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ORIGINS IN THE ANIMAL KINGDOM

IT IS OFTEN said that we of the twenty-first century still allow ourselves to be directed by Stone Age emotions, that we’re essentially Neanderthals with a tie. More than one colleague ranting and raving in the office has reminded us of a hunter swinging his club and putting the men of his horde in their place—while leaving the women for himself.

Such impressions, however, are not entirely correct. To be sure, we have at least partly inherited our feelings and behaviors from our ancestors. But why should this legacy have begun only in the Stone Age?

Our emotions, at any rate, seem to be much older. What animal lover has not sometimes observed signs of pleasure and distaste, love and hatred in his pets? When a cat is stroked, it purrs, stretches, closes its eyes, relaxes its limbs, and waits patiently for more. A dog that’s been scolded slinks to the corner. Even birds chirp to get attention, and it’s no coincidence that the concept of the “love nest” comes from their world. Birds seem to suffer almost as much as people in the absence of proximity to their own kind. A gray goose whose partner has died can remain without a mate and show all the symptoms of depression for years.

Such scenes touch us because we see our own emotions mirrored in animals. But they shouldn’t lead us to conclude that these creatures really do feel as we do. We are unable to read what may be feelings inside animals’ heads, and they have no language to express their inner lives. Whether animals feel, and how, remains thus far an unanswered question.

It is, of course, incontestable that on the surface animals show emotions that resemble ours. It is these behaviors, and not the unknown feelings, that account for our sense of having a secret relationship with them. The stronger and more basic an emotion is, the greater the similarity seems. The symptoms of fear, as we see them in cats, dogs, mice, and even pigeons and lizards, hardly differ from those of humans. But happier episodes from the animal world are familiar as well: cats playing, rats and mice exploring the world, or elephants entwining their trunks when they’re about to mate. One would say that these animals are showing signs of fun, curiosity, and perhaps even love.

Is it possible that animals fear without experiencing their fear, that they love without feeling their love? It’s helpful here to review the difference between emotions and feeling. An emotion is a program that runs automatically, usually involving the body; a feeling, on the other hand, is something we experience when we become conscious of emotion. Sometimes we manifest emotions without feelings—for example, when we blush without having been fully aware of our sense of embarrassment.

Awareness, then, is not a precondition for emotions, which can therefore be said to arise more simply than feelings. Although scientists do not know whether and what animals feel, there is no doubt that they are indeed capable of emotions. We know, too, that these emotions, which are engaged automatically whether the animal is threatened, unexpectedly rewarded, or having sex, function in animals much as they do in humans.

We can conclude, then, that the basic characteristics of emotions were present long before there were humans. They are a legacy from a very distant past that influences what we feel, and when, for emotions are a precondition for feelings. In fact, the emotion determines the feeling. We see an apple, after all, only when there is an apple to be seen (unless we’re hallucinating), and it is the same with feelings like pleasure and fear.

Because emotions comprise the core of every feeling, we have good reason to be concerned with their origins, and in animals we can study the origins of our more complicated feelings. Dogs, cats, and mice do not show the wealth of emotions that people are capable of, but precisely because they follow more rudimentary patterns, what is essential is much more obvious. In the mirror of the animal world, we recognize ourselves.

THE EVOLUTION OF FEELINGS

In the course of evolution, brains and emotions developed in synchrony. The more brains developed, the bigger and more complex they grew, the richer and more differentiated emotions became.

Why did nature spend so much energy in creating ever more capable brains? To equip a jellyfish that moves through the ocean and filters microorganisms from the water with intuition and an ingenious mind would have been a waste. It needs no more than a simple nervous system that controls digestion, responds to light so that it knows up from down, and to fire off poisonous stingers when its next meal brushes against it.

But an animal that actively chases after its prey depends on many more reflexes and emotions than a mere jellyfish. It has to recognize its victim, gauge the right moment to attack, and understand when it is better to flee if the would-be breakfast defends itself too aggressively.

Every creature has its own recipe for survival, a mixture of camouflage and cunning, physical strength and speed. An alligator confronts its enemies with its armored skin and powerful jaws, a horse gallops from danger, and the tiger’s strength and speed render it almost invulnerable. It is the abilities of the body, correctly engaged by the brain, that always determine the fate of a living being. But over the course of evolution the center of strength has shifted upward, as the brain has grown and come to consume an ever larger portion of the body’s metabolic energy—most of all in the human, whose brain requires more than a third of the body’s energy.

Thus, Homo sapiens depends almost entirely on intelligence and intuition and hardly at all on the body. Without these qualities he would be lost, since, when it comes to size and agility, he is hopelessly inferior to other animals of his size. Even our nearest biological relative, the chimp, can easily grab a human and twirl him through the air.

In evolutionary terms, however, large and significant parts of our brain are much older than the human species. And in spite of the changed demands, most of these parts of the brain still function as they did in the heads of fish and lizards. To these primitive circuits we owe some of our special qualities—the terror, for example, with which a person turns and runs when encountering a harmless snake, though the same person may race a motorcycle down highways at 100 mph.

We carry around with us, along with evolution’s achievements, some of its relics, for nature seldom discards anything that was once useful. Countless details in the brain are as useless as an appendix. Nothing basic has changed under the scalp since the age of dinosaurs—evolution has, as it were, only added things on. The architecture in our heads is like that of a very old city: fascinating, charming, but full of buildings that today would have been planned completely differently—and better.

OUR THREE BRAINS

The history of a city also resembles the development of the human brain in that it didn’t happen gradually but in distinct phases. Our brain’s structure still articulates three stages of rapid expansion—named after the creatures in which their characteristics first developed most strongly: the reptilian brain, the limbic (or mammalian) brain, and the neocortical (or human) brain.

The reptilian brain is considered the oldest of these parts. It is identical with the brain stem, to which the cerebellum also belongs. Lying at the upper end of the spinal cord, it controls the basic functions of life: digestion, breathing, and the heartbeat. The brain stem also controls simple movements like bending and stretching the large muscles, as well as posture. But above all, its circuitry plays a key role in the creation of emotions. Hunger and fear begin in the brain stem, which explains why lizards, too, are capable of fear and can even learn to be afraid of certain stimuli.1 But the brain stem is not only a source of negative emotions: not just panic and anger but also excitement and pleasure would be unthinkable without this ancient area of the brain.

The brain’s next layer developed during the dinosaur era as small, shrew-like animals were preparing to bear live offspring. Although its rudiments were already present in reptiles and amphibians, only when the first mammals emerged from the ocean to begin their triumphant march across the earth did it grow to a size that exceeded all other parts of the brain. The hippocampus and the amygdala—responsible for storing memories of feelings and places—belong to the developing nervous centers that allowed more flexible behavior and enabled animals to learn more easily to distinguish friend from foe, to locate food, and to discover which foods tasted especially good.

It’s no coincidence that the subsequent enormous expansion of the emotional repertoire occurred at the same time as the emergence of the first mammals. Care for their brood, attachment to a partner or to a group of other animals of the same species, as well as the enjoyment of play all call for more than the simple responses of fear, hunger, and pleasure available to reptiles. The long period of mammalian child rearing required more developed brains, because the necessary social emotions depended on new, more powerful and capable brain circuitry. Species with simpler brains like crocodiles show little interest in caring for their offspring. Although the mothers jealously guard their eggs and tend to their brood, it isn’t long before a young croc has to hide from its parents if it doesn’t want to be eaten. A baby mouse, on the other hand, is suckled, licked, and stroked by its mother for weeks. The adult animal shows emotions that, in humans, we explain as nurturing love.

The last big stage in development set in a good one hundred million years ago, when the cerebral cortex greatly expanded, primarily in apes, dolphins, whales, and most of all in humans. The neocortical brain spans the brain’s older areas like a dome. Because these animals with the big, new brains could learn better and more quickly than other creatures, they could adjust to changed conditions to a degree previously unthinkable. The enlarged cerebrum enabled them to plan actions in advance and to deceive other animals, to live together in complex communities, like apes, or to use a kind of language to communicate with others in the same species, like whales.

Subtle emotions like empathy also have their roots in the cerebral cortex. One of the most important scientific surprises of past years was the discovery that altruism is not so much an achievement of human culture as an accomplishment of the neocortical brain of which other animals are also capable. Behavior researchers like the Dutch primatologist Frans de Waal have gathered extensive proof for this thesis, especially from apes. Female chimps support each other during labor, young chimps of both sexes stick together against a tyrannical alpha male, and healthy animals in the group tend those who are sick.2

In terms of size and capability, the human cerebral cortex exceeds that of all other animals by far. We have an enormous variety of emotions at our disposal, and, most important, we can experience them as our own: We recognize feelings; we can juggle them in our imagination; we can get upset about things or enjoy them, even if they are utterly without consequence for our survival. To these expanded spheres of our cerebrum alone we owe our capacity to suffer the pangs of unrequited love on a movie screen, or to feel the triumph of our hometown team.

The more highly developed an animal is, the more complicated are its emotions. This straightforward rule becomes apparent when we look back over five hundred million years of natural history—which is how long it took for the simple nervous system of the jellyfish to evolve to the human brain.

But as many and varied as our feelings are, they all rest on basic emotions, like desire and fear, that existed in animals long before there were humans. And it is still the oldest areas of the brain that give the beat to the music of our emotions. The cerebrum, on the other hand, elaborates luxuriantly on the melody of feelings. Where simple animals are governed only by volition, we know desire and the heady rush of power, longing and silent veneration.

THE ORCHESTRA OF HORMONES

It is by no means only our brain’s structure that shapes who we are. No less significant are the fluids that flow through it. The brain, after all, is not lifeless and dry like a computer, but alive, damp, and wobbly. In addition to blood and water, more than sixty different transmitters circulate within it—molecules that have an enormous effect on our actions and feelings. “The fluid brain,” is what Jean-Didier Vincent, one of neurobiology’s most original writers, called this concert of substances.

Some of them will play an important role in the following chapters, and they, too, have a long past: dopamine, a transmitter that is responsible for volition, excitement, and learning, also controls desire—even in bees. Naturally occurring opiates like beta-endorphin that are released when we experience pleasure (as well as pain) are also present in insect brains. Serotonin controls the flow of information in the brain and is one of the very oldest transmitters of all, having been found even in the simplest nervous systems of mollusks and cephalopods, like squids.3

These neurotransmitters are ever present in the brain. It is touching to watch a cat licking her young, nursing them, and carrying them carefully in her mouth to a better hiding place. This behavior, too—the essence of motherliness—is controlled by a neurotransmitter. If oxytocin is injected into the brain of a rat that has never given birth, this virginal animal is transformed within minutes into a loving mother that looks after another rat’s babies as if they were her own.4 Very similar mechanisms are at work in humans.

The thought that a few chemicals can have such a big influence on our inner lives, that they can change our mood on a dime and can even determine our behavior may scare or even anger some people. Though we have witnessed often enough how a few glasses of wine can transform a shy guest into a sparkling entertainer, or, for that matter, into a chatterbox who won’t leave your side, the effects of alcohol are more like a temporary mechanical breakdown, a temporary clouding of reason, than like a fluid brain in action.

The power of molecules calls our self-image into question. We like to see ourselves as intelligent beings who are animated by hopes, thoughts, and wishes, not by chemistry. When we fall in love, or look with pride at our children, can we really believe that this experience of life’s deepest joys is nothing but the flow of a few chemicals in the brain?

Hardly. But even at the physiological level, things aren’t quite that simple. The formulas dopamine equals pleasure and oxytocin equals maternal love are merely conditionally correct, if only because these transmitters do not act alone. Particular neurotransmitters play a leading role in the creation of certain emotions, but they are just one voice in the choir. Thus, the oxytocin injection changes young rats into motherly animals by setting in motion a kind of domino effect that immediately releases a whole series of other substances in the brain, which, in turn, change behavior.

Just as the interplay of molecules in the brain is incredibly complicated, so is their interaction with the body. Chemical formulas aren’t sufficient to explain what we feel. Neither one single transmitter nor a whole concert of such substances is capable of creating an emotion on their own. Rather, they have to act on a complicated web of brain circuits that then release reactions in the body. Moreoever, when we experience an unconscious emotion as a feeling, our cerebral cortex—the most complicated structure in all of nature—steps into action.

Though we are not simply marionettes moving at the whim of molecules, it is easy to overlook the fact that our rich inner life cannot be created in a vacuum. Thoughts, feelings, and even dreams aren’t castles in the air but are built on a very solid foundation, and that foundation is chemistry. Our inner lives and the transmitters in our brains can be compared to a work of art and the materials from which it was made: the frescoes of the Sistine Chapel are infinitely more than Michelangelo’s color powder. But without these pigments he could never have painted his view of the cosmos. And in just this way we’re much more than the architecture of our brains, more than the substances that flow through our heads. Without them, however, we would have no inner life.

LIVING WITH THE PASSIONS

The American evolutionary scientist Sarah Blaffer Hrdy writes in her book about the history of motherhood: “Every living organism, every organ of every organism, not to mention tissues and molecules, whether or not they are still in use, bears the accumulated imprints of multiple past lives. Never permitted the luxury of starting from scratch to produce the perfect solution, natural selection recycles workable solutions for a ‘good-enough’ fit, meaning simply: better than the competition.”5

Some people may be relieved to think that evolutionary biology certifies our imperfectability and lets us off the hook. After all, we’re much too hard on ourselves, too often feeling that we’ve got no room for error and berating ourselves for falling short once again.

What we feel and what we want is to a large extent determined by programs that are older than the human species. By no means, however, does this make us into powerless creatures, helpless in the face of nature, for we are able to control these emotions. But we can’t just get rid of them—even if some religions would like us to believe otherwise.

Many ascetics have made it their goal to overcome their passions and failed. Even someone with an extraordinary degree of self-control like Mahatma Gandhi, whose profound altruism enabled him to fast and suffer physical abuse, didn’t succeed. Gandhi’s story shows how far a man can go in fighting his nature—and where the boundaries lie. As a young man, he indulged a strong sex drive that later caused him feelings of great guilt. In accordance with certain branches of Hinduism, he saw the sexual act as a waste of energy that he should put in the service of the spirit. So he chose a life of chastity. But he continued to struggle with his sexuality even in old age. In order to test himself and to extinguish his desire, the aged man went to bed with naked girls, forbidding himself to touch them. Gandhi achieved his goal, but afterward his desire was as strong as it had been before. He may have benefited from his experiment in further training a willpower that was already superhuman—but it did not succeed in dulling his natural instincts.

The suggestion of the philosopher Immanuel Kant that we should see human passions as illnesses of the soul comes from a similar mindset. But if we follow this advice, we’re declaring war on ourselves.

There are more realistic ways of living with our emotions. Above all, we should accept the legacy left us by evolution. We can’t change our predispositions—nor do we have any reason to do so. In contrast to all other animals that ever existed, we are not completely helpless in the face of our drives. We can decide which to follow and which we want to avoid, and we can shape our lives so that they are in harmony with our inclinations. Since Aristotle and Buddha, sages have recommended the golden mean—an understanding of the emotions that no one has articulated as clearly as René Descartes in his “Passions of the Soul”: “. . . we see that in nature they are all good and that we only have to avoid misuse and excess.”6

There is no point in trying to find a drug against the passions, though a user’s manual would be very helpful indeed. Only by becoming familiar with something can we develop a healthy relationship with it. If we want to live with our passions, we first have to get to know them.