I would recommend that any atheist swears off using the word "mystical" . It 's merely a term of abuse with no actual meaning. When we remove it from your post above we get the statement "the disproven assumption that there is something special about human life." If that assumption has been disproven, why is it morally wrong to kill and eat babies? You don't have to be a mystic, whatever that is, to believe that killing people is wrong and killing animals is OK. Can I tell you exactly how to draw the line? No, but I know the line must be drawn somewhere. That's why discussions about where to draw the line are philosophical, not Scientific.