New Interpretations of Phylogenetic Tree

The origin of life are frequently studied by using phylogenetic tree. One of the reason is because it might be possible to know some properties of the last universal common ancestor (LUCA), which emerged on the primitive Earth. However, it would be impossible to know the properties of LUCA in detail, because the properties should be strongly affected by those of modern organisms, which were used in the phylogenetic tree analysis. Therefore, it must be careful about that there are large defects in the phylogenetic tree analysis. In this article, it is shown that such weak points of phylogenetic tree analysis, which is carried out according to a top-down approach, could be complemented by [GADV]-protein world hypothesis (GADV hypothesis), under which evolutionary processes from chemical evolution to the emergence of life could be reasonably presumed from a standpoint of bottom-up approach. Consequently, it was found that previous interpretations are wrong in some respects. For example, (1) order of appearance of the three biological domains was previously assumed as archaea and bacteria or eukarya. However, the order must be revised as bacteria, archaea and eukarya. Accompanied by the new interpretation, it could be also assumed that (2) the first life or the first universal common ancestor (FUCA), which appeared on the primitive Earth, was not thermophilic but mesophlic. Furthermore, (3) the position of LUCA could be definitely determined on the phylogenetic tree.