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Stable carbon and oxygen isotopes in human tooth enamel: Identifying breastfeeding and weaning in prehistory
Author(s) -
Wright Lori E.,
Schwarcz Henry P.
Publication year - 1998
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/(sici)1096-8644(199805)106:1<1::aid-ajpa1>3.0.co;2-w
Subject(s) - molar , enamel paint , weaning , tooth enamel , dentistry , δ13c , carbonate , prehistory , orthodontics , chemistry , biology , medicine , stable isotope ratio , zoology , paleontology , physics , organic chemistry , quantum mechanics
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 δ 13 C to document the introduction of solid foods to infant diets and δ 18 O to monitor the decline of breastfeeding. We report enamel carbonate δ 13 C and δ 18 O 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 CO 2 liberated by reaction of enamel with H 3 PO 4 in an automated carbonate system attached to a VG Optima mass spectrometer. Within a skeleton, teeth developing at older ages are more enriched in 13 C and more depleted in 18 O than teeth developing at younger ages. Premolars average 0.5% higher in δ 13 C 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 δ 13 C in childhood diets did not change systematically. First molars and premolars are similar in δ 18 O, 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 δ 18 O is heavier, because breast milk is more enriched in 18 O 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.