Archaeological dating labs
A greater appreciation for the risks of environmental contamination and studies on the chemical stability of DNA have resulted in concerns being raised over previously reported results.The dinosaur DNA was later revealed to be human Y-chromosome, Despite the problems associated with 'antediluvian' DNA, a wide and ever-increasing range of a DNA sequences have now been published from a range of animal and plant taxa.However, with the development of the Polymerase Chain Reaction (PCR) in the late 1980s, the field began to progress rapidly.Double primer PCR amplification of a DNA (jumping-PCR) can produce highly skewed and non-authentic sequence artifacts.Due to the considerable anthropological, archaeological, and public interest directed toward human remains, they have received considerable attention from the DNA community.Due to the morphological preservation in mummies, many studies used mummified tissue as a source of ancient human DNA.Tissues examined include artificially or naturally mummified animal remains, In June 2013, a group of researchers announced that they had sequenced the DNA of a 560–780 thousand year old horse, using material extracted from a leg bone found buried in permafrost in Canada's Yukon territory.In 2013, a German team reconstructed the mitochondrial genome of an Ursus deningeri more than 300,000 years old, proving that authentic ancient DNA can be preserved for hundreds of thousand years outside of permafrost.
The use of degraded human samples in a DNA analyses has not been limited to the amplification of human DNA.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.The first study of what would come to be called a DNA was conducted in 1984, when Russ Higuchi and colleagues at the University of California, Berkeley reported that traces of DNA from a museum specimen of the Quagga not only remained in the specimen over 150 years after the death of the individual, but could be extracted and sequenced.Unlike modern genetic analyses, ancient DNA studies are characterised by low-quality DNA. 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. (2012) tried to calculate this limit by studying the decay of mitochondrial and nuclear DNA in Moa bones. According to their model, mitochondrial DNA is degraded to an average length of 1 base pair after 6,830,000 years at −5 °C.Nuclear DNA degrades at least twice as fast as mt DNA.