Radiocarbon dating assumes that the carbon 14carbon 12 ratio
This same ratio is valid in all the reservoirs of carbon in this giant cycle.
In the biosphere, both carbon-14 and carbon-12 atoms are added to the food chain via assimilation; first by plants through photosynthesis and then by animals through consumption of the plants.
Atoms of carbon-12 have 6 neutrons, while atoms of carbon-14 contain 8 neutrons.
neutral atom would have the same number of protons and electrons, so a neutral atom of carbon-12 or carbon-14 would have 6 electrons.
The number given after the atom name (carbon) indicates the number of protons plus neutrons in an atom or ion.
Atoms of both isotopes of carbon contain 6 protons.
Because the ratio after death is related to the time that has passed since death, it is possible to determine the date of death by measuring the amount of radiocarbon present. This means that after 5,730 years half of the total amount of radiocarbon in a dead body disintegrates.
Long-term variations show systematic deviations of the radiocarbon age from the real age; that is as the date of the sample gets older the deviation increases.
This goes on until a very minuscule, undetectable amount remains.
In bodies less than 50,000 years in age the amount of radiocarbon can be detected.
For an older body, the amount of radiocarbon is so small that the instruments would be unable to measure the amount of radiocarbon present.
In addition, such a test obviously works only on the remains of things that were once alive, such as bones or wooden parts of an old structure.
Some Neolithic (later stone age) remains were dated back to fifty thousand years in Russia and Africa.