Not just old but old and cold?

The successful retrieval of ancient DNA from two geographically dispersed Neanderthal skeletons1,2 has fuelled a demand for more Neanderthal DNA sequences for analysis. However, these exceptionally well-preserved specimens were geologically young and the mean annual temperature of their cave sites low, so the survival of this ancient DNA could have been due to unusually favourable conditions. Here we calculate the thermal history of a range of Holocene and Pleistocene bones whose DNA quality has been tested and find that in only very few sites with Neanderthal remains is the preservation of DNA likely to match the quality of that from the skeleton found at Mezmaiskaya Cave2. We recommend that any additional Neanderthal destined for destructive analysis should be carefully selected, taking into account its integrated thermal history.