Vawter, Lisa and Brown, Wesley M., +quot;Nuclear and Mitochondrial DNA Comparisons Reveal

Vawter, Lisa and Brown, Wesley M., "Nuclear and Mitochondrial DNA
Comparisons Reveal Extreme Rate Variation in the Molecular Clock" Science 
234:194-196, 10 Oct. 1986.

     In a recent issue of Origins Research (8:2) we suggested that it was 
time to set back the molecular clock.  This research article goes one step 
further and suggests that we throw the "molecular clock" out altogether.  
From the abstract:

[The] disparity in relative rates of mitochondrial and nuclear DNA
divergence suggests that the controls and constraints under which the
mitochondrial and nuclear genomes operate are evolving independently, and
provides evidence that is independent of fossil dating for a robust
rejection of a generalized molecular clock hypothesis of DNA evolution.
(emphasis added)