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.

Can a human body become radioactive?

Exposure to radiation does not immediately make a person radioactive. The only type of radiation that is capable of directly causing other material to become radioactive is neutron radiation, which is generally only found inside nuclear reactors or in a nuclear detonation.