When "personhood" begins in the embryo: avoiding a syllabus of errors

The following essay was delivered at the conference "Ontogeny and Human Life" at the Ponifical Athenaeum "Regina Apostolorum," November, 2007. Sponsored by the Legion of Christ, the Pontifical Academy for Life, and the John Templeton Foundation, the sessions focused on when the conceptus became a "person." My essay focused on the scientific conclusions that could aid such discussions. Moreover, after listening to the philosophical, legal, and theological discussions that ensued, I responded theologically as well. New concepts in modern embryology have made scientists revise their views concerning the autonomy of embryos and the mechanisms that generate such embryos. There are interactions between the sperm and the female reproductive tract and egg which had never been known until recently. There are also interactions between the developing organism and its environment that had been unsuspected a decade ago. Gut bacteria induce the development of the mammalian digestive system and immune system by changing the gene expression patterns in the mammalian intestine. Conversely, chemicals in our technological society can adversely affect the embryo, rendering it sterile or prone to tumors later in life. While there is no consensus among scientists as to when human life begins, both Church and science can become allies in persuading governments to regulate or ban the production and use of these fetotoxic chemicals. These new views of embryonic development change many of the stories told about human embryos and fetuses, and they have implications concerning the use of science as evidence for theological positions.