Biology: Saving the Cave Paintings

For more than 16,000 years, the prehistoric paintings in France’s famed Lascaux Cave survived in splendid isolation. Then, after the discovery of the cave by four French schoolboys in 1940, man returned to the scene. He brought with him a mysterious blight that threatened to obliterate in a few short years the magnificent red cows, free-floating horses and other majestic creatures drawn so long ago on the cavern walls by talented Cro-Magnon artists. Now the archaeological crisis has apparently passed. French scientists have successfully diagnosed the illness of the ancient art gallery and prescribed a modern cure.

Almost from the day that the cave was unsealed and opened to outside air, light and visitors, archaeologists have been concerned about the effects of this exposure. By the 1950s, when as many as 125,000 people were visiting the site annually, the French had installed an elaborate air-conditioning system in an attempt to restore the original conditions of humidity, temperature and carbon-dioxide concentration in the cave. Nonetheless, the precautions failed.

Sistine Chapel. In 1960, a patch of green moldlike substance was discovered in a section called the Hall of Bulls (named for the lO-ft.-high creatures on its walls). The patch spread rapidly, and similar growths began to crop up elsewhere. This mysterious maladie verte so distressed French Cultural Affairs Minister André Malraux, an amateur archaeologist himself, that he appointed a commission of archaeologists, speleologists and other savants to save France’s “prehistoric Sistine Chapel.”

The commission immediately restored complete darkness and isolation for a recuperative period of three months. Instead of diminishing, however, the splotches only spread more rapidly. The French Government became so alarmed that in 1963 it closed off the cave to all but its own investigators. Preparing for the worst, it also ordered the national shrine photographed, so that the irreplaceable Paleolithic paintings would at least be preserved on film.

Two French biologists refused to panic. Taking samples of the splotchy growth back to their lab near Paris, Biologists Marcel Lefevre and Guy Laporte found that they were teeming with microorganisms. Yet only one was multiplying massively enough to produce the ugly green discoloration on the cave walls. The culprit, the scientists report in the British journal Studies in Speleology, was a hardy, spherical alga called Palmellococcus.

The microscopic plant probably flourished in the cave in prehistoric times, but reappeared only when man brought it back with him in the mud and dirt of his shoes. Palmellococcus’ life was made all the more comfortable when man installed artificial lights in the cave, circulated the air with huge blowers and, most important of all, introduced a host of algal nutrients.

Like other algae, Palmellococcus thrives on light, moisture, mineral salts and carbon dioxide. Yet when it can feed on such organic substances as sweat, pollen and bacteria—which were also brought into the grotto—it will multiply well even in dim light. If enough of these nutrients are present, it can survive without any light at all. In fact, it was this steady buildup of organic matter, Lefevre and Laporte say, that enabled Palmellococcus to proliferate even when the cave was shut down and left in total darkness.

To reduce the algae’s bacterial food supply, the scientists fumigated the grotto with an aerosol of powerful antibiotics (penicillin, streptomycin and kanamycin). Next, they tackled Palmellococcus itself. They found that a spray of formaldehyde mixed with detergent not only killed the algae—which gradually lost their color—but had no ill effect on the paintings themselves.

Maladie verte’s rout has been so successful that scientists and other selected visitors are now again being allowed into the cave to study the paintings. If adequate protection against new contamination can be devised, Lefevre and Laporte hope that the public also may some day again be allowed to see the remarkable artistry of Cro-Magnon man.