Dating the tree of life
There are two techniques for dating in archaeological sites: relative and absolute dating.Relative dating stems from the idea that something is younger or older relative to something else.In fact, levels of Carbon-14 have varied in the atmosphere through time.One good example would be the elevated levels of Carbon-14 in our atmosphere since WWII as a result of atomic bombs testing.Therefore, radiocarbon dates need to be calibrated with other dating techniques to ensure accuracy.Plants are not the only organism that can process Carbon-14 from the air.
He had assumed that amounts of Carbon-14 in the atmosphere had remained constant through time.
Rodents, for example, can create havoc in a site by moving items from one context to another.
Natural disasters like floods can sweep away top layers of sites to other locations.
In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
Although relative dating can work well in certain areas, several problems arise.