Posted on 06/22/2004 9:09:45 AM PDT by blam
Ancient hair gives up its DNA secrets
Anna Salleh
ABC Science Online
Tuesday, 22 June 2004
Hair from a 2300-year-old bison (Image: TH Loy)
Analysing DNA from ancient strands of hair is a new tool for learning about the past, molecular archaeologists say, including whether hair samples belonged to Sir Isaac Newton.
Until now, scientists had thought analysing the hair shaft was of relatively little use as it contained so little DNA.
Dr Tom Gilbert of the University of Arizona led an international team that reported its work in the latest issue of the journal Current Biology.
The researchers said they had extracted and sequenced mitochondrial DNA from 12 hair samples, 60 to 64,800 years old, from ancient bison, horses and humans.
The researchers said their results confirmed that hair samples previously thought to belong to Sir Isaac Newton were not his, a finding that backed previous isotopic analysis.
But the focus of their research was to explore the potential of extracting ancient DNA from hair samples.
The most common samples used for ancient DNA analyses are taken from bone, teeth and mummified tissue.
Until now, when the hair root hadn't been available for analysis, scientists had thought analysing the hair shaft was of relatively little use as it contained so little DNA.
But isolated strands of hair are often the only clues to human habitation in ancient times.
Now Gilbert's team said it had developed a method to extract and sequence ancient DNA from hair shafts.
The researchers said the ancient DNA in hair was much less degraded than DNA from other tissues.
They argued this was because it was protected from water by the hair's hydrophobic keratin, the protein polymer that gives hair its structure.
The team also found that hair DNA had a low level of contamination and argued that keratin may protect the DNA from contamination with modern DNA sequences, like DNA from human sweat.
The scientists also said that analysing hair DNA, and potentially DNA from other keratin-containing samples like ancient feathers and scales, would minimise the destruction of valuable archaeological samples caused by sampling teeth or bones.
Hairy development
"It's a nice development," said Dr Tom Loy, an Australian expert in ancient DNA from the University of Queensland.
He said that molecular archaeologists had generally ignored extracting DNA from hair.
"[But] on the basis of their article it looks as if it's quite, quite feasible," he told ABC Science Online.
He said the method may be useful in shedding light on the origin of strands of ancient hair discovered a decade ago at the Pendejo Cave site in New Mexico.
"It would be very important to find out whose hair it was," said Loy, who said previous attempts had been unsuccessful.
He was enthusiastic about the idea of being able to extract ancient DNA from feathers.
"Often times feathers are found in caves and in some cases as residues on artefacts," he said.
But Loy was sceptical about using the method to extract ancient DNA from scales and was not convinced by the argument that keratin protected ancient DNA from contamination.
"People still don't fully understand how things get contaminated," he said.
Kennewick Man's Relatives?
A strand of hair from "Pendejo Cave"? This has got to be a dirty joke.
I recall watching the History Channel about 1 yr ago, and correct me if I'm wrong, but didn't researchers obtain some hair strands of Napoleon's? After testing the scientists found huge amounts of arsenic poisoning in the strands. The body can't be examined because of the French Govt. However, scientists believe that his body should be in good condition since arsenic preserves the body from decaying.
Some care needs to be taken with the New Scientist. The first person kidnapped in "The Ipcress File" was reading the New Scientist.
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