In 1790, German scholar Georg Christoph Lichtenberg was puzzled; eighty years later so was Charles Darwin, both wondering if people blush in the dark.  Because blushing is a social response to shame or embarrassment they, and many experts, thought it might not happen when no-one can see your face.  But now German and Dutch scientists have used a thermal imaging camera in pitch darkness to measure the heat in a subject’s face on hearing an embarrassing story.  They concluded we DO blush in the dark and their report was published in the Annals of Improbable Research.  Sylvia Mountford.