The famed Lascaux caves in France have been shuttered since 1963, when green algae and mosses began to cover the 15,000- to 17,000 year-old murals of bulls, horses, and other creatures. The deterioration was blamed on chemical reactions with visitors' breath. As a consolation, the government built a replica cavern nearby, which remains a top tourist draw. But the spread of fungus in the original cave hasn't stopped, thanks in part to global warming, researchers said at a recent meeting about the artwork. Ideas to fight the fungus include the use of biocides and an elaborate climate control system.

The world's earliest known oil paintings are found in a series of intact – albeit weather-beaten and looter-ravaged – caves in Afghanistan's Bamiyan Valley. Archaeologists dated the paintings to the mid-seventh century, which is several hundred years before the painting technique emerged in Europe. The murals depict Buddhas and mythical creatures and were made with what appear to be walnut and poppy-seed oils, scientists say. The site of the paintings is perhaps more infamously known as where the Taliban blew up two giant stone Buddha statues in 2001.

Painted walls and overhangs in South Africa are helping scholars piece together the millennia-long history of the San, a group of hunter-gatherers who became extinct after European colonization in the 19th century. More than 40,000 paintings in 500 rock shelters have been discovered. They depict animals such as the eland – a type of spiral-horned antelope – and hunters and are thought to represent religious beliefs of the San. Researchers hope that by firmly dating the paintings, they can see how the people changed over time.

The star symbol right of center in this rock carving may represent the fiery death of an ancient star in the year 1006. If so, it would be the first North American representation of a celestial event, previously known from astronomers' records in Asia, the Middle East, and Europe. The supernova of 1006 was likely as bright as the quarter moon, according to computer simulations. This piece of rock art was discovered in the White Tank Regional Park outside of Phoenix, Arizona.

The more than 10,000 carvings and paintings of bulls, sheep, hunters, the hunted, warriors and wildlife all etched and stroked onto the cliff walls along Utah's Nine Mile Canyon make up what is known as the world's longest art gallery. The rock art dates to between A.D. 700 and 1300 and archaeologists believe it is the creation of the Fremont people, who were the ancestors of modern-day Utes. But the rock isn't the only draw to the remote stretch of Utah: It's also rich in oil and gas. A rush to exploit the natural resources has raised concerns that dust kicked up by industrial truck traffic could harm the artwork.