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. This means that although they are very similar chemically, they have different masses.

What isotope is used for dating living things?

Radiocarbon (14C) dating All living organisms take up carbon from their environment including a small proportion of the radioactive isotope 14C (formed from nitrogen-14 as a result of cosmic ray bombardment).

How does UTH dating work?

As its name suggests, uranium-series dating uses the radioactive decay of uranium to calculate an age. When uranium decays, it goes through a series of decays until it eventually reaches a stable isotope. So, for example, uranium 238 will decay to uranium 234, which will decay to thorium 230.

Why is carbon dating not useful for dating fossils from millions of years ago?

Carbon dating cannot be used on most fossils, not only because they are almost always too old, but also because they rarely contain the original carbon of the organism. Also, many fossils are contaminated with carbon from the environment during collection or preservation proceedures.