Radioactive dating in archaeology is used to determine the age of ancient materials by measuring how much of a radioactive isotope has decayed over time. The most common method is radiocarbon dating.
How it works:
- Carbon-14 formation
- Cosmic rays in the atmosphere create radioactive carbon-14 (C-14).
- Plants absorb C-14 during photosynthesis, and animals get it by eating plants.
- Living organisms maintain balance
- While alive, organisms have a constant ratio of carbon-14 to carbon-12.
- After death
- The organism stops taking in carbon.
- The C-14 it contains starts to decay into nitrogen-14 with a half-life of about 5,730 years.
- Measuring decay
- By comparing the remaining C-14 to stable carbon-12, scientists calculate how long it has been since the organism died.
Time range
- Radiocarbon dating works best for organic remains up to about 50,000 years old.
- Beyond that, so little C-14 remains that it’s hard to measure.
Examples in archaeology
- Dating bones, wood, charcoal, cloth, and other once-living materials.
- Establishing timelines for ancient civilizations, cave paintings, burial sites, or artifacts.
- Used alongside other methods (like dendrochronology/tree rings) for cross-checking.
In short: Archaeologists use radioactive dating—especially radiocarbon dating—to put an age on artifacts and remains, helping reconstruct human history.