Ancient DNA is DNA isolated from ancient specimens. It can be also loosely described as any DNA recovered from biological samples that have not been preserved specifically for later DNA analyses. Examples include the analysis of DNA recovered from archaeological and historical skeletal material, mummified tissues, archival collections of non-frozen medical specimens, preserved plant remains, ice and permafrost cores, Holocene plankton in marine and lake sediments, and so on. Unlike modern genetic analyses, ancient DNA studies are characterised by low quality DNA. This places limits on what analyses can achieve. Furthermore, due to degradation of the DNA molecules, a process which correlates loosely with factors such as time, temperature and presence of free water, upper limits exist beyond which no DNA is deemed likely to survive. Allentoft et al (2012) tried to calculate this limit by studying the decay of mitochondrial and nuclear DNA in Moa bones. The DNA degrades in an exponential decay process. According to their model, mitochondrial DNA is degraded to 1 base pair after 6.830.000 years at -5 °C. Nuclear DNA degrades at least twice as fast as mtDNA. As such, early studies that reported recovery of much older DNA, for example from Cretaceous dinosaur remains, may have stemmed from contamination of the sample.
Read more about Ancient DNA: History of Ancient DNA Studies, Problems and Errors, Antediluvian DNA Studies, Ancient DNA Studies, Ancient DNA Studies On Human Remains, Researchers Specializing in Ancient DNA
Famous quotes containing the words ancient and/or dna:
“I am ... willing to admit that some people might live there for years, or even a lifetime, so protected that they never sense the sweet stench of corruption that is all around themthe keen, thin scent of decay that pervades everything and accuses with a terrible accusation the superficial youthfulness, the abounding undergraduate noise, that fills those ancient buildings.”
—Thomas Merton (19151968)
“Here [in London, history] ... seemed the very fabric of things, as if the city were a single growth of stone and brick, uncounted strata of message and meaning, age upon age, generated over the centuries to the dictates of some now all-but-unreadable DNA of commerce and empire.”
—William Gibson (b. 1948)