Electron spin resonance dating of human bones from Brazilian shell-mounds (Sambaquís)

Electron spin resonance (ESR) signals from bone increase with exposure to radiation. This permits the dating of ancient bone from its exposure to natural radiation over the centuries. The ESR technique was used for dating human bones from Brazilian shell mounds. The results were compared with 14C dates on charcoal found near the bone. The natural radiation dose rate of the bones was about 0.01 Gy/year (1 rad/year), similar to that found in Japanese shell-mounds. Ages of the bone samples dated ranged from 2000-5000 years BP.