In the 1960s, preliminary explorations of ancient biomolecules were made. For example, using simple protein comparisons, isozyme variations Teosinte was shown to be the progenitor of domesticated maize. In the 1970s, DNA sequencing was developed. This allowed accurate phylogenetic comparisons, although from limited sequence information only, for example, the comparison of chloroplast DNA from wild and cultivated barley. However, the field progressed slowly because of methodological difficulties presented by aDNA. The methodological revolution, provided by the invention of the polymerase chain reaction (PCR), through which we can amplify tiny amounts of DNA, allowed aDNA research to blossom.
Early efforts (1980s) concentrated on samples that appeared to have excellent morphological preservation, for example, mummies and frozen specimens and museum skins including the quagga and marsupial wolf. However, this methodological revolution and the indiscriminate use of the technology also led to problems. There was a rush to get the oldest and most unusual sample; it seemed like anything was possible, so there were many studies on what later became called ‘antediluvian DNA’ - from dinosaurs, insects encased in amber, and fossil plant remains, the findings of which were subsequently called into question. However, these high-profile results and the resulting controversy allowed significant advances in our understanding of how aDNA can be used to the greatest effect, including the way we now use a series of lines of evidence to advance the argument for the authenticity of the aDNA from the samples we study (see the section entitled ‘How can we argue for the authenticity of our aDNA’).
Since the 1990s, enormous advances have been made. We can now analyze aDNA from a wide range of preserved materials (e. g., mummified skin and other body parts, bone, feces, charred seeds, teeth, wood, hair). Furthermore, the survival of aDNA in specimens up to several thousand years old is now well established and even retrieval of DNA from remains of the Late Quaternary (up to 100 000 years ago) is possible. These scrupulous studies have provided the basis for regained confidence in the field of archaeogenetics.
World History
