Higher rates of amino acid substitution in rodents than in humans.

An analysis of 54 protein sequences from humans and rodents (mice or rats), with the chicken as an outgroup, indicates that, from the common ancestor of primates and rodents, 35 of the proteins have evolved faster in the lineage to mouse or rat (rodent lineage) whereas only 12 proteins have evolved faster in the lineage to humans (human lineage). The average rate of amino acid substitution is significantly faster in the rodent lineage than in the human lineage. In addition, the average rate of insertion/deletion is also faster in rodents than in humans and there is a positive correlation between the rate of amino acid substitution and the rate of insertion/deletion in a protein sequence.