Oxygen isotope analysis
Carol Chenery, British Geological Survey
Oxygen isotope analysis of dental enamel can assist in determining a persons place of origin.
Tooth enamel stores a chemical record of their owners’ childhood living environment, such as local climate and geology. Each tooth opens a window of information covering the short time of tooth enamel formation. The mineral apatite that makes up the structure of our teeth and bones is the main component of tooth enamel. Its chemical composition is primarily calcium, phosphorous and oxygen with trace amounts of other elements including strontium and lead. Of these elements the isotopes of oxygen and strontium are the strongest independent indicators we have of the local natural environment.
Nearly all of the oxygen that goes into the formation of tooth and bone comes from the water we drink and virtually all the water we drink is ultimately derived from precipitation as rain or snow.
The element oxygen has 3 different forms called isotopes, which are chemically the same, but have slightly different physical properties due to a small difference in their weight.
The oxygen isotopes ratio of the water you drink depends on the source of the water in precipitation, the distance from the coast, latitude and altitude and the local temperature of precipitation. For our purposes we are interested in the ratio of heavy (oxygen 18) to light (oxygen 16) isotopes. Drinking water in warm climates has more heavy isotopes (higher ratio) and in cold climates has more light isotopes (lower ratio). We can compare the oxygen isotopes ratio in teeth with that of drinking water from different regions and determine where a person might have lived, at the time their teeth formed.
Oxygen isotope analysis of dental enamel from the two burials at Amesbury indicate that the “Archer” came from a colder climate region than we find in Britain today, possibly from some where in central Europe - the dark blue-green area in the oxygen isotope map. An early formed tooth from the younger man has an oxygen isotope value that is compatible with living in southern England or Ireland but the value obtained from his wisdom tooth suggest that he may have spent his late teens in the Midlands (yellow area on the map) or north-east Scotland (mid green area on the map). However these results for the younger man do not rule out a European origin.
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