The sequences of proteins and DNA have become increasingly important in phylogenetic inference

The first protein to have its amino acid sequence worked out was insulin, which was sequenced by Sanger in 1954. Protein sequencing became an automated process through the 1960s, and the sequences of some proteins, such as hemoglobin, became available in enough species for large-scale phylogenies to be inferred.

DNA sequences followed on, about 20 years later. It was Sanger again who sequenced the first decent sized sequence of DNA, in this case the whole genome (containing 5375 bases) of the bacteriophage X174, in 1977. DNA sequencing since then has expanded, almost explosively, and most current molecular phylogenetic work is concerned with DNA sequences.