Analysis of one million base pairs of Neanderthal DNA.

Neanderthals are the extinct hominid group most closely related to contemporary humans, so their genome offers a unique opportunity to identify genetic changes specific to anatomically fully modern humans. We have identified a 38,000-year-old Neanderthal fossil that is exceptionally free of contamination from modern human DNA. Direct high-throughput sequencing of a DNA extract from this fossil has thus far yielded over one million base pairs of hominoid nuclear DNA sequences. Comparison with the human and chimpanzee genomes reveals that modern human and Neanderthal DNA sequences diverged on average about 500,000 years ago. Existing technology and fossil resources are now sufficient to initiate a Neanderthal genome-sequencing effort.

Evidence for reproductive isolation between cave bear populations.

The European cave bear (Ursus spelaeus), which became extinct around 15,000 years ago, had several morphologically different forms. Most conspicuous of these were small Alpine cave bears found at elevations of 1,600 to 2,800 m. Whereas some paleontologists have considered these bears a distinct form, or even a distinct species, others have disputed this. By a combination of morphological and genetic methods, we have analyzed a population of small cave bears from Ramesch Cave (2,000 m altitude) and one of larger cave bears from Gamssulzen Cave (1,300 m), situated approximately 10 km apart in the Austrian Alps (Figure 1A). We find no evidence of mitochondrial gene flow between these caves during the 15,000 years when they were both occupied by cave bears, although mitochondrial DNA sequences identical to those from Gamssulzen Cave could be recovered from a site located about 200 km to the south in Croatia. We also find no evidence that the morphology of the bears in the two caves changed to become more similar over time. We suggest that the two cave bear forms may have represented two reproductively isolated subspecies or species.

No evidence of Neandertal mtDNA contribution to early modern humans.

The retrieval of mitochondrial DNA (mtDNA) sequences from four Neandertal fossils from Germany, Russia, and Croatia has demonstrated that these individuals carried closely related mtDNAs that are not found among current humans. However, these results do not definitively resolve the question of a possible Neandertal contribution to the gene pool of modern humans since such a contribution might have been erased by genetic drift or by the continuous influx of modern human DNA into the Neandertal gene pool. A further concern is that if some Neandertals carried mtDNA sequences similar to contemporaneous humans, such sequences may be erroneously regarded as modern contaminations when retrieved from fossils. Here we address these issues by the analysis of 24 Neandertal and 40 early modern human remains. The biomolecular preservation of four Neandertals and of five early modern humans was good enough to suggest the preservation of DNA. All four Neandertals yielded mtDNA sequences similar to those previously determined from Neandertal individuals, whereas none of the five early modern humans contained such mtDNA sequences. In combination with current mtDNA data, this excludes any large genetic contribution by Neandertals to early modern humans, but does not rule out the possibility of a smaller contribution.

New discoveries and interpretations of hominid fossils and artifacts from Vindija Cave, Croatia.

Beginning with excavations during the 1970s, Vindija Cave (Croatia) has yielded significant Middle and Upper Paleolithic fossil and archaeological finds. We report on seven recently identified hominid fossils, a newly associated partial hominid cranial vault from level G(3), nine possible bone retouchers, and a revised interpretation of the Mousterian artifact assemblage from the site. This new information reinforces our knowledge of the complex biocultural phenomena revealed in unit G and earlier deposits at Vindija. Six of the new hominid fossils derive from stratigraphic units G and I, while one lacks exact provenience. All specimens preserving diagnostic anatomy are from Neandertals. One of the postcranial remains, a radius fragment which exhibits Neandertal-like anatomy, comes from level G(1)and is congruent with the previously established association of Neandertals with an early Upper Paleolithic industry at the site. The partial cranial vault represents the most complete Neandertal from Vindija. The possible retouchers derive from unit G. Our analysis of these artifacts suggests that both percussion and pressure techniques may have been used by Neandertals in the final stage of tool production (retouching). This paper also presents a revision of the artifact analysis for late Mousterian level G(3). We separated raw materials into two main groups due to the differing ways that the materials fracture and the differing morphology of the debitage. The use of raw material in level G(3)is different from earlier Middle Paleolithic levels at Vindija. This indicates that the G(3)late Neandertals were making choices regarding source material somewhat more like the Upper Paleolithic people at the site. When interpreted within a larger regional framework, the Vindija archaeological and hominid fossil remains demonstrate a complex, mosaic pattern of biocultural change in the Late Pleistocene of south-central Europe.

Ancient DNA analyses reveal high mitochondrial DNA sequence diversity and parallel morphological evolution of late pleistocene cave bears.

Cave bears (Ursus spelaeus) existed in Europe and western Asia until the end of the last glaciation some 10,000 years ago. To investigate the genetic diversity, population history, and relationship among different cave bear populations, we have determined mitochondrial DNA sequences from 12 cave bears that range in age from about 26,500 to at least 49,000 years and originate from nine caves. The samples include one individual from the type specimen population, as well as two small-sized high-Alpine bears. The results show that about 49,000 years ago, the mtDNA diversity among cave bears was about 1.8-fold lower than the current species-wide diversity of brown bears (Ursus arctos). However, the current brown bear mtDNA gene pool consists of three clades, and cave bear mtDNA diversity is similar to the diversity observed within each of these clades. The results also show that geographically separated populations of the high-Alpine cave bear form were polyphyletic with respect to their mtDNA. This suggests that small size may have been an ancestral trait in cave bears and that large size evolved at least twice independently.