An international team has announced the development of a method for extracting DNA from hair. Until now it was thought that the hair shaft without the root was of little use as it contained limited amounts of DNA. Most ancient DNA analysis has therefore concentrated on bone, teeth and mummified tissue. But a team headed up by Dr. Tom Gilbert of the University of Arizona has extracted and sequenced mitochondrial DNA from 12 hair samples from between 60 to 64,800 years old, from bison, horses and humans.
     The researchers say that the ancient DNA in hair was much less degraded than DNA from other tissues because it was protected by hydrophobic keratin, the protein polymer that gives hair its structure. Hair DNA had a low level of contamination and the team believes that keratin may protect against contamination with modern DNA sequences from such agents as human sweat. DNA samples from hair and other keratin-containing samples like feathers and scales would greatly reduce the destruction of valuable archaeological samples like teeth and bones.
     Dr. Tom Loy, an Australian expert on DNA at the University of Queensland, welcomes the development and is enthusiastic about the possible ability to extract DNA from feathers. “Often times feathers are found in caves and in some cases as residues from artefacts.” But Loy is sceptical about whether the method would be effective on scales, and is unconvinced that keratin protects against contamination. “People still don’t understand how things get contaminated.”
     In passing, the researchers have also produced results that show that hair previously thought to belong to Sir Isaac Newton was not his, confirming earlier isotopic analysis. The research is published in the current issue of the journal ‘Current Biology’.

Source: News in Science (22 June 2004)