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

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

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

Bone is a composite material consisting of: 60 wt% hydroxyapatite: HA Ca 5 (PO 4, CO 3 ) 3 (OH, CO 3 ) OXYGEN + 40% collagen (protein) N, C ATOMS CARBON

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

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

years M1 M2, P1, etc M3 teeth bones hair, etc. death Stages of life recorded

PALEODIET Nutrient molecules: protein: C, N, H, O Fat: C, H, O Carbohydrate: C, H, O δ 13 C, δ 15 N, δ 18 O of each nutrient varies depending on the source

C4 PLANTS δ 15 N (‰) (AIR) δ 13 C (‰) (PDB)

IsotopicAnalysis δ 13 C(bone collagen) = δ 13 C (food*) + 5‰ [* mainly dietary protein (?)] δ 13 C (CO 3 -apatite) ≈ δ 13 C (food) + 11 ‰ δ 15 N (collagen) = δ 15 N(diet) + 3 ‰ [“trophic level effect”]

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

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

MALIBU site Los Angeles

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

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

After AD 700 maize replaced wild carbohydrates…

Paleoclimate Isotopes as indicators of Temperature: paleotemperatures Mollusk shells in middens Speleothems Teeth, bones Humidity, Rainfall δ 13 C  C3 vs C4 plants (wet vs dry) δ 15 N in collagen: rainfall (aridity) δ 18 O cycles in tooth enamel: seasonality of rain

Paleoclimate Isotopes as indicators of Temperature: paleotemperatures Mollusk shells in middens Speleothems Teeth, bones Humidity, Rainfall δ 13 C  C3 vs C4 plants (wet vs dry) δ 15 N in collagen: rainfall (aridity) δ 18 O cycles in tooth enamel: seasonality of rain

δ 18 O Paleotemperatures: Sclerochronology Isotopic cycles in marine shell carbonates  Season of occupation of midden-sites Matthieu et al., Paleo 3, 2005 Winter collection

Paleoclimate Isotopes as indicators of Temperature: paleotemperatures Mollusk shells in middens Speleothems Teeth, bones Humidity, Rainfall δ 13 C  C3 vs C4 plants (wet vs dry) δ 15 N in collagen: rainfall (aridity) δ 18 O cycles in tooth enamel: seasonality of rain

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

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)

δ 18 O(bone) δ 18 O(water) δ 18 O bone tells us δ 18 O of local drinking water

δ 18 O of meteoric water varies regionally Decreases with Increasing latitude (poleward) Distance from sea (source of water vapor) Elevation Temperature

Strontium isotope ratios 87 Rb  87 Sr t 1/2 = 10 gy Sr/ 86 Sr limestones young, low-Rb  old, high Rb modern seawater

White, Price & Longstaffe: Anc. Mesoamerica 2007 seawater.7092

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

Possible sources: δ 18 O and 87 Sr/ 86 Sr White, Price & Longstaffe, 2007

Teotihuacan

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

Forensics: The lady from Mammoth Lake

Native American or SoutheastAsian? Hair was available for analysis

HAIR SAMPLE Maize-rich diet

δ 18 O of water (SMOW, ‰) Mammoth native tooth bone

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

δ 18 O of water (SMOW, ‰) Mammoth native tooth Local water --> HA Oaxaca village bone

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

Conclusions Potential isotopic records: birth  childhood  ??  late adult life Isotopes can be used to trace trajectories of 1.Migration: O, C, N, Sr But not high specificity: 100’s ’s km 2 Need “candidate sites”

Isotopes can be used to trace trajectories of 2.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

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)