Carbon-14 is also passed onto the animals that eat those plants.
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.
Carbon dating, or radiocarbon dating, can be helpful in determining the relative age of an object, but has many limitations.
By examining the object's relation to layers of deposits in the area, and by comparing the object to others found at the site, archaeologists can estimate when the object arrived at the site.
Sometimes, archaeologists will date an object by carbon dating another object nearby.
This method of dating obviously relies on assumptions about the relationship between the object and the actual tested material.
This is not necessarily unusual in science, but one must keep in mind how assumptions and interpretations are related.
At worst, this may lead to circular and self-confirming dating, though other methods of dating can reduce the risk.