And here's one small piece of the evidence.
Have you seen pictures from an "echo" in a pregnant mother? Well, if you haven't, this is what you'd see:
This image was taken from an article in Pharyngula, a science blog. There is, undoubtedly, no question that all animals evolved from a common ancestor, as evidenced by the series of pictures. Animal embryos are nearly identical in all species.
Oh, you're probably seeing the small human at the bottom right of the picture and wondering
is it inhuman to abort that?. That's for you to decide, but you should be aware that, even at the late embrionary stage depicted in that corner, the small "baby" (if you would like to call it that) does not feel anything at all.
Thus, I don't see how aborting an embryo could be construed as "homicide". Otherwise we'd be calling tumor-removal surgeries "homicides" as well (seeing as an embryo has about the same thought and feel capabilities of a tumor...).
On the matter of whether the embryo has a soul or not... well, let's just say I don't believe in "souls". But it definitely isn't a person, and it should definitely not be regarded as one. Women wanting to carry their pregnancies on should obviously be allowed to -- and women wanting to terminate theirs should have the same right as well.