A rational and naturalistic definition of ethical norms must stipulate the preservation of the DNA typical of the species and the maintenance of its intra specific variability. Indeed, this aim of preserving the DNA of the species and preserving its intra specific variability is the basic principle of bioethics. The historically limited behaviour can be related to morality which can assume different norms in different hostorical contexts. Morality could therefore be governed by religion or normalized by discipline. Ethics, instead of (...) that, would be a purely biological and ecological discipline. (shrink)