activities on lower limb entheseal changes. Finally, results from the separate fibrous and fibrocartilaginous datasets appear to be largely congruous, implying that activity patterns in the Cis-Baikal may have similar effects on the morphology of both types of entheses.