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

Abstract

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 delta13C to document the introduction of solid foods to infant diets and delta18O to monitor the decline of breastfeeding. We report enamel carbonate delta13C and delta18O 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 0.5/1000 [corrected] higher in delta13C 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 delta13C in childhood diets did not change systematically. First molars and premolars are similar in delta18O, but third molars average 0.7/1000 [corrected] lower than first molars (P = 0.0001) and 0.5/1000 [corrected] lower than premolars (P = 0.0003). First molar and premolar delta18O 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.

Land use and mobility during the Neolithic in Wales explored using isotope analysis of tooth enamel

“…The deciduous molars of two children sampled by this study (from Penywyrlod) have not been included in the above comparison of oxygen isotope ranges, as they begin formation in utero (AlQahtani et al, 2010) and, following birth, values within these teeth may be influenced by consumption of breast milk, which has a higher δ 18 O value relative to fluids consumed by the mother (Britton, Fuller, Tütken, Mays, & Richards, 2015; Roberts et al, 1988; Wright & Schwarcz, 1998). The deciduous second molar of child 74.23H/9.18/P20 from Penywyrlod (Figure 5) exhibits the highest δ 18 O carbonate value (28.2 ‰; δ 18 O phosphate 19.4 ‰) of all the individuals sampled in the present study: the possibility that this is a consequence of breastfeeding cannot be excluded.…”

“…759) argue to represent occupation of western Britain. However, as formation of deciduous molars continues in the months following birth, it is possible that oxygen isotope ratios in enamel from these teeth could also be influenced by consumption of breast milk, which may confer higher δ 18 O values than drinking water (Britton et al, 2015; Roberts et al, 1988; Wright & Schwarcz, 1998). The remains of this individual, dated to 1670–1500 cal BC (95% confidence; SUERC‐57789), were found outside Chamber 2 of the long cairn (Table 1).…”

Reconstruction of breastfeeding and weaning practices using stable isotope and trace element analyses: A review

“…Wright and Schwarcz (1998) measured d 13 C and d 18 O values of M1, P, and M3 whole enamel (corresponding to 0-3, 2-6, and 9-12 years of age, respectively) from the Guatemalan site of Kaminaljuy u (ca. 700 BC to 1500 AD).…”

Stable isotope evidence for an amphibious phase in early proboscidean evolution

“…It has also been noted that teeth forming later in life contain more 13 C and less 18 O than those formed earlier (51). Therefore it is important to consistently use teeth known to have formed later in life for isotopic studies wherever possible, e.g., M3 and P4 (25), and this has been done here, although the position (i.e., M1, M2, M3) of Barytherium molars could not be determined with confidence.…”