Venerable John Paul II and Bioethics

From "Personalistic Bioethics: The Dignity of the Human Embryo from the Moment of Fertilization" by Etsuko Akiba (published by The Institute of Oriental Philosophies' Journal of Oriental Studies, Vol 17, 2007)

“Pope John Paul II offered the following description in his “The Gospel of Life.” “From the time that the ovum is fertilized a life is begun which ... is the life of a new human being with his own growth. This has always been clear, and ... modern genetic science offers clear confirmation. It has demonstrated that from the first instant there is established the programme of what this living being will be: a person, this individual person with his characteristic aspects already well determined” (n° 60). That is, the fact that a person’s life begins at the time of fertilization is not something that Pope John Paul II decided, nor is it simply a theological doctrine or an ethical interpretation. It is the position taken from modern genetic science. Therefore, if we were to word this differently, we could say that if modern genetics had asserted that “the human life does not begin at the time of fertilization,” then the position of the Pope would also be different. This goes without saying. What we must acknowledge here is that the Pope is honestly incorporating the scientific truth into his position.

The human being is a “totality and unity as body and spirit,” an integration of these two, and thus in an early stage embryo, in which a new existence begins physically, it is thought that the spiritual soul is already present. Consequently, “the human being is to be respected and treated as a person from the moment of conception; and therefore from the same moment his rights as a person must be recognized.”

If you're up for some serious reading on bioethics, check out this entire piece. It's very long, but well worth the time. You might also pick up a copy of Evangelium Vitae.