The limestone cave of Liang Bua, on the Indonesian island of Flores, is widely known as the hobbit cave, the site where the surprisingly tiny and enormously controversial extinct human relative Homo floresiensis was discovered. But to the scientists who excavate there, the site is known as something else entirely: the rat cave.

“The first time I went to the excavations at Liang Bua, I remember watching the bones coming out of the ground and being amazed at how it was almost all rat,” recalls Matthew Tocheri, the Canada Research Chair in Human Origins at Lakehead University.

Now, Tocheri and an international team of scientists have examined the rat bones and found evidence for major shifts in their past populations—including