It's common in isolation games.
Starting with hunting, the starting scout gets assigned this task.
If not starting with hunting, I do try to remember (and get the opportunity to) build a scout before I reach compass, but that doesn't allways happen.
Failing that, I do try to find time to build a explorer (40H).
If not that, the scientists get to jump into the boats. It's just that they don't have anything useful to do at all.
You reach a coast of Asoka, and you unload the GSci there and next turn your wander inland and find Boudica, next turn you wander even further and meet Churchil.
I do take care and only move 1 movement (or 1.5 movements on roads) with the GSci though, should be 100% safe (Unless suprised by a barb horsearcher inside AI culture...?)
I much prefer to have a scout/explorer on the AIs continent though as they stick around. The scientists go up in smoke when they do their thing, and I want to keep watchful eyes on what the AIs are doing after that too.