Sorry, no out that way either. Unlike with fertilization, nothing special happens to the genes. They just start dividing: and not really all that differently than how cells normally divide, albiet with a lot of the restrictions that limit their adaptability removed. And yet, the eventual result is the same. Again, if we are trying to say that there is something special and unique about fertilization, then declaring all othre methods to be “moral equivalents” isn’t going to cut it. The existence of all those other methods evaporates the specialness of the “moment” of fertilization in the creation of a new human being. It isn’t necessary, and it isn’t sufficient.
Nothing special happens with the genes? There is a new combination of genetic material. I hope you don’t think that I’m saying that there is something mystical happening with fertilization - far from it. But if you are looking for some point at which something is different, fertilization is a far better choice than either implantation or development.
In some sense you could say nothing special has happened to our genes since DNA first evolved. Except for some duplication and recombination, we’re not genetically any different from that first molecule. That doesn’t seem very helpful in this discussion.
What is special is that haploid cells become diploid. Seems significant enough for me. Being able to do it in the lab does not change the significance.
No, there isn’t: not in the case of cloning, not in the case of parthogenesis, and so on. Nor is “new combination of genetic material” accounted as relevant to anyone’s humanity anyway.
Things are different at every single step, every single stage. In fact, especially in terms of function, which is what I would argue is the only thing really relevant to the moral capacity, you only really see anything radically different from any other cell well past even the blastocyst stage. Prior to that, whatever ends we might be envisioning, all we have is just another dividing cell: nothing very different from any other dividing cell in terms of its overall functional capacity.
After having been originally diploid in the first place. Or, alternatively, you could simply skip the step into haploid and just start dividing into a new person. If you can skip a step and still end up with the same result, is that step really so significant? It’s not necessary and not sufficient.
And significant enough for what, anyway?
I’m gonna have to ask for a cite on this, since an unfertilized egg has only 23 chromosomes. I’ve never heard of a haploid neuron.
Some reading:
More recently, several experiments have been done in human embryos that induce the eggs to simply double their chromosome number and then start dividing. Since we’re just dealing withs As,Gs,Ts, and so on, there’s nothing special about this or that happening with genetical material. Making it happen in real life is merely a technical issue.
http://www.cbsnews.com/stories/2003/05/05/tech/main552408.shtml