BERLIN (AP) - Scientists say they've found the remains of an ancient female whose mother was a Neanderthal and whose father belonged to another extinct group of human relatives known as Denisovans.

Researchers reported Wednesday in Nature that DNA from a bone fragment found in a Siberian cave revealed the first direct offspring from a mix of these two groups. Past genetic studies have indicated that Neanderthals, Denisovans, and members of our own species occasionally mated and had children. This is the first to find an offspring of such a mixing.

Svante Paabo of Germany's Max Planck Institute for Evolutionary Anthropology says finding a first-generation child among the few remains of ancient human relatives discovered so far was surprising, but could suggest mixing between the two groups was more frequent than previously thought.