Recently, Dr. S. PÞÞbo of Munich determined a mitochondrial DNA sequence from the Neandertal type specimen, and it was independently confirmed in our laboratory. Sequence analysis indicates that it is unlikely that Neandertals contributed mtDNA to contemporary human populations; however, this conclusion rests on this single sequence. A more definitive demonstration requires an assessment of the range of mtDNA variation in Neandertals. Such analyses require the successful retrieval of authentic DNA from additional Neandertal remains. The objective of this research is, therefore, to provide a thorough assessment of the prospects for retrieval of DNA from at least 10 additional Neandertal remains. This will be accomplished by analyzing a number of remains by a two-step procedure. First, a small quantity of bone powder will be analyzed for amino acid racemization, which has been shown to be a reasonable proxy for DNA. Second, for those specimens for which the degree of racemization is low enough to suggest DNA might survive in sufficient quantity and quality for analysis, DNA will be extracted and primers specific for the previously-determined Neandertal mtDNA sequence will be used in PCR amplifications. All amplification reactions which yield a PCR product of the expected size, and for which amplification and extraction controls are suitably negative, will be cloned and the sequence of at least 10 clones determined. Similar work will be carried out in parallel by Dr. PÞÞbo's laboratory in Munich. Specimens that yield a Neandertal-like sequence (as judged by comparison with the sequence obtained from the Neandertal type specimen), and which are replicated in both laboratories, will be judged as yielding reliable and authentic Neandertal DNA. These specimens would then be the subject of future analysis to determine additional mtDNA sequence information. The use of Neandertal-specific primers, which is only now possible, means that a lack of success cannot be attributed to the inadvertent use of primers that select against any authentic Neandertal DNA. Hence, specimens that do not yield Neandertal-like sequences can be truly said to lack sufficient DNA for analysis. In this way, the goal of this work, namely a robust assessment of the likelihood of obtaining additional authentic Neandertal mtDNA sequences, will be achieved.
