Humans may also be uniquely identified by hair: study

Proteins in human hair could be as effective as DNA profiling in identifying unique individuals, researchers from the U.S. Lawrence Livermore National Laboratory have found.

Currently, DNA profiling is commonly used for identification in forensic science and archaeology because DNA is unique to each individual.

However, environmental and chemical processes can degrade DNA, limiting its usefulness over time, the researchers reported this week in the U.S. journal PLOS ONE.

In contrast, protein is more stable than DNA and has variations that may be unique to the individual, they said.

In the new study, Brad Hart from the Lawrence Livermore National Laboratory and colleagues found a total of 185 hair protein markers in an examination of male and female hair samples from 66 European-Americans, five African Americans, five Kenyans and six skeletal remains from the 1750s and 1850s.

The number and pattern of each person's hair protein markers, they said, were unique. Although the number of individual protein markers that can be used to differentiate people could go as high as 1,000, they estimated the 185 protein markers would be sufficient to distinguish one person out of a population of one million.

The researchers also predicted that once their technique is optimized, it will be possible to use a small number of human hairs, possibly as little as one, to distinguish an individual among the world's population.

The new identification technique using protein may offer another tool to law enforcement authorities for crime scene investigations and to archaeologists.

"We are in a very similar place with protein-based identification to where DNA profiling was during the early days of its development," said study co-author Brad Hart, director of the lab's Forensic Science Center.

"This method will be a game-changer for forensics, and while we've made a lot of progress toward proving it, there are steps to go before this new technique will be able to reach its full potential."

Currently, the sample preparation, instrument run time and analysis period for the protein identification method requires about 2.5 days, study co-author Deon Anex, a chemist at the lab, said, noting the team expects the cost to be competitive with other similar technologies.

"The discovery phase has been quite complex, but once the technique is established, we believe it can be made into a routine procedure for use in crime labs," Anex said.