The Last Adaptation (A Brief History of Organic Life)

As a result of a thousand million years of evolution, the universe is becoming conscious of itself.

—Julian Huxley

The first hard evidence of culture in the human lineage comes in the form of crude stone tools fashioned more than 2 million year ago. What made our ancestor start using stone tools? The consensus among archaeologists, according to one of them, is that the habitat was becoming "drier, less forested, and/or more dangerous"; these "environmental pressure for survival" forced early hominids to innovate.

Once again we are face-to-face with the dreaded "equilibrium fallacy," the idea that life changes only when jostled by an outside force.But we’ve also seen—just a few pages ago—how a type of equilibrium fallacy can analogously bias one’s view of biological evolution. The assumption that a species will change only in response to a changing habitat—and never because of competitive "arms races" among its members—was shown to abet under-appreciation of natural selection’s complexifying tendencies. Now we have an example of the equilibrum fallacy that is doubly worthy of wrath, because it combines these two malign effects; it entails a warped view of biological and cultural evolution.

For here, more than 2 million years ago, with the first stone tools, our ancestors are in the midst of gene-meme co-evolution. The brain has been growing via biological evolution for some time. But cultural evolution is also in motion. Even before the first stone tools, there were no doubt tools made of less durable stuff, since lost to posterity. And anyway, culture, which today goes well beyond material technology, did so back then, too. Tools aside, inventing or imitating new tricks—for hunting or cavenging or foraging or fighting—would have come in handy. So handy, in fact, that biological evolution would have encouraged this sort of cultural play; to the extent that useful memes paid off in Darwinian terms, aiding genetic proliferation, then natural selection would favor genes for processing memes: genes for innovating, observing, imitating, communicating, learning—genes for culture.

This sort of co-evolution can become a self-feeding process: the brainier that animals get, the better they are at creating and absorbing valuable memes; and the more valuable memes there are floating around, the more Darwinian value there is in apprehending them, so the brainier animals get. In all probability, the first stone-tool-using hominids were already on this co-evolutionary escalator. That would help explain the growth in brain size that had recently distinguished them from the dim-witted Australopithecus afarensis, as well as the ensuing eons of rapid growth—all told, a near-tripling of cranial capacity over 3 million years.

Once you’re on this sort of escalator, powered by the positive feedback between the two evolutions, there’s no obvious reason to stop. If you don’t suffer some grave, species-wide misfortune—a meteor collision, say—you’re probably headed for big brains and big-time culture. And somewhere along the way, stone tools are pretty sure to get invented. This is not an event that needs a special "explanation." It is just a stage that the escalator passes through (though environmental quirks could of course affect how fast the escalator reaches it).

So, for the destiny-minded observer, the big question isn’t: How likely were stone tools? Given the co-evolutionary escalator, stone tools were automatic. The big question, rather, is: How likely was it that the escalator would get cranked up in the first place? My view (surprise!) is: pretty darn likely. Because however dazzling the cultural achievements at the top of the escalator, the various genetically based assets it takes for a species to embark on the escalator in the first place aren’t all that exotic.

That isn’t to say that our particular ancestor were destined for embarkation. Indeed, our lineage was just flat-out lucky to find itself in possession of the portfolio of key biological assets. But there’s a difference between saying it took great luck for you to be the winner and saying it took great luck for there to be a winner. This is the distinction off which lotteries, casinos, and bingo parlor make their money. In the game of evolution, I submit, it was just a matter of time before one species or another raised its hand (or, at least, its grasping appendage) and said, "Bingo."

THE ESCALATOR’S ENGINE

Before running through an inventory of the biological assets that seem to grant admission to the co-evolutionary escalator, let’s pause to appreciate the escalator’s subsequent momentum; let’s see what’s wrong with the dreaded equilibrium fallacy in this particular context. Why is it silly to say that early hominids wouldn’t bother to improve their subsistence technology unless the environment turned suddenly hostile?

For starters, because the environment was already hostile! When you’ve got a meager et of tools, no knowledge of fire, prowling predators, and a brain half the size of a human brain, survival can be a real adventure. If crude stone tools help you kill animals, or even chop up animals some other predator killed (and perhaps use the hide as a blanket at night), that’s a plus.

But the larger problem with this version of the equilibrium fallacy is that organisms aren’t designed to merely survive; they procreate, too. For example, within a "polygynous" species, males compete to mate with as many females as possible. Were our distant ancestors polygynous? Yes. Early hominid males were vastly larger than females. This sharp "sexual dimorphism" is a tell-tale sign of polygyny. It signifies that for generations big strong males have had lots of offspring by lots of females, while little crawny males, having gotten sand kicked in their face, have had few or none.

This dynamic—"sexual selection"—is one example of the type of intra-species "arms race" discussed in the last topic. It explains why rams have big horns (rams with little ones got butted out of the sexual arena), why peacocks have gaudy tails (peahens coffed at dull-tailed males), and why our various primate relatives—gorillas, chimpanzees, baboons—exhibit sexual dimorphism commensurate to their degree of polygyny. And it explains why early hominid males might have eagerly embraced new stone technologies.

The more females whose favor they could win, the more progeny they could have. And one way to win the favor of a female primate is to give her meat—a precious treat amid a diet of fruits and vegetables. Crude as it sounds, various primates have been seen engaging in sex-for-meat waps. That includes human beings, when observed in their natural habitat, a hunter-gatherer society—though typically excellence at hunting seems to aid a man’s Darwinian prospects in subtler ways (such as elevating his social status, which in turn can lead to sex).

In short: it wouldn’t take a suddenly worsening climate to interest males in technology that made it easier to kill or butcher animals—especially if the technology conveniently doubled as an aid in killing or intimidating rival males! As zoologists have noted, it may be no coincidence that the human skull gets thicker around the time the hand axe is invented.

For that matter, the genes of females, too, would benefit from cultural innovations that helped nourish them and their offspring. But we’re getting ahead of the story. To assume that our ancestor were capable of shaping tools and using them purposefully is to skip over the question of how our species got into the culture business to begin with. What particular biological assets does it take to get onto the co-evolutionary escalator? What exactly did our ancestor have to acquire via genetic evolution before cultural evolution could pick up much momentum?

GETTING A GRIP

Culture is at bottom a way of learning from the learning of others without having to pay the dues they paid. Suppose you are an elephant. Suppose nearby human beings start carrying guns and trying to kill you. Wouldn’t it be nice to learn about this threat without risking the discomfort of a mortal gunshot wound?

In outhern Africa early this century, a population of more than 100 elephants faced this very situation. Citrus farmers had hired a hunter to annihilate them. They were easy pickings at first, naively unafraid. But after watching some comrades die, the elephants grew averse to humans and began emerging from the bush only at night. This isn’t too surprising—and it isn’t culture, either; it’s just firsthand learning. What’s surprising is that these tendencies lasted into the next generation, even though the hunting had long since stopped. Apparently young elephants emulate their elders’ aversions, thus tapping into the older generation’s hard-earned intellectual capital. This is culture—the transmission of information from one individual to another by non-genetic means.

Culture in this elementary sense doesn’t require all that much in the way of intellectual firepower. Just watch and imitate. Even bird brains can do it. In England, back in the day of milkmen, a bird called a titmouse discovered that by pecking through a milk bottle’s aluminum foil cap, it could help itself to the cream at the top. The idea caught on. Before long, no bottle of milk in the British Isles was safe.

Clearly, imitation can be a powerful force. But teaching—active instruction—speeds things up. Since organisms so often live near off-spring and other close relatives, actively imparting key knowledge can, by the logic of kin selection, be good for the organism’s own genes; so a genetic inclination toward teaching can evolve. When researchers gave tainted fruit to baboons, older males tried it, rejected it, and thereafter threatened young baboons that showed interest in it. Aversion to the fruit spread through the whole troop, though most baboons never tasted it.

These two prerequisites for a human-level culture—learning by imitation, and active teaching—don’t by themselves get you anywhere near a human-level culture. What other biological assets helped put our ancestor on the co-evolutionary escalator? One, no doubt, is tool use.

Tool use per se is no human monopoly. Sea otters use rocks to break abalone shells. The Galapagos woodpecker finch, when in the mood for a grubworm, puts a thorn in its beak and pries the worm out of a tree’s bark.

I don’t envision sea otters bursting onto a path of headlong genememe co-evolution anytime soon. There’s a limit to the technological level you can reach when you’re working with flippers—even if we give natural selection a couple of million years to make the flippers more supple. Indeed, we’re the only species with the sort of manual dexterity it takes to, ay, build a model airplane. But we didn’t start out that way. Millions of year ago, back before our ancestor began flailing with sticks and throwing rocks, hands were cruder. Still, they at least had the property of grasping, which meant that tool use was possible. And as the tools grew in number—as culture evolved—biological evolution moved in lockstep, culpting our hands into fine instruments.

A number of animals can grasp in at least a rudimentary way. Kangaroos, and for that matter kangaroo rats, are pretty dexterous. Squirrels sit up on their hind legs and fiddle with nuts. To be sure, none of these mammals has the much-ballyhooed opposable thumb. But the raccoon, a quite bright animal, comes close, with its strikingly humanlike paws (a comparison it encourages by washing food before meals). Bears, too, feed themselves by "hand." And, of course, various primates have hands deft enough for elementary tool use.

Chimps are especially handy. Among the things they’ve been seen doing: throwing rocks at leopards; attacking a fake leopard with sticks; taking twigs, stripping them of leaves, poking them down into a termite nest, then pulling them out and eating the termites; pounding nuts open with sticks and stones. Chimps even use sticks to brush each other’s teeth.

Some chimps crumple up leaves, turning them into sponges with which to extract precious water from the hollows of trees. Chimps also use leaves to wipe the last bits of delicious brain from the skulls of freshly killed baboons. Leaves are also chimpanzee Handi-wipes, used to cleanse the body of feces and other adulteration. Jane Goodall reports that one young female chimp, dangling above a visiting scientist, put her foot on his hair and then "wiped her foot vigorously with leaves."

This sort of tool use doesn’t seem to be narrowly programmed by the genes. There is innovation and, by observation, cultural transmission. Chimps at Goodall’s Gombe Stream Park used sticks as lever to pry open wooden boxes full of bananas. In the Yerkes primate laboratory, one chimp learned how to use the water fountain, and pretty soon all the chimps were doing it.

Of course, there’s a difference between using a water fountain and inventing one. Still, once you’re in the tool-use business big-time, natural selection could move you toward inventiveness—especially if you have ome other things going for you. Which brings us to the next item in our inventory of biological prerequisites for rapid genememe coevolution.

HEAVY SYMBOLISM

Learning by observing, teaching by threatening, and using sticks and stones can do a lot for a culture, but if your species hopes to get to the point of attending operas and anthropology lectures, the biological infrastructure for language is a must. How many species have language? Well, only one if by language you mean, for example, Spanish. But if by language you mean something more generic—a symbolic code by which information is transmitted from one organism to another—then it’s all over the place. Bees convey the location of flower with their famous waggle dance. Ground squirrels emit a warning call on sighting a predator, as do many birds. Ants send out chemicals that mean everything from "Invaders!" to "Food!" Some ants even squeak "Help!" (not in so many words) when trapped, and the sound brings comrades to their rescue. East African vervet monkeys have several warning calls, depending on the predator; one means "snake," one means "eagle," one means "leopard," and each elicits an apt response (looking down, looking up, or running into the bush). Mastery of this language takes cultural fine-tuning. Young vervets may look up, see a pigeon, and give the "eagle" call. Adults then look up and, by failing to join in the call, induce an enlightening chagrin.

Why is there so much communication in the animal kingdom? Because there are so many non-zero-sum relationships. All of the above are examples of communication among kin—among organisms that have the common Darwinian interest of getting their shared genetic information into the next generation. As we’ve seen, the logic of non-zero-sumness is literally the reason that communication exists. And the profuseness of non-zero-sumness is the reason that communication so pervades life.

Obviously, none of the above species is close to embarking on the sort of cultural evolution that got us from the Stone Age to the sophisticated technology of the information age; none of these animals could possibly formulate a message a complex as, "Have you tried just turning it off and then turning it on again and seeing if that solves the problem?" But the point is that, once a species has the biological infrastructure for any system of communication at all, natural selection could enrich the infrastructure a necessary. In fact, it tends to. If you count all kinds of signaling—visual, auditory, chemical, etc.—vertebrates, ranging from fish to primates, usually have a repertoire of between ten and forty distinct messages. That’s more than they started with.

Why have these "vocabularies" tended to grow? Perhaps because a communicating animal can find itself caught up in an intra-species arms race. If communicating helps you outreproduce your neighbor, then natural selection can favor advances in the biological hardware for language. And the better the average hardware, the better an individual’s hardware has to be in order to outreproduce rivals—and so on.

But why exactly would subtlety of language help your Darwinian prospects in the first place? To some extent the answer is obvious: "Snake" is more valuable information to hare with your kin than "predator." Still, in the case of our pecies, the subtlety of language goes well beyond a mere expansion in the number of nouns. Why? That brings us to another biological asset that can move a species toward the co-evolutionary escalator: a rich social life, which favors both linguistic skill and intellectual skill more broadly.

SOCIAL CLIMBING

Primates that live in large social groups tend to have a large neocortex—the locus, in our species, of things like speech and abstract thought. Over the past few decades, students of primate psychology (including human psychology) have started to fathom why exactly this might be so—why social skills, and thus socially fluent brains, can pay off in Darwinian terms.

Two dimensions of social life seem especially conducive to the evolution of intelligence. One is hierarchy. In many species high social status helps an animal get genes into the next generation, usually by easing access to food or mates or both. So natural selection can favor things that help animals get high status.

How does intelligence help an animal gain status? Sometimes it doesn’t. The term "pecking order" comes from chickens, a not notably cerebral species; their ticket to widespread admiration is pecking other chickens into submission. And even among brainy primates, physical combat often plays a big role in social sorting. Still, with some primates, other assets come into play, such as savvy. This is especially true when social life feature its second major intelligence-boosting dimension: reciprocal altruism.

Hence the vampire bat’s donation of blood to a needy friend, who will return the favor when fortunes are reversed. Reciprocal altruism even in this bare form calls for brains: remembering who has helped you and who hasn’t—and treating them accordingly. (Vampire bats have much bigger forebrains than other bats.) But reciprocal altruism can demand whole new kinds of braininess in a context of ocial hierarchy, when friendships become alliances, and the favors swapped include social support.

Such is the case with two of the biggest-brained primates, baboons and chimpanzees. Many an alpha male chimp has gotten where he is not by single-handedly vanquishing rivals, but by intimidating them with the help of a faithful lieutenant or two. In return, the lieutenants get the alpha’s valued support in their own squabbles (and maybe even—such is the alpha’s magnanimity—easy access to ovulating females). The primatologist Frans de Waal was the first to report in depth on this dynamic. The title of his classic topic, Chimpanzee Politics, strikes some people a recklessly anthropomorphic, but those are mostly people who haven’t read it. Chimp societies demonstrate how a complex and competitive social landscape would favor various intellectual strengths—not just remembering who has helped or hurt you, but cataloguing personality quirks of allies or enemies and monitoring social dynamics, sensing shifts in allegiance. "Machiavellian intelligence" is the term of art. (A "Machiavellian" intelligence needn’t include deception, but it can. The evolutionary psychologist Steven Pinker describes a chimp who was shown several boxes containing food and one containing a snake; he led other chimps over to the snake and, "after they fled screaming, feasted in peace.")

We tend to overlook the deeply social orientation of human intelligence, precisely because it is so deep. But the mental tricks that constitute it become vivid when suddenly they’re missing. Autistic children have trouble putting themselves in other people’s shoes. Normal four-year-olds know that people who haven’t looked inside a box don’t know what’s in it. Autistic children lack this instinct for ascribing mental perspective to people; they are "mind blind." They may be very smart—capable of superhuman mathematical  feats—but they lack key parts of our evolved social intelligence.

So far as getting on the co-evolutionary escalator goes, one key implication of coalitional contention is the emphasis it places on communication. If your team wants to subvert the dominant male, advanced planning is advisable. For that matter, if your team just wants to go hunting, and bring back huge hunks of meat that fill the dominant coalition with envy and females with sudden affection, communication is nice. Chimpanzees have been known to hunt collaboratively, with some of them chasing monkeys while others lie in ambush. Imagine how often their plans could benefit from fine-tuning—if only they could communicate more subtly.

Again, an intra-species arms race: the better that individuals communicate, the more cohesive and subtle their coalitions can be; the more cohesive and subtle the average coalition, the better a communicator you have to be for your coalition to prevail.

Chimpanzees, lacking complex language, do the best they can. De Waal recounts the case of a female chimp named Puist, who had helped a male named Luit chase off a rival, Nikkie. Later, when Nikkie threatened Puist, she turned to Luit and held out her hand, asking for support. When Luit demurred, Puist, furious, turned on him, "chased him across the enclosure and even hit him."

Luit probably got the message—that he was being punished for "cheating," for failing to uphold his end of a non-zero-sum deal. And maybe that message would prompt Luit to make amends, restoring an alliance that could benefit both him and Puist in the long run. Still, anything that removed ambiguity from the message—such as the genetic evolution of the means for articulating grievances—would have made such restoration even more likely, and thus would have been good for both chimps. As usual, clearer communication abets non-zero-sum gain—and, as we’ve already seen, natural selection pays attention to non-zero-sum gain.

THE PANDA’S THUMB

So there you have it: the basic equipment needed for a species to hop on the co-evolutionary escalator: learning, learning by imitation, teaching, some use of tools, along with elementary grasping abilities, a mildly robust means of symbolic communication, and a rich social existence featuring, in particular, hierarchy and reciprocal altruism (a combination that, in turn, brings Darwinian logic that can turn a mildly robust means of communication into a full-fledged language).

As things worked out, our ancestor were the first to put this package together. If they had died out, would they have been the last? These kinds of "What if" games are a pretty mushy form of analysis. But they are a favorite of people who say that the evolution of intelligence was unlikely, so let’s play them for a few paragraphs.

Stephen Jay Gould notes that tens of thousands of year ago, even as Homo sapiens thrived, our near relatives, the Neanderthals, died out. He asks: What if we, too, had suffered their fate? Wouldn’t that have been the end of intelligent primates?

Gould fails to mention the very good chance that our ancestors caused the Neanderthals’ demise—perhaps by crowding them out of their niche, or perhaps less subtly, by knocking them over the head and eating them. In other words, the passing of the Neanderthals doesn’t show how easy it is for even quite brainy primates, who think the world is their oyster, to be struck down in the prime of life by some fluke; the passing of the Neanderthals shows how easy it is for quite brainy primates to be struck down by roughly-as-brainy primates. If our own ancestor had died out around that time, it probably would have been at the hands of the Neanderthals, who could have then continued on their co-evolutionary ascent, unmolested by the likes of us.

But anyway, so what if all members of the genus Homo indeed had been wiped out? I’d put my money on chimps. In fact, I suspect that they are already feeling some co-evolutionary push; if they’re not quite on the escalator, they’re in the vicinity. For that matter, their near relatives (and ours), the bonobos, have much the same ingredients for co-evolution that the chimps have, if perhaps in milder form. Some zoologists suspect that chimps and bonobos have long been "held back" by the presence of humans—kept from moving out of the jungle onto grasslands and, more generally, from filling the human niche. Obviously, if humans went extinct, that would no longer be a problem.

And what if all the apes had been wiped out—chimps, bonobos, even gorillas and orangutans? Well, monkeys, though more distant human relatives than any apes, can be pretty impressive. Baboons are cleverly coalitional, and macaques are quite creative. Japanese researchers put groups of macaques on separate islands and watched cultural evolution work. Especially noteworthy was the prodigious Imo. At age two she invented and popularized sweet-potato washing. She later discovered a way to separate wheat from sand: throw the mixture in the water and skim the wheat off the top. The idea caught on.

What if somehow the entire primate branch had been nipped in the bud? Or suppose that the whole mammalian lineage had never truly flourished? For example, if the dinosaur hadn’t met their untimely death, mightn’t all mammals still be rat-sized pests scurrying around underfoot? Actually, I doubt it, but as long as we’re playing "What if," let’s suppose the answer is yes. So what? Toward the end of the age of dinosaurs—just before they ran into their epoch-ending piece of bad luck—a number of advanced species had appeared, with brain-to-body ratios as high as those of some modern mammals. It now looks as if some of the smarter dinosaurs could stand up and use grasping forepaws. And some may have been warm-blooded and nurtured their young. Who knows? Give them another 100 million years and their offspring might be riding on jumbo jets.

Again, I’m no big fan of "What if" games. Biological evolution, like cultural evolution, is too subtly complex to be anticipated by flow charts with an "if-then" statement at each nexus. Organic history is indeed, as Gould would say, exquisitely contingent; alter any little detail in the past, and any living species could, for all you know, be history. But, again, the same cannot be said of any living property. You can track down and wipe out every species with some particular valuable asset—eyesight, say, or grasping ability—but, if the asset is truly valuable, it will probably reappear sooner or later.

Consider one of Gould’s favorite animals, the giant panda. At some point, apparently, its ancestor were separated from the ancestors of mainstream bear and found themselves in a land loaded with bamboo. The modern panda spends ten or twelve hours a day munching bamboo stalks. In stripping the stalks of leaves, pandas use something that mainstream bear don’t have—a thumb that works strikingly like a human thumb, letting the hand grasp finely. But there’s one difference: whereas a human thumb has four fingers to work with, a panda thumb has five; the panda "thumb" is the hand’s sixth digit. Natural selection fashioned it by reshaping a small wrist bone and rerouting some muscles. Why didn’t natural selection just do what it did in our lineage—turn the fifth digit into a thumb? Because, writes Gould, "the panda’s true thumb is committed to another role, too specialized for a different function to become an opposable, manipulating digit." Faced with this roadblock, natural selection improvised around it.

And what is the moral of the story? The absence of higher purpose in nature. "If God had designed a beautiful machine to reflect his wisdom and power, surely he would not have used a collection of parts generally fashioned for other purposes." Maybe not. But if God were designing a machine that designs machines—if he were designing natural selection—he might well imbue this creative process with exactly the resourcefulness that the panda’s thumb embodies. This is the resourcefulness that made the eventual advent of a second great creative process—full-blown cultural evolution—so likely. The panda’s thumb illustrates that, whatever the fate of our species, one of its key properties, grasping, was all along likely to proliferate—because grasping is a useful technology. Natural selection, metaphorically speaking, seeks out and exploits technological opportunities, and it does so ingeniously, using unlikely raw materials when necessary. As Gould himself says, what is marvelous about the panda’s thumb is that "it builds on such improbable foundations."

What is true of grasping ability is true of the other properties that I’ve listed a basic biological prerequisites for gene-meme co-evolution. Wipe out humans, even apes, even primates, and all these properties would still exist, because all have been invented independently, multiple times. Even what may be the rarest of them, reciprocal altruism, has been invented numerous times in the mammalian lineage—in primates, in dolphins, in bats, in impalas—as well as in other lineages, such as fish. Give evolution long enough, and reciprocal altruism will arise yet again—and again and again and again. (And recall, from part I, that reciprocal altruism, along with status-seeking and the coalitional impulses emanating from these two properties, does more than help animals get on the co-evolutionary escalator. Once they’re at the top, and cultural evolution begins to move fast, these feature help it propel the species toward great social complexity.)

As biological evolution proceeds, and more and more species possess one or another of the several key biological prerequisites for admission to the co-evolutionary escalator, it is just a matter of time before all of these properties wind up in a single species. Of course, that species, looking back, will marvel at the incredible series of lucky breaks that steered it toward the escalator. Who would have guessed that our ancestors, after spending time winging through trees, evolving long, slender digits, would then emerge from the jungle and put deft grasping to a different and pivotal use? What mind-boggling good fortune that tree-swinging happened to be on our ancestors’ resumes!

It’s true. We’ve been very lucky. The winner of a bingo game is also very lucky. But there’s always a winner.

So far, of course, all the basic prerequisites for culture have come together decisively only once; we alone have made the ascent up the co-evolutionary escalator. Then again, it’s been only around 600 million years since multicelled animals made an appearance in the fossil record. And it took only 100 million years to get from crude, rodentsized mammals to lots of brainy, socially complex mammals, several of which are very near the co-evolutionary escalator (if not on its first step). Astronomers tell us the earth has billions of years before the sun signs off. How likely is it that—if our species were suddenly removed from the picture—evolution could go that long without ever again happening to deposit all of these key properties in a single species?

The answer is "at least somewhat likely" if you buy Gould’s view of evolution, in which a randomly fluctuating environment provides no reason for complexity to consistently grow. But if you realize that often the key evolutionary environment of organisms is other organisms, and that multicelled organisms in general tend to move toward greater complexity, turning the biosphere into a hotbed of competitive innovation and ever-ramifying diversity, the answer is "not very likely at all."

THE EVOLUTIONARY EPIC

Consider one "near miss," one species that has come tantalizingly close, but not close enough, to the co-evolutionary escalator. Dolphins are among the most distant mammalian relatives of human beings—more distant than squirrels, rabbits, and bats. Yet they have great intelligence, a complex social life featuring coalitional competition, and a still-unfathomed but probably non-trivial language. They might well be gliding up the co-evolutionary escalator even now—if only it weren’t for those damn flippers! Indeed, look how robust their culture is even with that handicap. One population of dolphins in Hawaii has invented a new form of creative expression: air art.

Various dolphins, and for that matter some beluga whales, can send circles of air out of their blowholes, rising upward like smoke rings. But these Hawaiian dolphins take a whole new approach. They start by creating big underwater swirls with their fins, then turn around and blow air into the swirls. The resulting rings are big, limpid, and beautiful. Some dolphins wim through their rings. Some dolphins make two little rings and then coax them toward fusion, creating one big ring. Each artist has its own style.

And no artist was trained by humans. Though captive, these dolphins have never been rewarded for their work. They are naturally creative, culture-making animals. They are also, together, a social brain. By observing each other, and trying to improve on what they see, they’ve collectively turned the first crude, serendipitous creation of air art into an array of diverse memes.

Maybe the most amazing meme comes from a dolphin named Tinkerbell. She swims along on a sinuous path, releasing a string of little bubbles, and then, by brushing the bubbles with her dorsal fin, joins them together into a corkscrew pattern—or, as described by researchers, a "helix."

It isn’t a double helix, but the symbolism is fitting enough. For memes—once a species has ascended the co-evolutionary escalator, at least—are true to the spirit of genes. Cultural evolution, like biological evolution, carries life to higher and higher levels of organization. And it does it the same way biological evolution does it: zero-sum dynamics intensify non-zero-sum dynamics; competition between entities encourages integration within them. In both evolutions, the two big barrier to non-zero-sumness—the information barrier and the trust barrier—are met and overcome with ingenious technologies.

We’ll never know for sure whether another billion or so years would indeed yield another species as intensely cultural as we are. Because once gene-meme co-evolution shifts into high gear, natural selection is effectively over. Certainly it’s over for the species at the top of the escalator; cultural evolution long ago supplanted genetic evolution as our key adaptive mechanism, and it has now put us on the verge of taking control of our genetic evolution, replacing natural selection with artificial, test-tube selection. And we’ll increasingly be steering the evolution of other species, as well. We’ve long done that in a slow, ham-handed way (witness cows, pigs, and potatoes), but now we’ll be doing it in a lightning-fast way (witness potatoes with built-in organic pesticides). All in all, the shape of life on this planet is now moving so fast via cultural evolution that evolution by natural selection is, for practical purposes, standing still.

The various biological adaptations that got us onto the co-evolutionary escalator— learning by imitation, language, and so on—could be said to amount to one big biological adaptation: adaptation for advanced culture. And this adaptation could be called the last adaptation—at least, the last biological adaptation that will be produced in our species by natural selection. But it is far from the end of the road, and far from the last adaptation of one sort or another that will be necessary.

Edward O. Wilson has suggested that the "evolutionary epic" serve as our binding myth in the modern scientific age—a myth not in the sense of an untruth, but in the sense of a story that explains our existence and helps us orient ourselves to the world. "Every epic needs a hero," he writes. "The mind will do." In a sense, yes; the human mind represents the triumph of our lineage against great odds; its survival, by pluck and luck, as countless others perished; its ascent toward comprehension of itself and its creator, natural selection. At the same time, there is cause to pay tribute to another mind: the "mind" that mediates natural selection. It is the relentless burgeoning of this creative biosphere, the self-accelerating growth in its innovation, that set the stage for our triumph. This giant mind all but ensured that, whether or not the human species finally reached a reflective intelligence, some species would.

We are thus generic and unique. We embody, in some essential way, the natural imperative toward intelligence (and the natural tension between conflict and integration, between zero-sum and non-zero-sum logic); yet we also bear the distinctive marks of our peculiar history.

Now humanity, having emerged from one great global mind, has finally, in the modern era, given birth to another. Our species is the link between biosphere and what Pierre Teilhard de Chardin called the "noosphere," the electronically mediated web of thought that had taken crystalline form by the end of the second millennium. This is a mind to which the whole species can contribute, and a mind whose workings will have consequences for the whole species—epic consequences of one sort or another.

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