In February 2002, a speleological team exploring the karstic system of Miniş Valley, in the south-western Carpathian Mountains near Anina, revealed a previously unknown chamber with a profusion of mammalian skeletal remains. The cave, which seemed to have served primarily as hibernation room for the Late Pleistocene cave bear (Ursus spelaeus), presented unusual arrangements such as the placement of some remains on raised rocks, suggesting a certain human involvement in the accumulated deposits. In fact, speleologists Ştefan Milota, Adrian Bîlgăr and Laurenţiu Sarcina discovered a complete human mandible on the paleosurface. The karstic chamber was designated as "Peştera cu Oase" (The Cave with Bones) and the human mandible as "Oase 1".
Two laboratories independently yielded radiocarbon dates of about 35,000 BC years, or about 40,500 years in calibrated, calendar years for the inferior jaw. Congruent discrete traits and overall proportions of the fossil “Oase 1” revealed specific modern human attributes, placing it close to European early modern humans among Late Pleistocene samples. The fossil belongs to the few findings in Europe which could be directly dated and is considered the oldest known early modern human fossil from Europe. From a location close to the Iron Gates in the Danubian corridor, it may represent one of the earliest modern human populations to have entered Europe.
Against this background, particularly noteworthy is the fact that "Oase 1" exhibits morphological traits combining a variety of archaic Homo, derived early modern human, and possibly Neanderthal features.
In June 2003 a further research team discovered additional human remains on the cave's surface. Thus, an entire anterior cranial skeleton was found along with a largely complete left temporal bone and a number of frontal, parietal and occipital bone segments.
While "Oase 1" inferior jaw is fully mature, the facial skeleton is that of a mid-second decade adolescent, therefore corresponding to a second individual, designated as "Oase 2". Further analyses have revealed that the left temporal bone represents a third individual, assessed as adolescent versus mature female, designated as "Oase 3". However additional finds and work have shown that the temporal bone derives from the same cranium as the "Oase 2" facial en parietal bones. The lack of archaeological signs such as torches, charcoal or tools could suggest that the human remains may have washed in the cave through fissures.
The "Oase 2" and "Oase 3" confirm a pattern already known from the probably contemporaneous "Oase 1" mandible, indicating a mixture of archaic, early modern human and Neanderthal morphological features. Thus, the specimens exhibit a suite of derived "modern human" features like projecting chin, no brow ridge, a high and rounded brain case. Yet, these features are associated with several archaic aspects of the cranium and dentition that place them outside the range of variation for modern humans, like a large face, a large crest of bone behind the ear and big teeth that get even larger toward the back. This mosaic of Neanderthal and modern human reminds similar traits found in a 25,000 years old fossil of a child in Abrigo do Lagar Velho or in the 31,000 years old site of Mladeč.
Peştera cu Oase is subject to ongoing investigation. The on-site findings from the 2005 campaign are currently cross-examined at the Romanian "Emil Racoviţă" Institute of Speleology, Australian National University, (electron spin resonance and uranium-series dating on 21 bone/tooth samples and 29 associated sediment samples), University of Bristol, (uranium-series analysis on 22 bone samples), University of Bergen, (uranium-series dating on 7 samples), University of Oxford (AMS radiocarbon dating on 8 bone/tooth samples), Max Planck Institute (stable isotope analysis and ancient DNA on 37 bone/tooth samples), University of Vienna (AMS radiocarbon dating on 25 bone/tooth samples).
A skull found in Peştera cu Oase in 2004/5 bears features of both modern humans and Neanderthals. According to a paper by Erik Trinkaus and others, published in the Proceedings of the National Academy of Sciences in January, 2007, this finding suggests that the two groups interbred thousands of years ago. Radiocarbon dating indicates that the skull is between 35,000 and 40,000 years old, making it the oldest modern human fossil ever found in Europe.