During life, DNA is organized into very long, delicate strands, called chromosomes. After death, these long strands of DNA are no longer repaired and maintained by cellular enzymes and they begin to break down in predictable ways.
Ancient DNA fragments are typically ultrashort molecules and carry extensive amounts of chemical damage accumulated after death. Their extraction, manipulation and authentication require specific experimental wet-laboratory and dry-laboratory procedures before patterns of genetic variation from past individuals, populations and species can be interpreted. Ancient DNA (aDNA) refers to the study of DNA extracted from specimens that died decades, hundreds or sometimes thousands of years ago. Examples include the analysis of DNA recovered from archaeological finds, museum specimens, fossil remains and other unusual specimens.
Biological findings of Paleontology and Archaeology are important carriers of information from the past and can provide with a unique point of view for the study and understanding of our origin, evolution, history, environment and heritage. This information, that addresses some of our most fundamental and primordial concerns, is the basis on which we can build our self-consciousness, understand our existence and gaze towards our future.
The field of aDNA consists a wide and highly multidisciplinary research domain.