They are not Human :

"I hate race discrimination most intensely and in all its manifestations. I have fought it all during my life; I fight it now, and will do so until the end of my days." -Nelson Mandela-

A brilliant science fiction movie, adapted from a adapted from Alive in Joburg, a 2005 short film directed by Blomkamp and produced by Sharlto Copley and Simon Hansen; produced by the renowned director Peter Jackson, comes one of the most astonishing aliens' film.

"The year is 1982, a giant spaceship from the outter space overshadows a sunny day in Jahannesburg.  During months people from earth became afraid and paranoid, and after months of setup, humans decide to make the first move and make their way into this "mothership".   What they find it's fairly stunning, an ill and starved bunch of shrimp-shaped aliens who claimed to be lost and disoriented; they also confesed not to have any warlike intention but just want to leave..."
Everything seems alright up to this point, after months of international agreements the nations of the world let a Multi-National United enterprise to take care of the aliens in a "humanitarian" way. Then aliens are "forced" to settle down in the district 9 close to the district inhabited by Nigerians refuegees.  But conflicts don't take long to come on the scene, and the african population complains about having to share their country and resources to these "outter space strangers", under this pressure the government decided to move in the aliens further away, where they'd live in better conditions"..  

What does human truly mean?:

The magnificence of this fantastic film it's found in the concept of "intergalactic racism";  although aliens mean no harm to humans (like other films have suggested), humans exert an extreme supremacy over them.  Local population quickly name these creatures derogatorily "prawns", because of their crustacean features and  their need to look for food in trash cans.  It's very absorbing, how a social segregation was born upon another, as quickly as "white people" from Johannesburg determined places restricted for "white people" only, also assigned the places forbidden for "Non-humans".   Based on the constant argument they're not human "prawns" are treated roughly in despite of their show of emotions, conscience and pacific behavior.     The movie shows an excellent instant to reflect about questions like:
*Is it human nature to exert power and feel superior by simply emphasizing external differences?
*If someone or something doesn't show human standard features does it make it Non-human?
*Is humanity a physical condition or is it related to moral and conscience behavior?
*Does a creature need only of conscience and feelings to be accepted and consider as human?
*What makes us human and what does not?

The widening gyre of events starts when one of the unconcerned humans who works for MNU it's turned into one of these "scabby" aliens, and starts being chased by the people he loved most, just like in the "Metamorphosis" by Franz Kafka.   Now thanks to things have turned out against him, he'll understand the real pain and suffering the humanity has caused to this extraterretrial civilization.

It's ironic how the word "human" or "humanitarian" changes by the progress of the movie, because beyond the Apartheid metaphorical effect, there's an undertone about how easy humans loose their values and remorse when they're told someone/something it's unlike them and therefore doesn't deserve to be treated justly.

*If it's hard for humans to adapt and accept to their skin color and cultural diversity, my question for you is.
How would they deal with an alien visitor?