USING 87SR/86SR IN TEETH AS CLUES TO THE LIFE HISTORIES OF ENSLAVED AFRICANS BURIED IN NEW YORK CITY

In 1991, 408 burials of 18th century enslaved Africans were discovered in lower Manhattan. We have analyzed 87Sr/86Sr in tooth enamel and dentine from 31 of these individuals as well as in two burials and the local well water from near Elmina, Ghana a major slave shipment port. Since 87Sr/86Sr is particularly high in the ancient high Rb/Sr cratons of west Africa, Sr isotopes may distinguish New York-born from African-born individuals. 19 individuals in our sample display decoratively filed teeth, an African custom believed to have been repressed in the New World. The remaining 12 individuals are young (< 25 years old at death) and lack decorative modification. This later group displays tightly clustered 87Sr/86Sr in first molar dentine and enamel (~0.71159 +/-0.00072), apparently the indigenous NYC value. This group may comprise native New Yorkers. The remaining nineteen with decorative teeth show enamel 87Sr/86Sr ranging widely (0.7085 to 0.7275). Sixteen of the modified group show dentine 87Sr/86Sr generally quite unlike that in their enamel, and closer than their enamel to 0.71159 whether their enamel fell above or below that value (avg dentine: 0.71240+/-0.00185). Two modified individuals have the NYC value, and one (#165) shows enamel ~0.718 and dentine ~0.719. The enamel-dentine differences may be due to recalcification of dentine during later life, and/or to diagenetic alteration after death. If, as suggested by #165's result, recalcification during life is more important, a rough estimate of residence time in NYC may be derived from the proximity of the dentine 87Sr/86Sr to 0.71159 relative to the enamel value. At 0.7355, the Ghanian well water is our highest measured ratio. Ghanian dentines show 87Sr/86Sr closer to 0.7355 than their corresponding enamel, also suggesting that these individuals were not native to their burial place.