When, a few years ago, many countries were preparing to legislate on assisted reproduction, embryo experimentation and stem cells, sophisticated arguments were generated in order to weaken the ethical status of the human embryo, so that the public is convinced that these embryos were not, strictly speaking humans. Image of a fictitious and forged embryo. The author makes this book a brilliant and documented major biological arguments employed analyzes: the irrelevance of fertilization, the absence of embryo in the early stages of development, monozigótica twinning, formation of chimeras tetragaméticas, totipotency of blastomeres, the massive loss of very young embryos. He concludes that such arguments are not only weak and do not prove what they claim, but together constitute a paradigmatic example of how a weak biology necessarily lead to a misleading bioethics. Gonzalo Herranz, Professor of Histology, Embryology and General Pathology, has been Professor of Medical Ethics at the University of Navarra and is one of the main representatives of professional ethics of medicine in Spain and Europe.