How can a skeleton show what someone ate?

Foods carry distinctive isotope ratios that pass into body tissues, so measuring carbon and nitrogen in bone collagen reveals the broad makeup of the diet, such as the importance of maize, marine foods, or animal protein.

Can isotopes show if someone was a migrant?

Yes—strontium and oxygen isotopes locked into childhood-formed tooth enamel reflect where a person grew up, so values that differ from the local environment can identify people who migrated.

Diet and Isotope Analysis

Diet and isotope analysis reconstructs what past people ate and where they lived from the chemistry and wear of their bones and teeth, turning the skeleton into a record of subsistence, mobility, and life history.

Definition

The set of bioarchaeological methods—stable isotope analysis and dental wear study—used to reconstruct the diet, breastfeeding and weaning histories, and geographic mobility of individuals and populations from skeletal and dental tissues.

Scope

This area covers the chemical and morphological evidence for ancient diet and movement: stable carbon and nitrogen isotopes for reconstructing food sources and trophic level, strontium and oxygen isotopes for tracking residence and migration, and dental wear and microwear for inferring food texture and processing. It integrates analytical chemistry with archaeological and ecological context to study subsistence change, weaning, and population movement.

Sub-topics

Core questions

What did past populations eat, and how did subsistence change over time?
How can the chemistry of bone and teeth reveal where a person lived and whether they migrated?
How are breastfeeding and weaning reconstructed from isotopes?
What do patterns of dental wear reveal about diet and food processing?

Key theories

You are what you eat, isotopically: The principle that the carbon and nitrogen isotope ratios of body tissues reflect those of the diet in predictable ways, so that bone and tooth chemistry records the proportions and trophic level of foods consumed.
Geographic signatures in skeletal chemistry: The principle that strontium and oxygen isotopes incorporated from local water and geology become fixed in dental enamel during childhood, allowing later detection of individuals who grew up elsewhere.

History

Isotopic dietary reconstruction began in the late 1970s when carbon isotopes were used to detect the spread of maize agriculture, and expanded through the 1980s and 1990s with nitrogen isotopes for trophic level and strontium and oxygen isotopes for mobility. Combined with longstanding dental-wear studies, these methods made skeletal chemistry a central tool of bioarchaeology.

Debates

Diagenesis and the reliability of isotopic signals: Concern over how far post-burial chemical alteration of bone, and uncertainties in tissue-diet fractionation and baseline values, compromise dietary and mobility reconstructions, and how best to screen for contamination.

Key figures

Stanley H. Ambrose
Julia A. Lee-Thorp
M. Anne Katzenberg
T. Douglas Price

Seminal works

ambrose1993
leethorp2008
katzenberg2008

Frequently asked questions

How can a skeleton show what someone ate?: Foods carry distinctive isotope ratios that pass into body tissues, so measuring carbon and nitrogen in bone collagen reveals the broad makeup of the diet, such as the importance of maize, marine foods, or animal protein.
Can isotopes show if someone was a migrant?: Yes—strontium and oxygen isotopes locked into childhood-formed tooth enamel reflect where a person grew up, so values that differ from the local environment can identify people who migrated.