Cetacea are completely non-technological, and aquatic.
Assume for the sake of argument that, except as compelled by those
two facts, they are psychologically human. (A pretty unlikely
assumption, by the way). What *would* they talk about?
Work? They are, variously, hunters and gatherers. Being completely
non-technological, there aren't a lot of techniques available to them
and they've been doing this for hundreds of thousands of years. It's
a good bet that all good techniques are common knowledge.
Girls? Remember their speech mechanism. A guy talking about his
girlfriend, even if he mumbles, can be heard clearly for several
hundred miles.
Possibly the current location of food. But that won't produce a lot
of vocalizing.
The single good bet I can come up with, is that they chat
about their kids.
Human observers, watching a bunch of mothers chat about their kids,
often can't later figure out what was said even when they understand
the language!
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