How we cite our quotes: All quotations are from Birdman or (The Unexpected Virtue of Ignorance).
Quote #7
SAM: These dashes represent the six billion years that the earth has been around, and so each dash represents a thousand years. And this [breaking off and handing Riggan a square perforated square of toilet paper] is how long humans have been around: 150,000 thousand years. I think they're trying to remind us that that's all our ego and self-obsession are worth. [In a moment, Riggan will forget about the significance of the toilet paper and use it to wipe his face.]
It doesn't get much more straightforward that this. Sam's exercise reminds her of the insignificance of all of humanity, and thus her own insignificance. It's an exercise meant for rehab patients to center their focus on something other than themselves. What to make of Riggan's dismissal of it is more ambiguous. Does he further the exercise by corroborating the insignificance of the human race? Or is this just another example of how selfish he is as he uses all of humanity to clean his face?