By Richard Kemeny/SmithsonianMag.com
Deep in the forests of northwestern Jamaica, a secluded cave has sheltered an unabridged account of the environment since the early Bronze Age. The cave’s inhabitants live in near-total darkness, swarming out to feed at night through a mist of their own urine and retreating back inside to roost. The colony of five thousand or so bats then add to the archived climate record much as their ancestors did before them: by swooping down from the walls and defecating on the cave floor.
“People might think of guano as just a big pile of crap,” says Jules Blais, an environmental toxicologist from the University of Ottawa. But buried in that pile are the secrets of the past.
Guano, a sticky brown paste and a staple in many tropical caves, is a festering compilation of a colony’s droppings, remnants of nearby plants, fruits and insects, as well as the odd fallen bat. Guano piles can reveal exactly what the bats were eating as well as details about the environment the bats were exposed to. Conditions in the soil, water and atmosphere are consumed, processed and left—via the bats’ digestive system—in accumulating layers on the floor, like pages in an …..