By Declan Butler
Lascaux, a cave in southwestern France that holds a dazzling gallery of ice-age paintings, is under siege again. Recent blunders in conservation efforts at the cave have altered its microclimate, and its paintings are again threatened by fungi. But with this month marking the 70th anniversary of the cave's discovery, scientists are hoping that a newly independent scientific board and fresh management will bring a more robust, research-based approach to conserving the fragile, 18,000-year-old rock art.
Conservation problems have a long history at Lascaux, which was closed to the public in 1963 after green algae grew on the walls. Following treatment with formalin and antibiotics and the installation of a special ventilation system, it enjoyed four decades without major problems. But in 2000, the entrance to the cave was widened and its roof demolished to install a larger ventilation system. This, and heavy rains during the work, allowed water to enter the cave, precipitating a crisis when a white fungus, Fusarium solani, proliferated on the walls and paintings.
The fungus was quickly controlled. But the cave's microclimate was radically altered by the infiltration of water, by the drastic counter measures--including the application of quicklime to the cave floor--and by the new ventilation system, which upset the natural airflow. In 2007, the cave faced a new invader, a black fungus. These mistakes underscored the need for a more multidisciplinary approach, as any intervention can have collateral impacts on microbial, hydrological and other aspects of the cave, says Muriel Mauriac, an art historian and conservation expert who was appointed curator of Lascaux in April last year.
In 2008, concerns about the state of the cave prompted the United Nations Educational, Scientific and Cultural Organization (UNESCO) to threaten to place Lascaux--a UNESCO World Heritage site--on its World Heritage in Danger list. It was "a warning shot across the bows," says Mauriac. In February, France's culture ministry replaced the existing international scientific committee--which was peppered with government officials, including Lascaux management--with a smaller one made up exclusively of scientists. Giving the committee greater scope to offer independent scientific advice was one of UNESCO's key demands.
Michel Goldberg, a biologist at the Pasteur Institute in Paris and a fierce critic of recent conservation efforts at Lascaux, says he's generally pleased that the new board contains many more researchers from the hard sciences and fewer from the art world, although he bemoans its lack of experts in key areas such as subterranean climate or mycology. Also positive, he says, is that Mauriac seems to be postponing new work until the incoming board has had its say. "The current administration seems much more careful and less interventionist," he notes.
But board member Robert Koestler, director of the Smithsonian Institution's Museum Conservation Institute in Suitland, Md., complains that his repeated requests for access to existing research data on the cave, and to be able to invite outside experts, have been met with stonewalling. "All we get are reports and presentations on the ecology, hydrology and three-dimensional modelling of the climatology of the cave," says Koestler. "But we don't have the data."
Yves Coppens, a palaeoanthropologist at the Collège de France in Paris who chairs the board, assured Nature that members' requests for outside experts and data will be fulfilled in coming meetings. (Scientific American is part of Nature Publishing Group.) The initial meetings were intended to be introductory, he says.
The immediate problem the board must tackle is the black fungus. Few areas of the paintings have been affected so far, according to Mauriac, who adds that the fungus currently seems to be stable in some parts of the cave and receding in others. But it could ultimately do more damage than previous infestations, because it stains the walls with melanin, and the stains remain even if the fungi are killed.
Researchers have yet to identify the fungus, with two laboratories putting forward different candidates, one a Ulocladium species and the other Scolecobasidium. Nor have they decided on the best way to kill it, although fungal enzymes that attack black fungi are a potential solution. Tackling the melanin stains on the rock art will also be difficult, as aggressive treatments are ruled out.
The broader challenge, say scientists, will be to understand the workings of the cave well enough to stabilize its subterranean environment and stave off any future microbial attacks.