Linnaeus created his model during the eighteenth century, which proved useful for scientific knowledge at that time. However, recent discoveries of archaebacteria in deep-ocean thermal vents, hot springs in Yellowstone, and brine marine environments justified another look at the five-kingdom model. Analysis of archaebacteria indicates that they are more similar to eukaryotes than their bacterial prokaryotic cousinsThe six-kingdom model contains the same original four kingdoms, but splits the Moneran kingdom into kingdom Archaea bacteria to include the newly discovered bacteria type with internal membranes, and kingdom Eubacteria, which contains the more common forms of bacteria. Interestingly, cladistic analysis indicates that organisms in the kingdom Protista are actually more different from each other than originally suspected. In fact, most mammals are more closely related to certain archaebacteria than some protists are related to each other