Preservation of DNA in the Fossil Record

All organisms store their genetic makeup in either the DNA or RNA polymer, hence the preservation of Deoxyribonucleic Acid (DNA) in the geosphere and its retrieval from fossil organisms has intrigued the molecular biologist for many years. An ancient sequence would enable the scientist to place an extinct species in a phylogenetic context, to look at the diversity of extinct animal and human populations or even to trace disease associated bacteria or viruses back through time. The DNA molecule, although stronger than RNA, has a limited lifespan estimated at 10⁴ years in most geological settings. The advent of the Polymerase Chain Reaction (PCR) has enabled the retrieval of small amounts of DNA and in essence opened fossils to DNA analysis. Most research involving ancient DNA revolves around extraction, PCR amplification and sequencing of DNA from the remains of extinct animals and plants. There has been little work on the actual factors involved in the preservation of DNA. A more thorough understanding on the environments where this molecule is likely to be preserved would help molecular biologists focus their search.