Stem Cells - Brutes or Angels: Human Possibility in the Age of Biotechnology - page 49

Definitions for Informed Opinions
Good decision making requires accurate information, and reliable infor-
mation requires a vocabulary appropriate for the problem at hand. one
hindrance to informed discussion about the moral status of human em-
bryos is ambiguous use of the terms embryo, fetus, human life, human being,
and person. Without clear definitions we often talk past each other rather
than with each other. The following definitions allow us to examine the
ethical issues with a common vocabulary.
Embryo and fetus. Physicians and developmental biologists distinguish be-
tween human embryos and fetuses on the basis of developmental stage. em-
bryonic development begins with the fertilized egg (zygote) and continues
for eight weeks. fetal development includes the period from eight weeks
until birth. The significance of the eight-week point is that by then organ
systems have formed, though they still must grow and mature before be-
coming fully functional.
Human life. All living human cells manifest “human life.” human cells
growing in a laboratory dish, cultured tissue fragments, organs, embryos,
and fetuses are all examples of human life. even eggs and sperm, whether
within an individual or not, are forms of human life. so if a cell, or group
of cells, has a human genome and is alive, it is human life, as distinguished
from petunia or chipmunk life. many types of human cells are grown in
the laboratory, and thousands of cell biologists around the world study hu-
man life by researching such cells.
Human being. All forms of human life do not qualify as human beings. A
human being is an organism belonging to the species Homo sapiens. 9 An or-
ganism is a cell or group of cells with interdependent parts that cooperate
to perform vital functions and which itself is not simply part of some larger
living entity. Amoebae, sponges, jellyfish, mushrooms, fertilized human
eggs, and human embryos and fetuses are all organisms. human embryos,
whether inside the womb or in a laboratory culture dish, are therefore hu-
man beings. so too are all living, postnatal Homo sapiens, in clud ing those
who are asleep, otherwise unconscious, comatose (with or without life