Using DNA sequencing on ancient pack rat nests made of plants, insects, bones, fecal matter and urine could give us a look into Earth's past, according to research published Thursday in the journal Ecology and Evolution.

Pack rats are nocturnal rodents that use plant materials to build nests in dry caves.

Because pack rats have a limited foraging range, their middens are made up of contents representative of the local environment at the time the materials were collected.

"Midden contents are so well preserved that fragments of ancient DNA can be extracted and analyzed across millennia," Rob Harbert, an assistant professor at Stonehill College, said in the statement.

Scientists focused on a sequencing technique for comparing DNA, called shotgun, that randomly chooses DNA fragments to sequence