loneliness? The amount and richness of communication like the number of participants, number of parallel communications, number of the topics and the range of opinions, etc. is most probably much higher when using smartphones then when it is subject to the limitations of physical presence. Our species brain development is basically history of social communication, and the smartphones transcending those limits of physical presence is the next step for the brain development of our species. Granted the adjustment period may have its quirks, like absence of non-verbal parts of communication - face emotions, gestures, etc. - that our brain evolved to expect and not receives anymore and thus doesn't get the associated dopamine - may feel like loneliness.