However, there is strong evidence which suggests that radioactive decay may have been greatly accelerated in the unobservable past.
We must also assume that the ratio of C-12 to C-14 in the atmosphere has remained constant throughout the unobservable past (so we can know what the ratio was at the time of the specimen's death).
The carbon-14 atoms that cosmic rays create combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis.
Animals and people eat plants and take in carbon-14 as well.
Carbon generally forms four covalent bonds with other atoms in larger molecules.
Atomic number 6; atomic weight 12.011; sublimation point above 3,500°C; boiling point 4,827°C; specific gravity of amorphous carbon 1.8 to 2.1, of diamond 3.15 to 3.53, of graphite 1.9 to 2.3; valence 2, 3, 4.
The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant.