Carbon 14 dating assumes that the carbon
Carbon 14 dating assumes that the carbon - Free older adult webcam
The new method is based on the fact that over the past 60 years, environmental levels of radiocarbon have been significantly perturbed by mid-20th-century episodes of above-ground nuclear weapons testing.
They found that for teeth formed after 1965, enamel radiocarbon content predicted year of birth within 1.5 years.
To determine year of birth, the researchers focused on tooth enamel.
Adult teeth are formed at known intervals during childhood.
All the people whose tissues were tested for the study were residents of the United States.
Atmospheric dispersion tends to create uniform levels of carbon-14 around the globe, and researchers believe that these would be reflected in human tissues regardless of location.
The researchers found that certain soft tissues — notably blood, nails and hair — had radiocarbon levels identical to the contemporary atmosphere.
Therefore, the radiocarbon level in those tissues post-mortem would indicate the year of death.Unlike tooth enamel, soft tissues are constantly being made and remade during life.Thus, their radiocarbon levels mirror those in the changing environment.However, the researchers suggested that soft tissue radiocarbon content would be transferred to, and preserved in, the pupal cases of insects whose larvae feed on these tissues.Such insects are simply another link in the food chain.Barring any future nuclear detonations, this method should continue to be useful for year-of-birth determinations for people born during the next 10 or 20 years.