"Life begins at conception"

 
Mary Elizabeth Williams declares herself a pro-choice liberal, but wants to concede that "life begins at conception". To her, this is undeniable common sense. But in fact, there is actually a very solid reason to doubt that any human's lifespan starts as early as conception.  At conception, what exists is a single-celled zygote.  That zygote contains the makings of not just the embryo (fetus