What does the canary in the cage, seen inside the Alien ship, and brought by the human scientists, refer to or symbolize?
Adding to Steve-O excellent answer, it is interesting to note that animals used for this purpose are referred to as Sentinel species. I haven't read the story the book is based on, but I understand the author is obsessed with linguistics, so there may indeed be a deeper meaning.– DukeZhouFeb 3, 2017 at 21:04
I assume you're referring to the canary in the cage that they bring into the alien vessel the first time they go inside. I can't find a screenshot of it, otherwise I would include one for clarity.
Historically, people working in mines would bring a canary with them underground. The idea was that if the cavern began filling up with otherwise undetectable toxic gasses (for example - carbon monoxide or methane) then the bird would die before any people did. As such, the bird's death would serve as a warning signal for the miners to get out.
When they entered the alien vessel, they wore radiation suits for protection, even though they explicitly said they knew radiation levels were nominal. They had no idea what to expect inside, after all, as this was a vessel from another world. So, they took every possible precaution. Including, apparently, a canary in a cage - to see if it died from being exposed to anything.
Coming back to an old answer years later, but just wanted to add something I recently learned myself: Apparently, the canaries used in the mines didn't usually die, they just fell unconscious. The miners would bail out when the bird stopped singing, and as they tended to treat the bird like a pet, they would take it with them so it could recover once outside. I'm sure some of them did die, but at least it wasn't a foregone conclusion.
Wow I much obliged for this useful information about the canar. Thanks– HmzawyFeb 3, 2017 at 2:12
3Yeah - you can take as many sensors as you like, but in a situation where you really don't know what to expect, taking a canary or other fragile animal will give you perhaps enough warning of danger to get out.– iandotkelly ♦Feb 3, 2017 at 15:42
Differentiation. To explain to the visitors that language differ as specie differ. No better way to display this but by bringing in the bird. That was why as soon as they understood the communication, the bird was no longer featured.
Unless you have a source for that, I highly doubt it. Nowhere during the movie the importance of the canary for language purposes is explained. See the other answer.– LucianoApr 10, 2017 at 13:44