Vitaly A. Likhoshvai1, Tamara M. Khlebodarova2 1Institute Cytology and Genetics SB RAS, likho@bionet.nsc.ru 2Institute Cytology and Genetics SB RAS, tamara@bionet.nsc.ru Fossil record of Earth describing the last 500 million years is characterized by evolution discontinuity as well as recurring global extinctions of some species and their replacement by new types, the causes of which are still not clear. We developed a model of evolution of Earth’s biota based on the universal laws of living systems functioning – self-reproduction, dependence of reproduction efficiency and mortality on biota density, mutational variability in the process of self-reproduction and selection of the most adapted individuals. We have shown that oscillatory dynamic of biota density is generated due to only these four factors in populations with sexual type reproduction. The same factors can explain such aspects of punctuated evolution observed in the fossil record as extinction catastrophes, rapid growth phases and stasis phases of species diversity. Therefore, both cyclic and intermittent dynamics of changes in the diversity of organisms with sexual reproduction that make up the Earth’s global ecosystem observed in the last 500 million years may well be explained solely by internal laws of self-development with no impact of external factors.