genetic and other birth defects create something less than human? Brian do you care to rephrase that? It sounds heartless. Do you like the taste of foot?
I struggled with what to call those who were different than normal. Humans have 23 pairs of chromosomes; but some people are born with three rather than two at chromosome 21.
Is this online statement about Down's Syndrom any better: Down syndrome is the most common chromosome abnormality in humans? Would you prefer "abnormal humans," which is an accurate description -- those who are different from normal. If we say that humans have two copies of chromosome 21; what do we call someone with three copies of chromosome 21 and all the differences from the norm it produces?
There are defects that produce people who are shorter than the normal range - or taller.
A friend was born with a defect that is sometimes referred to as "frog legs". (Doesn't that designation sound like "less than human"?) His legs were not properly attached. They would never work. They were amputated. He walks on his hands. I recently read that he climbed Mt. Kilimanjaro. Sometimes cases like that are called "differently abled" and he certainly is.
I was trying to point out three potential outcomes for a human fertilized egg: it can grow into a normal human being. Something can happen and it becomes dead cells, e.g., never attaches to the uterus; or defects from normalcy may happen as the human person develops and is born. ("Defective human" is also a problematic phrase.) Yes, what I said could seem heartless. Please offer better terms.
I'm not going to jump on the terminology bandwagon here, since others have obviously mentioned that. The potential outcomes for a fertilized egg are:
1. It dies
In some cases, it dies straight away. In others, it grows a bit but fails to thrive and dies. In others, it takes a few years and it dies. In some, it retires, and dies after a solid century. Every single combination of human genetic material assembled via sexual reproduction in the entirety of human history has died or will die (aside from situations in which there was external intervention).
The question then isn't whether zygotes die - they do, and they eventually will. It's not whether those with genetic anomalies die - they do, and they will. It's not even whether fully developed, allegedly healthy adults die - they do.
Once you strip the notion of "Human-ness" from the remarkably clear notion of biology, it's a constant muddle. A zygote is alive - it has a metabolic process, it has distinct DNA, and it grows. Once we step away from that, we have to look at some point where that which is biologically human becomes an "actual" human in some remarkably undefinable way.