A group of German scientists have found the DNA of extinct humans — without finding any skeletal remains.

The researchers, who are currently excavating even dig sites in Belgium, Croatia, France, Russia and Spain, have found genetic remains of ancient humans like the Neanderthals and their cousins, the Denisovans, in sediment samples, the New York Times reports.

Ancient human DNA has been found in cave dirt in Croatia, but without any skeletal remains, scientists say.