Researchers have long puzzled over the identity of 430,000-year-old early humans whose bones and skulls (shown at left, with chimp and bonobo skulls on right) lay piled in the aptly named Pit of Bones in Spain. The fossils have some Neandertal characteristics, but DNA from their mitochondria, a cellular organelle, suggested that they were most closely related to another kind of early human, the Denisovans of Siberia, Russia. At a meeting last year, researchers reported the feat of extracting nuclear DNA from the Spanish bones, and announced that they were in fact Neandertals. Now, the team has published that conclusion in Nature, Science News reports, but the finding raises another puzzle: Why do the nuclear and mitochondrial DNA point to different kinship? Researchers hope for more genomic data from these and other very ancient fossils to find out.