Biology: Saving the Cave Paintings

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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.