ABSTRACT
Until as recently as the 1960s, it was widely supposed that the common ancestor of humans and our closest relative, the chimpanzee, dated from some 20 or 30 million years ago. This seemed to allow plenty of time for the apparent physical and mental differences between our two species to have evolved. Over the last 30 years, however, the analysis of molecular data, beginning with the work of Sarich and Wilson (1967) comparing the albumens of living primate species, has forced a reappraisal of our similarities to other apes and of the dates of divergence between the different species. Comparisons of DNA sequences have confirmed the major conclusions of this earlier work, showing that humans are much closer to the chimpanzee than was previously suspected. The modern consensus is that the hominid and chimpanzee clades diverged only 5 or 6 million years ago (Cann, 1987; Waddell & Penny, 1996), and by one estimate the chimpanzee has about 99.6% of its amino acid sequences and 98.4% of its DNA nucleotide sequences in common with our own species (Goodman, 1992).
