Macaulay, V. A., Richards, Martin B., Forster, P., Bendall, K.E., Watson, E., Sykes, B.C. and Bandelt, Hans-Jurgen (1997) mtDNA mutation rates--no need to panic. American Journal of Human Genetics, 61. pp. 983-986. ISSN 1537-6605

Readers of the recent paper by Howell et al. (1996)
might be forgiven for thinking that, after all the controversy
surrounding the reconstruction of the original mitochondrial
gene trees (e.g., see Maddison 1991; Templeton
1993), the field was once again in difficulties
because of (a) a serious underestimation of the mutation
rate by a factor of almost nine and (b) the resulting
misdating of past divergences. We believe that such an
interpretation would be unduly pessimistic.