We are entering an era where most anyone can quickly talk to most anyone else who can talk. Talking will get easier as more people speak English, and perhaps as automatic translation is improved. Easy talking wasn’t true before the widespread use of telephones, and it won’t be true after our descendants spread across the stars, or think billions of times faster. The next few centuries will contain the easiest talking era in all of history.
For similar reasons, our current era is likely unique in having the least contact with strange cultures. Our distant ancestors heard rumors from travelers about distant strange cultures. Our descendants may also have contact with strange cultures when they re-engineer themselves and fragment Cambrian-explosion-style into a vast space of possible creatures, grouped into local cultures. Or they may spread across space, and diverge culturally due to the rare slow contact across such vast distances.
I also suspect our era is uniquely rich, in terms of thinking-talking folks having a median income so far above their subsistence levels. (This goes with a uniquely high econ growth rate and low-vs-median income inequality.) Most animals have always been pretty close to subsistence level, and until the industrial revolution so were most humans. Today median world income is now roughly five times subsistence level and rising. But eventually incomes must fall, as we may learn to make people much faster (as in brain ems), or when econ growth rates fall below feasible population growth rates.
In what other ways is our era likely unique? You will of course have diverse opinions, but I’m most interested in analyses based on assumptions I share: our lineage probably won’t go extinct, we’ll keep growing, spread across space, redesign our minds and bodies, and eventually learn all tech, all within a mostly competitive framework.