The recent discovery of yet another extinct hominid species (Homo longi) raises a deeply puzzling question: Why are we still here? Evidently there were a number of hominid species co-existing with us on the planet only a few hundred thousand years ago, but now there is only Homo sapiens left. All the other hominid species went extinct—but not us! What makes us so special? These other species had a relatively brief life in the evolutionary limelight and then succumbed to the pressures of natural selection; they didn’t have what it takes. But they were very like us physically and clearly had their foot in the door. So what makes us so different—why are we alone still here? Maybe we were the best in the line by some measure, but why aren’t we still living with those other species in a subordinate role? Shouldn’t we be living a world of multiple hominid species—or alternatively, zero hominid species? Our unique persistence is an evolutionary puzzle.
I conjecture that it was a mental difference that made the difference, not a physical difference (we are not impressive physically): but what mental difference? I will not be bucking orthodoxy if I say that it was language: we had language and they didn’t. But that is just the beginning of an answer, because language has many properties that don’t explain what needs explaining. It isn’t that we could communicate with each other but they couldn’t: there is no reason to believe that, and communication is a common trait in the animal kingdom. I imagine our human-like cousins were as much chatterers as we are—a noisy rambunctious lot. No, I think it was an internal cognitive trait conferred by language construed as a property of the brain. Our bodies looked and functioned just like other hominid bodies, but inside our brains there lurked a mechanism alien to their (sometimes large) brains. But what mechanism might that be? Recursion has been proposed and the idea is not without merit: iteration, embedding, infinite productivity. This is certainly a powerful mental tool, but does it suffice to explain our species superiority? It is suspiciously abstract and general, not connected intimately to the environmental challenges faced by a species such as ours. No doubt cognitive recursion fed into our dexterous hands, enabling feats of tool construction alien to our species cousins (they would probably be stunned at our technology if they were still around). But still, what is it about this that kept us going while they perished? Why weren’t we just a passing cognitive-manual novelty act?
I have a simple idea. One fact about us that stands out is that we are everywhere: we have spread ourselves across the planet. We are natural travelers. That alone would not explain our differential survival, but in conjunction with the mental-manual adaptation I am talking about we start to perceive a subtle superiority. We can move elsewhere when times get tough and use our brain to deal with the new environment. Most species have a fairly fixed brain that can’t adapt to drastic re-location, but we have a brain that can rise to the occasion, because our brain is pre-adapted to novelty. The combinatorial power of the brain mechanism that underlies language allows us to handle novelty in the world around us—we are not fazed by the shock of the new. Our minds are inherently novelty-generating machines, because language is a structure with novelty built right into its architecture. We can thus process new terrains, new animals to hunt, new climates and weather patterns to contend with. We became a geographically mobile species, forever on the move, not afraid of new worlds—because we had the cognitive wherewithal to cope with novelty in the environment. The novelty inherent in language (and exhibited in recursion) allowed us to process the novelty of changing circumstances. Our extinct relatives by contrast didn’t possess this cerebral adaptation (they didn’t undergo the necessary mutation) and so they were baffled by the new and different, as most animals are. Our versatile brain joined with our dexterous fingers allowed us to survive in novel circumstances, so mobility became an option for us. This creative property of language is not well understood, despite its familiarity, and it may well have dimensions not currently recognized (it may not be just like a digital computer’s computations); but the theory is that this internal adaptation is the root of our capacity to survive while our hominid relatives died out. In short, we are traveling thinkers—we are not stay-at-home eaters and drinkers. We are combinatorial brains lodged inside roaming bodies, and not just roaming bodies but globe trotting bodies. Here I see an analogy with birds, also known for their globe trotting ways. They have those two little wings (like our two short legs) but they also have considerable powers of cognitive flexibility in dealing with the facts of geography (consider the miracle of migration): could this be an offshoot of their remarkable vocal capacity? The bird’s brain can evidently combine sounds into complex rule-governed patterns (we need not call this language), more so than most species, and they are also world travelers capable of adjusting their behavior to changing circumstances. Their wings take them there but their brains enable them to deal with the journey and the destination. Birds are our brothers, our kindred spirits—creative gypsies, as it were. We are both geographical savants, relatively speaking: we both excel at navigating far-flung environments, using our ability with creative syntactic systems. For birds and humans life is a road trip. 
Most animal brains are steady-state pre-programmed conservative machines, content to mirror a relatively unchanging world. But human brains (and bird brains) fizz with combinatorial activity, containing a frenzy of sequencing and re-sequencing, with a passion for novelty; and this enables them to respond to a rapidly changing world that calls for constant updating and rethinking. At the root of this is the trait we call language, which is fundamentally a device of almost limitless recombination, almost too creative. What is all that creative firepower for? Isn’t it a drain on our energy resources? Most animals get by quite nicely without it. But we evolved this unusual trait for some reason (possibly originally as a tool for thought), and it turned out to help enormously with the geographical demands of hominid life back in the days of multiple hominid species. It made moving on not a recipe for extinction. The result was that we survived and they didn’t. It helped not just with communication and individual problem solving but also with the nomadic life-style. It enabled H. sapiens to become global gypsies. It is amazing to see how we humans can survive in radically different environments placing completely different demands on the inhabitants: this is our singular trait, our species character. It is what enabled us to survive and prosper but our relatives not so much; and it springs from the brain mechanism that makes language possible. We have a lot to learn about this capacity, but it seems to be the main reason we are still here. Without it we would now just be skulls and fossils. 
 It is an interesting fact that we humans are so into traveling and tourism: we don’t want to stay home all the time—we long to venture forth to foreign lands. Tourism is in our genes. We feel creative when we are abroad meeting new challenges. Is this a manifestation of our old enthusiasm for moving on when the occasion warrants? New sentences, new locales: two sides of the same coin. And travel writing: using language in the service of geographical adventure. Language, we might say, is an adventure in symbols; travel is an adventure in geography. Thus we arrive at the linguistic theory of geographical competence—the abstract combinatorial structure of language is the basis of our ability to cope with new environments. And that was the key to survival in the early hominid days.
 I have suggested that there is a similarity between geographical capacity and linguistic capacity, in that both involve creativity. I have implied that the linguistic function came first, leading to the offshoot of geographical competence across varying domains. But it is not to be ruled out a priori that things were the other way about: the mutation that allowed for geographical versatility came first and then led to the capacity for linguistic creativity. That at least is a conceptual possibility. I think it is unlikely to be true, however, because language would need extra adaptations in order to exist as it is, but we should always be careful about claiming functional priority. The more likely hypothesis is that language came first and then its machinery was repurposed to form the capacity to handle geographical novelty. Language may also have been the basis for mathematical competence, and a similar story could hold true for the human ability to thrive in very different environments. In a slogan: geography recapitulates grammar.
Fascinating. However there is some serious research that suggests that Neanderthals also had some linguistic abilities. So probably talking is not sufficient for hominid species survival. E.g. here: https://www.sciencefocus.com/news/neanderthals-could-talk-like-humans-study-suggests/
I have no doubt that they did, as do many contemporary animals, but it doesn’t follow that they had language in the way we do, as Chomsky has long pointed out. Making communicative sounds with your mouth isn’t the issue; formal structure is. What we have is in a class of its own, as syntax reveals. This powerful system is what underlies other human competences, arguably. The Merge operation is central (see Chomsky).
Anything that can be called a “language” presupposes a reliable coordination of resources between the conveying and grasping of communicative intent. Productivity and creativity are all very well, advantageous beyond measure, but neither is necessary to any kind of lexical/computational resource enabling of the (larger) systematicity at issue—that which mediates the conveying and grasping of communicative intent. Have you seen the new documentary about Anthony Bourdain? Who takes the tennis “gold” in the Olympics? (sigh), Novak.
Then is the language of thought contradictory? What about inner speech?
Inner speech is a contingent performative aspect of the modern exercise of human intelligence. Its sole benefit is as a condition on the reflective graspability of one’s own thoughts, as input to further unconscious cogitation. conducted in a computational medium eager of recursion and iteration, leaching creativity from the indefinite plasticity of our conceptual competence. This is in only partly in jest. No thoughts on Bourdain or tennis “gold”?.
But inner speech is not communicative, so not linguistic according to you.
I haven’t seen the documentary and I imagine Novak gets gold. Pity about Simone Biles.