=== THE LINE ===
* Human (stranger)
* Human (acquaintance)
* Human (family)
* Human (self) ?
In our society, you can eat everything above THE LINE, and nothing below. The ordering and placement of THE LINE are both somewhat subjective, but you get the point.
My theory is that THE LINE will constantly move up that list until it's not acceptable to eat any animals. It will take a very long time. This is not to say that societies where THE LINE is in a different place than ours are necessarily better or worse societies.
In the interest of full disclosure, I enjoy eating the occasional animal.