r 2 can vary from 0 to 1, and represents the percent of the data, which is the closest to the line of best fit. The larger the coefficient of determination of two vectors is, the more similar are the protein sequences. In Tables 2 and 3, we give the similarity/dissimilarity matrices for the eight ND6 sequences based on Euclidean distance and coefficient of determination amongst nine-component vectors. As shown in Tables 2 and 3, it is obvious that ND6 proteins of human, gorilla, and chimpanzee are more similar to each other. In addition, ND6 proteins are more similar for (G. seal, H. seal) and (mouse, rat). However, ND6 protein of wallaroo is very dissimilar to others amongst the eight species. The results are consistent with the known fact of evolution (Yao et al., 2009) .