This is a difficult question to answer.  I’m a theologian and not a biologist, and I make no pretense to being an expert in the latter field.  Nevertheless,  I hope to contribute meaningful ideas to the discussion.  First of all, I think the question is insufficient.  It should be, “Is an embryo in a woman’s womb human by nature?”  The initial question isn’t complete since we normally think of a human as anything from a baby to an old man or woman.  The revised question deals more honestly with the nature of life in the womb and broadens the discussion.

To answer the question, we need to define what it means to be human.  I think the answer lies in understanding two main concerns:  the physical aspect and essence of humanness.  By physical, I mean the obvious external appearance and function of the human body that is governed and constructed by biological distinctions.  By the essence of humanness, I mean the human element that is essential to being human – separate from the physical aspect.  I’ll explain more about this later.

The Physical

Physically, we are bilaterally symmetrical.  The human body can be divided vertically into two halves that are mirror images of each other.  We have 46 chromosomes, walk erect, have large brains, opposable thumbs, etc. We are similar in structure to primates but different in several areas such as brain capacity, reasoning capacity, and complex language ability ¹ I am aware of the experiments with apes regarding sign language.  To some extent, they can communicate, convey ideas, and even reason.  These abilities are very limited and pale in comparison to human capacities. locomotion by walking erect, etc.  Though various animals share aspects of human qualities to much lesser degrees, people are superior to animals in these areas.

The essence of being human

The issue of the essence of what makes someone a human is more difficult of an issue.  Instead of the cut-and-dry science of physical definition, determining the essence of what makes someone human requires a more reasoned and even philosophical approach.  Let me illustrate.

If a person was involved in an accident and lost both arms and legs, would he still be a human?  Yes, of course.  Let’s also say that he lost his genitalia.  He is still human by nature, though without the ability to reproduce.  Therefore, it is clear that being a human is more than simply having arms, legs, and genitalia.  Let’s further say that the same person is also in a coma in a hospital.  Is the person still human?  Again, yes.  Just because he is not functioning properly (i.e., talking, walking, eating, etc.) does not mean he stopped being human.  Even the fact that he is completely dependent upon others for his very life does not mean he is not human.  He still has human nature even though he depends, without knowing it, on others to remain alive.  Therefore, it is obvious that there is more to being human than physical qualities. There is an essence to being human that (1) cannot be covered by mere physical descriptions and functions, and (2) is independent of certain physical and functional qualities.  Humanness is innate, and this innateness must be included in the discussions of taking life in the womb.

When does this humanness begin?

The question then becomes, “When does this humanness begin?”  I cannot give an authoritative answer, but I see two further issues that now require examination.  First, if we don’t know when life becomes human, why take a chance in killing it?  If it is unknown when the life in the womb “becomes human,” then it is better to be safe than sorry.  Second, the thing in the womb is undoubtedly alive, whether it be a single-celled zygote or a fully developed baby.  Its nature, then, is human.  It has human DNA and is alive.  By necessity, it is human by nature.  Is the life in the womb that of a dog, cat, ape, fish, bird, etc.?  Obviously not.  Obviously, it is a human embryo.  Of course, the objection that abortionists will raise is that the embryo is only a potential human and not a full human because it cannot live independently of the mother.  To answer that, let’s go back to the illustration above concerning the accident victim.

If you remember, the man in the hospital has no arms or legs and is in a coma.  He is completely dependent upon others.  The only real difference between him and an embryo is that he is alive and has been born and because he is also completely dependent upon others to live.  Does this disqualify him from the title of human?  Of course not.  Therefore, we can see the claim–that life in the womb isn’t human because it is completely dependent on its mother–is not a sufficient reason to deny its humanity.  So, is an embryo human in nature?  Yes.  Is it alive?  Yes.  Therefore, we have a life that is human by nature growing in the mother’s womb.  Is it right, then, to kill it?