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## Radiocarbon Dating and Its Complications
The radiocarbon dating of the Leicester skeleton provides an instructive example of how apparent complications in scientific results can be resolved through more sophisticated analysis rather than treated as problems with the identification itself.
Radiocarbon dating works because living organisms incorporate atmospheric carbon-14 — a radioactive isotope of carbon — into their tissues through food and respiration. When an organism dies, it stops incorporating new carbon-14, and the carbon-14 already present begins to decay at a known rate, with a half-life of approximately 5,730 years. By measuring the ratio of carbon-14 to stable carbon-12 in a sample, laboratories can estimate how long ago the organism died.
The complication with the Leicester skeleton was that the initial radiocarbon dates were slightly too old — placing the most probable death date earlier than 1485. The cause, when investigated, was the marine reservoir effect: the diet of the individual showed a high proportion of freshwater fish, whose carbon isotope ratios differ systematically from those of terrestrial foods because the carbon in freshwater systems is partly derived from old limestone rather than from recently atmospheric carbon dioxide.
The marine reservoir effect is a known complication in radiocarbon dating that can be corrected when dietary information is available. The isotope analysis of the skeleton’s bones, which identified the high proportion of freshwater fish and high-status aquatic birds in the diet, provided exactly the dietary information needed to apply the correction. When the Bayesian analysis incorporated both the radiocarbon dates and the dietary isotope data, the probability distribution shifted appropriately, placing the likely date of death in a range consistent with 1485.