RE: Lisa’s assumption that an embryo becomes a person when the heart first starts to beat is an odd point of demarcation. Does she eat meat? Fish? All of these have hearts that beat.

If we want a more defensible standard for the beginning of personhood, why not the time that brain activity begins (around the end of the first trimester)? After all, we tend to agree that a person in the hospital, being maintained by artificial life support, is dead when brain activity ceases. And the human brain differs in important ways from other mammalian brains, whereas the heart does not.