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TINY traces of organic dyes might be the best indicator of whether there was
once life on Mars. Pigments similar to the green chlorophyll of Earth plants
could still be hanging around on the Red Planet. Such chemicals can last
billions of years and would be a definitive sign that life thrived on the
planet, microbiologist David Wynn-Williams of the British Antarctic Survey told
a recent meeting of the Royal Society of Chemists in Birmingham.