Figure 1

Taxonomic classification of Homo sapiens lineage. Each central box represents a major node representing a distinct group of species. In each box (other than cellular organism), letter notation for that node is given in square bracket. Each side box (other than archaea and bacteria) was derived by subtracting the sequences from the next higher node from those in the previous lower node. The number of human domains originated at archaea, bacteria and eukaryotic nodes are given in parenthesis. For archaea and bacteria, the number of domains with their remote homologs found both in archaea and bacteria (archaea+bacteria subnode) is 13,052, found only in archaea not in bacteria (archaea_only subnode) is 1,021 and found only in bacteria not in archaea (bacteria_only subnode) is 15,294 (see Methods).