The ancestors of humans and other primates like apes and monkeys may have originated in Asia, not Africa, a new study in the journal Nature reports.

There has long been debate about the matter, but a recent discovery of anthropoid fossils including two previously unidentified species and one known species provides new clues.

The fossils are about 38 million years old and were uncovered in a rock formation in southern Libya. The anthropoids were small, rodent-size creatures that looked similar to larger, modern-day primates, but weighed just 4 to 17 ounces.

“At least one of these anthropoids appears to be clearly related to the older Asian form described in Myanmar,” said Jean-Jacques Jaeger, a paleontologist at the University of Poitiers in France and the study’s lead author. “This indicates that there was migration from Asia.”