Rickety old ship

PITY the poor sailors of the Mary Rose. In 1545, the lives of more than 400 men (and one dog) were lost when Henry VIII's flagship took on water and sank between the Isle of Wight and the English mainland. There it, and the remains of at least 179 sailors, rested for more than four centuries. What was left of the ship was raised in 1982, and the remains became the spoils of the Mary Rose Museum in Portsmouth. As if that were not ignominy enough, now people are shooting lasers at the sailors' bones.

It is all in the name of science, of course. The heavily silted conditions of the seabed protected a significant portion of the ship and its contents from the ravages of the sea. An astonishing array of objects was beautifully preserved; visitors to the museum can even sniff 16th-century rope. But the human remains amounted to scattered piles of bones (and the canine remnants, too; it took until November 2014 to discover that the ship's dog Hatch was a he, not a she). Archaeologists of the Mary Rose Trust cannot even match the bones to come up with a solid figure of just how many people were left on the wreck.

That looks set to change. Alex Hildred, a researcher at the Mary Rose Trust who was part of the 1982 recovery mission, recently ran into Allen Goodship, of University College London's (UCL) Institute of Orthopaedics and Musculoskeletal Science, at a conference. Dr Goodship's team had been testing a technique called Raman spectroscopy as a means to diagnose bone conditions.

Raman spectroscopy, named after the Indian physicist who won the 1930 Nobel prize for inventing it, is an incredible tool for chemical sleuthing. When a laser beam is shone on a sample, much of its light is simply scattered and reflected unchanged. But a tiny fraction of the light's energy is absorbed by the sample's constituent molecules, making them vibrate at characteristic frequencies. As a result, the tiny colour shift in a fraction of the beam is a fantastically precise measure of the molecules it has encountered.

Along with colleagues at the Royal National Orthopaedic Hospital, Dr Goodship and his team had shown successes diagnosing genetic bone disease with the technique in living patients (using a colour of light that passes through flesh but bounces off of bone). That gave Dr Hildred an idea. She had been looking for a means of examining the sailors' bony remains nondestructively; precise tests such as studies of DNA require drilling into or chipping off bits of bone, and they do not always succeed. But Raman spectroscopy does its work without so much as touching its subject.

Dr Hildred provided two sets of five tibias—shin-bones—to the team: one set that appeared normal and healthy (at least at the time of the ship's sinking), and one that showed curvature characteristic of rickets, a once-prevalent disease attributed to malnutrition. Jemma Kerns, of UCL, led a project comparing them to fresh bone from cadavers. Raman tests showed that the evidently healthy bones from the Mary Rose are, from a chemical standpoint, just like those of a healthy person today. Moreover, as the team reports in the Jounal of Archaeological Science, the bones showing evidence of rickets looked chemically different from healthy ones, providing the researchers with a kind of fingerprint for the disease.

That opens up an enormous line of enquiry. The idea that these chemical clues are preserved in archaeological bone suggests that all manner of conditions might be diagnosed, perhaps even some that do not affect the bones' appearance and manifest only chemically. Dr Kerns has already shown, for example, that chemical differences in bone are indicators of degenerative joint disease as well. The collaboration is in discussions about just which conditions it will try to diagnose next.

The technique will also pay dividends for the living, as some conditions might give themselves away in bone chemistry before they can be diagnosed by more conventional means. And it could finally provide a means definitively to match the Mary Rose bones to their rightful owners and come up with a conclusive number of sailors who went down with the ship.