I have some sort of flat-footed questions to ask: First, what is the significance of being a "distinct, living and whole human organism"? And why single out these particular features? Also, how do you define the terms "distinct," "whole", "human" and "organism"? (And why think we've got the right definitions?)Me:
Thank you in advance for your answers.
The reader correctly summarizes my position--namely, that embryos are distinct, living, and whole members of the human species regardless of their size or location. As is true of infants, toddlers, and teenagers, embryos are human individuals at a particular stage of their development and thus they do not differ in kind from the mature adults they will one day become.
Each of these points can be clarified as follows: To say the embryo is distinct means it is different in kind from any cell of its parents. Sperm and egg, for example, cease to exist at fertilization, their role restricted to surrendering their constituents into the makeup of new entity, the embryo. From the start, this new entity not only directs its own internal development, it has something completely different from both parents: its own unique chromosomal structure. Later, it will bear other distinctions such as different blood type and different internal organs. (For a summary of the science of embryology, see here.)
That the embryo is living seems obvious on the face of it, as dead things don’t grow. Scientists generally agree that anything that exhibits irritability (reaction to stimuli), metabolism (converting food to energy), and cellular reproduction (growth) is alive. Not only does the embryo exhibit all of these things, it develops itself in ways conducive to its own survival and maturation. True, there is some limited disagreement about how we should define “life,” as some things have only some of the characteristics of living things (for example, viruses). However, just because we don’t know if a specific thing is alive does not mean we can’t know if anything is alive. And anything the exhibits the three qualities above is living.
It’s also clear the embryo is human, since it comes from human parents and has the genetic constitution characteristic of human beings. Put simply, human parents produce human offspring. To deny this, one must explain how two human parents can produce offspring that is not human but later becomes so.
Most importantly, the embryo is a complete or whole human organism rather than part of another living entity. All of its cells work together in tandem toward the growth of a single entity, the embryo. Mere clumps of cells do not function this way. Maureen Condic, Assistant Professor of Neurobiology and Anatomy at the University of Utah, writes:
From the earliest stages of development, human embryos clearly function as organisms. Embryos are not merely collections of human cells, but living creatures with all the properties that define any organism as distinct from a group of cells; embryos are capable of growing, maturing, maintaining a physiologic balance between various organ systems, adapting to changing circumstances, and repairing injury. Mere groups of human cells do nothing like this under any circumstances. The embryo generates and organizes distinct tissues that function in a coordinated manner to maintain the continued growth and health of the developing body.Robert George and Patrick Lee summarize embryonic development this way: “From conception onward, the human embryo is fully programmed, and has the active disposition, to develop himself or herself to the next mature stage of a human being.”