A painting that is alive! A particular type of rock art called the 'Bradshaw art' has maintained its color in spite of years of exposure to extreme weather conditions.
Researchers have found that the paintings have maintained their vivid colors even though they have never been repainted due to the replacement of the original paint with a bio-film of living, pigmented micro-organisms.
The researchers involved in the study include Jack Pettigrew, University of Queensland, Australia; Chloe Callistemon from Brisbane; Astrid Weiler from Germany; Anna Gorbushina, Institut für Geologische Wissenschaften, Germany; Wolfgang Krumbein, H. Steinitz Marine Biology Laboratory, Israel and Reto Weiler, Univerisity of Oldenburg, Germany.
The researchers made a survey of 80 figures from 16 different locations within Australia's Kimberley region. The team reported that bio-films, which are regarded as a major cause of deterioration of Australian rock art, are working in just the opposite manner for the 'Bradshaw art'.
The tolerance of the bio-film organisms to extremes of weather, radiation and osmotic pressure have led to the indefinite survival and replenishment of the paintings.
A study of samples from the rock art exhibited a collection of a great variety of microbes. Among the frequent inhabitants was a black-pigment, thought to belong to the Chaetothyriales fungi group. Another reddish pigment, suspected to be a species of Cyanobacteria, was found along with the black pigment.
When the black fungi had a major presence, the overall color of the paintings was mulberry while, if the red 'cyanobacteria' dominated a particular painting, the overall color was a well-recognized 'cherry' (or 'terracotta') shade.
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