Heh, yeah. I actually made that point in my very first paper on abortion for English 101; one of my references was a cartoon that showcased two scientists talking about abortion. Paraphrased, it went like this:
Mr. Scientist: Well, they’re talking about abortion again.
Mrs. Scientist: We’ll never know when human life begins. They should just stop and let things be.
Mr. Scientist: Who knows. (grabs an egg to make an omelette)
Mrs. Scientist: (swipes the giant egg) That’s the egg of the California Condor! You’ll kill it!
Mr. Scientist: (huffily walks away) Well, I suppose YOU know when life begins for that then!
Same principle, really. The points offered by “The Angry Vegan” were fun to dissect. :D