When does life begin?

To listen to all the news on Abortion, one side is full of misogynists who want to keep women barefoot and pregnant, while the other-side is full of lazy, selfish, morally corrupt baby killers who use abortion as their only form of birth control.  We all know that those extremes don't really portray most people on either side.  Throwing those stereotypes around like mud doesn't do much to help get to the heart of the matter either.

There's talk about the mother's, the father's, and even grandparent's rights.  But, during all this debate, there is next to no mention of the fetus or baby, other than choosing which word to use to refer to it/he/she.  This lack of discussion confuses me.

I have my own opinions of course, but I'm curious what other people think.  At what point do the two cells become "living?"  At what point does the developing fetus become "human?"  At what point does it gain "human rights?"  Are those human rights different because the fetus lives in and is dependent upon another human?  How?  Do those rights change over the course of the pregnancy?  If so, how?  Does the fact that a woman is carrying a fetus change her rights?  Where do the two beings (woman & fetus) rights intersect?

I'm only interested in this small part of the topic of abortion.  Abortion is an emotional subject.  But, I ask that we try to keep the emotions in control.  I'm interested in serious contemplation and discussion.  The ability to sit back, cool off, and think about what I am going to say is one of the benefits of internet based discussion.