Bacteria lurking on human hands could apparently be used to identify criminals in future, rather than the conventional swirly fingerprints that we all have. So says a paper published online in the Proceedings of the National Academies of Science.

Biologist Noah Fierer from the University of Colorado at Boulder and his colleagues compared bacteria found on three individuals’ computer mice and keyboards (yuck!) and compared those bacteria to the bugs found on those people’s fingertips. Frierer says that these bacteria from the hands match the bacteria on the specific computer kit that those individuals owned better than on the other two people’s and could be used for identification in a forensic setting.

Fierer also did a test to work out whether the bacteria on an object are more similar to the bacteria found on the owner’s skin than to the bugs on the general population. This involved sequencing the bacteria found on 9 computer mice, and comparing the sequences to a database of bacteria from the hands of 270 individuals. In all 9 cases, the bacterial community on each mouse was significantly more similar to the bacteria on the owner’s hand than to other hands in the database.

So how does this help forensics? Well, it may not because the study has some limitations. First is the small sample sizes – as pointed out nicely by Ed Yong in his blog. Yong also questions the likelihood of this technique making it to the forensic bench, arguing that “forensics requires a far higher threshold of certainty than skin bacteria are likely to provide”.

Nevertheless, the thought of grubby hands and forensics has grabbed the interest of a number of reporters. Wired, NPR, The Beeb, LA Times.

But don’t expect to have your keyboard swabbed for bugs just yet. As Martin Blaser, chairman of medicine at New York University, told the LA Times, “this is not ready for prime time.”

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