Stable and radiogenic isotopes in Archaeology and Anthropology

1. Stable and radiogenic isotopes in Archaeology and Anthropology Henry P. Schwarcz McMaster University Hamilton, Ontario, Canada Christine White and Fred Longstaffe University of Western Ontario London, Ontario, Canada

2. Definitions (loose!) Anthropology: How people live (“culture”) Archaeology: How people Lived (prehistory and later) Paleoanthropology: Who “people” were (evolution)

3. The samples: Bones, teeth Time depth: 3 My to recent

4. Bone is a composite material consisting of: 60 wt% hydroxyapatite: HA Ca5(PO4, CO3 ) 3 (OH, CO3) OXYGEN CARBON + 40% collagen (protein) N, C ATOMS

5. Diagenesis: when bad things happen to good bones During burial: Collagen degrades: C/N ~ 3.2? Hydroxyapatite “crystallinity” increases O, C isotopic exchange with soil-water? We can test for these and exclude bad bones

6. Stable isotopes can help inform: Paleodiet: “you are what you eat + x ‰” Migration: where did people come from? Paleoclimate: rain, drought, cold, heat

7. Stages of life recorded M1 teeth M2, P1, etc M3 bones hair, etc. death 0 10 20 30 40 50 60 70 years

8. PALEODIET Nutrient molecules: protein: C, N, H, O Fat: C, H, O Carbohydrate: C, H, O δ13C, δ15N, δ18O of each nutrient varies depending on the source

9. δ15N (‰) (AIR) C4 PLANTS δ13C (‰) (PDB)

10. IsotopicAnalysis δ13C(bone collagen) = δ13C (food*) + 5‰ [* mainly dietary protein (?)] δ13C (CO3-apatite) ≈δ13C (food) + 11 ‰ δ15N (collagen) = δ15N(diet) + 3 ‰ [“trophic level effect”]

11. Marine consumers: how far would you go for sushi? You are here

12. Walker and DeNiro Am. J. Phys Anth., 1986 Seal Conclusion: Everyone was eating seal meat, but more in the islands

13. Los Angeles MALIBU site

14. Schwarcz & Walker, in prep. Walker & DeNiro Same trend as on Channel Islands: females have higher trophic level

15. Travelling foods: Maize arrives in Ontario ~ AD 700 Maize from Mexico

16. After AD 700 maize replaced wild carbohydrates…

17. Paleoclimate Isotopes as indicators of Temperature: paleotemperatures Mollusk shells in middens Speleothems Teeth, bones Humidity, Rainfall δ13C C3 vs C4 plants (wet vs dry) δ15N in collagen: rainfall (aridity) δ18O cycles in tooth enamel: seasonality of rain

18. Paleoclimate Isotopes as indicators of Temperature: paleotemperatures Mollusk shells in middens Speleothems Teeth, bones Humidity, Rainfall δ13C C3 vs C4 plants (wet vs dry) δ15N in collagen: rainfall (aridity) δ18O cycles in tooth enamel: seasonality of rain

19. δ18O Paleotemperatures: Sclerochronology Isotopic cycles in marine shell carbonates  Season of occupation of midden-sites Winter collection Matthieu et al., Paleo3,2005

20. Paleoclimate Isotopes as indicators of Temperature: paleotemperatures Mollusk shells in middens Speleothems Teeth, bones Humidity, Rainfall δ13C C3 vs C4 plants (wet vs dry) δ15N in collagen: rainfall (aridity) δ18O cycles in tooth enamel: seasonality of rain

21. East Africa: calcite in soils C3,moist-------------------C4, hot,dry Levin et al., EPSL, 2004

22. Migration: O and Sr isotopes Where does he/she come from? Isotopic labels can tell us something About place of origin (but not everything) These are questions in Archaeology/Anthropology Forensic Science (murder victims)

23. δ18O bone tells us δ18O of local drinking water δ18O(bone) δ18O(water)

24. δ18O of meteoric water varies regionally Decreases with Increasing latitude (poleward) Distance from sea (source of water vapor) Elevation Temperature

27. Strontium isotope ratios 87Rb  87Sr t1/2 = 10 gy limestones young, low-Rb ------------------ old, high Rb .700 .705 .710 .715 87Sr/86Sr modern seawater

28. White, Price & Longstaffe: Anc. Mesoamerica2007 seawater .7092

29. Moon Pyramid, Teotihuacan, Mexico In use from AD 1 to 650: Sacrificial victims…from where?

30. Possible sources: δ18O and 87Sr/86Sr White, Price & Longstaffe, 2007

31. Teotihuacan

32. Conclusions Childhood residences of all the sacrificial victims at the Moon Pyramid were foreign to Teotihuacan and could be sourced to regions over Mesoamerica where Teotihuacanos are known to have exerted influence. White, Price & Longstaffe: Anc. Mesoamerica 2007

33. Forensics: The lady from Mammoth Lake

34. Hair was available for analysis Native American or SoutheastAsian?

35. HAIR SAMPLE Maize-rich diet

36. Mammoth native tooth bone -14 -12 -10 -8 -6 -4 δ18O of water (SMOW, ‰)

37. DNA evidence: might be from a village in Oaxaca, Mexico

38. Local water --> HA Mammoth native Oaxaca village tooth bone -14 -12 -10 -8 -6 -4 δ18O of water (SMOW, ‰)

39. This part of her history is still unclear! Victim’s bone? We need more rain data

40. Conclusions • Potential isotopic records: • birth  childhood ?? late adult life • Isotopes can be used to trace trajectories of • Migration: O, C, N, Sr • But not high specificity: 100’s - 1000’s km2 • Need “candidate sites”

41. Isotopes can be used to trace trajectories of • Diet: C, N isotopes: • movement of hunters/gatherers • coast<--->inland • spread of cultigens • 3. Climate: O, C in soils, animal bone + teeth • drought • seasonality • temperature

42. Acknowledgements • Tracy Prowse • Phil Walker • Martin Knyf • Natural Sciences and Engineering Research Council of Canada (NSERC) • Social Sciences and Humanities Research Council of Canada (SSHRC)