I would certainly agree that humans have the capacity to be the most socially involved beings. I would also argue that even though we have social needs and require human contact to some degree, we can still technically survive without it (after a certain age) with the technological advances we have. Theoretically, one can live in isolation, and some do. I think our infrastructure and society make it very easy for people to isolate themselves. Without going into too much detail, I wonder if one can argue that we live less socially than other primates? How does this affect our long-term stress? I think most of us would agree that isolation is not healthy, but does it cause the same kind of stress as social rejection?
I also wonder, at what point did the unhealthy levels of long-term stress begin in homo sapiens? We've learned that oppression can cuase long-term stress, and I suppose oppression has been around since humans began to have power over one another. So, I think we can safely say that long-term stress that leads to health problems is a rather old problem for humans. It makes sense that higher dependence on social interaction allows us to bind to one another, but the trade-off is that we do not handle long-term social rejection well.