How could humans recognize another species as sentient / intelligent?

There is this fantasy in fiction that humans meet another species and figure out that it's intelligent. This usually happens with dragons, dolphins, aliens, collectively intelligent plancton...

But sentience could theoretically be so different from what humans experience.

Let's put aside the fact that even recognizing life might be complicated. Say tomorrow a group of scientists encounter in a previously unexplored part of the world (mountain top, ocean bottom, innermost forest) a small animal. How would they recognize that it is an intelligent sentient being assuming that it actually is?

Follow-up question (or prequel to this question): What more than sentience do you need from a species for its intelligence to be recognizable by humans?

posted over 9 years ago

Sheraff‭

11 reputation 23 0 2 0