Authors' abstract: DNA was extracted from the Neanderthal-type specimen found in 1856 in western Germany. By sequencing clones from short overlapping PCR products, a hitherto unknown mitochondrial (mt) DNA sequence was determined. Multiple controls indicate that this sequence is endogenous to the fossil. Sequence comparisons with human mtDNA sequences, as well as phylogenetic analyses, show that the Neanderthal sequence falls outside the variation of modern humans. Furthermore, the age of the common ancestor of the Neanderthal and modern human mtDNAs is estimated to be  [around 600,000 years, or] four times greater than that of the common ancestor of human mtDNAs . This suggests that Neanderthals went extinct without contributing mtDNA to modern humans.