David Haig (Harvard University)
We divide the flux of life into identifiable things that we call individuals, with beginnings and ends, for pragmatic purposes. One seemingly convenient beginning is the fertilization of an egg by a sperm, but are genetic individuals useful ways to carve nature at the joints in everyday human affairs? Monozygotic twins are a single genetic individual in two bodies. A whole-body chimera is two genetic individuals in one body. Clearly the human individuals to which we want to assign rights and responsibilities are not genetic individuals but much closer to organized human bodies with pleasures, pains, hopes, fears and desires.
