A team of scientists from the U.S. and Argentina used a new technique to discover what killed three Peruvian mummies 500 years ago, according to IO9.com.

The group used a technique called shotgun proteomics to analyze proteins taken from the lips of the Andean Inca mummies, first splitting the proteins from the DNA and then running them through a high-resolution mass spectrometer, in order to glean insight into how their immune systems responded to bacteria.

In this case, the team says, at least one of the mummies died of a lung infection, based on an earlier CT scan and evidence of Mycobacterium sp.

"Existing methods, such as antibody-binding immunoassays, are ill suited for archeological applications because they require fresh tissues, use a small number of targeted antibodies, and are prone to both false positives and false negatives," they wrote in PLOS One, an online research journal. "Proteomics approaches can identify and quantify proteins directly."

They also said the proteomics technique offers three advantages over the more traditional practice of DNA microbe amplification: proteins outlast DNA by up to millions of years; protein detection is less likely than amplification to be derailed by contamination; and even a small sample of proteins can lead to a "more resolved picture" of immune system responses.

[Peruvian Mummy photo by swishphotos on Flickr, creative commons licensed]