Nature 417, 432–436 (2002).

Figure 4b of this Letter included a sequence (Thailand-2 AJ319571), which we now realise is highly likely to be a chimaera between sequences Thailand-6 (AJ319575) and Thailand-7 (AJ319576), also shown in the phylogenetic tree. The chimaeric sequence is one out of twenty-three halite sequences shown in Fig. 4b, and did not occupy a pivotal position in the discussion; its inclusion in the phylogenetic tree therefore does not affect our general conclusions. The chimaeric sequence has now been removed from the databases. We are grateful to E. Willerslev and A. Cooper for bringing this to our attention.