I had a chance to re-read your post and think it holds more in it than I initially caught on to. You are right that we are extremely social creatures and I hadn't properly considered that a SENSE of connectedness might just be the manifestation of a DESIRE for connectedness. There have long been debates on what these basic underlying pillars of humanity are and more and more science points towards empathy as a central tenant. Empathy is impossible without a sense of similarity or a sense of commonality.The question of course remains is this real or imagined?

I still think we can tease out some objective scientific truth from experiences that claim a sense of genuine connectivity as opposed to a psychological manifestation of the idea. A simple idea for an experiment that I've had is putting a participant in some type of sensory deprivation helmet and test to see if they could notice if a person (or perhaps group of people) came up behind them during the experiment or not. Obviously you would have a control sober group and then different groups testing various psychedelics and see if the results are more than chance noise.