Independence is irrelevant. If the embryo was just a part of another thing like the say, the mother, it wouldn't be so clearly different biologically.
Lots of parts of your body are very biologically different. You heart is very different from your ear, but they are both still part of your body.
Again, it's irrelevant. If something happened during my development inside the womb, it wouldn't matter that you call me a separate individual after birth. That development is part of my life. It can have very profound impacts on my life and none on that of my mother.
IVF embryos exist outside of mothers. They are grown for days without the environment of a specific woman, and they can even be transplanted into new women. And even if they couldn't, so what? That's the evolutionary path our species has taken. Every human in existence started out in the same fashion, that's part of the biological development for our species. Other species lay eggs, but the embryo is still a new individual.
Things that happen to the eggs or sperm also have a huge impact on your life, but we don't consider that as part of your life span.
Independence, by the very nature of the term, is exactly what we are talking about. We are talking about if they are a part of the woman or not. An embryo actually can't exist without the mother. Just because they can be fertilized in a dish doesn't mean it is going anywhere without attaching itself to the insides of a woman.
I honestly have never heard of an embryo being transferred from one woman to another. Has that been done successfully?
It would be interesting to hear about, though not all that relevant to this discussion if it isn't an option that is available to any significant number of women.
It's one defining characteristic. There's no human on earth alive with only 23 chromosomes. You going back to sperm and egg is too far to consider my life beginning. Even more to the point, my life began with a specific sperm and egg.
It is not a defining characteristic since it isn't sufficient to determine if someone is a human or not. It could also meant that they are a Reeves's Muntjac, or a Sable Antelope.
Let's go over some basic facts. The genetic assortment that occurs after fertilization makes a new genome. The cells begin dividing, and forming layers that will later develop into specific tissues. The cells are metabolically active, with many important biochemical pathways. The pathways in the embryo are different from those of the mother, they need to be for development to continue in that environment. If those biochemical pathways are interrupted, the cells can die. It has unique biological rhythms which can be measured.
It's living tissue (required for a human), it's a new genetic assortment (required to differentiate from the mother), it has unique biological rhythms to that of the mother (also required for a different individual), it has it's own organs (a requirement) and it can be killed (ending the life of the new human). Clearly that's a new individual.
I don't know how many times I can tell you that I am not arguing about basic biological facts.
The really odd thing, is that none of this matters. I'm still pro-choice, because I don't believe that I should be able to tell someone else what to do with their life and body. I think I should be able to end my life if I want. I think IVF is great for couples who can't get pregnant in the conventional fashion, even if it means embryos will be destroyed, or used for research. And the fact that I think life begins when there is clearly living tissue and a new genetic assortment has sweet Ƒuck all to do with what I think about abortion. My views are closer to Colpy's perhaps, which as you and others have already mentioned, is pretty much on par with what the various provincial Colleges of Physicians and Surgeons already have in their codes of practice.
I'm sure you can see the connection though, no? The only reason that people bring up this discussion is to establish reason to ban abortion. You are advancing ideas that people are just going to use to turn around and tell you that your views on abortion are wrong.
In the end I don't think we have ever been talking about the same thing though, since you have kept yourself firmly rooted in just spouting off biological steps and have avoided talking about what I have been talking about, as in when it is an independent being and would therefore be wrong to kill.