How DNA Moves Through the Ground

Understanding why the DNA movement concern was taken so seriously requires a brief explanation of how organic material behaves in sediment — something that has become much better understood in the decades since ancient DNA analysis became a standard archaeological tool.

Sediment is not an inert storage medium.

It is a complex chemical and biological environment in which organic molecules are constantly being transformed by chemical reactions, consumed and transported by microorganisms, and physically moved by water and other agents.

The assumption that organic material stays precisely where it was deposited — that the carbon, nitrogen, and other elements in an ancient coprolite are the same carbon and nitrogen that entered the sediment when the feces were originally deposited — is often an approximation that must be carefully evaluated.