Shadows of Forgotten Ancestors (59 page)
Read Shadows of Forgotten Ancestors Online
Authors: Carl Sagan,Ann Druyan
Some parts of the brain are proportionally much larger in humans than in other primates: The cerebral cortex in general, responsible for thinking, is proportionally much larger in humans than in chimps (or in our non-human primate ancestors); so is the cerebellum, in charge of keeping us steady on our (two) feet.
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The frontal lobes are far more prominent in humans than in chimps; they’re thought to play an important role in foreseeing the future consequences of present action, in planning ahead.
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Still, purported distinctions in brain anatomy must be treated with caution: There are many primates not yet studied with sufficient care, and there have been so many erroneous claims. For example, in humans different information is stored in, and different abilities controlled by, the two hemispheres of the cerebral cortex—a surprising finding that emerges from patients whose bundle of neural fibers connecting the two brain hemispheres has been cut.
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This asymmetry, called “lateralization,” is connected with language, and, arguably, with tool use.
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So, of course, the conceit arose that only the brains of humans are lateralized.
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Then songbirds were found to have their songs stored almost exclusively in only one hemisphere of their brains,
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and lateralization was discovered in chimps that had learned language.
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In any case, the
qualitative
differences between chimp and human brains, if any, are few and subtle.
So is that all there is to it? Give the chimps a bigger brain and the power of articulate speech, maybe take away some testosterone, cancel the ads for ovulation, burden them with some more inhibitions, give them a shave and a haircut, stand them up on their hind legs, and get them out of the trees at night? Would they then be indistinguishable from the earliest humans?
The possibility that we might be “no more than” deluxe model apes,
that the differences between them and us might be almost wholly differences of degree and not of kind, and that the differences of kind, if they exist, might be elusive—all this was a source of profound discomfort from the earliest days in which human evolution was seriously considered. Just a few years after
The Origin of Species
was published, Huxley wrote:
[D]esiring, as I do, to reach the wider circle of the intelligent public, it would be unworthy cowardice were I to ignore the repugnance with which the majority of my readers are likely to meet the conclusions to which the most careful and conscientious study I have been able to give to this matter, has led me.
On all sides I shall hear the cry—“We are men and women, not a mere better sort of apes, a little longer in the leg, more compact in the foot, and bigger in brain than your brutal Chimpanzees and Gorillas. The power of knowledge—the conscience of good and evil—the pitiful tenderness of human affections, raise us out of all real fellowship with the brutes, however closely they may seem to approximate us.”
To this I can only reply that the exclamation would be most just and would have my own entire sympathy, if it were only relevant. But, it is not I who seek to base Man’s dignity upon his great toe, or insinuate that we are lost if an Ape has a hippocampus minor [in its brain]. On the contrary, I have done my best to sweep away this vanity …
We are indeed told by those who assume authority in these matters … that the belief in the unity of origin of man and brutes involves the brutalization and degradation of the former. But is this really so? Could not a sensible child confute, by obvious arguments, the shallow rhetoricians who would force this conclusion upon us? Is it, indeed, true, that the Poet, or the Philosopher, or the Artist whose genius is the glory of his age, is degraded from his high estate by the undoubted historical probability, not to say certainty, that he is the direct descendant of some naked and bestial savage, whose intelligence was just sufficient to make him a little more cunning than the Fox, and by so much more dangerous than the Tiger?
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Suppose you own a personal computer. It’s roughly the size of a typewriter, sits on your desk, and outcomputes any hundred mathematicians.
There was nothing remotely like it on Earth only a few decades ago. Building on the strengths of this model, the manufacturer now introduces a relatively minor variant with a faster and more powerful microprocessor and a few new peripherals. Surely this is not as remarkable an accomplishment as the invention of the personal computer in the first place. But the new computer, you find, can perform a range of functions the old one couldn’t. It can figure certain problems out in a reasonable span of time that previously would have taken—for all intents and purposes—forever. There are whole categories of problems you can now solve that you couldn’t come within hailing distance of before. But if solving these problems were somehow important for the survival of the personal computer, pretty soon there would be a large number of personal computers with the added capabilities. Perhaps our uniqueness is no more than, or only a little more than, this: an enhancement of well-established pre-existing talents for invention, forethought, language, and general intelligence, enough to cross a threshold in our capacity to understand and change the world.
Still, depending on what else they are allied with, greater reasoning skills need not—necessarily and in all circumstances—be adaptive and improve survival. “Reason more than anything else
is
man,”
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said Aristotle. Mark Twain countered:
I think it is open to dispute … [The] strongest count against [man’s] intelligence is the fact that with that [historical] record back of him he blandly sets himself up as the head animal.
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If we imagine that we are purely, or even mainly, rational beings, we will never know ourselves.
We are too weak to destroy or seriously damage the planet, or to extinguish all life on Earth. That is far beyond our powers. But what we
can
do is to destroy our global civilization and, just possibly, sufficiently alter the environment as to render our own species, along with vast numbers of others, extinct.
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Even at levels far short of those that can cause our extinction, our technology has given us awesome powers—our ancestors would have thought them god-like. This is merely a statement of fact. It is not a remonstrance and is not intended to define us. But it leads us back again to the question of whether we
have any choice in the matter, or whether there is some deeply buried part of our nature that, despite the comparative intelligence and promise of our species, will sooner or later arrange matters for the worst.
“We are conscious of an animal in us,” wrote Henry David Thoreau, “which awakens in proportion as our higher nature slumbers.”
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The idea is, in a way, obvious; it emerges from even shallow introspection. It goes back at least to Plato,
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who described how in dreams, “when the gentler part of the soul slumbers and the control of Reason is withdrawn … the Wild Beast in us … becomes rampant.” That Wild Beast, Plato goes on, “will cast off all shame and prudence at such moments and stop at nothing”—including incest, murder, and “forbidden food.” The idea of the beast within is also familiar to us from Sigmund Freud, who called it the “id,” Latin for “it,” and from neurophysiology, starting with the work of J. Hughlings Jackson.
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A more recent incarnation can be found in the perspective of the neurophysiologist Paul MacLean,
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who identifies many of the control centers for sex, aggression, dominance, and territoriality in a deep-lying, ancient part of the brain called the R-complex—“R” for reptile, because we share it with the reptiles, who lack much of a cerebral cortex, the seat of consciousness.
We go to great lengths to deny our animal heritage, and not just in scientific and philosophical discourse. You can glimpse the denial in the shaving of men’s faces; in clothing and other adornments; in the great lengths gone to in the preparation of meat to disguise the fact that an animal is being killed, flayed, and eaten. The common primate practice of pseudosexual mounting of males by males to express dominance is not widespread in humans, and some have taken comfort from this fact. But the most potent form of verbal abuse in English and many other languages is “Fuck you,” with the pronoun “I” implicit at the beginning. The speaker is vividly asserting his claim to higher status, and his contempt for those he considers subordinate. Characteristically, humans have converted a postural image into a linguistic one with barely a change in nuance. The phrase is uttered millions of times each day, all over the planet, with hardly anyone stopping to think what it means. Often, it escapes our lips unbidden. It is satisfying to say. It serves its purpose. It is a badge of the primate order, revealing something of our nature despite all our denials and pretensions.
The danger seems so obvious. Surely there is something in us deeply seated, self-propelled, and on occasion able to evade our conscious control—something that can do harm despite what we understand to be our best intentions: “The good that I would I do not; but the evil which I would not, that I do.”
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Sometimes, we use our “higher nature,” our Reason, to awaken the Wild Beast. It’s that stirring animal that terrifies us. If we acknowledge its presence, some fear, we will be sliding toward a perilous fatalism: “That’s what I’m like,” the criminal might plead. “I’ve tried to behave myself, abide by the law, be a good citizen, but there’s only so much you can ask of me. I’ve got an animal inside. It’s human nature, after all. I’m not responsible for my actions. Testosterone made me do it.”
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Such views, if widely held, could unravel the social fabric, it is feared; therefore, it is better to suppress knowledge of our “animal” natures and pretend that those who perceive and discuss such natures are undermining human self-confidence and playing with fire.
Maybe what we’re afraid we’ll find if we look too closely is some resolute malevolence lurking in the heart of man, some unquenchable selfishness and blood lust; that down deep we’re all mindless crocodilian killing machines. It’s an uncomplimentary self-image and of course, if widely held, it
would
work to undermine human self-confidence. In an age when the global environment is within our power to ruin, the notion is not cheering for our future prospects.
What is odd about this point of view—apart from the notion that criminals and sociopaths really take heart from the scientific finding that humans have evolved from other animals—is how selectively it makes contact with the data about animals and, especially, about our closest relatives, the primates. There we can also find friendship, altruism, love, fidelity, courage, intelligence, invention, curiosity, forethought, and a host of other characteristics that we humans should be glad to have in greater measure. Those who deny or decry our “animal” natures underestimate what those natures are. Isn’t there much to be proud of, as well as to be ashamed of, in the lives of the monkeys and apes? Shouldn’t we be glad to acknowledge a connection with Imo, Lucy, Sultan, Leakey, and Kanzi? Remember those macaques who would rather go hungry than profit from harming their fellows; might we have a more optimistic view of the human future if we were sure our ethics were up to their standards?
And if our intelligence is our distinction, and if there are at least
two sides to human nature, shouldn’t we be sure to use that intelligence to encourage the one side and restrain the other? When we reconfigure our social structures—and in the last few centuries we’ve been tinkering with them like mad—isn’t it better and safer to have our best understanding of human nature firmly in mind?
Plato was afraid that when the superimposed social controls are slumbering, the wild beast within will incline us to incest “with a mother or anyone else, man, god, or brute,” and other crimes. But monkeys and apes and other “wild beasts” hardly ever commit parent-child or sibling-sibling incest. The inhibitions are already up and running in other primates, and for good evolutionary reasons. We demean the other animals when we attribute to them whatever predispositions to incest we find in ourselves. Plato feared that the animal within will incline us to “any deed of blood.” But monkeys and apes and other “wild beasts” are powerfully inhibited against shedding blood, at least within the group. The established lexicon of dominance and submission, friendships, alliances, and sexual partnerships keeps real crimes of violence down to a dull roar. Mass murder is unknown. True main-force warfare has never been observed. Again, we undervalue our non-human ancestors when we blame them for our violent proclivities. Very likely, they had inhibitions in place that we routinely circumvent.
Killing an enemy with teeth and bare hands is emotionally far more demanding than pulling a trigger or pressing a button. In inventing tools and weapons, in contriving civilization, we have disinhibited the controls—sometimes thoughtlessly and inadvertently, but sometimes with cool premeditation. If the beasts who are our nearest relatives engaged recklessly in incest and mass murder, they would have rendered themselves extinct. If our non-human ancestors did, we would not be here. For the deficiencies of the human condition, we have only ourselves and our statecraft to blame—not the “wild beasts,” and not our distant ancestors, who cannot defend themselves against self-serving accusations.
There is no reason for despair or timidity here. What we should be ashamed of is the counsel that urges us to avoid self-doubt even at the cost of hiding our nature from ourselves. We can solve our problems only if we know who it is we’re dealing with. To balance whatever dangerous tendencies we perceive in ourselves is the knowledge that in our ancestors and close relatives, violence is inhibited, controlled,
and, in encounters within the species at least, devoted mainly to symbolic ends; that we are gifted in making alliances and friendships, that politics is our business, that we are capable of self-knowledge and new forms of social organization; and that we are able, better than any species that ever lived on Earth, to figure things out and to build things that never were.