The Body as Its Own Document
A skeleton is a written record in bone. Bioarchaeology reads it — reconstructing how a person aged, ate, worked, sickened, and moved — and aggregated across a cemetery, it recovers the health and demography of whole populations that left no census.
What the Bones Say
| Question | Where the answer lives | Reliability |
|---|---|---|
| Age at death | Tooth eruption/wear; bone fusion; pubic-symphysis wear | High in young, coarser in old age |
| Biological sex | Pelvis shape (definitive), skull robusticity | High for adults; poor for children |
| Stature | Long-bone length via regression | Good |
| Disease and injury | Lesions, healed fractures, joint wear | Only bone-marking conditions leave traces |
Age reads most sharply in the young — teeth erupt and bones fuse on a tight schedule — and blurs in adults, where methods estimate a range, not a birthday. Sex determination leans on the pelvis, reshaped by childbirth's demands, and is unreliable before puberty because those differences have not yet developed.
Chemistry: Diet and Origins
Bone chemistry preserves biography the bones' shape cannot:
- Carbon isotopes (δ¹³C) distinguish diets — notably whether staple crops were "C3" plants (wheat, barley) or "C4" plants (millet, maize) — letting archaeologists watch maize spread across the ancient Americas plate by plate.
- Nitrogen isotopes (δ¹⁵N) rise with trophic level, revealing how much meat and fish versus plants a person ate, and even flagging the nitrogen spike of breastfeeding infants.
- Strontium and oxygen isotopes, locked into tooth enamel in childhood from local water and rock, reveal where a person grew up — so a skeleton buried in one region but bearing another region's isotopic signature is a migrant, caught in the act millennia later.
The survivorship trap — the "osteological paradox": a skeleton with healed disease lesions belonged to someone whose body fought the illness and lived long enough to remodel bone; a victim who died fast may show no lesions at all. So a cemetery full of lesions can mean a healthier, more resilient population, not a sicker one. As always, the evidence needs an interpreter — the bone states a fact; the meaning is an argument.