[temp8964]

No. Brain alone does not define humanness. You can do a few thought experiments, such as:

lab-grown full function brain, would it be treated as a human?

lab-grown baby with brain development stopped at day x, would it be treated simply as a pile of meat?

adult after accident left with x% brain function, would it be treated simply as a pile of meat?

Just use your brain, you will see it is not that easy.

[michaelmrose]

A fully functional lab grown brain would BE a human regardless of how it would be treated.

If the baby or the human had a sufficiently damaged or deficient brain it WOULD be a pile of meat. If they weren't treated as such it would be because of an emotional connection as opposed to a logical reason. This is all you've posited in this comment. Emotional situations designed to confuse the issue. I am using my brain, specifically to cut through the fog.