Pack rats, aka woodrats, build their nests, called middens, from plant debris, rocks, animal parts, paper, and almost any other bits of detritus nearby. Frequently, they urinate on their middens. The urine crystalizes and encases the nest material, preserving it for as long as 50,000 years by some estimates. For paleobotanists, middens are a great source of information about how flora has changed over time. Zoologists study the animal remains and poop. And climatologists analyze the material for insight into past climates, even the most recent ice age that ended more than 11,000 years ago. In Smithsonian, Sadie Witkowski digs into the topic, including a story about what historians learned excavating rats' nests in the walls of the 1808 Charleston, South Carolina home of slave trader Nathaniel Russel:
Among the mass of organic matter, they found sewing pins, buttons, marbles, part of a uniform waistcoat, and even fragments of printed paper that could be dated to November 1833. The paper was darkened and curled but still legible once it was gently opened.
"It was protected from rain and moisture, and even though it's sooty, it didn't burn," (University of Delaware art conservator Susan) Buck says. "So we just have all these fragile materials that normally wouldn't survive." Among the material, the team recovered scraps of an early writing primer, suggesting some of the enslaved workers living in the kitchen house has been learning to read and write.
To move beyond the written record, historians and conservators have looked for new clues in unlikely places. Common rats that surely plagued the occupants of the kitchen house on Nathaniel Russell's estate have left behind an invaluable cache of items that reveal new details about the lives of people who are too frequently absent in the historical record.
"When you open up a rat's nest, it's completely unexpected. You just can't be prepared for it," (architectural preservation researcher Rucha) Kamath says. "Sometimes you come across nothing; sometimes you come across a whole treasure chest."
More: How Can Little Critters Teach Us About Climate? (NOAA/National Centers for Environmental Information)