Human Dignity and Bioethics

Commentary on Dennett | 97
that we associate with freedom and reason. On this approach the
soul can be understood not as a separate entity that comes to occupy
the body, but as the genetic information contained in the DNA that
provides the dynamism for the development of a human organism.
The view just presented is not only consistent with present-day
science, it also allows us to see that talk about “a mere bundle of living
human tissue becoming a person” is a remnant of the rejected dualistic
metaphysics. This discredited picture requires one substance, “a
mere bundle of living human tissue,” what biology textbooks would
more accurately call “an embryo” or “a fetus,” and a second item that
was not previously there, not even in latent form, that provokes a
drastic change, a change that ex hypothesi does not preserve the substance’s
identity. Since the previously existing organism continues to
exist after the arrival of the new item, the resulting “person” would
be a new entity, a composite of the body and something arriving at a
later point in time.
It makes much better sense to accept the scientific evidence, under
the assumption that each one of us is essentially an integrated
human organism. On this view, the gradual changes that take us to
adulthood seem to preserve identity (we say that it is the same organism
that is growing and maturing), and those changes may be interpreted
as a successive activation of functions that were already latent
“in the genes.” None of this is old myth, and all of it is consistent
with present common knowledge.
Let us press on and ask whether contemporary science shows
gradualism or a clear articulation at the inception of a human life.
Since I am not a scientist, I am here relying on biology and embryology
textbooks in use at American universities. 3 The picture that
emerges, in summary, is this: through meiosis human organisms produce
gametes, that is, cells that have half the standard number of
human chromosomes. Each gamete (either sperm or egg) is a specialized
cell that lies at the end of a line of development and is thus
unipotent. By itself it cannot go any further. Neither an egg nor a
sperm is an organism, and each of them is destined to die within a
short period of time. If, however, a sperm manages to penetrate the
zona pellucida of the egg and the two fuse, then a radical change takes
place: a new cell emerges that stands at the beginning of a line of development.
It has the full complement of human chromosomes and