Full of sound and fury: The recent history of ancient DNA

The discovery that DNA survives in ancient remains and can be amplified by the polymerase chain reaction has added a direct temporal dimension to evol utionary studies. Initial reports suggested that the time period open to in vestigation was vast, extending back into the Cretaceous period. However, a ttempts to replicate of results involving DNA purported to be over a millio n years old have not succeeded. Theoretical studies suggest that DNA is unl ikely to survive intact more than about 100,000 years. However, even over t his time period, the evolutionary questions that can be addressed are far r eaching and include systematics, paleoecology, the origin of diseases, and evolutionary processes at the population level.