Thumbs, Toes, and Tears Page 14
This part of the brain, says Edelman, made the difference between something he calls “primary consciousness”—the sort of awareness of the world that many mammals experience—and “higher consciousness,” that special brand of self- and world-awareness that you and I experience every waking moment. If chimps and orangutans today have some sense of self, and if toolmaking and gestural language require some level of self-awareness, then Homo erectus probably lived life in a twilight zone somewhere between chimps and us, more self-aware than any other creature of its day, but far from deeply thoughtful.
The question is what other forces were at work that built brains that became capable of something as remarkable as self-awareness? One of the key influences, maybe the key influence, was not simply the physical world, not even, strictly speaking, our inner, thought world, but the place where we interact with one another: our social world—the one space where all of our life’s key forces converge.
Chapter 7
Words, Grooming, and the Opposite Sex
Once you have become permanently startled, as I am, by the realization that we are a social species, you tend to keep an eye out for pieces of evidence that this is, by and large, a good thing for us.
—Lewis Thomas
Humans are the most social creatures on Earth. Our need to interrelate is deeply threaded throughout our DNA and our brains. Chimps and gorillas are also extremely social, which means the common ancestor we share with them very likely was as well. Jane Goodall describes two chimp friends she watched when they were reunited after being separated in Gombe National Park. At first sight both chimps hopped and screamed and danced and hugged at being together again. They acted the way you and I might after seeing a long-lost relative. But then they did something we probably wouldn’t. They began to groom one another. They huddled together and attentively and affectionately set to work picking nits.
There are good reasons for doing this in the wild. The jungles of Africa are filled with fleas, ticks, and parasites that survive by hopping a ride on the other living creatures around them. If left to their own devices, they would drain their hosts dry or infest them with enough disease to kill them before either they or their hosts could reproduce. So grooming serves a real purpose; it is a survival technique, and having two or more sets of hands to do the work is clearly better than one.
But there may be other reasons grooming evolved. It is also a way of connecting. When chimps comb through one another’s fur, calming neurotransmitters cascade into their brains that make them feel warm and safe.1 You and I experience the same soothing echoes of grooming when someone we care for runs his or her fingers through our hair, strokes our arm, or holds our hand.
Our tree-swinging ancestors had very good reasons to connect as strongly with one another as possible, given that the environment they lived in was filled with danger. Psychologists Robert Seyfarth and Dorothy Cheney have found that in the jungle, grooming relationships can improve a primate’s chances of staying alive, accumulating power, building successful alliances, and making babies. In the early 1990s both scientists2 conducted studies of vervet monkeys and found that they will pay much more attention to the distress calls of individual monkeys they have recently groomed than those they haven’t. In fact, the more attentive the grooming, the more likely different individuals were to help one another out.
This makes grooming both a survival technique and a form of communication. In fact, Liverpudlian psychologist Robin Dunbar has speculated that nitpicking may have laid the early foundations for human conversation, the simian version of a phone call, or a chat over a drink at the local bar.g Earlier primates may have started out staying in touch by tidying one another up, he says, but in time we expanded that primal form of socialization and communication to include a new and remarkably potent talent we were developing: speech. Following Dunbar’s logic, speech must then be about more than the practicalities of exchanging information. It also must involve vulnerability and emotion, not to mention scheming and manipulation.
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Seeing similarities between the relationships we develop in the human world and those in the simian one isn’t new. Goodall watched plenty of complex, human-style dramas unfold among the cast of primate characters she watched and named during her years in Gombe. It is easy to see ourselves in the alpha chimp Goliath’s fall from power, Merlin’s slow march to madness, Flo’s unlikely attractiveness and never-ending romances, the regal warmth and wisdom of David Graybeard, and the touching friendship between David and William, a story that could have inspired Of Mice and Men or Midnight Cowboy.3
After years of scrutinizing the likes of Flint and Figan, Gilka and Goblin, Goodall also made some disturbing and surprising discoveries that remind us of ourselves. She found that chimpanzees are capable of murder, organized hunting, complex relationships, and convoluted emotions. Every one of these discoveries astounded the scientific world, and revealed how the smoldering embers of our own humanity may have found their way across time into the world we inhabit today. Change the setting, push the complexity of the relationships, the deceptions, and the struggles for status, and the personal losses and victories begin to look like the plots of Austen, Trollope, or Hemingway.
If Goodall’s stories have a human ring, you can imagine that by the time Homo erectus had arrived, the dramas unfolding among these troops of migrating toolmakers and hunters were beginning to look even more familiar. After all, they had placed a good deal of distance between themselves and the primordial rain forests of their tree-swinging ancestors. They were now fully bipedal, their hands were free, and their thumbs were entirely opposed. Their brains had more than doubled in size since Lucy’s time and were still growing rapidly. Erogenous zones for some time now had been sending clear sexual signals, while at the same time their faces were becoming more expressive, conveying in greater depth the complicated thought-world evolving within. And narrowed birth canals forced the arrival of “younger” children that were more helpless and, above all, more impressionable than ever. They were growing up more intelligent than any other earthly creature. All of this made them increasingly less confined by the dictates of their genes.
The day-to-day social relationships within the troop would also have become increasingly complex. Each member had to compete, subtly or otherwise, not simply for mates with the best DNA, but also for mates that would be reliable caregivers and partners. Primal versions of fidelity and truth, not simply sex and brute strength, had become key forces in the battle for survival. (See chapter 2.) Cooperation was paramount, but so were social talents like shrewdness and insight. The growing complexities of sexual and social politics presented a whole new kind of evolutionary challenge that upped the social stakes.
Handling all of this intrigue required sophisticated communication and big brains capable of powering it. But which came first? The need or the brains? Speech that smoothed communication or cerebral adaptations that enabled refined forms of it? For decades the common wisdom among anthropologists has been that the demands of hunting in groups, making tools and weapons, and eating more meat were the primary drivers of brain growth. And all of those almost certainly contributed to our intellectual evolution.
But could they alone have been responsible for the wealth of neurons we all enjoy today? They leave out one immensely important part of our ancestors’ daily life: their struggle to deal with one another, to compete for power, for status, for the affections of potential mates while, at the very same time, building close alliances and friendships. Is it possible that complex social dynamics like these were the true primary movers pushing the extraordinary development of our intellects?
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In 1988, two British psychologists, Richard Byrne and Andrew Whiten,4 proposed that monkeys and apes often observed the behavior of other monkeys and apes as they interacted, and then used that knowledge to decide how they would act toward those they had watched. If they noticed that an ape was aggressive, for example, then they tended
to be more deferential when dealing with that ape. Or if they noticed a particular ape was generous, they might try, at some point, to take advantage of that generosity. In effect Whiten and Byrne found that primates, simply in the course of their daily lives, used the knowledge they gathered interacting with one another to manipulate individuals in a social group to their own advantage. This meant they were juggling an enormous amount of information almost constantly. Byrne and Whiten called this the Machiavellian Intelligence Hypothesis.5
If apes do this, then our ancestors surely did as well—at least that was the thought Robin Dunbar had in mind when, in the mid-1990s, he began to explore the work of Byrne and Whiten. Dunbar theorized that the more intelligent our ancestors became, the more complex their increased intelligence made their lives. And the more complicated their lives, the more intelligence they needed to handle it all. In fact, he found a direct correlation between the number of relationships individual primates deal with in a group and the size of their brains, or more precisely their neocortices.
The neocortex is the “thinking part” of any mammal’s brain, as opposed to the limbic system or the brain stem, both of which are considerably more ancient. In most mammals the neocortex comprises about 30 to 40 percent of total brain mass. In some primates it can claim up to 50 percent of the cerebral real estate. But in humans it accounts for a whopping 80 percent, an area that packs roughly 100 million yards of axons and dendrites into a space the size and thickness of a formal dinner napkin. Its various regions handle all of the higher levels of cognition—planning, imagining, language, spatial calculations, and the intelligent consideration of what we see, feel, hear, smell, and touch.h And most of it evolved in the short evolutionary space of the past one million years.
Dunbar’s studies revealed that when the size of a group of primates increased by one, the number of relationships a member of that troop now had to track increased by one plus all of the connected relationships that both members had in common.
Consider what would happen if a primate named Joe lived in the same troop with Mike. And imagine that Joe was a friend of Mary’s, but Mike didn’t know Mary. Under those circumstances Joe and Mike might normally compete, sometimes ferociously, for Mary’s attention. But let’s say Mike did know Mary, and let’s further assume they were allies. Since Joe wouldn’t normally want to anger Mary (they are friends), he might be a touch more cordial to Mike (unless, of course, Mary was his mate and Mike was trying to horn in, but that’s another story).
If this sounds complicated, that’s because it is. One-on-one relationships are a two-way street. Add third and fourth parties and you get a traffic jam. The complexity of any social interaction goes up exponentially every time you add another to the mix. Dunbar calculated that within a group of 20 primates you would have to keep track of 19 direct relationships, but 171 indirect relations that those 19 have with others.6 So if you go from, say, 4 direct, close relationships to 20, then your immediate circle of friends increases fivefold, but the indirect, ever-changing relationships you now need to constantly keep in mind increase thirtyfold!
This is even more complicated than it first appears because not only does the number of relationships increase, but because they are all intertwined and constantly changing, the emotional complexity rises as well. For every action within the troop, there isn’t one, simple opposite and equal reaction, there were multiple opposite and unequal reactions that spread like wild rows of falling dominoes. None of it would have had the clean feel of Newtonian physics or algebraic equations. It would have had the feel of chaos, and chaos—ever-changing, unpredictable situations—requires as much intelligence as a creature can muster. (As a species, we abhor uncertainty, and so our brains constantly struggle to reduce it.) Think of how much time and energy we put into imagining what the boss is thinking or how we can out-maneuver a rival, plant an idea, win the affection of a lover, or consider the best way to reward or discipline our children.
What made the world of our ancestors peculiarly tough was that they could not afford to make enemies within the troop any more than we can within the circle of people we deal with in our daily lives. Their world was too small. If every conflict among these troops came to a fight to the death, we would have evolved into nothing more than a species of vicious and conniving primates. Or more likely we would be extinct. But mostly we aren’t vicious and conniving (though we certainly can be). Mostly we are wary, but open. It is more in our nature to trust than fear. That means that winning friends rather than bullying must have evolved as an essential survival technique.
Given this situation, a new tool was required. Not a flint knife or a hand ax, but a talent for understanding others and helping them to understand you. A talent for communication.
These circumstances would have created a kind of arms race: our ancestors’ brains would have evolved greater intelligence to handle the increasing complexity of intratroop relationships, which would have in turn selected for increasingly intelligent minds that could track the progressively complicated relationships, and so on. Though Dunbar’s work hints at this arms race and it makes intuitive sense, a genetic study published in 2005 and conducted at Howard Hughes Medical Institute indicates that the genes that create the instructions for building the human brain did indeed change enormously, especially in the past four hundred thousand years. The study, conducted by a team headed by geneticist Bruce Lahn, at the University of Chicago, compared the sequence of the human Abnormal Spindle-Like Microcephaly Associated (ASPM) gene to the same gene in six other primate species—chimpanzees, gorillas, orangutans, gibbons, macaques, and owl monkeys (as well as cows, sheep, cats, dogs, mice, and rats). ASPM genes are strings of DNA linked to a severe reduction in the size of the cerebral cortex, parts of which handle planning, abstract reasoning, and other higher brain functions. The analysis revealed that the human brain’s genes had changed markedly, apparently to allow increased brain growth, whereas the other primates’ hadn’t.
The forces driving these rapid changes had to be powerful; otherwise we wouldn’t see them in the genetic record. Like Dunbar, Lahn suspects it was the social pressures created by increasingly intelligent and complex interactions that drove the selection for smarter hominids. After all, said Lahn, “As humans become more social, differences in intelligence will translate into much greater differences in fitness, because you can manipulate your social structure to your advantage.” Put another way, smooth social skills must pay off handsomely.
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If smooth social skills are an advantage, and if they require equally smooth communication, does this explain the evolution of speech? Why not simply evolve into highly intelligent creatures who communicated by lovingly picking parasites out of one another’s bodies? Dunbar’s answer is that when it comes to communication, grooming, soothing and useful as it was, had its limitations. Not only was it vague as a way to communicate, but it also was a one-on-one activity. You can’t groom two or three or four others simultaneously, but you can hold a conversation with more than one. Eventually, as brain size and troop size grew, and as more communication was needed, grooming simply failed to allow enough time for all of the members of the troop to “converse” and to keep track of one another.
Dunbar theorizes that this shift would have first begun about two million years ago, around the time Homo habilis emerged. Shortly afterward, the first rudimentary forms of speech would have followed. Forced into a corner of sorts, evolution would have stumbled upon a more efficient way of staying in touch, not with hands and fingers, not even by gesturing, but by grooming, as Dunbar puts it, “at a distance”—making sounds at one another that accomplished the same social, if not hygienic, goal. The big advantage of “sound” grooming would have been that our ancestors could more effectively track all of the complex and far-flung relationships within the troop.7
Dunbar doesn’t subscribe to the gesture theory of language origin. For him, language finds its foundations in the contact and alarm calls of
African monkeys and apes—the sounds they automatically scream and hoot when they are in danger or want to get the attention of those around them. He bases this belief on the work of Seyfarth and Cheney. Their exhaustive observations of vervet monkeys has revealed that they use different calls to warn of predators: one for eagles, another for snakes, still another for leopards, and so on—a simple kind of vocabulary where a sound stands for, or symbolizes, different dangers.8 Gelada baboons use subtly different moans and whinnies and grunts to communicate simple messages when grooming. Something like these, he believes, are sounds that in our ancestral past could have represented meanings that evolved into the stabs at some of the first words. (This is generally reminiscent of the Pooh-Pooh theory of language.)
But as the time budgets for grooming were squeezed, vocal chatter would have had to increase to supplant less efficient one-on-one grooming. Dunbar estimates that between two million and five hundred thousand years ago, creatures who were roaming in increasingly larger troops would have been forced to spend about 30 percent of their time grooming and communicating if they hoped to successfully keep tabs on one another.9 Dunbar believes that this would have merged with larger brains and greater vocal control to create the first protospeech.10