Which isotopes are commonly used in forensic isotopic analysis to assess origin and diet?

• A. Hydrogen, helium, neon, argon
• B. Strontium, oxygen, carbon, nitrogen
• C. Phosphorus, sulfur, calcium, potassium
• D. Uranium, lead, cesium, barium

Answer: (B)

Isotopic analysis in forensics relies on stable isotope ratios in body tissues to reveal where a person grew up and what they ate. The most informative set for origin and diet includes strontium, oxygen, carbon, and nitrogen.

Strontium isotopes come from the local geology. The ratio of strontium-87 to strontium-86 in the diet and drinking water mirrors the rocks in a region, and as tooth enamel forms in childhood, that geographic signal becomes locked in. By comparing enamel Sr isotopes to geographic baselines, you can infer where a person likely originated.

Oxygen isotopes in body water vary with climate, latitude, altitude, and water sources, so the δ18O value in tissues reflects the geographic and climatic conditions where someone lived. This helps narrow down geographic regions associated with early life.

Carbon isotopes track dietary sources. The difference between C3 and C4 photosynthetic pathways in plants leads to distinct δ13C values in foods, and those signatures pass into the diet and tissues. This helps distinguish plant- and animal-based, terrestrial versus marine, and even regional dietary patterns.

Nitrogen isotopes indicate trophic level. Higher δ15N values generally point to greater consumption of animal protein and marine foods, while lower values reflect more plant-based or lower-trophic-level diets. This provides insight into long-term dietary habits.

Together, these isotopic signals provide robust information about where someone lived during formation and what their typical diet was, making them the standard toolkit for forensic origin and diet analysis.