A correct classification of microorganisms and higher forms of life has wide implications in pathology, therapeutics, ecology, anthropology, geology and in most natural sciences.

In recent years, prevailing taxonomy is being extensively changelled by the new data based on homologous DNA and protein sequences which are studied in different and closely related species with powerful computer methodology (phylogenetic trees). The quickly accumulating molecular data has helped to define a new kind of microorganisms (archaea) and also has dramatically changed our view of relatedness among living organisms. Examples are found in birds, fishes and also in humans. The relationship among species is now possible to be measured quite exactly with powerful computer programs which construct phylogenetic trees.

Evolutive biogeography and mechanisms of evolution are also being disclosed with the new genetic and paleogeographical data; these are being compared with the new taxonomies obtained with phylogenetic trees. For the first time, paleogeographical and climate events are being correlated with objective evolutive events and the species generation.

After full analysis of many genes and many species an altogether new view of the living natural world will emerge, also with a particular reference to humans and their ancestors.

In the present symposium, all these new molecular, evolutive and paleografical data are going to be discussed and the conclusions may be an step forward in nature understanding.