Radiocarbon dating works by comparing the three different isotopes of carbon. Isotopes of a particular element have the same number of protons in their nucleus, but different numbers of neutrons. While the lighter isotopes 12C and 13C are stable, the heaviest isotope 14C (radiocarbon) is radioactive.

What is carbon dating and what can they tell archaeologists?

Over time, carbon-14 decays in predictable ways. And with the help of radiocarbon dating, researchers can use that decay as a kind of clock that allows them to peer into the past and determine absolute dates for everything from wood to food, pollen, poop, and even dead animals and humans.