A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago.
How do scientists know how old an object or human remains are?
Carbon-14 is radioactive with a half-life of about 5700 years, but as C-14 atoms decay, new ones are created.
The amount of C-14 in the atmosphere settles into an equilibrium where creation of new atoms is equal to the decay of old atoms.
A real case of contamination with old carbon is that of modern sea shells that dated at 1500 years old.