Stable Isotope Analysis
Definition
A technique that measures the ratio of stable (non-radioactive) isotopes of elements such as strontium, oxygen, and carbon in a biological sample. In tooth enamel, these ratios reflect the geological and dietary environment during the period of enamel formation in childhood, and are used in forensic investigations to estimate the geographic origin of unidentified individuals.
- Elements measured
- Strontium, oxygen, carbon, among others
- Sample type
- Tooth enamel, bone, hair
- Reflects
- Geological and dietary environment during formation
- Main forensic use
- Estimating geographic origin of unidentified remains
- Enamel timing
- Fixed at time of formation in childhood
Common questions
Why is tooth enamel preferred over bone for this analysis?+
Enamel does not remodel after formation, so its isotope ratios stay fixed at the childhood period when it formed and are not overwritten by later diet or location changes. Bone remodels continuously through life, so it instead reflects a more recent, blended period.
Can stable isotope analysis give an exact country of origin?+
No, it narrows the likely region by comparing measured ratios against reference isoscape maps built from known geology and water sources, but overlapping ratios across different regions mean the result is a probable zone rather than a single confirmed location.
How does stable isotope analysis differ from radiocarbon dating?+
Stable isotope analysis measures non-radioactive isotope ratios to infer diet and geographic origin, while radiocarbon dating measures the decay of radioactive carbon-14 to estimate age. The two use different isotopes for entirely different questions.
Related terms
- Cementum
- A thin, bone-like mineralised tissue that covers the external surface of the tooth root. Deposited incrementally throughout life in alternating translucent and...
- Cementum Annuli
- Incremental growth layers in cementum, deposited at a rate of approximately one pair of translucent and opaque bands per year throughout adult...
- Cortical Bone
- The dense outer shell of long bones, also called compact bone. Porosity is less than 10 percent. High mineral density, slow water...
- Dentine
- The mineralised tissue forming the bulk of the tooth, surrounding the pulp chamber and root canal. Contains a network of dentinal tubules,...
- Enamel
- The outermost layer of the tooth crown, formed by ameloblasts before tooth eruption. Composed of approximately 96% hydroxyapatite mineral by weight. Acellular...
- Hydroxyapatite
- The calcium phosphate mineral (Ca10(PO4)6(OH)2) that constitutes approximately 70 percent of bone dry weight. Its crystals bind to DNA fragments electrostatically, slowing...
- Inhibitor Removal
- Laboratory steps applied to degraded bone before PCR amplification. Collagen hydrolysis products, humic acids, and heavy metals in aged bone inhibit DNA...
- Lines of Arrested Growth (LAGs)
- Alternating dense and loose concentric rings in bone cortex visible in histological cross-section, analogous to tree rings. Each LAG marks a period...
- Odontoblast
- A specialised cell of neural crest origin that forms dentine. The cell body sits at the pulp-dentine junction while a long cellular...
- Osteon (Haversian System)
- The basic structural unit of compact cortical bone: a central Haversian canal surrounded by concentric lamellae of mineralised collagen. Osteon diameter and...
- Population Assignment
- A genetic method that compares a specimen's microsatellite or SNP profile to reference databases of known-origin individuals, assigning the specimen to the...
- Radiocarbon Dating (C-14)
- Age determination from the ratio of radioactive carbon-14 to stable carbon-12 in organic material. Atmospheric C-14 spiked during nuclear testing (1950s-1960s), allowing...
Explained in these topics
- Ageing, Sexing, and Geographic Provenance of SpecimensMeasurement of the ratios of stable isotopes (typically strontium-87/86, oxygen-18/16, carbon-13/12) in tissue. These ratios reflect local geology, hydrology,...
- Bone Biology and Forensic SignificanceThe measurement of naturally occurring isotope ratios, such as 13C/12C, 15N/14N, 87Sr/86Sr, and 18O/16O, in bone collagen or mineral. Carbon and nitrogen ratio...
- Dental Tissue and Its Forensic Applications