Could another species someday replace us as Earth’s dominant intelligent life and, if so, which species? To answer that question, we need to understand just what intelligence really is. And why, from an evolutionary standpoint, an organism would even want it.
Once we understand those things, we can start speculating about what the next intelligent, human-like species will be on Earth. What makes intelligence uniquely human? This isn’t an easy question to answer, as plenty of animal species show remarkable levels of what we would think of as intelligence, particularly our fellow primates, cetaceans like whales and dolphins, and even elephants.
Let’s run through some of the potential criteria for human intelligence. How about something crucial, like our use of tools and technology? Humans don’t have a monopoly on this – birds can use tools in a very basic way as part of their foraging, and even incredibly simple organisms like cephalopods are known to cover themselves in coconut shells for camouflage. But it’s chimpanzees that really approach human levels of tool use – they’ve shown signs of flexible tool use, and a 2007 study revealed chimpanzees sharpened their sticks to use as spears, which is the first systematic use of a weapon ever observed outside humans.
Even that can be picked apart – defining intelligence is fiendishly difficult, particularly if you’re trying to not be too biased towards humans – but let’s just say we want to know what it would take to create another species that was intelligent in pretty much the same way humans are.
What would it take for a new intelligent species to evolve?
First of all, humans would almost certainly need to be extinct – or, at the very least, to have completely abandoned the planet – for any other intelligent species to have much of a chance. We already occupy the environmental niche that would produce a human-like intelligence (more on that in a moment), and besides it’s hard to imagine humanity passively sitting back and watching an entirely new intelligent species emerge.
Of course, it would take millions of years (or, at the absolute least, hundreds of thousands) for such a species to evolve, so it’s not like any single generation of humankind would observe such a rise. But we’ve already reached a point in our development where we have the power to control and reshape much of the planet, and part of that domination likely means – at least subconsciously – that we will prevent the rise of a second intelligent species by holding our preferred environment in relative stasis, preventing new, intelligence-breeding niches from opening up.
So let’s keep the discussion to animals. This is for practical rather than philosophical reasons: by some standards the world is now and always has been dominated by bacteria despite the nominal end of the “age of microbes” some 1.2 billion years ago. This was not because bacteria ceased to be, or declined in prevalence, but rather because in our myopia we tend to place more importance on the large multi-cellular organisms that came after. The overall ecosystem of Earth is more complex and sophisticated now than it was when bacteria, trilobytes, or even dinosaurs were the dominant species. This means that unless there’s another massive die-off, the next dominant species will likely be highly adaptable, if not extra-ordinarily intelligent (and likely self-aware).
True success and dominance at this point probably requires evolution of a means of force multiplication. That means evolving tools and/or behaviors that maximize the production/collection of food.
So we’re looking for smart, adaptable, non-aquatic social animals in need of just an evolutionary jump or two to take them over the top. If they already use tools, that’s a good sign. If they already use complex group-based food gathering tactics, that’s another good sign.
Possible candidates: Chimps and Bonobos
Our closest relatives are the obvious choice. Tool users. Highly social. There’s a reason “Planet of the Apes” was popular. It doesn’t take much imagination to envision these guys taking over the world. For ever other species’ sake, let’s hope its the Bonobos, not the Chimps. Much like us, chimps are assholes.
Other monkeys/apes – There are a lot of smaller monkeys out there, spread over much of the Earth. It would take them longer, and the end result would probably look a lot different than us. But our more distant primate cousins like gibbons, macaques, and colobus have many of the fundamentals in place. Old-world monkeys probably have some advantages over the New-world monkeys.
Crows and Ravens
Ravens and their hillbilly cousins, crows, have vexed us for centuries. Admittedly, any species that can be outsmarted by some straw shoved into size 42 coveralls and Grandpa’s flannel shirt has a long way to go to fill our shoes. However, their perseverance in the face of our advanced anti-scarecrow weaponry demonstrates the drive, ambition, and intelligence needed to climb to the top of the food chain.
Sociability is a big plus for them. Their main problem is a lack of manual dexterity. Hard to see them evolving quickly in our general (tool using) direction. That said, with humans gone, canines would very quickly become the apex predator in much of the world.
A harmless herbivore, you say? Not so. Given that we’ve driven nearly all of their natural predators to extinction, we believe the deer population is now a bottle of Diet Coke just waiting for the Mentos to be dropped. To back up that claim, statistics show that deer kill more people than lions, tigers, and bears.
No matter who dominates the planet after we’re gone, humans will be remembered, perhaps even revered with feelings akin to those we have for the dinosaurs—Earth’s most famous top dog of yesterday’s epoch. Imagine it: Young octopi will play with cheap plastic replicas of humans, depicted with a thick pelt of garishly colored corporate logos. Or perhaps the most popular raven film of all time will be “Holocene Park,” a tale of hubris-filled crow scientists who bring extinct humans back from the dead by combining fragments of our DNA with pigs.
But even if neither of those scenarios come to pass, you can be certain that the long and glorious reign of Humanity will not be forgotten—our millions of tons of toxic and nuclear waste will see to that.