Tuesday, January 25, 2011
Jack Pettigrew of the University of Queensland and his research team may have discovered why vibrant rock paintings from the Bradshaw rock artworks in western Australia's Kimberly region have not lost their visual intensity in the 40,000-70,000 years since they were painted. According to a a new study published in the journal Antiquity, the paint is long gone; the figures of humans and megafauna depicted are colored by a biofilm of microbes that are direct descendants of microbes that infected the original paint. The microbes in question are predominantly a black fungi, Chaetothyriales, which replicates by cannibilizing its predecessors, and a reddish organism that seems to be a cyanobacteria. Cyanobacteria obtain energy through photosynthesis. Pettigrew speculates that both the fungi and bacteria were in the original paint in the Bradshaws, and that over tens of thousands of years the fungi has provided water to the bacteria and the bacteria in turn has given carbohydrates to the fungi.