[On the ontogenetic origin of human beings: the scientific solution].

Every living being is the result of a genome-environment interaction. Neither human oocytes nor spermatozoids have human functional genomes, but the zygote that they constitute may have a human functional genome and other functional genomes such as those of the hydatidiform mole, polyploids, and non-human living beings. When the zygotic human functional genome is integrated and activated, the biotic humanity is acquired. This may occur when the paternal chromatin decondenses; the nuclear environment and envelope of both nuclei are changed to constitute pronuclei; the replacement of sperm protamines by histones; genome imprinting modifications; centriole duplication; and more importantly, the fourfold genome replication. Other propositions on the origin of humans are: embryo implantation [6-7 days post fertilization, (dpf)]; the appearance of the antero-posterior axis; the limit for monozygote twining (13dpf) and the appearance of the neural tissue (16dpf). They are refuted because some mammals do not implant; embryo axes are present in the zygote; some animals regenerate complete individuals from each part in which they are divided; plants do not have neural system; a human whose brain was destroyed by cancer continues to be a human. Alternative propositions coming from philosophies, theologies, perceptive knowledge, beliefs and intuitions and based on conceptualizations like person, anima, soul, organization, socio-cultural relations are ideologically or religiously biased and based on irreducible beliefs such as faith. They lead to disagreement rather than to agreement.