An ontological view of the human embryo. A paradigm

Centro de Biologia Molecular, CSIC-UAM, Facultad de Ciencias, Canto Blanco, 28049 Madrid, Spain. Calonso@cbm.uam.es

In the present paper I analyze the existing paradigms explaining the ontological status of the organisms originating during a given developmental process and the potentiality these paradigms offer. These paradigms give us a hint of the ontological and ethical status of these organisms. It is described that during the history of human thought two theories have been developed to explain the origin of living organisms. One theory placed the world's origin and the origin of living organisms in a transcendent reality while the second stated that the growing complexity of these organisms was rooted in an internal 'dynamis' (the internal potential of a thing, generally a living thing, to acquire new properties) that is present in each one of them. These paradigms are analysed concluding that at the time they were formulated there was no formal understanding of the process of development because the emergence of novelties through evolution was not included in them. At that time growth and development were two aspects of the same thing. A critical turning point in biological and philosophical thinking was provided by the founders of the DNA paradigm as the program directing development. Due to new insights, a paradigm is presented here which includes the epigenesic information as an essential element of the program of development together with the DNA. The consequence of this paradigm is that the program of development is time- and space-dependent and that the biological elements which originate during the process are not preformed but adopt specific values. This way of thinking introduces new approaches to the analysis of the value of the human embryo with repercussions in the ethical discussions on research programs using embryonic stem cells.