New details of our past are coming to light, hiding in the nooks and crannies of the world, as we refine our techniques to go looking for them. Most lauded is the reconstruction of the evolution of humanity since our African origins around 300,000 years ago, by analysing our living and fossil DNA. Replete with the ghosts of African and Eurasian populations of the deep past, these have been resurrected only through the ability of science to reach into the world of the minuscule by studying biomolecules.
Now, digital analysis of rock surfaces reveals how other ghosts of the deep past - this time from almost 2,000 years ago in North America - have been coaxed into the light. Writing in the journal Antiquity, Professor Jan Simek of the University of Tennessee and colleagues have published images of giant glyphs carved into the mud surface of the low ceiling of a cave in Alabama.
