It is used to detect the relationship between two closely related organism that are found from ancient period of time.
It is also use to detect the age of a newly discovered fossil.
Not only in the field of archaeology,it also used in the field of geology, sedimentology, for studying different lakes.
Isotope of iodine is used in medical field, to detect the cancer cells.
The isotope of carbon is used to detect the release of carbon in the ecosystem to monitor the release of old carbon which is stored in the soil thus it helps to detect the climate change which is done by anthropologenic disturbance.
