Adam's Tongue: How Humans Made Language, How Language Made Humans

by Bickerton, Derek

  • How can you compare communication systems that use chemical signals, or shapes sketched in space, with a system that uses either sounds or manual signs?

  Very easily. What such a system works with is quite immaterial. We saw in chapter 1 that ACSs use an immense variety of media—sounds, smells, gestures, lights—but that all these systems are saying the same kind of thing. What matters is not the medium but the message. Language sends the same messages regardless of the medium. You can use flags (did you ever see Monty Python’s semaphore version of Wuthering Heights?) or the dots and dashes of Morse code: the same rules hold as in the spoken version. If bee or ant systems are sending messages that go beyond the usual ACS messages, that contain at least one feature that is otherwise found only in human language, then any difference in the means by which those messages are sent is quite irrelevant.

  • When all’s said and done, we’re dealing here with a system of signals that form a closed (and very small) set of instinctive behaviors (meaning they can’t be voluntarily added to) that are not real symbols, since they can be used only in a narrowly defined situational context (in contrast with words, which can be used in any situational context). How could things like these possibly be precursors of language?

  They’re not—at least, not in the sense in which some abilities of cotton-top tamarin monkeys are precursors of language. Tamarins can distinguish speech sounds from nonspeech sounds just as efficiently as newborn humans, though neither babies nor monkeys can do this when the same sounds are played backward. So here we have a (presumably homologous) precursor of adult human speech discrimination. But in this chapter we weren’t looking for “precursors” in the sense of “things that might ultimately, sooner or later, have turned into language, or been used for language.” What we were looking for were ACSs with features that breached at least one of the rigorous constraints binding on almost all ACSs. We were looking for abstract models of how language might have developed, not for precursors in the deep-homology sense.

  Language isn’t just unique—it’s unnatural. The question is not so much why our species got it and no other did, it’s why any species got it at all—why every species since the primal bacterium didn’t go on happily using its ACS until the world got swallowed by an expanding sun or frozen by a dying one.

  What a different world we’d be living in (or rather, wouldn’t be living in) if that were so!

  But it’s not. For good or ill (it could turn out to be either), we somehow got language, and the only way I can see that we or any other species could have got it is by constructing some kind of niche that, by its very nature, forced us to break out of the prison of the here and now.

  BACK TO THE PALEOLITHIC

  It’s time now to leave the hymenoptera to their fascinating yet strangely restricted lives. On the savannas, the forerunners of humanity are in motion. Let’s get with them. It’s a risky procedure—not for you, dear reader, but for me. To give you the full impact of what happened I’m going to have to go out on a limb, not too far, I hope, but a little beyond what the known facts will fully support. So bear in mind, certain aspects of what I’ll describe may be proven, by subsequent research, not to have been completely accurate. But in essence, something like what I’ll describe to you has to have happened. We know our forebears scavenged large dead animals, we know they faced fierce competition from other scavenger/predators, and it’s a reasonable inference that they could have succeeded only by recruiting sufficient numbers. And, as I see it, there’s only one way they could have done this—the same way ants and bees did it, by breaking the ACS barrier and achieving displacement.

  So let’s go back and see what could have happened, somewhere around two million years ago.

  8

  THE BIG BANG

  WHAT EVOLVED INTO WHAT?

  “If apes evolved into humans, how come there are still apes?”

  I was having breakfast, listening to a radio talk show; I nearly fell out of my chair. The caller was dead serious, though. Moreover, his tone had that gotcha smirk in it, like he’d just demonstrated irrefutably what dumb clucks all those highfalutin’ professors were—they’d never thought of that, had they? I was so stunned I didn’t hear how, if at all, the talk show host responded. But sure enough, that same week in the letters column of a giveaway newspaper the exact same argument popped up (fortunately in the next issue another letter-writer provided readers with the hundred-word version of Evolutionary Biology 101).

  What, I wondered, is our educational system up to? Could the old Dover school board have made it any worse? And then I thought, Uh-oh—maybe everyone concerned could plead mitigating circumstances.

  You see, our caller’s flawed understanding of the ape-human transition—that the one was supposed to have just, uh, turned into the other—was a perfectly correct understanding of what most experts used to say, and a few still say, about the transition from one ancestral human species to the next. As far as the apes, the great tree of evolution branched every which way; then we came out of the branches, just as in real life we came out of the rain forest, and there we were, out on a limb, at the end of a long bare branch with nary a twig on it.

  Australopithecines turned into Homo habilis, habilis turned into erectus, erectus turned into primitive sapiens, sapiens turned into Neanderthals, and Neanderthals turned into us. You could see this in the human family trees shown in old textbooks—gorillas and chimps and orangutans all obediently branching, and then a long straight line going right through four or five species to a dead stop, us. We might be descended from apes, but those diagrams at least put a decent distance between us and them.

  Then, to the embarrassment of many, more and more quasi-human species began to show up in the fossil record. Clearly our branch had branched, after all, but for a while you could still save the day by dismissing these side branches as botched jobs, subhuman discards that at least had the decency to seek a quick extinction, while the unbroken human line marched triumphantly onward and upward.

  As recently as the beginning of this century, a serious debate between the “Out of Africa” and multiregional hypotheses was still raging (“Is ‘Out of Africa’ out the window?” a headline in Science demanded). The “Out of Africa” hypothesis (based largely but by no means entirely on mitochondrial evidence) held that our species evolved in Africa between one and two hundred thousand years ago, subsequently replacing all other varieties of Homo. The multiregional hypothesis (based on claimed physical similarities between humans in specific regions of the world and prehumans in those same regions) held that prehuman species in all parts of the inhabited world, erectus and Neanderthals and primitive sapiens alike, had undergone an “improvement in grade,” whatever that was, and that all, more or less simultaneously, had evolved into us.

  You couldn’t blame our caller for being confused. After all, the process he thought evolutionists upheld in general—one species turning into another—was the exact same process that evolutionists had upheld, and a few still uphold, when it came to our own species and its immediate ancestors. If the multiregionalists were right, and if what they believed went back to the dawn of humanity, then there shouldn’t be any apes!

  Nowadays a majority in all the relevant sciences accepts “Out of Africa.” It’s hard to see how anyone could do otherwise, given the known ways in which biological evolution works. The old one-straight-line-to-humans family trees are gone. But, amazingly enough, the conventional, branching ones didn’t replace them for long.

  As the human family multiplied, as Homo heidelbergensis, Homo ergaster, Homo antecessor, Homo helmei, Homo rudolfensis, and now Homo floresiensis appeared upon the scene, folk gave up on family trees. Now what you typically see are separate plain or colored blocks with names attached to them, scattered haphazardly over a six-million-year space, parallel to one another, with some overlapping and some not, sometimes with spidery lines connecting some of them but most of the time showing you nothing whatsoever about what evolv
ed into what.

  All these Homos are supposed (at least by some) to be separate species. Bear in mind that not many paleontologists accept all of them as genuine species, very few would agree on the same list, and probably no two would totally agree on which fossils belong in which species. In part that’s because an old saying among paleontologists (but it applies in any field of study) divides humans into two kinds: lumpers and splitters. If you’re a lumper, you want to put several superficially different types into the same category; if you’re a splitter, you want a separate category label for every type. Is there any way to get beyond lumping and splitting?

  Yes there is, but you have to stop obsessing about bones and their minuscule variations and start looking at biological evolution, in particular at speciation and how it comes about.

  I’m going to spend the next few pages talking about speciation.

  Is this just a detour? Are we going away from language again? No way! Once again we must take our bearings from Dobzhansky’s dictum: “Nothing in biology makes sense except in the light of evolution.” And speciation lies at the heart of evolution, whether it be evolution of language or evolution of anything else—get that right and all the stones and bones obediently fall into place. Darwin didn’t call his book The Origin of Species for nothing, even though the book is about “descent with modification” and not really about how any new species becomes distinct from other species. He knew that speciation was where the rubber meets the road, even if it would take more than a century for people to begin to get a handle on it.

  The birth of language was just part—had to be just part—of what is often misleadingly referred to as a “speciation event.” In evolution, most of the really interesting stuff happens when one species branches out from another and sets up, so to speak, in business for itself.

  ONE MODEL OF SPECIATION

  Crucial as speciation is, it’s still far from completely understood; it’s still possible for creationists and Intelligent Designers to use it as a wedge issue. Both creationists and IDers make a distinction between micro-evolution and macroevolution. Microevolution’s fine by them, even natural selection, just so long as it stays micro. Things get wetter or drier, hotter or colder; naturally, already existing species adapt to those or any other environmental changes. What creationists and IDers balk at is macroevolution, the emergence of new species. There is where they see the Designer’s fine hand, and the rarity of forms intermediate between one species and another doesn’t help much.

  So let’s see what we do know about speciation, and then we’ll see what it looks like when viewed from the perspective of niche construction.

  People often use the expression “speciation event,” as if you could buy tickets for one and still get home by dark. I’ve been guilty of using that term myself. But I was fortunate enough to be at a meeting where Robert Foley and Marta Lahr of Cambridge University gave a talk on speciation that for some reason was not included in the published proceedings. A pity; it was an eye-opener for me, and deserves a far wider airing.

  According to Foley and Lahr, speciation, far from being an event, is a process that may span as long as a million years or more. (Confirming this conclusion, genetic findings made since their talk suggest that human and chimp ancestors went on interbreeding for more than a million years after their original split.) Most biologists see the process as beginning when some group from a particular species somehow gets separated from the main body. This development sets in motion a cascade of changes.

  First of all, the smaller population doesn’t contain all the genetic material of the species as a whole. It’s a skewed sample, so that soon the two populations are going to look recognizably different. When that happens, members of the smaller group will prefer to mate with other members of that group, even if the two groups come back into contact and regain access to each other.

  Next, as the two populations continue to diverge, the new one may find itself able to exploit food sources that the older population couldn’t (and/or, conversely, unable to exploit food sources that the older population could). This outcome has the advantage that both groups may subsequently be able to share the same territory and still avoid expensive and wasteful competition for the same resources.

  Finally, certain changes (perhaps physical changes in the sex organs, differences in the number of chromosomes, or some other cause) mean that members of the new species can now no longer mate productively with members of the old species. The onset of this stage is the most generally accepted threshold for speciation, even though universally recognized species such as lions and tigers, or horses and donkeys, can still produce viable, and very occasionally even fertile, offspring. (Maybe even humans and chimps could; for a rundown on the most determined attempt to date, Google Ilya Ivanov.) But the point Foley and Lahr were making is that there’s no point at which you could say, “Last year/century/millennium this wasn’t a new species, but now it is.” As with so many natural processes, there’s no point at which you can draw a nonarbitrary line, yet when the process began there was only one species, and now there are two.

  So macroevolution is only microevolution that keeps on trucking in a new direction. It’s just illogical to believe in one and not the other.

  However, this isn’t the only way speciation can come about. Speciation can come about through niche construction, and it’s highly likely that this was true for at least some hominid speciations.

  SPECIATION VIA NICHE CONSTRUCTION

  Consider the first three of the six successive niches of our ancestors listed in chapter 6: omnivore (australopithecines), omnivore plus bone-cracker (late australopithecine, early Homo), omnivore plus preferential meat-eater (later Homo, probably starting with ergaster or erectus). None of these niches involve differences of place, climatic zone, or whatever—there’s no highland man, coastal man, cold-weather man, or the like. All the species concerned were principally distinguished not by where they lived or what kind of climate they needed, or even by their physical form—all were more or less bipedal, all retained whole suites of apelike characteristics. Ergaster and erectus may have been quite a bit bigger than their predecessors, but that was all. They were distinguished from one another mostly by the way they made their living—what they ate and how they got it.

  If you look at a map showing archaeological sites where remains and artifacts of human ancestors have been found, you’ll see sites linked to different species clustering together in the same places. That proves nothing, of course, since the same sites could have been used by different species in different epochs. But there’s at least one piece of evidence that suggests they shared the same landscapes at the same time.

  It was long believed that habilis was the direct ancestor of erectus, the one evolving into the other in the good old no-more-apes fashion. However, recent discoveries have shown that the two species overlapped by as much as half a million years. And according to Maeve Leakey, head of the team responsible for these discoveries, “The fact that they stayed separate as individual species for a long time suggests that they had their own ecological niches, thus avoiding direct competition.”

  That’s because niche construction can drive speciation equally as well as geographical separation. It just changes the order of the Foley-Lahr stages in speciation. The change of resource selection comes first. We can imagine some protohumans persisting with the old bone-cracking, marrow-extracting routines, while others chose the more dangerous route of exploiting the first fruits of technological advance—the flakes that were created as a by-product in making bone-splitting tools—and using this technology to challenge the big beasts for the meat of large dead herbivores.

  The most plausible hypothesis is that the group ancestral to erectus split off from habilis (or perhaps had a quite distinct ancestry) by going from a catchment strategy based on extracting bone marrow to a territorial strategy based on exploiting carcasses of large herbivores. Such a novel lifestyle would select for both behavioral chang
es and physical changes. Erectus would have had to acquire a rangier build, essential for covering the longer distances that the new lifestyle would demand, and erectus was indeed taller and leaner than habilis. Doubtless other changes occurred that don’t show in the fossil record, such as an ability to withstand thirst, and improved throwing skills. (You’ll see why in a moment.) Even if erectus did branch from habilis, erectus females wouldn’t want children by habilis males anymore. The two species might well coexist in the same territory, using it at different times for different purposes.

  What could have set the process in motion?

  We can’t know, of course. Maybe among the bone-cracking marrow eaters there arose some Stone Age Einstein. (They must have varied in intelligence, just as we do.) Maybe this never-to-be-known genius discovered that the flakes from a bone-chopper could cut hide—how, we’ll never know, short of time travel. Maybe he cut himself by accident with a particularly sharp flake. (No, I’m not suggesting that the first word was “Ouch!”) If so, perhaps the memory floated to the surface on one of those rare days when, in the course of searching for bones, his band saw, in the distance, a large dead mammal with prospective feasters already congregating around it.

  From time to time our remote ancestors must have witnessed such sights, and been fascinated by them. They would have clustered together, staring from a safe distance. All that meat! None of it for them! Why should they have to wait for the other beasts’ leavings?

  That time, or maybe another, perhaps they approach more closely. They and the scavengers regard one another with the usual interspecies suspicion. Tails are swished by those that have them. The protohumans watch intently, reading the motions of the beasts for the least sign of possible aggression. When none comes, two or three of the younger ones suddenly run forward, briefly mount the hill of dead flesh, and just as quickly race back to their companions—a dare, a show-off for the females. But one happens to have a sharp flake in his hand and as he retreats he stoops suddenly and takes a swipe at the hide under his feet, and the blade goes in and comes out again.