Strange as it may sound, it is quite possible we share our planet right now with other creatures equal or even greater in general intelligence to us.
I'm not talking about invisible aliens or anything bizarre like that (though, hey, those might be around too, you never know!) -- I'm talking about cetaceans. Dolphins, whales, and so forth.
They have huge associational cortices ... i.e. huge parts of their brains not devoted to anything obvious like perception or motion. And they've proved capable of learning all sorts of complex things, including language with serious syntax. We know they communicate among each other in sophisticated ways, for instance mentioning each other by name during social conversations; but we don't really understand much of their language or to what extent it really is a "language" in the human sense.
Maybe their big brains are largely just huge mapping systems for getting around in the ocean. But there's much evidence that cetaceans have extremely complex social structures, just as humans do -- and it's widely conjectured that human intelligence largely arose out of the need to navigate human society (so that social complexity and cognitive complexity recursively "pumped each other up").
It is tempting to hypothesize that cetacean consciousness, compared to human consciousness, has more to do with shaping and flowing and less to do with causing and building.
Ultimately, though, we don't really know how smart cetaceans are, or in what ways they're smart, because we've put precious little resources into serious studies of cetacean cognition and communication. We may have an intelligent "alien species" right under our noses ... but rather than studying them with maximal intensity we're murdering them as part of our commercial fishing practices!
What cetacea haven't done, that we humans have, is build complex tools. They do (like some birds and apes) use tools, but they don't make tools to make tools, and so forth. This is why we are far more likely than them to launch a Singularity -- even if they are "smarter" in important senses.
But still, we may have something to learn from them -- and advanced technologies may eventually break down the barriers and allow us to communicate with them. When an AGI serves as translator between human and dolphin --