Ancient DNA (aDNA) is
Due to degradation processes (including cross-linking, deamination and fragmentation) ancient DNA is of lower quality in comparison with modern genetic material . The damage characteristics and ability of aDNA to survive through time restricts possible analyses and places an upper limit on the age of successful samples Allentoft et al. (2012). There is a theoretical relationship between time and DNA degradation , although differences in environmental conditions complicates things. Samples subjected to different conditions are unlikely to predictably align to a uniform age-degradation relationship . The environmental effects may even matter after excavation, as DNA decay rates may increase , particularly under fluctuating storage conditions . Even under the best preservation conditions, there is an upper boundary of 0.4-1.5 million years for a sample at around to contain sufficient DNA for contemporary sequencing technologies .
Research into the decay of
The first study of what would come to be called aDNA was conducted in 1984, when Russ Higuchi and colleagues at the
Double primer PCR amplification of aDNA (jumping-PCR) can produce highly skewed and non-authentic sequence artifacts. Multiple primer,
Single primer extension (abr. SPEX) amplification was introduced in 2007 to address postmortem DNA modification damage.